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3/20/2017 5:03:23 PM
Posted: 3/2/2012 1:32:30 PM EDT
Hello all - new to the forum. I have a Colt SP1 with birdcage purchased in the mid seventies. Just purchased a Kel-Tec PLR 16 which uses the 5.56 round. Is it feasable to change the AR over to fire the hotter 5.56 round or should I just use .223 in both If it is possible what parts would I need to make it happen. Thanks in advance.
Link Posted: 3/2/2012 1:46:16 PM EDT
Your Colt SP1 is chambered for 5.56.
Link Posted: 3/2/2012 1:47:38 PM EDT
The Colt SP1 is chambered for 5.56
Link Posted: 3/2/2012 4:25:38 PM EDT
I guess I didn't make myself clear. The AR-15 uses the .223 round and is stamped as such. The Kel-Tec uses the 5.56 NATO round and can fire either the .223 or the 5.56 NATO. The reverse is not true for the Colt. Most experts say that it is not wise to fire a 5.56 NATO round in a weapon designed for .223 due to higher pressures. I would like to use the NATO in both if possible ie cost to convert the AR.
Link Posted: 3/2/2012 4:27:35 PM EDT
[Last Edit: 3/2/2012 4:28:23 PM EDT by KBAD]
The caliber stamped on the receiver doesn't matter. What's on the barrel? If it's the original colt barrel, it's a 5.56 chamber
Originally Posted By fe468stroker:
I guess I didn't make myself clear. The AR-15 uses the .223 round and is stamped as such. The Kel-Tec uses the 5.56 NATO round and can fire either the .223 or the 5.56 NATO. The reverse is not true for the Colt. Most experts say that it is not wise to fire a 5.56 NATO round in a weapon designed for .223 due to higher pressures. I would like to use the NATO in both if possible ie cost to convert the AR.


Link Posted: 3/2/2012 6:16:31 PM EDT
Originally Posted By fe468stroker:
I guess I didn't make myself clear. The AR-15 uses the .223 round and is stamped as such. The Kel-Tec uses the 5.56 NATO round and can fire either the .223 or the 5.56 NATO. The reverse is not true for the Colt. Most experts say that it is not wise to fire a 5.56 NATO round in a weapon designed for .223 due to higher pressures. I would like to use the NATO in both if possible ie cost to convert the AR.


No, you've made yourself perfectly clear...
Link Posted: 3/2/2012 6:56:35 PM EDT
Originally Posted By KBAD:
The caliber stamped on the receiver doesn't matter. What's on the barrel? If it's the original colt barrel, it's a 5.56 chamber
Originally Posted By fe468stroker:
I guess I didn't make myself clear. The AR-15 uses the .223 round and is stamped as such. The Kel-Tec uses the 5.56 NATO round and can fire either the .223 or the 5.56 NATO. The reverse is not true for the Colt. Most experts say that it is not wise to fire a 5.56 NATO round in a weapon designed for .223 due to higher pressures. I would like to use the NATO in both if possible ie cost to convert the AR.




+1

Your Colt barrel should be stamped, and it should say 5.56. What the receiver says is of no consequence.

If your barrel is not stamped 5.56 please take a picture of the stampings for us.
Link Posted: 3/3/2012 5:17:18 AM EDT
The only stamping on the barrel itself is C MP Chrome Bore. Nothing has been done to the rifle so it should be able to fire the 5.56 NATO?
Link Posted: 3/3/2012 5:40:40 AM EDT
Originally Posted By fe468stroker:
The only stamping on the barrel itself is C MP Chrome Bore. Nothing has been done to the rifle so it should be able to fire the 5.56 NATO?


Correct, as we've tried to tell you, all the Colt ARs are chambered for 5.56. The sole exception being the R6010 which was an export model chambered for .222 Remington for sale in countries that restrict military calibers from civilian purchase.
Link Posted: 3/3/2012 9:27:53 AM EDT
Not to confuse the issue but, if your Colt is a mid 70's production it is likely a 1:12 twist barrel.
This means that you cannot use 5.56 NATO whic is a 62 grain bullet but would have to use the 55 grain round.
Luckily for you, there is plenty of XM193 ammo out there which is the original mililtary 55 grain round for the Colt.
Link Posted: 3/3/2012 11:10:39 AM EDT
Originally Posted By motoguzzi:
Not to confuse the issue but, if your Colt is a mid 70's production it is likely a 1:12 twist barrel.
This means that you cannot use 5.56 NATO whic is a 62 grain bullet but would have to use the 55 grain round.
Luckily for you, there is plenty of XM193 ammo out there which is the original mililtary 55 grain round for the Colt.


That's a good point.
Link Posted: 3/3/2012 3:05:16 PM EDT
Originally Posted By motoguzzi:
Not to confuse the issue but, if your Colt is a mid 70's production it is likely a 1:12 twist barrel.
This means that you cannot use 5.56 NATO whic is a 62 grain bullet but would have to use the 55 grain round.
Luckily for you, there is plenty of XM193 ammo out there which is the original mililtary 55 grain round for the Colt.


62gr should shoot fine. I wouldn't count on anything much heavier especially in arctic climates, but 62 should be gtg. It would handle a 22lr conversion great too.
Link Posted: 3/3/2012 3:23:11 PM EDT
[Last Edit: 3/3/2012 3:23:28 PM EDT by SSeric02]
Originally Posted By gee223:
Originally Posted By motoguzzi:
Not to confuse the issue but, if your Colt is a mid 70's production it is likely a 1:12 twist barrel.
This means that you cannot use 5.56 NATO whic is a 62 grain bullet but would have to use the 55 grain round.
Luckily for you, there is plenty of XM193 ammo out there which is the original mililtary 55 grain round for the Colt.


62gr should shoot fine. I wouldn't count on anything much heavier especially in arctic climates, but 62 should be gtg. It would handle a 22lr conversion great too.


There is a reason the M855 is painted with a green tip; so as not to be confused and used in the 1/12 twist variants as the M16A2 and M855 were introduced in the early/mid 80s. Will it maybe shoot OK out of some guns in some conditions? Sure. But I wouldn't count on it.

http://ammo.ar15.com/ammo/project/perf_112.html
Link Posted: 3/3/2012 3:36:25 PM EDT
Originally Posted By SSeric02:
Originally Posted By gee223:
Originally Posted By motoguzzi:
Not to confuse the issue but, if your Colt is a mid 70's production it is likely a 1:12 twist barrel.
This means that you cannot use 5.56 NATO whic is a 62 grain bullet but would have to use the 55 grain round.
Luckily for you, there is plenty of XM193 ammo out there which is the original mililtary 55 grain round for the Colt.


62gr should shoot fine. I wouldn't count on anything much heavier especially in arctic climates, but 62 should be gtg. It would handle a 22lr conversion great too.


There is a reason the M855 is painted with a green tip; so as not to be confused and used in the 1/12 twist variants as the M16A2 and M855 were introduced in the early/mid 80s. Will it maybe shoot OK out of some guns in some conditions? Sure. But I wouldn't count on it.

http://ammo.ar15.com/ammo/project/perf_112.html


IMI M855 is an exception...
Link Posted: 3/3/2012 3:39:58 PM EDT
Originally Posted By SlightlySkewed:
Originally Posted By SSeric02:
Originally Posted By gee223:
Originally Posted By motoguzzi:
Not to confuse the issue but, if your Colt is a mid 70's production it is likely a 1:12 twist barrel.
This means that you cannot use 5.56 NATO whic is a 62 grain bullet but would have to use the 55 grain round.
Luckily for you, there is plenty of XM193 ammo out there which is the original mililtary 55 grain round for the Colt.


62gr should shoot fine. I wouldn't count on anything much heavier especially in arctic climates, but 62 should be gtg. It would handle a 22lr conversion great too.


There is a reason the M855 is painted with a green tip; so as not to be confused and used in the 1/12 twist variants as the M16A2 and M855 were introduced in the early/mid 80s. Will it maybe shoot OK out of some guns in some conditions? Sure. But I wouldn't count on it.

http://ammo.ar15.com/ammo/project/perf_112.html


IMI M855 is an exception...


Correct, it's just US M855 that is painted for the above given reasons.
Link Posted: 3/3/2012 4:03:42 PM EDT
5.56 NATO was a 55gr 12 twist round long before the 62gr round was developed.
Link Posted: 3/3/2012 6:12:13 PM EDT
Originally Posted By Combat_Jack:
5.56 NATO was a 55gr 12 twist round long before the 62gr round was developed.


I'm not sure the 55gr M193 was ever NATO standardized, as up until the 80s we were the only ones who really used the caliber, everyone else in NATO was using 7.62. But, you are correct, the 55gr M193 was THE 5.56 round long before the SS109 and M855.
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