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How does rifling twist rate affect velocity and/or accuracy? Part 7

# How does rifling twist rate affect velocity and/or accuracy? Part 7

by Tom Gaylord, a.k.a. B.B. Pelletier

This is Part 7 in this lengthy test series that looks at the effects of the rifling twist rate on both velocity and accuracy of a pellet rifle. Today, we’ll look at the 1:22 barrel, which means the pellet will turn once in each 22 inches of barrel it traverses. Of course, the Lothar Walther barrel in the .22-caliber AirForce Talon SS rifle I’m using is only 12 inches long, so the pellet doesn’t even turn one time before it leaves the muzzle, but that twist rate sets the pellet in rotational motion as it flies through the air to its target. The rotational speed will be less than what the 1:16 factory barrel imparts, and much less than the 1:12 barrel we have also tested.

Dennis Quackenbush made the two custom barrels I’m testing against the factory barrel with its 1:16 twist. So far, we’ve tested velocities with 2 different pellets at 3 different power settings for all three barrels (see Parts 2 and 3), and I did a short analysis of those tests in Part 4. Then, we tested the accuracy of the custom 1:12 barrel with both pellets at all 3 power settings at 10 meters, and again at 25 yards. Next, we did the same thing with the factory barrel.

Today, we’ll look at the accuracy of the 1:22 barrel with both pellets at all 3 power setting at 10 meters and again at 25 yards. In the next report, I’ll summarize the entire test to this point for you — comparing all 3 barrels for both power and accuracy. After that, I plan on testing all three barrels for accuracy at 50 yards. At that distance, the pellets will be spreading and accuracy benefits should show up vividly.

On to today’s test — the 1:22 twist-rate barrel.

Ten-meter testing

First up was the 14.3-grain Crosman Premier pellet. I had to remove and remount the scope, and the pellets were now striking to the left and low of the bullseye, but I left it there because where the pellets land doesn’t really matter in this test.

Ten pellets made a group that measures 0.258 inches between centers. Besides being tight, it’s a very round group, indicating the pellet likes this twist rate and power setting.

Ten Premiers on zero power made this nice round group at 10 meters. It measures 0.258 inches between centers.

Next came 15.9-grain JSB Exact pellets on zero power. They also made a round group, but it was larger, at 0.324 inches. This is still a very nice group, but not as nice as the Premier group on the same power setting.

Ten 15.9-grain JSB Exact Jumbos on zero power made this group at 10 meters. It measures 0.324 inches between centers.

Next, the power was dialed up to 6, and I shot a second group of Premiers. This time, the group was wider than it was high and measured 0.293 inches between centers. That’s smaller than the previous group of JSBs but slightly larger than the Premiers on the zero power setting.

Ten Premiers on power setting 6 made this group at 10 meters. It’s more horizontal than vertical and measures 0.293 inches between centers.

Following that, I shot 10 JSB Exacts on setting 6. They gave a group that is more vertical and measures 0.309 inches between centers.

Ten 15.9-grain JSB Exact Jumbos on power setting 6 made this group at 10 meters. It measures 0.309 inches between centers.

I noticed at this point in the test that both pellets were loading very easy into the breech. I wouldn’t call them loose — just very easy to load.

It was time to dial the power up to 10 and see what happened. Premiers went first, and 10 of them went into 0.288 inches. That’s just slightly larger than the first 10 on zero power.

Ten Premiers on power setting 10 made this group at 10 meters. It measures 0.288 inches between centers.

And, finally, I shot 10 JSB Exacts at 10 power. They spread out more than expected, giving a group measuring 0.53 inches at 10 meters. That was by far the largest 10-meter group.

Ten 15.9-grain JSB Exact Jumbos on power setting 10 made this group at 10 meters. It measures 0.309 inches between centers and is the largest 10-meter group made by the rifle.

What I see here is that Premiers are very stable in the 1:22 barrel. There is little difference in group size at any power setting. JSB Exacts, on the other hand, get progressively worse as the power increases. If we see this much dispersion at 10 meters the difference should be even more visible at 25 yards.

25-yard testing
First up at 25 yards was the Crosman Premier with the power set to zero. The 10-shot group landed very low on the target paper, and measured 0.671 inches between centers.

Ten Premiers on power setting zero made this group at 25 yards. It’s very low on the paper and measures 0.671cinches between centers.

Next, I tried 10 JSB Exacts at the zero setting. They were horrible — making a vertical group measuring 1.949 inches between centers. I won’t shoot this pellet at this power at 50 yards because they would go off the paper!

Ten 15.9-grain JSB Exact Jumbos on power setting zero made this 1.949-inch group at 10 meters. That’s all for this pellet at this power setting.

Next, the power was increased to 6 and Premiers were loaded again. Ten of them made a horizontal group that measures 0.845 inches between centers.

Ten Premiers on power setting 6 made this group at 25 yards. It’s horizontal and measures 0.845 inches between centers.

Then it was the JSB pellet’s turn. Ten Exact Jumbos landed in 1.797 inches, which is a little smaller than the group when the power was set to zero. If I try to extend this pellet and power setting out to 50 yards, I’m very likely to get a 7-10-inch group.

Ten 15.9-grain JSB Exact Jumbos on power setting 6 made this 1.797-inch group at 10 meters.

Finally it was time to try the pellets on power setting 10. Here they would be traveling their fastest, which means the spin rate would also be highest for this barrel. According to the theory, the groups should get smaller.

Premiers went first, and 10 of them landed in a group measuring 1.082 inches between centers. That’s larger than both groups that went before. Since the velocity increased, the Premiers spread out. Interesting!

Ten Premiers on power setting 10 made this group at 25 yards. It’s horizontal and measures 1.082 inches between centers.

Finally, it was time to try the JSB Exact Jumbos on power setting 10. This time the theory did play out as expected, because 10 pellets made a group measuring 1.172 inches between centers. It’s smaller than the group from both of the lower power settings, and those groups decreased in size as the power increased.

Ten 15.9-grain JSB Exact Jumbos on power setting 10 made this 1.172-inch group at 10 meters.

Conclusions
Premiers behaved differently than JSB Exact Jumbos in this test. They did not become more accurate as the velocity increased, and I think I can suggest a reason why. JSBs are longer than Premiers. Premiers measure 0.269 inches in length, while JSB Exact Jumbos measure 0.296 inches in length. At their widest, which is the skirt, Premiers are 0.220 inches in diameter, while JSBs are 0.222 inches across. So, JSBs are longer than Premiers, in relation to their diameter, and that makes them harder to stabilize.

The JSB Exact Jumbo on the left is longer than the Crosman Premier on the right. That makes it harder to stabilize and it needs to spin faster.

That was one of the problems I had with the .22 Hornet centerfire rifle I reported on last week. It shoots its bullets very slow, relative to other .22 centerfires, yet the twist rate is 1:16, where other .22 centerfires are 1:12, or in the very specialized instance of the .223/5.56mm, anywhere from 1:7 to 1:12. That’s why I’ve been writing about these rifles — so we can all gain an appreciation for how twist rates affect accuracy. The .22 Hornet can only do its best with short, fat bullets of relatively light weight. Now, you see the same thing in a pellet rifle.

Today, we see a very dramatic result of how the twist rate affects accuracy. We learned in our test of the smoothbore pellet gun that while a gun may be accurate at 10 meters, it may fall apart at 25 yards. Today, we see that in a rifle that has a very slow twist rate doing the same. If we wanted to use this twist rate, we would need to shoot only very short pellets so they could stabilize. See how it works?

Next, I’ll write up a summary article of the test to this point so we can get a grip on all the data that’s been generated. Of course, it’s all here for you now. All you have to do is go back and look at the results of all the testing to see how the twist rate affects both velocity and accuracy.

Following the summary report, I’ll test all three barrels at 50 yards.

Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.
Categories Ammo, Education / Training

### 50 thoughts on “How does rifling twist rate affect velocity and/or accuracy? Part 7”

1. Finally! I know you have to review all these new airguns to keep all this going and I have to admit that if I had writing skills this would be a fantastic job, and you do it well enough that even though I may not be in the least interested in the particular airgun you may be writing about at the time, I will read it because there is still much to learn in those reviews. But learning the whys and wherefores is the kind of stuff I crave.

I must admit, you do insert small tidbits of such into your reviews. Perhaps that is why I am almost fanatical about reading your little blog. But as any addict, I crave larger and larger doses, even to the point where I begin to do my own experimentation to satisfy my cravings. Duskwight and others know exactly what I mean.

I have already begun the experimentations with my TSS and my Edge. Though they do not compare to FWBs and such, my triggers are now pretty nice and when I take the time to go back in they will be even better. I am also beginning experimentation with that 12″ .22 Eun Jin barrel I got from you. Hopefully this weekend I will have my friend’s chrono to play with (I just have to get me one of those things). I also need to get my hands on an unaltered valve stem and tophat so I can shoot .177 in my TSS. I really would like to hang on to that HW barrel setup.

DRUGS!!!! I NEED MORE DRUGS!!!!

2. I hate to ask but would it be possible to summaries each report’s finding in to a table at the end of blog?

• Chris S.,

I know that tables are needed. This software is extremely difficult to work with in so many ways. But I do plan on using tables in the summary report I do next.

The problem is, it takes me two days of shooting and writing to prepare just one report like you see here. Making a table for it would add more time that I don’t have. But I know they are needed for visualization of the results.

B.B.

• Yes, yes, a summary table for the wealth of data. I’m learning about MS Excel now, and it’s amazing what can be done even with minimal spreadsheet technology. I’m getting addicted to the little charts and graphs.

Matt61

• Wait until you feel the inkling for some real statistical analysis — and spend a day downloading and installing R and all the contributed packages

Consider this abomination (real statisticians and mathematicians will want to take their nitroglycerin pills now)

http://wlfraed.home.netcom.com/BenjaminMarauderStats.pdf

And yes, I did use Excel for the formal tables (but data was not generated within Excel)… But there is no way I’d want to program Excel to generate those charts and statistical test results.

3. B.B.,
My guess is that as the power increases the skirts become more deformed in the barrel and that, together with the slower twist rate, would affect accuracy also???
I will rig up a water trap and shoot some JSB Jumbos, RS & Premiers using my TF 87 to see what they look like after firing.Will send pics.
Also can you send me your fax #. I have just completed the drawing of the solid pellet design and would like to fax it to you-try not to laugh too much-:)

Pete

• Pete..

PCPs are not as inclined to deform skirts like the higher powered springers will. It has to do with the peak impulse pressure.

You might run into some interesting results. Push some pellets through the bore to see what they look like and so you will have something for comparison after you shoot some into water. I did this with two of my HWs and found some interesting things.

twotalon

• twotalon, this is just a quick place to tell you that I am doing well a little over a year since surgery. Always good to read your words. I’m still sympathetic about your faulty Titan. Mine continues to behave quite well. I did do that basement bomber mod on the trigger, but I used a hardened washer. I have loved the trigger since then. Of course, I treat all guns as though they are loaded and will fire at random.

~Ken

• ken…

Glad you are doing well, and that your Titan is working good for you. I shouf check mine again to see how slow it is shooting now. I am guessing probably around 450 f.p.s. .

twotalon

• ken…

Now I really am going to have to chrono the Titan.
I shot a pine board with it, and the pellet bounced around the kitchen. Penetration into the board was about the depth of the pellet head….before it bounced out.

twotalon

• Art, that just not right. I hope you can find and fix the problem. I expect you should be able hit 700 fps with a 14.3 grain CPHP. ~Ken

• ken…

I know what’s wrong with it. I know a whole lot of things that are wrong with it. Not going to fix it.

twotalon

• Oh…ok. Well, do check out the link Edith provided below and enter you name for the AR-15 drawing if you like. ~Ken

• twotalon,Could you give me some stats., off the top of your head, about how many feet of water it takes to stop a particular pellet with a particular fpe or f/s value?I wanted to cap a piece of drain/waste/vent pipe,fill it with water and shoot down from the top and I have no idea how long to make it.I remember that you have done some work in that area.-Tin Can Man-

• I’d suggest you find a web copy of the Mythbusters episode on how far bullets travel in water.

Even a .50BMG only manages a few feet (in one way, the /slower/ projectiles will move further).

Pellets? Even a .177 pointed at 1000fps probably doesn’t span two feet.

• TCM….

I used a tall kitchen trash can 24″ from China-Mart. I set it out by the driveway and filled it to about an inch from the top and taped some thin plastic over the top to reduce splash. You will still get some so be sure to dry and oil your gun afterwards.

I only tried some .177 pellets. I did not pay a whole lot of attention to deformation of the skirts when I tried the TSS with the 18″ barrel. Shooting in excess of 1,000 f.p.s. .
I know I tried CPHP, Crow Magnums, CPL, and some Beeman hollow points .

The ones I looked at for skirt damage were shot with R7 and R9. I looked at Exact 8.4, FTT, CPHP, and something else. No heavies.

Something you might find interesting…..
Try some pellets that fit extra loose or extra tight of the same kind to shoot if you are using something of R9 power or more. Also , look at the skirts to see how well the skirts expand to seal the bore in the grooves. (myth busted !!!).

twotalon

4. I had an interesting challenge at the bb-gun shooting class last night. I was coaching a young girl who was shooting a Daisy 499.

Problem was, she was nervous and had gotten the hiccups! I tried the usual suggestions (try to relax, take long, controlled breaths, etc).

Finally, I told her to shoot between hics. Seemed to help.

(I also told her this has happened to me, too. It really has.)

Les

• Les

Few things are as frustrating as a case of the hiccups that won’t go away. The best remedy I have found is to eat a good tablespoon or two of creamy style peanut butter. Just in case you don’t have a jar of JIF handy (who in their right mind doesn’t?) have the hiccuper hold a pencil or pen in their mouth while they drink from a glass of water.

• To clarify

The pencil or pen should be held sideways in the mouth between the teeth with both ends outside of the mouth, NOT as one would hold a drinking straw in the mouth. On second thought, stick to the peanut butter just to be safe.

5. I’m curious how these tests would translate into something like an AR15. I’m asking this because I’m working on building an AR15 at this time. My build is a bit more involved since I’m milling my own lower receiver from a block of aluminum with a drill press. It won’t be long and I’ll be putting my lower together and beginning to build my upper. So with the many barrels out there with several twist rates I want to be sure I get the one that will give me the best accuracy.

For those that are interested, I have invested more than \$1000 into tooling to build an AK47. To build an AR15 my investment is around \$300 for tools and milling dies. Without the milling dies my tooling investment is around \$75.00

• How can this be? I thought that Third World peasants could churn out AKs for a cheap price. Maybe they are using the stamped model instead of the milled. And perhaps the equipment for ARs is much more plentiful in America.

Matt61

• I have the stamped receivers. Milled receivers are too hard on equipment since those are milled from solid steel and stamped are only sheet metal. Most countries that produce AK’s have the factory machines to do so, so it is relatively cheap for them. I only made 2 so far and I used all the stuff designed for the guys making them in their garage. So I have a spot welder, 12 ton hydraulic shop press and cheap drill press mounted on an old table. I then had to buy all the drill jigs to get the holes in the right places, spot welding jigs to get the rails right, barrel press, riveting jig (no, pop rivets will not do the trick)….. in all it is a rather costly thing to do especially since the cost of the kits with new barrels has doubled with all this talk of assault weapons bans. When the kits were around \$300 I could afford to put one together every month. Now at over \$500-\$600 a kit I have to put that hobby on hold. So I’m working on an AR which only really requires a sturdy vice, a vice block to hold the upper while you work on it, a few cheap punches and an Armorer’s AR15 tool which will run you about \$30.00.

When you compare how the AK47 and AR15 are built the AK is welded, riveted and pressed together. An AR15 is totally bolted together with a few pins here and there. But the end result the AK hits harder, rarely ever jams, but is less accurate than the AR15 which is much more accurate, doesn’t hit quite as hard and in my experience is prone to jamming much more than the AK. One day it would be fun to see BB do a side by side comparison of these two rifles that are almost legendary.

• john,

Quite typical. Cheap mass-production guns require more starting investments but then they roll out like nails. Precision stamping is one of the most expensive in terms of start – but one of the cheapest in terms of process itself. AK was designed for the state, with huge factories in mind and AR was created for people, with “garage workshop” set of machinery and equipment.
However I think that modern tech can somewhat water-down that difference – cnc plasma sheet cutting is almost as fast as stamping initial sheet shape.

duskwight

• They moved to stamped receivers for several reasons. First is it is cheaper and faster to stamp them. Second is to make the AK a bit lighter. The AK47 is a very heavy gun compared to the AR15. I have fixtures here to stamp mine as well in my 12 ton hydraulic press. I also have the option of buying a pre-bent blank and drilling it myself which is not that hard to do.

6. You may remember the big brouhaha caused recently by a picture of a boy holding a firearm that resulted in a visit from the NJ social services and the local police to investigate what they believed was child abuse.

In response to that, one of my favorite websites asked parents & grandparents to send images of pictures of their kids & grandkids (and apparently their dogs :-)) holding guns. Here’s the avalanche of response:

http://girlsjustwannahaveguns.com/2013/03/hundreds-of-parents-send-in-photos-of-their-child-with-a-gun/

Edith

• Thank you, Edith. All of the pictures are good, but it is the dog that forced a laugh.
Oh, and I got to enter my name for the AR-15 drawing. ~Ken

• Edith,
Boy how times have changed. I remember in 1951, ten years old, walking down the main street in town with my Steven Favorite rifle on my shoulder with my uncle a WW2 vet . We would walk to the city dump to shoot rats (sorry about that) and nobody would even blink at that. Now there would probably be a swat team on hand to arrest us.

• Yes, the dog was my favorite one too. When I see dogs like this or with their heads poked out of moving vehicles, I do wonder what they are thinking about something that is completely outside of their instincts or comprehension.

Matt61

7. Anyone know BC of JSB Exact Jumbo and the Crosman Premier?

Since the JSB pellet is heavier than the Crosman pellet it has a lower muzzle velocity.

• I have an old copy of Chairgun (1.1 build 15) which lists Premier as 0.0190.

8. Those beautiful groups at 10 yards look a little small for 2 MOA. Shooting at my range is almost aesthetic as much as anything else. The sight of tiny round groups fills me with joy and any distortion is deeply annoying.

Tin Can Man, sounds like you’ve got a guest blog with the telephone book. I would have guessed that the pointed rounds would do better, but would not have imagined all the detail obviously. Do you suppose that a phone book is denser than solid wood of the same thickness, say a pine board? Intuitively it does not seem so since paper is softer, but there is reason to think that it is. The paper is wood crushed flat and then laid adjacent in sheets without any spaces. Lamination seems to have the same effect of increasing density whether it is in samurai swords, gun stocks, or phone books.

Speaking of gun tests, I noticed something else about hickock45 who has made something of a name for himself online. He has quite a playground with metal gongs and targets of various kinds set up at various distances out to hundreds of yards. He’s very capable of hitting at long range such as gongs offhand at 230 yards with an AK or even with shotgun slugs. But his forte is shooting high caliber guns at very close distances of within 10 yards. In other words, he could accomplish about the same with airguns!

Victor, that is really appalling about your doctors. They moan and complain as a profession about malpractice costs, but that doesn’t seem to have deterred some of them. I’ve encountered doctor arrogance before although thankfully not in a patient care setting. But once I asked a veterinarian why badgers are proportionally so much stronger than humans. I wondered about the physiological make-up of their muscles. She was quite dismissive and insisted that it was all psychological with the extra tenacity of badgers. I’m quite convinced that she’s wrong. As I found out recently from readings about the World’s Strongest Man competition, strength depends heavily on physiology. As just one variable, tendon thickness in the cross-section is directly proportional to strength. So, someone who has equivalent sized arms to look at but with thicker tendons will be much stronger. There was the case of a circus challenge where people were invited to lift a dumbbell with an extremely thick grip. No one could even come close until a future contender for the Strongman competition, lifted it with ease and a puzzled expression. There is only one other circus strongman in history who was capable of this feat. And if there are such extreme differences between humans you can imagine the differences between species. That explains a test where bodybuilders at the peak of fitness were pitted against chimps to trials of strength. The chimps who lay around all day in the zoo blew the bodybuilders away.

I have an insight into the arrogance of doctors from my years in medical school. Most doctors couldn’t give a hoot about patients. Their reasons for enduring the abuse of medical school are mostly about ego and certain hyperactive tendencies. And from my experience in other fields, I suspect that one of the outcomes of so-called professional training is the cultivation of arrogance. How refreshing to listen to Clint Fowler, master of the M1 Garand, who could not have cared less about the numbers of self-described famous people I have met along the way.

Matt61

• Matt61,

This one particular incompetent doctor, who sent me to her husbands golfing buddy, spent the first few minutes of every visit justifying her medical school training (I never asked), which I would later found out was from some Banana Republic. If it had been Mexico, I wouldn’t be so concerned because I’ve known people who got better treatment for things like cancer in Mexico, than they could get here. I use to take the position that I didn’t want to be snobbish about where my doctors went to medical school, but not anymore. I thoroughly investigate their education now.

Well, the doctor she sent me to was as arrogant as they come. When I fired him for making me blind and deaf (which fortunately was only temporary – blindness), he later could call me to “explain” that the problem here was that I was among the two 2% of people in my area, and that he simply was use to his patients being stupid. I kid you not! He said that 98% of his patients were stupid, and he just wasn’t use to having patients that were smart. I jumped all over him for saying such a stupid and arrogant thing. About three months later, after he forgot our conversation, he called to repeat the exact same stupidity. So, really, both of these doctors were arrogant and stupid. This is, partly, why a year ago I said that some of the dumbest people I know are doctors.

I’m not down on doctors. I owe my life to a few great doctors. I simply put them in perspective. They are no more special than mechanics, or anyone other trained professional. All fields have a similar breakdown ranging from utterly useless and incompetent, to truly great. You’ll find a similar percentage of good engineers, mechanics, or doctors, and similarly poor ones.

Victor

• Victor,

Not all doctors graduated at the top of their class.

As my brother says, “You can’t fix stupid.”

Edith

• Indeed. What do they call a person that graduates dead last from Medical School? They call them “Doctor”!!!!!!!!

Mike

• Edith,

Yup! And stupid is really is as stupid does. A stupid doctor trying to justify his obvious treatment of me as a stupid person because he believes that 98% of his patients are stupid is just stupid, and thus what a stupid person would do. Did I say the world “stupid” enough time in that last sentence?

Victor

• Matt61,I took some time today and set out to answer your pine board vs telephone book density idea.If I have it right you wondered which would stop a projectile better and I think other things besides density have an effect.So I chose a Crosman hollow point .177 cal.pellet (7.9 grain) to pound it’s way through both media.I reasoned that a pointed pellet might act like a wood splitter if it hit the grain pattern just right and that would skew the comparison.The rifle was the Benjamin 397 pneumatic 8 pump.The velocity developed for any # of pumps with this pellet has already been tested.At 5 pumps(approx.646f/s)the pellet stayed stuck in the 25/32 inch clear pine board.At 7 pumps (approx.732f/s) the pellet went through the board and kept going.It left a fairly clean exit hole.At 6 pumps (approx.689f/s and 8.33fpe)the pellet made it through the board and blasted a rectangular chunk of wood off with it.I used the same # of 6 pumps and fired the same way into the same thickness of phone book.The pellet did not go all the way through.There were 27 pages that were not torn ,though several of those were dimpled.They measured about 1/8 inch thick.So…if someone is shooting at you;grab a book and R U N . -Tin Can Man-

In case anyone is thinking about trying the BK Chipotle Whoppers…
They are lame. Extra ingredients needed. Salt, pepper, pickles, BBQ sauce, and a few jalapeno slices make them halfway edible.

twotalon

• TT

While skeptical, I will defer to your judgement.

I missed out on the BK bacon sundae. If it is released again, I will not make the same mistake.

10. JSB Exact Jumbos measure 2.296 inches in length.

Pardon? A pellet longer than a loaded .357mag cartridge?

I suspect the leading “2” is in error…

• That number was interesting to me as well. Not a complaint because I thank all you for the great daily content, but you also mention a 35 yard test directly above the section on 25-yard testing. Which is odd because my reading normally wouldn’t catch that. On the practical side I think that means you need to open the garage door or knock out a wall or two. Sounds like it is time for a remodel!

11. Great!

B.B., this time my expectations/calculations were perfectly right for the first time!
Just different longitudinal load in thas case – due to slightly longer pellet and it is the winner in slow twist rate. I just wonder if (RidgeRunner is right!) more tests could be performed – with even longer pellets of the same weight. And I must also notice that it may be so that longer pellet has more chances to get some aerodynamic drag-induced spin due to rifling marks working as propeller blades with longer lever of its body.
So the truth is still out there, but this time it is very near. I can feel it!

Some time ago I stumbled upon this http://www.bergerbullets.com/litz/TwistRuleAlt.php Well of course it’s for big supersonic powder-burning guys, but that may be some use in it for us.

Cylinder parts arrived, this evening I’m going to drop a few lines on it.

duskwight

• duskwight,

Okay, I’ll make you a deal. If, after I have completed this report with the final summary (following the 50-yard test), you want more testing of any kind, I will let you tell me what you would like to see. I can’t promise that I will test everything that everybody wants, but I will try to do as many of the things as I can, and still write a blog.

B.B.

• B.B.

First of all – thank you. It is a truly royal offer.
Second – I promise you I will cut my appetites to the minimum.

duskwight

12. Then, JSBs were shot at the same power setting. This time, they landed in a group that measures 0.092 inches between centers. This is better than a lot of 10-meter rifles can do for 10 shots at the same distance. People will argue that they can do better, but it’s always a 5-shot group they show.