Magazine affect accuracy?

[jn123]

Bought a LMT .308 MWS after hearing good things about them, but the first couple times at the range were quite frustrating. I would be shooting a really good group then throw a flyer out of no where. WTF? This was with a PMAG. The next time I took a KAC mag along as well. I soon noticed the flyers were gone with the KAC mag and the rifle shot quite well. When switching back to the PMAG the flyers came back---almost always in the vertical. In fact, the rifle shows more vertical stringing in general with the PMAG. I haven't tried this mag in my Stoner yet, so can't comment on that. Any thoughts about magazines affecting accuracy like this?

 

[Redmanss]

Re: Magazine affect accuracy?

Chamber a round from each type of magazine. Without firing it, extract it and inspect the projectile and casing for any serious gouging or other damage that doesn't otherwise occur. You may need to do this mid-string as the chambering force during firing is more than when chambering by hand alone. This is the only way a magazine could be effecting your accuracy.

No scrapes.... It's in your head and all you. If you have gouging or case damage, look for the way your P-Mag is aligning in comparison to your Knights to be somehow out of order.

 

[ORD]

Re: Magazine affect accuracy?

+1 on the above.

If a particular mag is allowing rounds to take a beating on the way into the chamber (whether on the feedramp/barrel extension or the chamber wall itself), then that is a different story with respect to damaged ammo causing accuracy issues.

I would suggest inspecting your ammo visually prior to loading a magazine as well as with either a concentricity gauge (or at a minimum, checking the OAL of each round with a good set of calipers)...then load a full mag and manually cycle through the mag. Afterwards, inspect each round again and look for damage to your bullets, cases/necks and see if you see any problems/changes in OAL/concentricity.

If there aren't any issues with the rounds you inspect...then the problem is between the ears and not within the mag!!

 

[Rovieairto]

Re: Magazine affect accuracy?

It's not likely caused by the magazine.
You may be experiencing OAL variations during the loading cycle caused by bullet set-back during feeding, or kinetic "pulling" while chambering.
This can effect pressure and can cause flyers.
If the rounds are feeding easier with the P-mag, then this effect could be exaggerated.

Single feed each round fully into the chamber before closing the bolt, and run the test again.
If the flyers disappear, then you probably have your culprit.

More positive neck tension, or "gasp" a crimp may help.