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Posted: 9/12/2004 8:19:40 AM EST
[Last Edit: 9/12/2004 8:20:12 AM EST by DRTYBERT]
I recently finished putting together an AR from parts collected from all over. It works great with green tip 5.56, but when I try to shoot 55 grain 5.56 through it it fails to extract about 1 round in 3. At first I suspected a gas leak, but that wasn't the culprit. Also, the buffer and spring are new parts from Olympic arms, so I don't think its that. I definitely want to shoot the 55 gr 5.56, because I have an abundant supply of it and it has much better performance when it hits tissue.

Here's my real question, then. Is it possible I have a gun chambered for .223 and not 5.56, and if so could this be my problem? Any way to check, and is it feasible to have it rechambered or should I just buy a new barrel in 5.56?

I must sound like a real dumbass, I've spent 20 years in the service now and I always thought .223 was just the civilian name for 5.56mm. Found out differently about a week ago. Time for an old dog to learn some new tricks!

Thanks for any info you guys can give.

John
Link Posted: 9/12/2004 8:45:41 AM EST
Which 55gr are you using? Some is just not up to M193 spec.
Link Posted: 9/12/2004 8:48:52 AM EST

Originally Posted By DRTYBERT:
I recently finished putting together an AR from parts collected from all over. It works great with green tip 5.56, but when I try to shoot 55 grain 5.56 through it it fails to extract about 1 round in 3. At first I suspected a gas leak, but that wasn't the culprit. Also, the buffer and spring are new parts from Olympic arms, so I don't think its that. I definitely want to shoot the 55 gr 5.56, because I have an abundant supply of it and it has much better performance when it hits tissue.

Here's my real question, then. Is it possible I have a gun chambered for .223 and not 5.56, and if so could this be my problem? Any way to check, and is it feasible to have it rechambered or should I just buy a new barrel in 5.56?

I must sound like a real dumbass, I've spent 20 years in the service now and I always thought .223 was just the civilian name for 5.56mm. Found out differently about a week ago. Time for an old dog to learn some new tricks!

Thanks for any info you guys can give.

John



1) You may have a .223 chamber, who made your barrel? Look on the top of the barrel for maker marks. If this was the case I would think 5.56mm ammo regardless of bullet weight would give you the same problems. A good smith can ream out the barrel, but I'm no expert on the process, there are guys here more in the know on this subject than I.

2) Check the brass of the 55gr rounds, are the case rims torn by the extractor? Could be soft brass.

3) Are the 55gr reloads? Maybe they were not sized correctly?

4) Since this is a Franken AR built from "parts all over" is your bolt a new part or used part? Could be your extractor is worn out.
Link Posted: 9/12/2004 1:14:23 PM EST
The shop I got my barrel from said it was a Wilson. No markings on it for chamber or maker.

The ammo is Winchester 5.56 55 gr, the kind in the yellow box. I've fired it from my duty guns many times without issue. No marks or problems with the brass once it was ejected.

The bolt and extractor are both in excellent condition. I swapped them out to another gun just to be sure.

Is the .223 chamber any tighter than the 5.56? I'm not really up on it, but that might explain why the green tip (with its heavier powder charge) had enough energy to force the bolt carrier back and extract the round but the 55 grain does not.

Thanks again for your replies.

John
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