I can’t figure this out.

[RickH]

Afternoon everyone,

I can’t figure this out. I just got back from another rifle match at the CMP in Anniston AL. I practiced for this last week. At that time, shooting from a standing position, I was able to put 60 rounds into about an inch, which was good enough for me. I was shooting the same Beeman AR 2078A I’ve been using for a couple of years at 15 meters. I didn’t see any elevation drops or any other problems after 60 shots. I didn’t empty the air chamber until this morning and put two new 12mg co2 cartridges in before I left. Two hours later the match started. Using the same weight Gamo red tip pellets it was shooting horribly. Group size about four inches. After 50 shots I was getting a 3-4 inch drop so I just quit shooting. Last week I was shooting outdoors in 70 degree weather with no wind. Today I was shooting indoors at about 72 but no wind. The rifle never got cooler than 68 degrees at all. I don’t suspect a leak because after 10 days there was still gas in the chamber and now, an hour after returning home, there is still pressure in the chamber. I don’t get it. Could the pressure vary that much in the 12mg cartridges? Going from 60 rounds and no drop to 50 rounds and a 3-4 inch or more drop seems extreme. What am I missing?

Rick H.

 

[Treefrog]

That's a chin-scratcher for sure, Rick.

Have you checked the current velocity to see how it compares to what it was before? Gas delivery could be a problem and that would show it. The felt filter inside the valve tends to come apart and start getting into the rest of the system after a while. it could be that, I suppose.

Roll Tide,

J~

 

[MLE]

Lot of factors to consider here. I know you’re probably turning the gun inside out at this point so I’ll propose an alternative: shooter error.

Obviously not knocking your skill. 1 inch groups off hand are nothing to sneeze at. All I can say is that in my own experience, something seemingly innocuous—like a sore back, too much caffeine, even a couple less hours of sleep than normal—can have an outsized effect on my accuracy. If you don’t find anything wrong with the gun, maybe take this into account.

 

[Motorhead]

Temp drops in the 60's or lower, Co2 off gassing pressure falls off a cliff.

https://www.pirate4x4.com/forum/attachment.php?attachmentid=2921056&d=1551081621

 

[ToddGeddes63]

I don't have a co2 air gun so I may be off base here,
I have used co2 framing guns and nailers, in construction. And agree the cooler temps can make them in consistent. I noticed and agree that @ 60 degrees and lower, the issues would begin. You can't get away from them ceasing & freezing. We switch over to another means. Maybe shoot pcp air guns in the cooler weather?

 

[Treefrog]

All above are making good points.

I recall choking badly at my first match, then practicing and training and practicing some more in order to win it a few years later. (I won a lawn chair the first year. The next year I won a box of ammo.) So you could very well be part of the problem.

Or it could be that the pellets with the same weight don't shoot as well (or to the same point of aim) as the others do.

There's a ton of info on making these guns more accurate out there if you're interested.

Luck,

J~

 

[DesertSilver]

Were you shooting at the same pace as you were when practicing? As had already been mentioned, nerves? I don't know much at all about CO2 airguns but I do remember reading about being Temp sensitive and if you were shooting a little faster than before maybe the internals of the gun dropped low enough to cause the pressure drop.

 

[JimBianchi]

Clean it

I found junk in my valve stem on my custom 2250b. Gun was all over the place, after cleaning it was back to a fly shooter at 15m. (Smear jelly on your target edges and between bull eyes you can pop flys)

 

[RickH]

I finally got it back out. The gun has been stored indoors as always, not humid and about 67 degrees temp. Took it out back and emptied the two old co2 cartridges. One of them didn’t look like it had punctured very well but both came out of the rifle empty. I took 2 new ones out of my pocket and put them in the rifle and after the tank filled, began shooting. Outside temp about 58. I didn’t get in a rush but made it through 60 rounds in about 30 minutes without any problems. A couple fliers but about 57 rounds into an inch. This time I let out all the co2 pressure after I was done. I can only come up with two possibilities; that co2 cartridge that didn’t seem to puncture properly was just a bad one because power started falling off way too soon. The other problem with group size was just me shooting poorly. I’ve been in enough competition events that nerves don’t bother me and I did break about every 10 minutes to relax. I know one of the other shooters from that day because we are in the same RC club. He had an older Anschutz 2002 that he wasn’t using and offered to sell it. Based on the stickers I found on the stock he’s shot this rifle in some major events including the Olympics. I have it now and while it is clearly the better rifle of the two I think I’ll keep both. I’ll work with the Beeman some more and the next match isn’t until February. Can’t wait.

Rick H.