Air Rifle Wandering Zero

[tuna]

I've got a Crossman 2100 bb gun that is amusing the chipmunks to no end. I spend a good 10 minutes to zero the rifle and the next day my sights are off by 3 to 4 inches. The drift is with both irons and the toy scope the gun came with, and is horizontal, vertical or any diagonal.
I know this is a cheap gun, but it should stay on a chipmunk at 20 yards, wouldn't you think? After missing, the chipmunks get gun shy after I rezero, and they hide until the next day, when the zero is off.


Change of weather? But by this much?

 

[76Too]

i have a ruger 10/22 takedown that's doing the same damn thing! i've sighted in rifles with the best of them and never had such a problem.

 

[mclina]

I have a Gamo Silent Cat and the scope would never hold zero for even a few rounds. The fiber optic sights were rock solid, though.

 

[tuna]

I get it isn't a great scope and could live with irons, but the irons aren't holding zero either.

 

[whatluck]

I have a Sheridan 397 and it still had it's zero after being in the closet for a year.

 

[Goodstuff84]

Are you using BB's or pellets? if you're using BB's that's most likely the problem. BB's tend to fly all over the place and even with pellets you have to find a pellet your gun likes. I have an old Sheridan silver streak that will group under 1/2" at 25 yards with the benjamin cylindrical pellets, but i've tried other brands and the groups have opened up as much as 3-4".

 

[tuna]

I'm using both, and the problem is with both.

BB and pellet POI differ about 4 inches, consistently. Both group well. When I adjust the scope or irons to get either one in the bull, they're fine for the rest of the day. One is in the bull, and one needs Kentucky bondage.

Then the next day, they're shooting 3 inches low (or high, left, whatever). I think the raccoons are sabotaging me because they owe life debts to the chipmunks.

 

[powerman]

oil /moisture on bb/pellet when cold bore?
temperature differences?
if you keep shooting does zero return to where it has the day before?

 

[thorin]

Have you used some pellgun oil on the seal? If the seal is a little dried up maybe it is sealing less well under certain temp conditions and you are getting variations in velocity.

 

[tuna]

Don't know if zero returns, since I'm always changing it. I oil it about every 200 shots.
I get some change due to weather but this is extreme.

 

[Spanz]

maybe you have crud in the barrel. They make small brillo-like fiber pellets you fire out the barrel to clean it, try a few of those.

 

[-B-]

the barrel is really just a straw it is moving from being used to no use IE cold to warm if you want accuracy you need to step in to a real pellet gun something with a real barrel that only accepts pellets

 

[Peicemaker]

It doesn't look like the barrel on that gun is a solid piece. There is probably an inner barrel that kind of free floats inside the sheet metal sleeve and is supported by a couple loose fitting plastic rings. It's just a cheap ass pellet rifle. Try investing in something a little higher quality. A break barrel gun with a nitro piston powerplant in .22 or .25 cal should do ya fine. Get a scope with an adjustable objective lens too. It really comes in handy with airguns.

 

[tuna]

Hmmm, ok that makes sense. I'm disappointed in this. I remember my old Daisy 880 as a kid was accurate all day long and I never messed with the sights once they were on. Guess I need to go a little higher quality.

 

[mac1911]

The 2100 is a cheap gun.....they "can" shoot ok.
I would stop shooting BBs through it. The rifling on these barrels is very thin.
I would clean the barrel.....even just a few patches through it . I use a piece of weedwhacker string with a slight buldge on one end formed buy heat....

Now is it a newer 2100?
Also another issue is its a pump gun. You would be surprised how touchy pump guns are to the "pumping" the "rhythm" of the pump can have effect on velocity. ...if you have a crony try it.

Ditch the cheap scope....if the receiver is plastic don't waste your time.

I had the 22 cal model and it could hold 1.5" @ 25 yards bone stock....with some mods....I could get just under 1".

I assume the barrel is shifting inside the outer shell. Also that scope might be shifting as well. Over tightening the rings can have a big inpact on those cheap scopes.



If your into tinkering the first mod mostly done is to eliminate barrel movement.
I used Teflon tape at the breach end. Helps deal things up a little and prevent movement.
The other was I used epoxy to bed the front of barrel. I used Pam spray to keep the barrel from sticking. In case I needed to remove again.

 

[mac1911]

If you visit the crosman forums and airgun networks there are plenty of tips to get that 2100 shooting its best. I will give you a run down of things I do to the "cheap" pellguns I come across
1. The barrel crown. Use a magnifying glass and inspect it. They are generally bad. You can give it a DIY crown with a brass screw and some fine lapping compound
Like this.....it does not take much.


The 2100 is not the easiest to take apart and put together but not "hard".

2. Is the trigger .....just polishing all the contact points on the trigger , sear and hammer can do wonders. Poke around long enough you will find info on what works best.
3. Finding pellets that work the best
I like the crosman premier that come in the large cardboard box and JSB diabolo match.

4. If your feeling adventurous you can go full on mods
http://www.network54.com/Realm/CFTech/FB2200.htm

Barrel crown
http://www.network54.com/Realm/CFTech/BioCrown.htm

 

[tuna]

Thanks for the link, I have a feeling I just lost my free time.

 

[mac1911]

clean barrel , stop using BBs..... buy a few different pellets find ones that shoot well and go buy more.... expoxy front of barrel to shroud..... quick and easy way.