The invention of rifling: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Part 1

The history of airguns

This report covers:

  • Fine rifling
  • The Trapdoor barrel
  • Bullet deformation is bad
  • Pope’s muzzleloading breech loaders
  • Dr. Hudson
  • Airguns and rifling
  • Twist rate
  • Diabolos and twist rate
  • One last question answered
  • Summary

I am running this report immediately after the Part 1 because of the questions several readers asked. I can see that the subject of rifling is not understood that well. I stopped the first report with the invention of Ballard rifling, which I said was shallow thin lands and wide grooves. Today I will start at that point.

Fine rifling

Ballard rifling was great because of what it did — or rather what it didn’t do. Ballard rifling did not deform the bullet as much as the other kinds of rifling I mentioned last time. You will recall that I said the development of the Trapdoor Springfield rifle marked a major advance in the development of ammunition. It did not do the same for rifled barrels.

Trapdoor Springfield
The U.S. Rifle model 1873 is best known as the Trapdoor Springfield.

Trapdoor Springfield breech closed
The breech is closed.

Trapdoor Springfield breech closed
And this is where the name Trapdoor came from.

The Trapdoor barrel

The Trapdoor barrel has three lands and three grooves of equal width. That means the lands are very wide. They are also 0.005-inches high. That’s fairly shallow for a .45 caliber rifle barrel, but the width of the lands is a problem for ultimate accuracy. The lands shave a lot of lead off the bullet as it traverses the bore. That’s why when the government developed a long-range rifle on the Trapdoor platform they gave the barrel six lands and grooves. The standard twist rate of one turn in 22 inches for the 405-grain government bullet was increased to one turn in 19-5/8-inches to stabilize the heavier 500-grain bullet fired in the long-range rifle. More on twist rates in a bit.

Bullet deformation is bad

It turns out that the more a bullet is deformed by the rifling, the less accurate it will be. That was what was so revolutionary about Ballard rifling. It didn’t deform bullets as much as most of the rifling that preceded it. It was very good, but it wasn’t the absolute best.
The deformity I refer to is in the form of lead “fins” left on the base of the bullets by the lands after the bullet exits the muzzle. Harry Pope believed these fins interacted with the exiting gunpowder gasses, causing slight instabilities at the muzzle of the gun.

bullet base
You can see how the rifling lands have left lead fins on the base of the bullet at the right, after it has traversed the bore. And this bullet went through a barrel that has Ballard rifling! According the Harry Pope, this deformity causes inaccuracy because of the interplay with the powder gasses and the irregular bullet base during the first few inches after the bullet leaves the muzzle.

Pope rifling

The best rifling was made by Harry Pope. Pope put 8 extremely narrow and low lands in his barrels. He understood that the bullet base shouldn’t be deformed. And then he did something else — something that made his bullets (and barrels) the most accurate ever made, up to that time. He made his rifles load the bullets from the muzzle and the cartridges load from the breech!

Pope’s muzzleloading breech loaders

Pope believed that the base of the bullet was critical to accuracy. He knew that rifling left lead fins around the base of each bullet fired, so he made rifles that loaded from the muzzle. There were fins of lead even with his extremely narrow and low lands, but because they were loaded from the muzzle the fins were on the front of the bullet, where they didn’t affect the accuracy.

To load a Pope rifle you first loaded a dummy cartridge into the breech. This cartridge had a plug that extended 1/10-inch into the bore past the end of the case. Then you loaded the bullet from the muzzle. It stopped when it came against the plug in the dummy cartridge. Then you removed the dummy cartridge and replaced it with a loaded cartridge. The rifle was now ready to fire. Pope got such superior accuracy with his barrels and method of loading that he was backed up for many years on barrel orders.

Dr. Hudson

Around the turn of the 20th century, another fine shooter named Dr. Hudson decided to change shooting forever. He breech-loaded his bullet and pushed it into the rifling with a mechanical device called a bullet seater. The seater pushed the bullet into the bore 1/16 to 1/10-inch deeper than the cartridge would go. Dr. Hudson used bullets with rings at the back that were just slightly larger than the bore of the rifle. These bands guaranteed sealing against the gasses, and left the rest of the bullet untouched by the rifling.

bullet seater
This bullet seater just slides the bullet deep into the rifle’s chamber. This is used in a rifle whose breech block pushes the dummy cartridge into the chamber to push the bullet into the rifling.

mechanical bullet seater
This lever-type seater mechanically shoves the lead bullet into the rifling of the bore. It’s used on rifles whose breechblocks do not lever the dummy cartridge forward. That’s what this device does.

All of these special loading methods are designed to extract the absolute finest accuracy possible from a rifle. They are not for regular shooters. They are for fanatics. But they showed riflemen everywhere what the finest rifling looked like and what it could do.

Airguns and rifling

The first modern air rifle was made by the BSA company in 1905 — right at the time all these important rifling lessons were coming together. This was decades before Marlin’s Microgroove rifling had been thought of and decades before polygonal rifling was tried. But BSA was aware of one thing from the start — light lead pellets are difficult to launch with just a small puff of air. Anything that inhibits their movement — like deep rifling or wide lands, is a problem.

So from the beginning airgun rifling had low thin lands. The diabolo shape of the pellet already stabilized it in flight to some extent, so the spin from the rifling was just gravy that added more range to the pellet.

Twist rate

The twist rate determines how fast the bullet or pellet spins in flight. Longer heavier bullets need to spin faster for a given caliber. But a large caliber bullet, say .75 caliber, needs less spin to stabilize than a small caliber bullet. If you think of the planet Earth as a large ball, it spins once in approximately 24 hours and is reasonably stable.

Back when round balls were the only bullets around, the twist rate of the rifling wasn’t so important. The Hawken brothers popularized a 1:48 twist (one turn of the rifling for every 48-inches of barrel length), but that was simply because that was the only twist rate their rifling machine could rifle! It wasn’t that calculated. It happened to work, but there were rifles on the market at the same time that had 1:72 and even 1:90  twist rates. Today you’ll find shooters who think 1:48 is magical because the Hawkins used it, without knowing (or caring) why they did.

When the change was made to conical bullets the twist rate became critical. A conical bullet needs to spin on its long axis to be stable, and the twist rate has to be calculated precisely to do that. My AR-15 has a 1:8 twist rate and stabilizes 69-grain bullets perfectly. Shorter 55-grain bullets spray all over the place — the length of the bullet is that critical.

Diabolos and twist rate

But airgun pellets are projectiles with high drag. They are not entirely stabilized by spin. In fact most of their stabilization comes from the aerodynamic drag on their tails. So the rate at which the rifling spins them is far less critical.

Early airgun barrels were made by BSA and were heavily influenced by the firearms they made. They used the 1:16 twist rate of a .22 long rifle cartridge and applied it to their airgun barrels. And just like the Hawkin Brothers before them, they used the same rate of twist on all their barrels, regardless of the caliber. That practice continued with all other airgun makers, pretty much through the rest of the 20th century.

Where a .22 rimfire bullet performs differently depending on the barrel twist rate, pellets aren’t nearly as sensitive. Here is how critical it is for bullets. A .22 long rifle (shooting a 40-grain lead bullet) barrel twist rate is 1:16, but a barrel made specifically for the .22 short ( a 29-grain bullet that’s much shorter) has a twist rate of 1:20 or even 1:22. For guns that shoot both cartridges, the long rifle twist rate is used. But with diabolo pellets the twist rate isn’t as important. So for a century, 1:16 worked well.

Is 1:16 the absolute best for all pellets and all calibers? Maybe not. But not very much research has been published about what works and what doesn’t. Barrel makers probably know more than they are telling, though.

One last question answered

Reader Matt61 said this, last time.

This is great. The first question that occurs to me is one that I’ve had for awhile and may seem trivial, but it nags at me. When the bullet “catches” the rifling, does that mean that the rifling cuts into the bullet to a depth equal to the height of the land + the depth of a groove? Cutting even that much into the surface of a bullet seems like a lot.

Matt, the “height of the land” IS the depth of the groove. They are not cumulative. They are the same. Metal is cut away to form a groove and the land is the metal that remains.

How does the bullet “catch” the rifling? I asked you to tell me how it worked when the bullet was loaded from the muzzle. When the bullet is loaded from the muzzle, it is forced into the rifling by hand and pushed down the bore until it stops. The forcing is what causes the rifling (lands) to “cut” into the side of the bullet. Or, if you shoot a patched ball, the cloth patch gets jammed into the grooves, leaving the edge of the round ball untouched by the lands. When the patch spins from the rifling, it spins the ball that’s inside.

A breech-loaded bullet does encounter the rifling when it fires. Or, if you push it into the rifling during loading like I have shown here, then you are the one who pushed the bullet into the lands. In many rifles, the lands are cut on a taper ahead of the breach. This allows the bullet to be engraved gradually as it moves forward. I hope this answers your questions.

Summary

I haven’t talked about things like gain twists (where the twist rate increases as the bullets advances down the bore) and choke-bored barrels. I have discussed them in the past, as you can see in the linked report. And I will mention them again in this series.

In the next report on rifling I will concentrate on airgun barrels. I’m not going to do that as the next history report though, because not everyone is equally interested in this subject. So I’ll give it a bit of a rest. But I will come back and tell you more about airgun barrels and rifling.

121 thoughts on “The invention of rifling: Part 2

  1. Thank you, again for this report! Lands and grooves have always been apart of my education on rifling! You make it easier to understand! I also want to mention that on thegodfatherofairguns.com I have a better less hassle free blog to read than on the PA site! Semper fi!


  2. Sorry dumb question, are rife barrel’s bore measured land to land or grove to grove? Bullets diameter is usually .001″ under the barrel bore? That is just a guess.
    Given a 14 grain pellet shooting at 700 fps, 1:16 twist rate, 14″ barrel; how fast is the pellet spinning?
    Great series, really gets at the heart of accuracy.
    -Y


    • Yogi,

      That’s NOT a dumb question! What country are you referring to? Because they do it different in different places.

      The Brits measure between the tops of the lands, so their .303 caliber actually uses a .312 inch bullet — because that is the width measured from the bottom of the grooves! Americans measure between the grooves, so their .30 caliber barrels measure .308 — .300 between the lands and .308 between the grooves.

      The Russians use their own measurement called a liniya that we translate to line. Their Mosin-Nagant rifle is called a 3-line rifle, and is considered a .30 caliber bore, though the barrel measures .312 most of the time.

      There is a lot more than this, but that’s the summary.

      B.B.


      • Just to add, even more confusing is when you get two names for the same round.
        5.45×45 NATO is the same as Swiss 5.6.
        Which .223 is the parent case for and as such are quite similar. You can fire .223 from a .223 or a 5.56 or a 5.6 rifle. However only fire 5.6 or 5.56 from rifles labeled for such use.






      • BB,

        I had to think about this for awhile, but then I realized that Pope knew something else. When I design machined castings and forgings, I try when possible to have the cutter leave the part on a tapered/chamfered edge, as this greatly reduces the burrs that are inevitably created (or if they are created, they tend to break cleanly away from the part). The same thing likely happens as the rifling (cutter) leaves the tapered nose of the bullet when it is muzzle loaded. It would be interesting to see if that is true for the typical conical bullets of his day…would it be possible to push a muzzle-loaded bullet out the breech of a Pope or similar era breechloader and compare it to one pushed out the muzzle from the breech end?


        • Ben,

          I would be possible to do that because the rifles we are talking about are breechloaders. Getting one with a real Pope barrel will be a challenge, though. The guns Harry actually made — not just those the Stevens company put his name on — sell for 5 figures.

          B.B.


      • G’day BB,
        Still confused.
        Does that mean the base of the bullet is of a smaller diameter than the front of the bullet?
        With a normal bullet today, pushing it down or up a barrel (with the front of the bullet facing forwards) will leave land marks on the part of the bullet with the largest diameter.
        Cheers Bob



        • Bob,

          A bullet that is loaded from the muzzle is the same diameter all the way down the outside.

          A bullet that is breech-loaded by mechanical means like I mentioned Dr. Hudson doing has bands at the base that are larger than the rest of the bullet.

          For example, I shoot a 34-40 Schuetzen rifle in which I breech-seat the bullet. The bullet base is 0.323″, but the body is 0.317, which is the top of the lands. The base, only, gets engraved by the rifling when I seat the bullet, and the rest of the bullet rides on top of the lands. That picture of the breech seating tool in this article is my Schuetzen.

          B.B.


  3. Fine report once again. I had no idea that the rifiling twist rate was tied so closely to bullet weight, (firearms). I could see people getting into accuracy issues real quick by using bullet weights not designed for the twist rate, (as you mentioned in your AR-15). Looking forwards to the air gun specific part. And yea,..I bet your right on your comment that the airgun barrel makers know a lot more than they tell.

    An interesting “check” would be to see what high end air rifles use for their twist rate,..say PCP’s of just .177. Compare 5-10,..and it might reveal a trend, or favorite. And since a “weigh in” from air gun barrel makers is not likely,..a weigh in from pro air gun shooters on twist rate might prove interesting as well. I would bet that would have already looked into the subjct at a (very) detailed level.



    • Chris
      Now do you see what I meant by twist rates being matched to bullet weights and the very in depth science behind all of it that is as much guess work in some respects as mathematical equations as to what works best for any given projectile.

      As BB says he is only touching the surface of a very complex and in depth subject that has as many variables as just shooting itself does if not more.

      BD


      • Buldawg
        Down below BenT mentioned that 13 part series BB did on twist rates back in 2013. You should read that. There is alot of stuff we talked about back then of what twist rate does.

        But you mention the weight and twist rate. Then think about what happens when you throw in the fit of the pellet in the bore and how well the skirt seals also when the air hits the pellets skirt. Then what happens when you throw in the power the guns making in relation to the weight of the pellet and the spin rate. And yes the spin rate of the pellet not the twist rate of the barrel.

        As you know they all make a difference. But BenT asked BB to link that 13 part series to this rifling report and I agree. There was alot of useful info in there.


  4. Now I am beginning to understand what drives riflemen in their quest for ultimate accuracy. There is a certain drive needed to push the envelope to what is hopefully possible.

    Very nice article to chew around for the weekend.


  5. Is this issue of fins on the end of the bullet why rebated bullets are becoming more popular with big bore shooters?

    I ask, because I think they are not going to be concerned with supersonic performance.


    • StevenG,

      Rebated barrels make no difference. The exhaust gasses still exit the muzzle and play havock with the base of the bullet. Yes, with a rebated muzzle they do it in a more confined space, but we are only talking a few ten-thousandths of an inch disruption.

      B.B.




          • I think I am not making myself clear.

            No, not standard boat tails. Rebated boat tails.
            http://www.corbins.com/rbt.htm

            These are swaged lead slugs in that shape. The idea being that since the base does not contact the rifling, they can be made of dead soft lead but present a clean base on exit of the air gun barrel.

            I am interested in building up a .308 shooting these kinds of slugs. To generate the same FPE as seen in 300 blackout. So around 500 fpe at around 220 grains.


            • StevenG,

              I just learned about something in shooting that I didn’t know. Now I have a whole new universe to explore and inhabit.

              Rebated boattails made from pure swaged lead! My brian in getting hot!

              When I read the website it looks like Corbin intends these bullets to have jackets. What do you think about that?

              Obviously I know nothing about these and cannot give you an ansewr. I need to study this.

              Thanks,

              B.B.


              • I think corbin does intend for jackets, but who says we can’t break the rules?
                In my admittedly limited understanding the jackets are of no use to us in air rifles as we will never drive the bullet fast enough to need it. If I could get them through the barrel I would but I think you once mentioned that jacketed bullets are bigger than the bore and we lack the ability to crush them down like a powder burner would.

                There are some folks casting them as well. I was most interested in swaged bullets simply because of the repeatability that method offers. Either way I do not intend to be the guy making the bullets, I have not enough time for my hobbies as it stands.




  6. Very interesting report indeed and a good one for the weekend to chew on as well.

    I to am interested in the rebated boat tail bullet/pellet designs as they appear to be one new advancement in design that has yet to be fully accepted by the masses. It is just like any new technology in that it has to be spread by word of mouth and assimilated to the major players for their own testing before it will be fed into the common market for us all to test and enjoy the benefits of the improved design.

    I am looking forward to the air gun specific rifling report as that is my main interest at this time and firearms are still of interest but more for protection and self preservation than competition shooting or for casual shooting due to the high cost of ammo. If I can hit my target at 200 yards with a powder burning rifle and 50 feet with a pistol that is all I ever see a need for use with them in my future.

    BD


  7. BB–You did not mention the false muzzle that Pope used. It was a short piece of barrel that was attached to the muzzle of the rifle . It was used to prevent the ram rod from damaging the rifles muzzle. It was removed when the bullet was seated at the breach end of the barrel. The false muzzle had a projection that blocked the front sight, to remind you to remove it before firing the rifle. Ed


  8. BB,

    Regarding airgun rifling and twist rates, I think you have published the first and only study that I’ve ever found on the matter. You should provide a link to your study of rifling twist rates that you did a 13-part series on (last report was on 7/24/13). That report shows clearly that a minimum twist rate exists for any given pellet weight and speed combination. It also backs up your statement that the 1:16 twist is fairly optimum for typical .22 pellets.



  9. BB, I’m reading your “choked barrel” report and you mention that smokeless powder doesn’t obturate the bullets, but black powder does. Is that a matter of pressure? I thought smokeless powders give greater velocities than black powder. How come they don’t cause any deformation?

    Thanks
    Ryan


    • Ryan,

      It’s not pressure but timing. Black powder is actually a low explosive that “burns” at 11,000 f.p.s. It hits the base of the bullet with 15,000 psi in an instant — like a hammer blow.

      By contrast, smokeless powder is not explosive. It actually burns relatively slow compared to black powder.

      These two are like a spring piston airgun (black powder) and a PCP (smokeless). The PCP may produce four times the energy as the spring gun, but it does so slowly. The springer, though much weaker, hits the base of the pellet like a hammer.

      B.B.



  10. The Daisy120 is together enough now to let me know it’s gonna be a lotta work to make it a good shooter but I don’t think this thing ever got broken in, the cocking linkage is getting into the wood producing the sawdust that had the trigger gummed up and the pull of the trigger is unmistakably direct sear.
    Firing cycle feels like someone just whacked the 2×4 you’re holding with one of equal or greater mass, definitely feel the Gamo blood in this gun!
    It’s hitting so hard I bet it’s over 650 if not in the 700’s a real life mini Magnum.
    🙂


    • Why don’t they make little guns that hot?
      Where the rear of the action butts to the stock on the right side of the stock is now in need of repair, don’t really know what happened but I noticed it after one of the Crosman pointed pellets flipped out of the breech causing a dryfire that was every bit as loud as either of my magnums.
      Back outta the stock now and will be looking for wood glue tomorrow while the seal soaks overnight.
      Looks like it almost jumped up in my face!


      • Reb
        Have you got close to the bottom of that trashcan yet as you keep pulling gems out of it as if is a bottomless supply of treasure just waiting to be discovered. you really hit the jackpot with that score it appears and I wish you the best in your endeavors to resurrect them back to life as you seem to be making quite good progress with them so far.

        BD



          • Reb
            Well at least you got some nice ones in the bundle and the 880 kits are under ten bucks so yea they are cheap to fix but just a pain to separate receiver halves and get it back together without everything flying out.

            BD


            • I prefer working on a 880 much more than a 953.
              I’ll be opening up a Grizzly later and we’ll see how that goes but it looks to be the same as the x53’s only a lot more plastic, Daisy must’ve expected these things to get abused because the barrel has me jealous, I thought I had a .22 barrel in the bottom until I didn’t see any rifling, thick and heavy.


              • Reb
                Yes the 880s are much easier than the x53s but still I hate the two sided receiver type guns as I just rebuilt a 2100 for a friend and getting all the pieces to stay put was a pain for sure so I much prefer the tube type guns better.

                I thought all them 880s styles had a small barrel inside a shroud with a plastic spacer to hold the barrel centered.

                BD


  11. B.B.,

    After reading this article, in addition to the other 10 articles of yours that I’ve read this week, and the dozens of others that I’ve read over the past year, I just want to say THANK YOU!!! I so much appreciate you investing the time and energy to share your airgun/gun knowledge with the community, and not just keeping it to yourself. Your articles have helped me numerous times on a ton of different issues.

    I also want to say that I greatly admire you for carrying on the torch despite the loss of your best pal. This shows a lot of strength and courage, and I’m sure the entire airgun community rallies beside you!

    THANK YOU!!!



    • Gear_Junkie,

      This blog is one of the things that helps me get through the days, weeks, etc. When I am writing I don’t have time to think about the situation, and that’s a small relief.

      You got it right when you said she was my pal. I have never been so close to another person as I was to her. I knew that all the time she was with me, but after she was gone, it hit me hard, because there is no going back. All those things I wish I had said and done are before me constantly now.

      Anyway, thank God for this blog!

      B.B.


      • BB
        There is always thing we wish we would have done or things we should have said when we lose someone near and dear but just know in your heart that she is still listening and hears your thoughts so while she is not here to smile at your words or actions, she is still smiling with and for you in all that you do and with every thought of her as they may be gone but are never forgotten and are always with us.

        My parents have been passed for over 30 years now and I still feel their presence with me every day and know they watch over me and help guide me in my worst of times some of which I am in again now myself health wise.

        BD



  12. BB,
    Can you recommend a air pistol that would be good for shooting airgun darts for around $100, I’m looking for something me and my son can have fun with in the garage this winter after we shoot both tubs of ground shot from his new 499.
    Thanks
    Ryan



    • RPM,

      I have a 499. They are a blast to shoot,…are they not? I would like to get a smaller I.D. front insert other than the ones that came with it. Or,..make one or adapt one. Any ideas anyone? Compared to a Red Ryder,…well,…there is no comparison. 😉 Chris



      • Chris, yes it is a blast, I’ve personally shot it just a bit, it’s technically a Xmas gift…. that I can’t keep my hands off!! Amazing how accurate that thing is, I was showing my dad this morning and he loved it also. the sights are a bit open, I like the post sight, thought about filing that down just a bit. Reb’s idea of black tape could work.

        I saw the Marksman 1010 but for $20 I didn’t think it would have been a good candidate.
        If I can’t find a good “dart” gun maybe an air soft pistol and little green army men will work.



  13. Reb,
    You mention a P17, ever since a guy at my club let me shot his P3 I’ve been wanting one like crazy, The trigger was sooo amazing!! It’s so much more expensive than the P17, have you shot both? do you think the triggers are worlds apart? I’ve never shot a P17 and don’t want to buy one and be disappointed.


  14. Yea, I think power would be to much for dart board, also if I bought a P3 id be hesitant to start running darts that could potentially damage the rifling through it. Thinking about a 1322, and trying the Milbro Mohawk Darts. can limit power with the multi pump and since I’d be shooting this setup most of the time in my garage in winter I’d like to avoid CO2.


    • RPM,

      I recently bought a Diana 66 which has been smootbored to 5.5 mm especially to shoot darts. This is a sport in the Shutzenvereins in the region around Aachen, Germany. They use a slab of lead to catch the darts. Maybe that is a good option here too,

      By the way, from the point of target shooting, the Diana is a mess. Smootboring is definitely not a good idea.

      Regards,

      August



  15. This is for Jim M. who recently got a TX200 in .22 and asked what pellets I had tried and the results.

    Pellet/Weight/FPS Avg./MM group @ 25 yds/Pellet fit:

    AA 13.43/655/15 (HO)/Light~Good
    HN 14.00/—/34 (HO)/—
    JSB 14.35/—/18 (HO)/Good
    RWS 14.50/686/14 (12 fpe kit)/Light~Good
    HN 14.66/691/20 (HO)/Tight
    JSB 15.89/631/14 (HO)/Good
    AA 16.00/603/22 (Stock)/Good
    Pred. Mtl. Mag./602/26 (HO)/Tight
    JSB 18.13/611/18 (HO)/Good
    HN 21.14/584/34 (Stock)/Tight

    A few notes,
    1) I had the stock version and then did a Vortek 12 fpe kit, and then the Vortek HO kit
    2) The stock and HO kit chrony results are near the same. (JSB 15.89 stock=631 and HO=643)
    3) Note that the FPS drops as the pellets get heavier,..in “general”, but not linier. They are listed lightest to heaviest.
    4) I would not put too much stock in the MM results. Those are my best at 25 yds. The testing and tunes were done over several months and I have improved since then, so I think it is fair to say that I could improve all of them slightly.
    5) I use millimeters to measure, as a ruler is quicker and mm offer more graduations than inches (25 vs 16 per inch)
    6) In summary, the JSB 15.89, and 18.13 seemed the best, with AA 16.0 and 13.43 close behind. That is based on averages and over multiple groups and showed the best repeatability.

    Hope some of this helps to narrow down your testing. By the way, all are domes except the Pred, Mtl. Mags.

    Chris



      • GF1,

        I do not shoot that good! And,….I might add,….I have a dial (“) and a digital (” + mm) calipers. 😉

        The group I got today with the LGU and 18.13 JSB’s might just warrant it though. One nice big hole at around 14mm at 30 yds. Doing the TX now with the same. Back in a few,…….


        • Chris USA
          Don’t matter how good you shoot. Calipers will give a way more accurate reading than a scale. But you should know that already I’m guessing.

          Did you try positioning your forearm like we talked about yet?


          • GF1,

            I did try. I tried a 10 shot group and even moved the rest and seat back. It might work, but my table/rest set up was not real condusive to it. And, even so,…my elbow was about 5″ off my knee. I will try again, just need to refine it a bit. The nice groups today were with the rest/holds that I normaly use.

            See commment to Reb on measuring,….I just don’t see the need yet, but I will give it some more thought.


            • Chris USA
              If your elbow was 5″ of your leg then you did nothing by moving your seat back.

              You got to get your seat and bech height set right so you can be setting up and your elbow can touch your leg.

              That should help you keep a more consistent line of sight because you will be able to place your cheek in the same spot easier every time. Plus the elbow on the leg will help steady your hold.

              Anyway.let me know if you try it again with your elbow touching your leg the next time around.


              • GF1,

                Well, lower the rest, and/or lower the table, and/or raise the seat.

                In all honesty, it sounds like a recipie for getting into the “lazy” bench shooter you mentioned awhile back. Yeah, it may be all good for the perfect bench set up, but I guess too,…even if my set up is not perfect or ideal,…I should still be able to adapt.

                I guess to me, a newbie,…I would think that bench would be much easier and field target would require a higher level of skill/versatility/adaptability. Hence, the ability to change and adapt to less than ideal conditions.

                I will try the new hold more,…I just need to re-configure my set up a bit. While not ideal on comfort,…it did seem to work!



                  • GF1,

                    Well,..one does need the proverbial “carrot” in front of the nose huh? I have done 3 in 1 and I can not still believe it. Several times. Odd enough, it has always been the first 3 shots of a 10 shot group. Groups as I got today are as much as I could ever hope for. If it gets better than that,..then great.

                    Improvement,….untill I reach my limits,….that’s what it really boils down too. Hopefully, I got a long way to go! 😉



      • Reb,

        When ,..and I stress when,…I can get 4, ten shot, one (bigger) hole’rs together on one target and they are all close to the same,…I might consider breaking out the calipers,…’till then,….my groups are pretty easy to measure with a mm scale. 🙂




        • GF1,

          The 14mm was on the LGU and was the first time I had tried anything other than the 15.89’s. So really, that is new data for the LGU. As for the 13mm,…that was in comparison to the 18mm mentioned above with the TX to Jim M. But yes, you are right, there is no beating calipers for accuracy.


          • Chris USA
            That’s a big improvement.

            That’s a .200″ better group.

            So that means that 13mm group is around .520″. At 30 yards there is nothing wrong with that size group.

            I think your shooting good enough to use calipers now. 😉


            • GF1,

              😉 Really???? I have graduated from 101 to 102. (not bad for 6 months)

              As I said to Reb,…when I get a bunch of 1 holer’s all looking the same, or consider field target, I will break out the calipers, till then,….the mm ruler is it.

              Punching cans and milk jugs is one thing,…..breaking it down to .001’s is another whole ball game.

              Diggin’ in and ain’t going no where,…… 😉


    • Chris — I’ll reply on the current thread. Just letting you know here, in case you get email notifications. I do, and can click on the link within the email and go straight to the post.

      Jim M.


  16. Buldawg,
    You got your ears on?
    Thanks for your help earlier! I’m eager to get into this 760 so I have some o-rings to match up then I’ll pull one of these 880’s apart for the same reason.


  17. Reb
    I need to know if it has a steel or brass bolt and all wood butt stock and fore arm , or wood forearm and plastic butt stock with steel or brass bolt or steel bolt with plastic forearm and butt stock and trigger cannot be pulled until bolt is cocked as those are the three year variant info i need to get you the right schematic for the 760.

    BD



      • Reb
        The all wood ones are first variants and the plastic stocked and forearm one is a hybrid since it has the brass bolt when it should have a steel bolt but its likely because its a Coleman branded one as well.

        BD


        • With the striker stuck at full cock I had to unscrew the acorn nut off to get it unmanned so I could rotate the plastic part of the bolt to the left, it’s a weird two -piece bolt but I figured this plastic stocked model would be closer to the newer 760’s I’m accustomed to opening up than the wooden ones that way I could learn progressively.



          • Reb
            The plastic stock ones like the third variant and up are a cock the hammer back to pump up and shoot whereas the first two variants are self cocker which means that the striker/hammer is held in the closed cocked position by the spring and trigger so you pump it up and as soon as you pull the trigger is blows the valve cap back off the end of the valve and exhaust all air pressure and then self cocks the hammer by closing the valve cap back on the end of the valve hence the term self cocker.

            The third variants and up the striker/hammer hits a valve stem in the rear of the valve that pushes the valve poppet off its seat and allowing the pressure to escape so the bolt actually cocks the hammer back against the spring and the trigger sear holds it there until the trigger is pulled and it strikes the valve to fire the gun and that is the only real difference in the two designs and it was a liability issue with the self cocker since they would shoot with just being pumped up without physically having to cock the hammer, like the so called lawyer triggers.

            BD


  18. Reb
    Here you go with the schematics that will be the gun you have with it likely being a cross breed of the second variant since it has plastic stock and forearm which according to crosman should be a third variant as the second has a plastic stock but wood forearm and either steel or brass bolt but the third variant has steel bolt only and plastic stock and forearm so it being a Coleman branded one it is likely a middle variant of the second and third mixed but these schematics should get you were you need to be.

    First variant years 1966 to 1975
    https://support.crosman.com/hc/en-us/articles/203360904-760-Owner-s-Manual-EVP-1966-1975-

    Second variant years 1975 to 1977
    https://support.crosman.com/hc/en-us/articles/203543230-760-Owner-s-Manual-EVP-1975-1977-

    Third variant years 1977 to 1980
    https://support.crosman.com/hc/en-us/articles/203543240-760-Owner-s-Manual-EVP-1977-1980-

    Just click on the owners manual or part diagram in the links and they should open the info you need and if not then let me know .

    BD



    • Reb
      Why cant you keep them all as you got them for a steal so just fix them as money allows and have a good start to your collection as the three wood stocked 760s are most definitely keepers in my book .

      BD


  19. Reb,
    I have two 880’s and have had them both apart. Parts are almost ridiculously cheap. I think you could probably assemble an entire 880 by buying individual parts, and spend no more than a new one would cost assembled.

    The hard part is getting the halves of the receiver aligned, with the washers and everything else trapped correctly in between. The plastic halves will crack easily if not aligned just right. If you overtighten the screws, the receiver will either strip out or crack.

    One of mine was a late-production US-made gun, the other an early Chinese-made gun. There was an improvement on the Chinese one. An extra screw location was added in the upper left corner of the receiver.

    The first one I re-assembled, I found a spring left over. It was the spring for the safety. I had to disassemble the receiver to install it.

    Les


    • I’ve had a few of the plastic receiver ones apart and so far fixed em all but this will be my first metal receiver, good news is I got 5 to play with to get it right I’m sure I can get a couple shooting pretty decent outta that.
      My brother really likes the 880 so I’ll see he has a chance at one and I’d kinda like to hang onto one myself just because no airgun collection is complete without a 880 and it might as well be one of the good ones.


  20. Reb,

    If you can find one, I think you’ll like the Daisy 856 even better. Except for the early ones, all 856’s shoot only pellets. So there is no bb hole to get pellets stuck in. Also, the 856 uses the forestock for the pump handle. It is much easier on the hand than the pump handle on the 880.

    My friend in NM has an early 856 with gold finelining. I tried to buy it from him, but he wouldn’t sell. He uses it for shooting mice in his garage.

    Les


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