[ARCHIVED THREAD] - Using 5.56 in a Colt SP1

Posted: 9/27/2008 8:27:40 PM EDT

Gentlemen,
I recently procured a early 80's vintage SP1 to replace the one I foolishly sold approximately 10 years ago when on an extreme M1 Garand kick and wanted to inquire with with you as to wether or not it is advisable to utilize XM193 in it. My prior rifle digested substantial quanties of it with no issues,But I have since been advised that only .223 is permissable in these rifles. May I get your opinions please?

Posted: 9/27/2008 8:30:39 PM EDT

[#1]

It's 5.56, the .223 on the side of the receiver is just the civi designation, the BBL itself is 5.56 leade. Shoot all the xM193 you want.

Posted: 9/27/2008 8:31:52 PM EDT

[#2]

Actually, the SP1 barrel is the SAME barrel that was issued on the vast majority of M16A1 rifles, thus, perfectly compatible with any 5.56 M193 ammunition.

Bang away!

Posted: 9/27/2008 8:31:58 PM EDT

[#3]

Congrats on the new baby and welcome aboard!

All Colt rifles have always been chambered for the 5.56 round despite the .223 marking on the receiver.

Posted: 9/27/2008 8:45:02 PM EDT

[#4]

Thank you very much for your information Gentlemen! My original understanding was that it was perfectly acceptable as well,But my friend was quite persuasive with his chamber pressure argument,I am glad this clears it up.

Posted: 9/28/2008 5:54:59 AM EDT

[#5]

Quoted:
Thank you very much for your information Gentlemen! My original understanding was that it was perfectly acceptable as well,But my friend was quite persuasive with his chamber pressure argument,I am glad this clears it up.

You need to start choosing your friends more carefully.

Obviously, thyis one doesn't know squat about Colt ARs.

(just kidding)

Posted: 9/28/2008 7:15:06 AM EDT

[#6]

The .223 Remington and the 5.56mm NATO cartridge are similar dimensionally; but the chambers are not...

AR15barrels.com has a pdf chart of the differences in the chamber dimensions...

AR15barrels tech

In the early year(s), the AR-15 was chambered in .223...and IIRC, early 5.56mm chambers were still to .223 specs...but the chamber was altered, and it was noted in TBR 1, but I don't have the book handy so I can't quote the exact year/model...

I'm sure there are other factors involved, but that's the little that I can recall...

I'm sure an expert here can explain more fully...

[ARCHIVED THREAD] - Using 5.56 in a Colt SP1

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[ARCHIVED THREAD] - Using 5.56 in a Colt SP1

[ARCHIVED THREAD] - Using 5.56 in a Colt SP1