View Full Version : Deadair mount on DSA barrel question

November 19, 2017, 19:16
Got a home-built FAL using a DSA 21" medium contour barrel, and I'm wanting to mount a Deadair mount to run my Sandman-S suppressor on it using a 9/16x24LH 3-prong flash hider adapter.

The problem I'm running into is the barrel is profiled in such a way that I cannot use any supplied shims to time the FH, and the FH bottoms out with muzzle threads still visible. I think it looks wonky, and would like some suggestions on any options that might help this. So, if anyone else is using a deadair mount to suppress your rifle, please show me how yours fits.

The barrel is designed to use this brake:

http://i292.photobucket.com/albums/mm21/animator752/IMG_6988_zpscwh3sm7x.jpg (http://s292.photobucket.com/user/animator752/media/IMG_6988_zpscwh3sm7x.jpg.html)

Here you can see the adapter, along with how the barrel necks down the last couple inches, and offers no shoulder for the FH to back up against. Any shims just slip over this turned-down area, so they aren't much help. You can also see the remaining threads visible. The FH is fully tightened at this point, and can not go on any further.

http://i292.photobucket.com/albums/mm21/animator752/IMG_6985_zpsmwp7pxuu.jpg (http://s292.photobucket.com/user/animator752/media/IMG_6985_zpsmwp7pxuu.jpg.html)

The can mounts up no problem, but I'm worried about the FH coming loose, in addition to just looking wrong:

http://i292.photobucket.com/albums/mm21/animator752/IMG_6986_zpsslhv3pgc.jpg (http://s292.photobucket.com/user/animator752/media/IMG_6986_zpsslhv3pgc.jpg.html)

Complete rifle, just because:

http://i292.photobucket.com/albums/mm21/animator752/IMG_6987_zpso7x6xbm6.jpg (http://s292.photobucket.com/user/animator752/media/IMG_6987_zpso7x6xbm6.jpg.html)

So I'm considering cutting the barrel down and re-threading it to make the FH fit better. Downside is I lose the ability to return to the current muzzle brake. I'd really rather not cut the barrel down unless I have to, so are there any other options out there that I'm just not aware of? I'm very new to suppressors and just don't know all the options that exist.

Or another option is to just not run this gun suppressed, I suppose, but that's no fun...:D

November 19, 2017, 20:10
I don't think you will get a lot of support on the suppressed FAL here. I did however have a similar issue on a SCAR 17 with no really good shoulder. I did not have the issue of bottoming out in suppressor mount as you have but i corrected mine with a perfect machined but thin spacer between barrel shoulder and back of mount. Just be sure you have not interfered with the alignment of your suppressor when tightening the mount to this shoulder spacer. If you went this route i would use a gauge rod in bore continuing through your suppressor to check this.

All of the above is the way i corrected my SCAR problem and i'm sure most anyone here knows more than i do.

November 19, 2017, 20:19
I would shoot it and not worry as long as it's tight. I shoot a suppressor with a QD FH. Timing doesn't bother me because it's correct with an IMBEL FH should I want to go back. It's bottoming out on the muzzle as most FALs FHs do.

Capt D
November 19, 2017, 20:30
The first thing you will have to find is the thread here on the Files about altering the gas plug, to best run the gun suppressed...the FAL was never designed to run with a suppressor, so the effect, once you do get it running you would have an over-gassed weapon.

Depending on how long threads on your barrel are, you might be able to use a jam nut (I highly recommend Rousch Sports' ones:
https://rouschsports.com/shop/tools/gunsmith-tools-ar15/go-nuts-jam-nut-stainless-steel-12-28-916-24-58-24/ ). To ensure concentricity, you will definitely want at least 1/2"-5/8" worth of threads positively engaging the muzzle device threads...lest you risk a baffle-strike. Considering the barrel's provenance as being born/profiled at DSA, I would imagine you would only have 1/2", or less, worth of threads to begin with, so the jam nut idea is likely out, unless you re-thread.

In short, I'd recommend you either send both barrel and device to one of the members here who do such work... or just go unsuppressed. Especially if you don't intend to adapt a gas plug to the task...unless you run OSS cans (I HIGHLY recommend them, too...). YMMV. --Art

November 19, 2017, 20:45
I'm aware of the gas plug mod, and will probably be picking up another plug soon to make myself.

I've toyed with the thought of machining a sort of sleeve to fill in the stepped-down area, that would have a tapered end enough to give me a good shoulder to butt the FH up to, as well as get it timed to my liking. I'll of course check concentricity once it's done.. but that was all I could think of aside from trimming the barrel...