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Posted: 1/13/2015 10:07:10 AM EDT
| What is the proper way to pin a flash hider to a 14 1/2" barrel to make it legal? Where do you drill the hole and how do you start it? Also, what size pin is recommended. This will be for a .30 caliber barrel (300 AAC BLK). I will not be using a suppressor on this rifle. |
| You just gotta drill in until you contact the barrel threads. So say the OD of your FH is .750" and your threads are 5/8-24, you'd want to go about 3/16" deep, (1/8" using these numbers as reference will just touch the threads' major diameter, and thus, not help permanently affix your flash hider) more than that and you'll be getting mighty close to the barrel bore, less and you won't be positively contacting the threads. I use 1/8" pins, start with a #3 center drill, then drill with a undersize drill (#33-36, or 7/64) and then 'drill ream' (chase) the hole with a 1/8" drill. Always use some form of cutting oil. Push in 1/8" dowel pin, weld over, done. If you drill thru to the bore, send me the barrel and I can shorten and rethread it and affix your flash hider for you. |
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The BATF have three approved methods of attaching a muzzle device.
1. Silver soldering. This means REAL silver solder (braze) that must melt above 1100 degrees. 2. Welding. The weld must go around at least 1/4?? of the device. I may be wrong, it may have to be 1/3rd or so. 3. Blind pinning AND welding. You have to weld over the end of the pin. This doesn't require much, so most any welder can put just a small bead on the end of the pin without having to put a huge glob on it. Yes you probably could fake the weld and you'd likely get away with it unless someone took a close look at it. That's illegal and at your own risk. Since the weld can be very small then filed flush and covered, just do it legally. You don't need to have an unsightly glob of weld on it. All the welder needs to do is "pop" a small bead on it and as long as you don't file it all away, you're good. |
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Quoted:
The BATF have three approved methods of attaching a muzzle device. 1. Silver soldering. This means REAL silver solder (braze) that must melt above 1100 degrees. correct 2. Welding. The weld must go around at least 1/4?? of the device. I may be wrong, it may have to be 1/3rd or so. 1/2, not 1/4 3. Blind pinning AND welding. You have to weld over the end of the pin. correct These requirements are derived from a 1998 opinion letter (still during the AW ban) which stated -some- acceptable methods, not the only methods, which meet the ATF definition of "permanently attached". No definitive ruling has been issued, so other methods may well still be acceptable, but those stated above are known to be acceptable. If you decide to go outside the realm of the known acceptable methods, you're on your own submitting a sample for determination, or taking your chances ex post facto. |
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Quoted:
One more question. What if you used a slightly oversized pin and hammered or pressed it all the way into the hole, cut it off and filed it flush with the FH and then painted it? How could anyone tell if it was welded? Do not f*@k around with this. Do it right and don't worry about it. BTW, do you know how to measure legal barrel length? On the assembled rifle with closed bolt, rod the bore from the bolt face to the perpendicular plane of the end of the barrel. Carefully mark the rod using a straightedge across the muzzle. Remove rod and measure from the bolt end to the mark - must be 16.0" or greater. Most people will calculate it so there's just a little extra length, say 1/8" to 1/4" just for good measure. When you permanently attach an object to the end of the barrel, you are making a barrel extension. Obviously it must be permanently attached by the approved methods so it cannot casually be removed, creating a 'short-barreled rifle' (SBR). |
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^^^ Sage advice.
I do my damnest to pin and weld whenever possible. I'm not a fan of putting the heat required to get silver solder to flow well on what is arguably the most critical part of the barrel. I TIG the pins as well with a .040 tungsten and 50 amps, it puddles the pin/FH nicely without too much heat on the barrel. Usually I can get just a small weld that is easily touched up with a drop of cold blue. |
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