It's said that "nothing lasts forever" and we can include our air rifles' accuracy in that statement. The St. Louis U High rifle team has 8 Anschutz 2002s and 10 8002 Club rifles. A couple of matches ago we realized that one of the 2002s showed signs of reduced velocity. It was tearing targets. We tested all of the 2002s over a chronograph and found that they all showed loss of velocity. Four of them over 100 fps and one of them inicated velocity variations of 30 fps. All of them were serviced in 2008. We didn't test the 8002s but when we switched the shooter who had been shooting the 2002 with the reduced and varying velocity to a 8002, he picked up 4 or 5 points in his prone 3P stages.
Our current plan is to send all of them back for servicing this spring with the worst four going first. We want them tested for velocity and if it is possible, tested for grouping. We don't have a machine rest but we considering the ESP rest and hope that Bill Ernst still makes it.
Our plan for the future is to test them for groups and velocity in the fall before the season starts and then try to do it again midway thru our schedule. If anybody has any more (or better) ideas, I'd like to hear them. Mike Barron
Air rifle accuracy
Moderators: pilkguns, Marcus, m1963, David Levene, Spencer
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ishoottrap
- Posts: 32
- Joined: Sun Feb 14, 2010 2:44 am
Don't know if it's a "better" idea....
How about "do it yourself"? The 2002s are very straightforward to service, parts are available from Pilkguns and Neal Step at ISS. If they're not leaking down (chronograph readings the same immediately after cocking as a couple minutes after cocking) then it's probably the breach seals. 2002 also has a pre-load adjust for the breach seals (eccentric in the forward pin of the top-latch linkage).
I just finished servicing one of these and an FWB-600, will post photos and a write-up later. Shoot me a message if you'd like to discuss.
-Scot
I just finished servicing one of these and an FWB-600, will post photos and a write-up later. Shoot me a message if you'd like to discuss.
-Scot
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ishoottrap
- Posts: 32
- Joined: Sun Feb 14, 2010 2:44 am
SSP vs PCP
Ah! I fear I am mistaken in my statement regarding servicing the 2002s. The 2002 I mentioned was a SSP, not a PCP. I have a small amount of experience with PCPs, an LG-100 but no experience with the cylinder itself.
Sorry for any confusion.
-Scot
Sorry for any confusion.
-Scot
A note on chronograph results. After I changed some seals on my FWB, I tried to adjust the balance between the regulator and the striker spring setting for most uniform velocity on the chronograph, and was not happy with the standard deviations I was getting on strings on ten shots. On a hunch, I measured the weight of a number of pellets, reputable brand, and found a wide variation. When I sorted out a batch of pellets all +/- 0.5 grain from the nominal 8.2 (tedious job!) the standard deviation came down to one third what it was before. And the settings then showed quite a sharp optimum, somewhere round 540 fps from memory but no doubt specific to the rifle, when I had both settings right. The pellet weight variation may not change the point of impact much (or it may), but it can certainly upset your assessment of what the rifle is doing.
And I just needed to top up my pellet box, and couldn't remember if the pellets in it were 8.2 gr air rifle pellets or 7.7 gr air pistol ones, so I weighed ten of them to identify them. The ten of them weighed 87 grains. Believe me, they vary!
And I just needed to top up my pellet box, and couldn't remember if the pellets in it were 8.2 gr air rifle pellets or 7.7 gr air pistol ones, so I weighed ten of them to identify them. The ten of them weighed 87 grains. Believe me, they vary!
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ishoottrap
- Posts: 32
- Joined: Sun Feb 14, 2010 2:44 am
lot to lot vs. in-lot variation
I agree that they do vary lot to lot by quite a significant amount. Not sure what pellets you are using but the H&N Finale Match haven't varied by anything approaching that magnitude within a lot for me. Lot to lot I have found significant variation.
-Scot
-Scot
Scot
Yes, maybe I had a bad batch last time. I am using RWS Meisterkugeln, their Professional, second grade (behind the R10 Premium grade) 8.2 grain diabolo shaped pellets, 4.49 mm; more than good enough for my grade of shooting.
I just measured 10 pellets straight out of the tin, and got 5 that were 8.2, one that was 8.3, two at 8.15 and one that was 8.1 grains. Credit where it is due - no complaints whatever. Much better than whatever it was that gave me trouble last time.
My point still holds. While precise weight may not matter too much when shooting, perhaps not at all for practice, if you are using a chronograph to test a rifle, you don't want pellet weight confusing the results. Next time I am testing over the chronograph, I will still measure the pellets first. With a batch like the present one, it will not take me anywhere near as long to pick out uniform 8.2 grain pellets as it did from the last batch.
Yes, maybe I had a bad batch last time. I am using RWS Meisterkugeln, their Professional, second grade (behind the R10 Premium grade) 8.2 grain diabolo shaped pellets, 4.49 mm; more than good enough for my grade of shooting.
I just measured 10 pellets straight out of the tin, and got 5 that were 8.2, one that was 8.3, two at 8.15 and one that was 8.1 grains. Credit where it is due - no complaints whatever. Much better than whatever it was that gave me trouble last time.
My point still holds. While precise weight may not matter too much when shooting, perhaps not at all for practice, if you are using a chronograph to test a rifle, you don't want pellet weight confusing the results. Next time I am testing over the chronograph, I will still measure the pellets first. With a batch like the present one, it will not take me anywhere near as long to pick out uniform 8.2 grain pellets as it did from the last batch.