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Posted: 9/3/2008 1:50:26 PM EDT
| Please be kind...your are dealing with a newbie here. I have been obsessively gathering info over the past weeks on building v. purchasing, manufacturers, etc. I have noticed that many of the lower receivers are marked "Cal. Multi". Does this mean that the rifle will safely fire both .223 and 5.56 rounds? TIA. |
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Lower has almost zero to do with what caliber you can fire from the rifle. i.e. most Colt rifles are shipped with cal .223 markings, and 5.56 NATO marked barrels. A standard AR lower (not an extended AR10/SR25/DPMS .308) can fire dozens of different calibers, hence the "multi" designation on some. The changes for caliber are all in the barrel and BCG, and magwell block for some calibers. My local store sells mixmaster rifles (at a premium  ) made from Colt 6450 lowers marked "9mm" but not drilled for magwell blocks, but the rifles fire 5.56/.223. The barrel will be marked with the proper caliber. HTH, ~Augee |
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The lower receiver really has little to do with what ammo will work in it , other than the obvious ability for it to fit in a mag that fits the receiver. AUGEE beat me to it. The "Multi" is to ease people's minds when they build up a 9mm, 40, 45, 50, 6.5, 6.8 or some other exotic or "non-standard" round for their AR. The upper contains the barrel and chamber, which is where it really matters. you may safely fire .223 in a 5.56 chambered barrel. You may experience high pressure symptoms if you fire 5.56 in a .223. |
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Augee.....thanks for the info. I guess I was specifically referring to complete rifles that had the CAL. MULT marking. I am looking at a particular rifle and I do not remember seeing anything stamped on the barrel, but know for certain the lower receiver was stamped MULT. so i figured that it was referring to the complete rifle. I need to verify with owner. Dave |
It's totally irrelevant what the lower reciever is marked; whether it's a complete rifle or a stripped part. ONLY THE MARKING ON THE BARREL IS IMPORTANT! And if there is no marking on the barrel, I guess you need to ask the opwner what it is. Any AR15 lower will work with any appropriate caliber upper. It does not matter what the hell is stamped on the lower reciever. Comprende?? |
I echo what the other posters have stated. Also, to illustrate the majority of the irrelevance of lower markings...you can have a lower marked .223 that has a chamber for 5.56 & vice-versa. Go by how the chamber is advertised but unfortunately not all chambers, say advervtised as 5.56 are such. There have been a few instances of incorrectly advertised chambers not being swhat they are supposed to be or some that are out of spec. Pay attention & be careful. Not a huge deal but it does happen. |
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