True Double Feed - Magazine?

Colorado S14

Pushing the Limits of Spontaneous Combustion
Belligerents
Minuteman
Dec 27, 2010
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Denver, CO
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While shooting a local PRS match this weekend with a homebuilt AR I got a couple double feeds. First the details:
Aero M4E1 upper and lower
Craddock 224 V barrel, Rock Creek blank
Tool Craft Bolt
Superlative adjustable gas block
C-Products mags.

The gun has 800 rounds through it with no issues thus far and has historically run like a top. I was running a Caldwell brass catcher during the match.

During two stages I had a true double feed, two live rounds jammed in the chamber, managed to clear one in time to finish the stage but the other was a shit show.

I have not labeled mags in past as they all ran fine but I will do so now and see if I can find a issue with a specific mag.

But, anyone else have any thoughts on other things that could cause this? A true double feed seems strange to me, I get an extraction issue but attempting to shove two live rounds up there is new to me.
 

hlee

Sergeant
Belligerents
Jul 14, 2012
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TX
The following is an analogy... I have a few Magpul AICS pattern magazines. If you seat one in the rifle, then slap the bottom you run a significant chance of forcing the magazine to barf several rounds into the action.

It is possible that your AR15 magazine did something similar when the bolt moved to the rear- the force of the follower pushing the rounds up actually pushing 2 into the action instead of allowing the bolt to strip one from the top it moved forward.

I have also seen (again with bolt rifles) instances where stripping one from the top caused the round underneath to move forward enough to pop free. This is also a possibility with an AR15 magazine.

Take several magazines next time. Use the same one until it gives you an issue. Mark that one and set it aside. If you don't have an issue, mark it as good and choose another to focus on at the next range trip.

I have a few Elander 6.5 grendel mags that have given me grief. I can't tell what is different, but they are less reliable than the others...