by Tom Gaylord
Writing as B.B. Pelletier
Air Venturi M8 is very much like the Bronco.
This report covers:
- First group high — Falcons
- JSB Exact 8.44-grain were best
- JSB Exact 10.34-grain domes
- JSB Exact RS pellets
- The final pellet
- Conclusions
This is a test of the Tech Force M8 breakbarrel air rifle at 25 yards. We learned in Part 3 how best to shoot the rifle, which is directly off a sandbag. We also discovered that, of the pellets tested, the best to that point were Air Arms Falcons, seated flush with the breech. That is where today’s test begins.
First group high — Falcons
I was surprised to see the same pellets that had been okay at 10 meters landing 1 inch higher and 1/2-inch to the left at 25 yards. Some movement is expected when you move from 10 meters to 25 yards, but not usually that much. The first group that you see below was actually fired at a bull beneath it. The good news is the pellets were landing higher, which meant I could adjust the scope to shoot lower. That’s almost never a problem.
The first group started out well but then I threw 5 shots wide of the main group and ended up with a 1.321-inch 10-shot group. That’s a little larger than I had hoped — even for 10 shots.
Ten Air Arms Falcon pellets made this 1.321-inch group at 25 yards.
JSB Exact 8.44-grain were best
Next I tried 10 JSB Exact 8.44-grain domes that one of our readers favored. They proved to be the best pellets for the M8 I am testing — putting 10 in 0.995-inches at 25 yards. The group is fairly round, which I always like to see.
Ten JSB Exact 8.44-grain domes made this nice 0.995-inch group at 25 yards. This was the best group of the test.
JSB Exact 10.34-grain domes
Next up were some JSB Exact 10.34-grain domed pellets that another reader recommended. These were a bust in the test rifle. When the first 6 landed over than 2-1/2 inches apart, I stopped shooting.
JSB Exact RS pellets
Next I tried some JSB Exact RS pellets that I thought might do well. They fit the breech snugly, but after the first 5 landed in 1.267 inches, I stopped shooting. Clearly this was not the right pellet for the M8 I’m testing.
Five JSB Exact RS pellets landed in 1.267-inches at 25 yards. This is another average pellet for the M8 I’m testing.
The final pellet
At the end of the test I returned to the Falcons, just to see if I had gotten any better as I was shooting. The first 5 pellets landed in a group measuring 0.995-inches, so another 5 might have opened that up a couple more tenths of an inch. At any rate, I did not feel like the Falcon was the best pellet for this rifle and I ended the test.
Five Air Arms Falcon pellets made this 0.995-inch group at 25 yards. It’s okay, but when I already shot a 10-shot group the same size with a different pellet I figured why not stay with that one?
Conclusions
This was a thorough test of the Tech Force M8 rifle. We now know that it is a very close cousin to the Air Venturi Bronco that has been discontinued. It has the same easy cocking, light weight, and wonderful 2-stage trigger that was found on the Bronco. It also has a conventional stock instead of the Bronco’s western-style stock. Many shooters will appreciate that.
In the 2 accuracy tests we saw that the M8 is a decent airgun — especially for the low price. You can spend a lot more and get disappointed. With the right pellets it should put 10 shots into about an inch at 25 yards. Five should go even smaller — perhaps 0.6 inches, or so.
If you want one, act now because when the supplies in stock are exhausted there won’t be any more M8s, either. I will keep looking for rifles of this power and price. When I find them, you’ll be the first to know.
BB
Although I liked my M8 I bought very much as far as the cocking and firing cycle was concerned and thought I had a winner with he first 100 shots as I was grouping at 20 yards in the 1/2 to 5/8″ ranges with ten JSB 8.44s so it was going to be a keeper but then it just started throwing flyers everywhere and was lucky to group inside 2 inches.
I had found the barrel joint had loosened on mine to the point that with very little effort I could get 1/16′ side to side movement at the muzzle brake while holding the stock at the breech block area so I was very disappointed in it and had to send it back very regrettably I might add. I had seen your response in part three that the action fork is squeezed in a vise and then hammered on the vise to set the fork to tighten the barrel and while that may work temporally I do not see how it can be considered a permanent fix or even an acceptable practice to repair the loose joint.
I am just glad the 124 came my way as I know its way over the M8s price range but it is easier to cock and much more accurate as it hold 1/4′ groups at 20 yards with the JSB 8,44s all day long and it a pleasure to shoot .
BD
Agreed, the 124 is a pleasure to shoot – it is my go-to rifle any time I go for a walk-about. Mine prefers JSB 8.44s as well.
Vana2
As some of you may remember I have been a staunch advocate (much to my chagrin) of the JSB 8.44s in the past. I have found them to almost always be the best pellet in my rifles. It makes life easier as well since I don’t have to stock umpteen different pellets.
While I’m at it I think it only fair that I should share my failures as well as my successes. We shot one of our competitions last Saturday. I think I’ll just say that the wind ate my lunch. Things started out well enough with my first target when I shot a 244 with 13Xs.(I didn’t know that till the scoring was complete of course). It would have been a great day if that had continued but on target two the wind kicked in. A swirling variable wind no less. I finished with a total of 710 with 26Xs. Oh well, there’s always next time.
G&G
Vana
I have only had mine about three weeks and it a mid 80s 124 with the Beeman San Rafael stamped into it so that places it between 79 to 86 if my memory serves me right of the timeline that BB wrote about.
I am still waiting to get my hands on a 74 year model that I rebuilt for a friend but he has not decided to let go of it yet.
Mine likes 8.44s the best as well and is also becoming my go to gun for just some good ole fun shooting without wearing me out or the need for support equipment to have fun.
BD
BD,
You hit it right on: good ole fun shooting.
Had my 124 for around 35 years now – its a low maintenance, steady performer. Replaced the piston and spring 4 years ago, change the breech seal occasionally and do routine maintenance.
Good luck on getting that 74 model!
Vana2
Yea I have been enjoying mine very much as well and it is supposed to have been tuned by Jim Maccari many year ago so it does shoot very nice but I believe it needs a lube job as it does have some spring twang when firing but it does not affect it accuracy or performance as it shoot the 8.44s at 725 to 730fps.
I am going to tear it down just to see what shape it is in and at the least lube it up and at most replace the piston and seal since I have new ones on hand to do so if it needs it.
I rebuilt the 74 model two years ago and it was shooting in the high 700s to low 800s I believe with CP 7.9s but honestly I don’t remember which pellets I used just that is was consistent 800 fps range and it was not even broke in yet and all I did was replace the disintegrated seal and clean and lube so it is still factory stock sans a Maccari seal. I am keeping my finger crossed hoping I get a chance to buy it down the road.
BD
Buldawg,
I think you know this but I’ll say it anyway. I pretty sure the idea is that by hammering the steel it rearranges the molecules which should hold. Actually that is a proven practice, but I’m with you in voicing my skepticism about it.
G&G
Tandwweir
Being a mechanic for 50 years yes I am very well aware of the squeezing the forks in a vise and then hammering on the vise does rearrange the molecules in the metal and set them to the new position as that is an old practice when gapping spark plugs that after bending the ground electrode you tap the side of the plug on a piece of metal to set the molecules so that the plugs life will be greatly extended by eliminating the rapid wearing of the electrodes metal from the high energy arcing that occurs 100,000 of thousand of times per minute with a engine running.
So while I understand the methodology behind the practice I also understand that metal fatigues over time and with the repeated cocking of the barrel and the inherent side loads that are inevitable while doing so will eventually cause the forks to spread back open and result in a loose barrel again so in my opinion the design is not a good or durable way to install a barrel/breech block in a spring gun and it should/needs a threaded retention type of means to control the fork spread that will always occur with time.
BD
Good old JSB Exacts…
Yesterday I was getting frustrated when shooting from a rest with my Diana 31 and SWS Thunder pellets (they are rebranded H&N). I thought they were good in the Diana because so far they seemed accurate and the rifle is quite calm when shooting them. I just couldn’t get them to group. Then I switched to the Exacts and instantly got a perfect group.
BTW, I can rest the 31 directly on a bag just fine, as long as I use the same position every time.
Stephan,
I think the reason you can rest directly on the bag is the power level of your 31. I am seeing more and more than lower-powered spring guns are smoother most of the time. Smoothness is usually what allows the gun to rest on a bag.
I’m not 100 percent sure of that, but my thinking leans that way.
B.B.
Don’t tell anyone, but I’m at the “other” power level at the moment 🙂
Actually, I find the gun no easier or harder to shoot with a different spring.
At full power, it vibrates a little less but the muzzle report is louder.
The accuracy and hold-sensitivity seem to be the same.
Cpt
I do all my backyard shooting off a rested bag regardless of guns used and my springers all group well off a bag but it is a 5 pound lead shot filled bag that is used to keep pressure on your femoral artery after a heart cath by being laid on your leg at the groin area. I don’t know if the lead versus another fill material has anything to do with it or not but it works for me.
BD
BB, why was the Bronco discontinued?
Javagonzo,
Mendoza, who makes the rifle, raised their prices so high that the rifle could no longer retail at a decent price. Pyramyd AIR absorbed several price increases over the years and never increased their price, but this last price increase from Mendoza broke the camel’s back.
B.B.
B.B.
Thank you so much for this report!
BB–My Bronco is 3@ years old and the barrel joint is still tight. It is still as accurate as when it was new. Is there a difference in the barrel joint design ( compared to the M8) ? Is the steel softer in the M8? Did Mendoza have tighter tolerances when they made the Broncos? Has this happened before with other guns (early ones better made than later ones)? Ed PS Now that I have a bug-a salt, I have a fly shortage, SEND ME MORE FLYS!
Wondered the same thing about the correspondence between the two rifles. Too bad the Bronco is discontinued. Good that it seems to have reappeared in the M8, but how did that happen? Is this another Chinese copy?
Matt61
Ed,
All Broncos are the same. There is no soft steel issue. If your rifle is tight, it should remain so.
I also have a fly shortage but I have killed several spiders and one lizard instead. The lizard was just knocked down where I could step on him.
B.B.
B.B.,
I was just looking at the New Products section and a question came to mind. Is there any word on when Hatsan will be releasing their line of Q.E. rifles with wood stocks? That ‘s when I’ll start considering one as just a fun gun to shoot with. Although, they are very accurate. But isn’t that the definition of fun when it comes to guns? I over simplify of course.
G&G
G&G,
No idea.
B.B.
BB
So no good luck with the JSB 10.34 grn pellets. I just wonder if the same model guns like different pellets?
I did try deep seating 4 different brand of pellets and it did not improve the accuracy with my rifle.
I shot those deep seated pellets over the last weekend. And the weather was real nice including zero wind. I was on the money that day. It’s like I couldn’t shoot wrong. Reminded me of the old house I lived at where the wind was blocked pretty much all the time.
I got some pretty good groups with all my air guns I was shooting that day. The M8 was doing 1.250″ groups at 35 yards and 1″ at 25 yards. And yep with the JSB 10 .34’s. They seem to work in my gun.
I will have to try some of the JSB 8.44’s. I wonder if they will improve the groups in my M8. I’m betting I will need another calm day for them for sure. But maybe the velocity that’s gained will help. We’ll see.
But I just have to add that the more I shoot the M8 the more I like it. It actually kind of reminds me of my HW50s I had. A nice little light weight gun. And the M8 is definitely easy to cock. And no issues with anything wrong with the gun yet. Time will tell. I guess I just got to keep shooting it to see. Which is a good thing. 🙂
What kinda groups are you getting with them?
Reb
Deep seated all the different brand pellets I tryed went all over the place. Probably 2″ group was the best at 25 yards with the JSB 10.24’s. The others were like 3″ or more. My gun definitely does not like deep seated pellets.
Like I said above normal seating the JSB 10.34’s did 1″ at 25 yards. The other brands I tryed just wouldn’t group either.
And my M8 is making good power. I didn’t work yesterday because the power was out at work so I played around turning the power up on my .25 caliber Mrod. Was trying to get a small velocity spread and higher fps along with being able to still group good. And I did. Very happy with the.25 Mrod where its at now. But my M8 chronyed at 720fps with the JSB 10.34’s.
All in all I’m happy with the M8. Especially at the price range it sells for.
I was tempted to plug in the numbers but that sounds close enough to just call it a12fpe gun?
Very respectable for an easy cocking all day shooter!
Just plugged em in and hit it right on the nose!
Thanks again B.B. for teaching me about the “magic number”!
Gunfun 1
Wow your gun is shooting a lot faster then my gun with JSB 10.34’s mine averaged 494fps, with JSB 8.4’s 568fps.
Dave
My chrony seems to show fast. Chris USA got a gun from me and we are getting pretty much the same chrony readings. Buldawg has got some guns from me and he has got slower readings than I get. With the exception of some rimfire rounds he had and I have. We got closer to the same reading but I was still a little higher.
Me and Buldawg both did a test. He tryed it first. He shot his M8 at a 16 oz. Mountain Dew bottle at 20 yards with the bottle empty and the lid on tight. And just laying on the ground.
His M8’s pellet just bounced off. It didn’t even penatrate the bottle. I did the same test and my m8 penetrated one side but djust dented the plastic on the other side. I used the jsb10.33 pellets. I forget what pellet Buldawg used.
I did shoot my FWB 300s at another bottle and it did the same as the M8 and its chronying about the same as the M8. I shot my Tx and .25 caliber Marauder at different bottles and they blew right through both sides. The Tx is getting up to around 800fos with the 10.34’s.
So who knows. But I think my chrony is reading fast.
David P and Gunfun1
My M8 was shooting either JSB 8.44s or CP 7.9s at the mountian dew 20 OZ bottle with the lid on tight and it did not penetrate it whether the bottle was on the ground loose or secured to my backstop and my M8 chronyed right about where yours is David at 490 to 500 fps with the 10.34s and around 550 with 8.44s and it would not group at 20 yards with the 10.34s near as good as it did with the 8.44s until the barrel loosened after 100 or so shots. it was grouping inside 1/2 inch at 20 yards with the 8.44s as long as I did my part and I really liked the gun but two things made me send it back, one the barrel came loose and two the lack of a scope stop pin hole allowing my scope to walk backwards on the rail.
GF1
We still have not determined why our chronys read different with air gun pellets but were within 10 fps of each other with the 22lr quiet rounds that state 710 fps on the box as we both got in the neighborhood of 690 to 720 fps averages with those 22lr rounds but with pellets we are 150 to 200 fps difference in velocities still. So if some others can post velocities they are getting with their M8s with similar pellets we may be able to determine which of our chronys are off or if its is just a difference of locations causing the varainces.
BD
Buldawg
Have no clue why the readings are different. But obvious that my M8 is hitting harder than yours was.
I have hit my Caldwell steel spinner out at 50 yards with the M8 and it hits it harder than my FWB 300 does. The 300 was making a little less fps than the M8 though also. It’s around 650 on my chrony.
Anyway that don’t really matter to me. The main n thing is I have a baseline number to go off with my chrony. That way I know if my guns that I have change in performance. Or if I make changes to a gun I know what it ends up at verses what it was.
The only problem with stating my chrony numbers they might not represent what the gun is truly doing.
But as you said your M8 was reading slower than mine plus it wouldn’t penetrate the plastic bottle and mine would. So there is some truth to the chrony readings we both got with the M8.
And I did order some JSB Exact 8.44’s yesterday. So I should have them by Saturday. I use to use the 8.4’s till I tryed the 10.34’s and they grouped better in the wind.
So we’ll see how the 8.4’s work out in the M8. Plus I will even try them in my Tx, FWB 300s and the HPA converted 1077.
I definitely know how all those guns shoot with the 10.34’s so I will be able to tell real quick when I try the 8.4’s.
I will post my results when I get them tryed.
Gunfun1
Yea I know the readings are only really a guide as to what a gun is doing when new or when something is changed to see if it helped or hurt.
Yea you got a good M8 as far as its shooting better than the one I had since it does penetrate the bottle whereas mine did not so that in itself is proof that it is shooting harder than mine did which I am glad you got a good one otherwise it would have went back as well.
I was just trying to see if other would post some numbers for theirs to see if you got an exceptional one or there is just a huge variance in the performance of the guns which could indicate some manufacturing/assembly differences in the guns.
I am interested to see how your guns perform with the 8.44s as I know they will shoot faster but then it like you say there is a tradeoff of the ability to overcome wind deflection and is why I shoot the 10.34s in my Ft matches instead of the 8.44s as they do stay on course better in the wind.
The only reason I use the 8,44s in the lower power spring guns is to keep velocity up so I don’t have as much hold over in sighting as if I used the 10 .34s.
I am planning to tear the 124 apart to see if it is in good shape inside as Loren told me that the piston that was installed by Maccari had some scratches on the seal button area that he thought may be affecting it some and I got a new piston with it and just received my new Macarri piston seal so when I get caught up I will take it apart just to look and see what the innards look like and if it needs the new piston and seal then it will get them and it has some spring twang so it may need a fresh lube job on the spring as well.
BD
Gunfun1
My number 1 pellet for my TX is 8.4 JSB’s, second is the 10.34’s.
David
I said it somewhere here but yep I use to use the 8.4’s and then tryed the 10.34’s.
I was getting pretty much the same results except that the 10.34’s were doing better in the wind. So I have St made the switch to them.
But one thing I have found is the design of the 10.34 JSB pellet verses another brand pellet that is the diabolo shape and same weight. The JSB 10.34 will shoot at a higher velocity than the other shape equal weight pellet. So that was another reason I liked the 10.34.
It’s got a flatter trajectory than other heavy pellets.
Buldawg
Oh and I meant mine was 20 oz bottles also. Not 16 oz like I said above.
And maybe the reason my M8 penetrated the bottle was because of the heavier 10.34 JSB pellet.
Gunfun1
I don’t think it was the heavier pellet as I tried the 10.34s as well and they bounced off even easier so I think you just got an above average gun as compared to mine.
remember mine had rust inside the breech area and a filthy barrel that took 6 patches to clean with three soaked in brake clean just to dissolve the grunge and three to clean the dislodged grunge out plus the Styrofoam inside the box had rust stains on the muzzle brake support and the breech support so it had been in a damp environment at sometime in its life before I got it and leads me to believe the compression chamber had rust build up inside as well.
BD
Buldawg
I’m just going to respond here instead of having 2 conversations going.
Yep I remember you saying that the seal was damaged or something in the 124. But your tallying up some kill marks with the 124 so far. So I say it’s got something left in it still.
And yes I agree about other people posting some numbers and what pellets they use and the group sizes to see if there is biuld issues and such. That’s like I was saying. Why is my gun grouping good with the 10.34 JSB’s and BB’s gun ain’t.
Maybe they ain’t holding the barrel tolerances good. Maybe one pellet head size is different than the other weight pellet and even the skirt size.
If one gun is making more power than the other it will for sure make a difference in the way the pellet skirt seals to the barrel.
If barrel tolerances change from gun to gun then its the same effect as the head sizes in a tin of pellets when you run them through a pellet gage.
So when I see people post different velocity’s from a gun. That makes me think about pellet sizing and power plant variation as well as barrel tolerances.
But in our case with me owning a gun and then you owning it. And I give you some of my pellets to try in and you get different shooting results. Well that’s another thing there because we both ain’t going to shoot the same. But when velocity’s don’t come out the same then that makes me wonder.
So there is different scenarios going on with your M8 verses mine. Two different guns, different pellets. I got my tin of pellets and you have yours. We didn’t send each other some of our pellets to try.
So I’m really thinking there is biuld issues that could be going on with the M8. And yes if I would of got one with a wiggling barrel and shoots at that low of velocity it probably would of went back. Low velocity I could maybe deal with. And the breech wiggle I’m kind of up in the air about that.
But also I think I would of kept the gun and tuned it. As in uping the power and would of gave the breech tightness some working over. On $130 gun yes maybe. On a $300 up gun it would of went back for sure. And that’s just me. Other people I’m sure know where they would go with that.
Hopefully as time goes we will hear more about how peoples M8’s are holding up.
Gunfun1
Loren said the 124 piston was scratched up where the seals end fit in the piston since the 124 use a seal that has an flared protrusion on it rear side that is fit into the front of the piston much like a TX seal that would be completely flat on the rear side and have the coned shaped flared retaining part as the back of the seal instead of sticking up off the front of the piston so that the seal cone is pushed into the piston instead of around the cone on the piston and he was saying the cone part of the seal was damaged or the hole in the front of the piston was so will not know until I take it apart. it is shooting the 8,44s at 725 to 730 fps with a 5 fps average spread so it not hurting to bad but does have some spring twang that at most needs a god lubing.
Yea some numbers from other will help in determining if there are assembly issues or barrel issues or possibly pellet issues but that would be harder to determine since as you say without shooting pellets from the same tins thru each gun it hard to do a conclusive test. I do believe that at least JSB has very strict tolerances for their pellets so that that would be far less of an issue than the guns manufacturing difference would be in different results.
If I did not have so many other air gun and bike projects going on I may have kept it and tuned and fixed the barrel joint as well but I don’t have the time and health to complete the projects I have now so taking on another one was not an option at this time. I also just did not see a easy way to fix the loose barrel issue that would be long lasting and durable thru use since it is a pin and not a screw or bolt and squeezing the forks together and hammering to set only weakens the metal so that every time it is done the metal suffers more and more fatigue to the point that it will no longer take a set and stay.
If mine was just low velocity like you I could have dealt with that but then you have a pinned barrel that has to come off to remove the piston and driving the pin in and out further wears and fatigues the joint so that a non loose barrel before tuning now may be a loose barrel that will not take a set and stay tight. I my opinion it is a poor design even for a 130 dollar gun as crosman spring guns at 100 dollar and less still have a screw to adjust the barrel tension as wear occurs and wear will occur in anything that moves.
BD
Buldawg
You do have access to some equipment I thought with your friend and that next door neighbor that drilled out that gauge hole in your tube on your Brod mod.
Buldawg
Was it the barrel loose or the breech at the pivot point on your M8?
Gunfun1
It was the breech block loose in the fork as I could see the block moving in the fork when grabbing the muzzle break and the stock at the breech block area and applying very slight pressure to the brake in a sideways direction.
BD
Buldawg
Ok that’s what I thought you said at one time.
And I believe I already have a fix in mind if my breech gets loose on mine.
Going to get rid of the pin and mill a flat on each side and nut and bolt it. I will probably drill the hole out bigger make a bushing out of some oilite bronze to push through the hole on our press at work then nut and bolt it.
The old Acme Gridly screw machines we have got that treatment for there bearings. The oilite bronze always lubricates the metal surface as its moved. It holds up in a high load environment with little wear.
So if the breech bolt ends up wearing out on my M8 that’s where I’m going with it.
Gunfun1
Its nice to have all that equipment at hand and know how to use it as the repair you just described would be just what I would do if I had the access like you do to the machines and install the oilite bushing with a cross bolt so that the breech block joint will never need attention again in our lifetimes or your kids as well.
BD
Buldawg
That posted in the wrong place. I was responding to the breech repair reply.
We’re out of room here.
Gunfun1
You still got a reply button so is it me that’s out of room with no reply button or just that your post was not in the right place as I still can respond.
Getting ready to eat something and then start on the Brod so may get it together by days end or tomorrow morning. Still no sleep last night and even took a sleeping pill so just running on fumes and doing the best I can with the little energy I cam muster.
BD
Buldawg
Well se if this goes in the right place also.
Yes I know you been saying you ain’t been feeling good. Did the rain stop there yet?
And I’m getting ready to go to work so probably won’t be able to respond back. But if you get anywhere on the Brod just post on today’s Friday blog on one of my replies and I will see it in my email while I’m at work. So talk later.
Guynfun1
The rain has stopped for now but it still overcast and a chance of rain so just pushing thru the pain and have come to the point that I am going to hurt regardless of the weather or what I do or do not do so going to work on the Brod as much as possible today and hopefully have it together by the am tomorrow.
I will post here with the progress I make so you can just respond here when you get time.
BD
Gunfun1
Meant post on the big bore antique blog not here.
BD
BB
Glad you had success with the JSB 8.4 that my gun likes. The barrel pivot area I had to tighten up on my gun also. When I close the barrel making sure it is all the way up, I came across this when pellets were sometimes below my point of aim. I been shooting off sticks with the barrel resting on them just in front of the stock at 25 yards depending on the variable wind been shooting acorns off a stump, I found a good use for that Oak tree.
Thanks so much for bring this gun to my attention I’m having a lot fun with it.
Yeah I was expecting high 5’s-low 6’s with such a heavy pellets but I hope mine has that kinda power when I get one.
BB– All Broncos may use the same steel, but is the M8 a Bronco in a different stock, or are there significant changes? My bug-a-salt has downed 2 wasps, (shot the wings) , but the credit for the kill goes to my hush pups.. Ed
Ed,
Yes, I came to that conclusion after testing the M8. It is essentially a Bronco without sights in a different stock.
B.B.
Ha, different points of impact at different distances is on the brain now. Thanks, Sam, for your interest and your comments about my sighting problems with the Saiga. I had assumed that the shift in point of impact between 25 and 100 yards was due entirely to bullet trajectory. The height of the optic above the bore is a different factor I had not considered. Your estimate of 2 inches is as good as I can do. Assuming this distance, how did you come up with 3 inches as the difference between my point of impact at 25 yards and 100 yards? Is that the 2 inch height of the scope plus the 1 inch trajectory height of the cartridge?
This topic of scope height over the bore has come up in earlier discussions. I believe I see the rationale. This seems like a version of parallax where instead of the eye being displaced from the sights, the sights are displaced from the bore. Admittedly, my grasp of parallax is shaky. However, I’m skeptical about this for a couple of reasons. The height of a scope above a bore is tiny compared to a shooting distance, even 25 yards. As you go further out, it gets even less significant. For such a small change in value to make any perceptible impact seems unlikely.
My second reason is by way of an indirect experiment. How exactly would scope height intervene in the sighting process? The distance is fixed; the trajectory is fixed, the mechanical adjustments to the sights are fixed. The only possibility I can think of is that various scope heights would change the click value of scope adjustment. So instead of the standard 4 clicks per inch at 100 yards, you would get some other number of clicks. As a matter of fact, I believe that scope adjustment consists of realigning the tube to change its angle relative to the bore which is the same phenomenon as variable scope height.
I tested this when sighting in at 25 yards which was one of my few achievements at this range session. With Mike’s bore sighting procedure, my first rested shot at 25 yards was 3.5 inches left according to the target grid. Doing the math for a scope that adjusts 4 clicks per inch at 100 yards, I dialed in exactly 56 clicks right. (Doing this based on one shot was a little reckless.) My next shot pinwheeled! So did the next two! If the click adjustment value for 100 yards works so precisely at 25 yards, then I’m guessing it must work at just about any distance. I suspect the parallax effect of scope height does exist to some degree, but it must be so small that it is corrected with the standard scope adjustments. That’s my understanding anyway. But my range sessions show that I am not only often but usually wrong…
Incidentally, my .3 CTC group at 25 yards would have been a little over 1 MOA at an imaginary 100 yard target. That’s why I continue to have high hopes for the gun. It is such a shame that I burned through the whole box of SSTs because that’s all I had. I do have some Tula to try, but I actually want to subject them to an independent accuracy test. Some reports indicate that it is not bad at all.
Matt61
B.B. do you have an old post explaining how near and far zero’s will change with a differant height over bore? Thank you.
Matt, next time try this. If you are dead on @ 25. But off the paper at 100- aim at the bottom of the paper, but centered, fire a round or 2. If you walk up and see nothing, aim at the top of the paper and try again.
Actually Sam, I did try this technique when all was lost, and it got me on paper. I was indeed way high at 100 yards. But then things got weird. The adjustment to get me zeroed was way over. And after that the accuracy was erratic. I think the barrel was too hot at that point.
Matt61
Sam.
/blog/2007/10/why-are-there-two-zero-points-when-sighting-in-a-scope/
B.B.
Or, if you live in SoCal,. Let me know when you are going shooting next- We head to the desert, I buy you a couple boxes and show you how.
Then I’ll go look for jack rabbits and you can bang away at my steel target.
This is tempting. You’re one of these lucky people who has unlimited space in the desert. And a steel reactive target to boot! Unfortunately, I have a crowded travel schedule with shooting trips and maybe even a PA show lined up. But thanks for the offer which I will keep in mind.
Matt61
We gonna see ya at the Texas show?
A greater sight height over bore pushes back your near zero for the same far zero.
Conversely if your near zero is the same (25 yards) the elevation of your barrel will have to be more to make the same near intersection as before, this will make you shoot high at 100.
You can demonstrate this to extremes by lying your rifle on its side on your living room floor and putting masking tape down at differant extremes of height over bore while making the same intersection on your wall 15′ away. Make a triangle with the same point on the wall and same distance to rifle and to imaginary sights. Only change height over bore. Go extreme change (from stock 2″ to 3′).
B.B.
In my opinion it’s 1 point to JSBs, 0 points to the rifle.
Frankly, I expected more from M8. Lack of open sights presumes precision worthy of installing a scope and using the gun’s potential, but it just happened not to be this way. I hoped it to be a mid-ranger with a great potential, a “poor man’s” HW-95 or 98, and targets show that I was rather far from being right, it shoots exactly for its price – decent, but no magic.
I also wonder why this moderately-powered springer is not as omnivorous as I expected it to be. In my practice more power always means more specific tastes, but this one likes only soft light-to-medium weight pellets of the top brand. Perhaps it’s something with the barrel profile – from what I’ve read on Broncos at PA they are also a very squeamish about pellets. Maybe some weights tuning can fix that. Well, as usual – wish I could put my hands on it and tinker with this gun a little,
duskwight
Just read about another loose break joint.
The Texas show is next weekend and then I’ll make up my mind.
what time does filming start at the star ranch?
P.S. still keeping you in my prayers GOD BLESS
Paw,
6 pm
B.B.
I received my M8 from PA about a week ago and so far I would say that I am pleasantly surprised, thanks BB!
The trigger seems pretty light and very crisp compared to any others I’ve used..which probably isn’t saying much since I haven’t had that much air rifle trigger experience.
The stock seems fairly decent for the money although I believe mine also has a little bit of putty by one of the stock screw holes other than that it seems nice and has some decent grain to it.
After going through break-in with an inexpensive tin of pellets I started some 10yrd target shooting of a sandbag rest once I found the hold sweet spot. I tried about 13 different pellet samples I picked up and it turns out the best pellet looks to be the inexpensive tin of 7.87g H&N Excite Hammers that I used for break-in, I was essentially pancaking pellets in the same hole and if one wasn’t in the same hole it was covering at least half of it. The next best or equally good were the 7.87g JSB Exact Match Express, that’s probably not to surprising since they are the same weight. This group had two extreme fliers one of which definitely was me and the other I didn’t think it was me but could of been and the other three dead center o the bull. I’m hoping what I’ve seen from these two will translate well to 20 & 30 yard targets. All other seemed to be spray and pray shot groups.
The others were Beeman FTS ECO, Beeman FTS Copper, Beeman Kodiac, RWS Superdome. JSB Match Exact, JSB Match Exact RS, H&N FTT(4.52 & 4.51), H&N Baracuda GREEN, PDG Domed, Crosman Premier Ultra Magnums(couldn’t get these to fit in the breech).
I paired the M8 with a BSA AR 2-7×32 Rifle Scope and BKL One Piece mount. I was surprised by the scope as the glass seems clear and settles in quickly after a turret adjustment and the turret clicks are very definitive and tight unlike my Leapers scope at twice the price which are loose and mushy and takes several shots to settle in.
All in all I like it and hope hope everyone else enjoys shooting it this weekend.