Changing POI in 10/22 with different magazine

[KJW]

I discovered today that my 10/22 had substantially different POI when I used a 10 rd mag vs ruger's newer 25 rd mag. Now I'm wondering if the difference may exist between different 10 rd mags too. I only had one of my three 10 rd mags with me so I couldn't test the hypothesis. It just seems so strange that the magazine could affect the POI so. Even if there's a slight difference in the angle of the top round in different magazines I would think that once the bolt pushes it forward into the chamber the round's position is determined by the confines of the chamber, which I would think would be pretty tight.
Has anyone else encountered this? Not only do I have to sight my gun in for a particular round, but now I have to sight it in for a particular magazine too?

 

[ghitch75]

is the barrel loose?......mag shouldn't make any difference in POI....

 

[Tydeeh22]

i dont believe the magazine would change how a round is chambered. perhaps a 10/22 expert can chime in. the chamber has its tolerances no matter how a round is jammed in there.

 

[KJW]

is the barrel loose?......mag shouldn't make any difference in POI....

No. The differences were reproducible. I had to shoot with each magazine several times to convince myself of it. If the barrel were loose I would expect the POI to change constantly regardless of the magazine. Furthermore, I got 1/2" three shot groups at 75 yds rested. I don't think a loose barrel would do that.

 

[KJW]

i dont believe the magazine would change how a round is chambered. perhaps a 10/22 expert can chime in. the chamber has its tolerances no matter how a round is jammed in there.

Thus my consternation

 

[IndyGunworks]

Rimfires are VERY picky especially when they dont chamber with the same amount of force. It does not surprise me that you are able to notice this. Now you got the bug of trying to figure out if YOU can predict it well enough to adjust for it.

 

[Tydeeh22]

sub moa groups are pretty decent for a 10/22, assuming it is "factory". i wouldn't worry much about the theory you have.

 

[KJW]

sub moa groups are pretty decent for a 10/22, assuming it is "factory". i wouldn't worry much about the theory you have.

It's not factory, I have a volquartsen trigger and a tactical solutions barrel.

 

[ghitch75]

No. The differences were reproducible. I had to shoot with each magazine several times to convince myself of it. If the barrel were loose I would expect the POI to change constantly regardless of the magazine. Furthermore, I got 1/2" three shot groups at 75 yds rested. I don't think a loose barrel would do that.

just askin'......i don't see how the mags would change POI......i shoot 3 diffident mags from my 10/22's and they all shoot the same.....only thing i can think of it the bolt is stoppin' in a different place with the different mag and the rd is short chamberin'...

 

[Double T]

Perhaps the weight difference is effecting your trigger pull and or follow through. Are you benching it or using a sling?

 

[1911ly]

I have a 10 round and a 25 round mag and I don't see any difference. Are you shooting from a bench and resting the mag on the table?

 

[KJW]

Perhaps the weight difference is effecting your trigger pull and or follow through. Are you benching it or using a sling?

Rested. If I could shoot 1/2" groups off hand at 75 yds with a sling I think I'd be in the biathlon in the olympics!

 

[1911ly]

Is the mag setting on the table?

 

[KJW]

Is the mag setting on the table?

No.

 

[1911ly]

No.

Ok just checking. I am leaning towards a bad magazine. Although I don't know for sure why. Hopefully someone with a lot more experience will chime in. Hopefully you will get it resolved.

 

[ghitch75]

did you read post 9?

 

[jrh84]

If I'm shooting for groups, I always "burn" the first round out of the mag into the dirt because it will have a different poi than the rounds that are loaded via recoil. My best guess is that it's due somewhat to the relatively sloppy tolerances in a factory receiver/bolt/barrel combination, and mainly the slight difference in the shooter releasing the bolt vs. the bolt returning to battery after ejection. I'm guessing slightly different mags could result in different tolerances, and therefore slightly different poi. I just picked up a BX25 today myself, maybe I'll try it out tomorrow and see if I can tell a difference with my setup.

 

[DRob]

Thinking out loud

What passes for a "feed ramp" on a 10/22 is actually the lips on the magazine. You'll notice the edges of the chamber are sharp with no chamfer. If the chamber is slightly over-sized, the rounds might be chambering differently from different mags but I think that's unlikely. I know your TacSol barrel is light but a common error with modified 10/22s is fully-floating the barrel. That barrel is hanging on the reciever with much less support than a bolt gun barrel might have. It is possible, perhaps, that different external dimensions of the different magazines are changing the reciever/barrel or bolt/barrel relationship due to the barrel being fully floated and free to move slightly. Try installing a pressure pad near the front end of the forearm to support the barrel. This is not an uncommon practice with heavy steel .920 barrels. It shouldn't take much. A piece of inner tube, card stock, or similar material might solve your problem.

Good luck.

 

[1911ly]

did you read post 9?

Yes but my attention span is short Hopefully you will get better answers from the more experience. This forum is great.

 

[SILVERBACK]

If the feed ramp is off a little it could be shaving lead off one side of the bullit , that would change POI.