Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.
Here's the delrin model of what I'm planning. The shoulder is 60* with a two start ACME stub thread (lead 8 pitch 4). Currently the holes are both 1/2 inch but I'm planning on the first hole to actually be 5/8 inch.
Anyhow, my question is on the threads. I allowed for 1/2 inch of threads just because that seemed like a good number. I see that leaves me with four full threads most of the time. I was wondering if I would be alright cutting that back 1/8 inch. That would remove one of the threads and leave me with apx 3 full threads. What's ya'lls opinion on that?
When I drew up plans for my QD i had a preset length i wanted in my head and when it came time for threads .50 popped in my head too.. I just left it at that and haven't had a problem. I don't see it being a problem especially with your tapered shoulder. it'll help lock down and center. Best -John
"A man is known by the silence he keeps. - Oliver Herford"
"Gunpowder, treason and plot. I see no reason why gunpowder, treason
Should ever be forgot..."
One problem I see is your thru hole. When you drill from the rear with the tap drill for the threads you want to drill that diameter into both ports, if the diameter tapers down before it breaks into the first port you will get some crazy POI shifts and bad groups.
curtistactical wrote:One problem I see is your thru hole. When you drill from the rear with the tap drill for the threads you want to drill that diameter into both ports, if the diameter tapers down before it breaks into the first port you will get some crazy POI shifts and bad groups.
It doesn't taper. It is milled with an endmill giveing a flat serface with sharp corners. It works as a brake of it's own with a port on the top. I took the idea from Benny Hill's 'Rolling Thunder' Muzzle Brake. If you're not familiar with them just do a quick google search. They've been very successful.
john.t.little1 wrote:When I drew up plans for my QD i had a preset length i wanted in my head and when it came time for threads .50 popped in my head too.. I just left it at that and haven't had a problem. I don't see it being a problem especially with your tapered shoulder. it'll help lock down and center. Best -John
Yeah, with a little more thought on the matter I think you are correct. Thanks!
curtistactical wrote:One problem I see is your thru hole. When you drill from the rear with the tap drill for the threads you want to drill that diameter into both ports, if the diameter tapers down before it breaks into the first port you will get some crazy POI shifts and bad groups.
It doesn't taper. It is milled with an endmill giveing a flat serface with sharp corners. It works as a brake of it's own with a port on the top. I took the idea from Benny Hill's 'Rolling Thunder' Muzzle Brake. If you're not familiar with them just do a quick google search. They've been very successful.
Thank you for the new information. I must confess that at first I thought
you were making some funny joke referencing a
BBC Benny Hill who was an outlandishly 'sexist',
in the best tradition of Vaudeville, funny British Comedian:
If the silencer becomes loose, it will end up unscrewing further with less effort than if you had a finer pitch. That could lead to a baffle strike.
Most thread over muzzle brakes that I have seen use a finer pitch thread pattern (Griffin, Wilson, SAS, etc). All of the ACME threaded devices use a retention method of some kind (YHM, AAC)
curtistactical wrote:One problem I see is your thru hole. When you drill from the rear with the tap drill for the threads you want to drill that diameter into both ports, if the diameter tapers down before it breaks into the first port you will get some crazy POI shifts and bad groups.
It doesn't taper. It is milled with an endmill giveing a flat serface with sharp corners. It works as a brake of it's own with a port on the top. I took the idea from Benny Hill's 'Rolling Thunder' Muzzle Brake. If you're not familiar with them just do a quick google search. They've been very successful.
Thank you for the new information. I must confess that at first I thought
you were making some funny joke referencing a
BBC Benny Hill who was an outlandishly 'sexist',
in the best tradition of Vaudeville, funny British Comedian:
Benny is one heck of a shooter. I met him in Corpus when I was a poor collage student trying to shoot IPSC on a budget. He's actually the father of one of my high school friends too. He's a great guy always willing to help out new shooters. I try to stop in at his shop to say hi whenever I'm back in Corpus.
Edit to note: Regarding the late comedian Benny Hill. I remember sitting up lat at night watching his shows on TV. I really liked his stuff. And on a side note; The Benny Hill in Corpus does have a more than just a little resemblance to the comedian. No kidding on that either.
Last edited by L1A1Rocker on Mon Oct 13, 2014 1:16 pm, edited 1 time in total.
If the silencer becomes loose, it will end up unscrewing further with less effort than if you had a finer pitch. That could lead to a baffle strike.
Most thread over muzzle brakes that I have seen use a finer pitch thread pattern (Griffin, Wilson, SAS, etc). All of the ACME threaded devices use a retention method of some kind (YHM, AAC)
The shoulder idea came about from the ThunderBeast:
And the ACME thread idea came about because I didn't like the idea of exposed V threads. Going with the double start makes it screw on much faster. As far as unscrewing goes, others have done this without having issues, so we'll see how it goes.
