TargetTalk

I have nineteen M853's for our shooting teams. 15 of them are about 10 years old, 4 are one year old. We have maintained them in very good shape. All of a sudden we have 4 rifles (2 old, 2 new) have periodically randomly dropping a round 8-9 rings on a target and on a couple of occasions a whole target below the target being aimed at. We have "benched" these to take all the variables we can out with the same result. We follow the 4-5 second rule about keeping the charging handle open to allow sufficient air into the chamber to pressurize. We have taken these rifles apart and repaced the seals and felt washer. We have inspected both the plunger and the silver air chamber. We have replaced the hammer spring (what Daisy told us to do). We have removed the clip, spring and piston in the air chamber and inspected them and used compressed air to ensure there are no obstructions. All of this has made absolutely no difference. Does anyone have any suggestions other than get rifles other than the 853 (I don't have a choice but to use them) Thanks.

What do your pellets looks like? That's one of the few variables left. Also checking the sights for movement, but that's a pretty dramatic change for sights alone.

Thank you very much for your response. I have checked the sights and made sure they are tight, checked the aperatures etc. It is interesting you should bring up pellets. Prior to this year, we have used the Daisy pellets. This year, we were issued (we are an Army JROTC unit) Meisterkugeln pellets. Everything I have researched about them indicate they are a far superior pellet. I have seen no indication of problems with them. They are a little harder to seat in the rifle but certainly more accurate. Our scores have certanly gone up. I have tried "double seating" them (pushing the bolt forward, pulling it back and pushing it forward again) and it doesn't make a difference. At least one of these rifles (one of the ones that is only 1 year old) has fired the whole season with these pellets and did not exhibit the problem until 12 weeks into the shooting season and I would estimate firing over 1000 pellets. The big problem is that it belongs to my #1 shooter. We did not have any problems prior to using these pellets, but we have 15 rifles that are shooting fine with them and the problem is only sporatic (once every 10-15 rounds or so) on the rifles we have problems with. I have inspected the entire bolt and particularly the chamber end of it to ensure it is not damaged/cracked/dirty. If, in your opinion, it is the pellets. Do you have any suggestions? Thanks again.

OK ... here's another guess.....

Make sure the piston o-ring is lubricated ... not with oil, but a grease.

I rebuilt a friends a few years ago, and the o-ring had a slightly "dry" spot that would cause it to "kink/curl" as it was cocked (losing some of the pressure) ... lubed the cylinder and the o-ring w/ a white grease and it seemed fine.