shibiwan Posted March 2, 2014 Report Share Posted March 2, 2014 Is it legal to have a 300 blk upper on a lower that is marked 5.56 ? Quote Link to comment Share on other sites More sharing options...
BLKSHEEP Posted March 2, 2014 Report Share Posted March 2, 2014 I've been wondering the same thing, I've been thinking about building a 300blk but the lower I want is marked 5.56 not multi Cal. ? <munch> Quote Link to comment Share on other sites More sharing options...
Dane Armory Posted March 2, 2014 Report Share Posted March 2, 2014 Shibiwan , this is AZ that does not matter. It would make a difference if it was a pistol and you wanted it engraved with "AR PISTOL" on the lower. Since yours has a 16" barrel you are good to go, Quote Link to comment Share on other sites More sharing options...
Rsquared Posted March 2, 2014 Report Share Posted March 2, 2014 It's perfectly legal to have a 300 BLK upper on a 5.56 lower. After all...that's the point isn't it? It's based off of using the 5.56 casing....just with a 30 cal projectile. That's how you start with the platform. And actually, I don't think that there are any dedicated 300 BLK lowers out there (could be wrong though). Mine is a DD lower (registered as a SBR lower) with a 300 BLK upper that I built. If you're not going below the 16" barrel length mark....it doesn't make a difference what anything is marked. Quote Link to comment Share on other sites More sharing options...
shibiwan Posted March 2, 2014 Author Report Share Posted March 2, 2014 (edited) Shibiwan , this is AZ that does not matter. It would make a difference if it was a pistol and you wanted it engraved with "AR PISTOL" on the lower. Since yours has a 16" barrel you are good to go, Gotta love AZ! Mine's a 14.5 but I'll be pinning on a long flash suppressor that will just make 16" and a little bit. BTW, did some checking on the interwebz after I posted and it looks like it is legal to do it. BATFE goes by the initial registration of the rifle and any caliber changes after the fact is legal. You could be nice and send them a change notification but that's not required. Edited March 2, 2014 by shibiwan Quote Link to comment Share on other sites More sharing options...
survivalshop Posted March 2, 2014 Report Share Posted March 2, 2014 (edited) Actually the BATFE has said that the Muliti Cal. is not legal because it has not got a caliber stamped on it . Required to have a Serial number & caliber , but it was discussed here before that almost all bolt actions would be illegal because they are made with serial number only ( most military rifles have the caliber/ser.# on the receiver ) & not caliber on the receiver , the caliber is on the Barrels . There BAFTE may have different standards for AR"S & they can change at a whim. Dedicated lower for 300BLK Edited March 3, 2014 by survivalshop Quote Link to comment Share on other sites More sharing options...
Masgtions99 Posted June 10, 2014 Report Share Posted June 10, 2014 (edited) I Is it legal to have a 300 blk upper on a lower that is marked 5.56 ? I've never seen any BATFE myself that says it's not legal. Case in point your own a glock or a 1911, you can chage uppers to make 9mm, 40. or 45. the regulation says the receiver/lower (part that makes it function) must be marked with a serial number and optional other information depending on the circumstances per the manufacturer. Another point is the 80% lower, no number at all required until it chages hands! Im not a legal expert but......the BATFE changes things on a whim! Edited June 10, 2014 by Masgtions99 Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted June 10, 2014 Report Share Posted June 10, 2014 The serial numbered receiver is the controlled portion and all the feds care about. Unless it's Friday, or a holliday, or cellophane remembrance day, or they just need something to do. Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted June 10, 2014 Report Share Posted June 10, 2014 Unless it's Friday, or a holliday, or cellophane remembrance day, or they just need something to do. Got me laughing good on that one Jon Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 11, 2014 Report Share Posted June 11, 2014 (edited) Marked caliber comes into play when you're registering a Short Barreled Rifle. After you have the stamp for your SBR 5.56 rifle, you can legally mount and shoot a short barreled 300BLK upper if you want - but you better not get rid of the shorty 5.56 upper. If you wanted to permanently convert your legal 5.56 SBR to 300BLK, forever, you better be sending in a form before you do it. Otherwise, it doesn't matter. On a state-view, it all comes down to pistol config. Some states require your AR pistol to be on a marked pistol lower. Research that for your state. Otherwise, it doesn't matter. Edited June 11, 2014 by 98Z5V Quote Link to comment Share on other sites More sharing options...
StainTrain Posted June 11, 2014 Report Share Posted June 11, 2014 Marked caliber comes into play when you're registering a Short Barreled Rifle. After you have the stamp for your SBR 5.56 rifle, you can legally mount and shoot a short barreled 300BLK upper if you want - but you better not get rid of the shorty 5.56 upper. If you wanted to permanently convert your legal 5.56 SBR to 300BLK, forever, you better be sending in a form before you do it. This is correct. Your barrel stamp will suffice on non-NFA items. Quote Link to comment Share on other sites More sharing options...
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