Does anyone know the caliber for colt SP1 Uppers?

[5.56RifleGuy]

Does anyone know the caliber for colt SP1 Uppers?

Mine is not stamped on the barrel. I know it is fine for 223 but I want to know if I would be alright shooting 5.56.

Thanks

[kraigwy]

Just took a gander at my SP1, it says .223

However, I really dont think that means much. When I shot for the NG, I had access to all the M193 I could shoot. I've shot 10s of thousands of 5.56 M 193 in the two SP1s I had.

It shoots either, although, good reload 223s shoot better then the ball 5.56. They dont like the heavier bullets but thats do to the 12 in twist, not the gun per se.

[5.56RifleGuy]

Alright thanks, the lower is an a3 lower marked 223 but i couldnt find anything on the upper. I figure since the chamber is all in the upper, that is what matters. I use 55 grain 223 and it shoots great out of the 1 in 12 barrel.

So really, what is the difference between shooting 556 vs 223? I have heard 556 has higher pressure, but does that mean faster round or something?

thanks
Devin

[kraigwy]

what is the difference between shooting 556 vs 223? I have heard 556 has higher pressure, but does that mean faster round or something?

Nothing that really matters, but you'll get people telling you all kinds of crap.

They have differant pressures because the army uses a differant system in messuring pressure.

For the AR, you wont tell the differance unless, like I said, you can put together some pretty accrute reload that will out shoot the M193s.

I have a bolt gun I carried as a LE Counter Sniper rifle before I retired. On duty I carried M-193s in it, again no differant except I could reload some better stuff, but the department sniveled when I got caught with reloads.

Like I mentioned before, I had access to lots of M193 ball, shot tons of it in both rifles with zero problems.

[RockyMtnTactical]

http://ammo.ar15.com/ammo/

[dreamweaver]

same as RMT posted, just specific to the recommendations for .223 vs 5.56
most folks agree; ok to shoot .223 in a 5.56 but not the other way around.


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

[5.56RifleGuy]

Thank you very much.

You have all been very helpful.

Devin