FN Herstal Firearms banner

1 - 19 of 19 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter · #1 ·
Hi, was wondering if anyone could provide me with some advice. I have a SCAR 17 (standard 16" barrel) and have recently attempted to suppress it using a Thunder Beast Arms 30BA. The SCAR shoots great unsuppressed; however, when suppressed, the POI is not repeatable at all. I don't experience a consistent shift which would be fine. At times I'm on target, then the POI might be off by several mils both horizontally and vertically.
Has anyone else experienced this or have any remedies?

Thanks.
 

·
Registered
Joined
·
208 Posts
I've run a variety of can's on my 17 and each have some POI shift, but it's repeatable. Not really had any problems. Never tried a TBA.
 

·
Registered
Joined
·
418 Posts
As Sten stated POI shift happens with all suppressors and some makes/models havefewer shifts than others.
A commonissue with the 17S is that it does not have a proper shoulder behind thethreads. This causes a problem becausethere isn't the mechanical interface required to ensure alignment.
Theissue is that the shoulder is what keeps the muzzle device straight and keepsthe can from moving during firing. Witha shoulder of insufficient diameter there is nothing to mechanically keep themuzzle device in line with the bore. Youhave to use the SCAR factory jam nut as the barrel shoulder.
(1)Screw the jam nut all the way back (towards the action) until it bottoms out("shoulders") on the shoulderon the SCAR barrel and make sure it's tight.

(2) Screw on your can using the normal precautions until it bottoms out (“shoulders”)directly against the jam nut.

(3) THIS IS CRITICAL, CHECK ALIGNMENT. In the instructions that came with your 30BA,there should be instructions on how to verify the suppressor is mountedstraight on the barrel. This involvesremoving the bolt (more involved on some semi-auto rifles like the SCAR) andlooking down the barrel from the breech (chamber) end. You should see the shiny barrel and then aperfectly concentric shadow from the suppressor. If the shadow from the suppressor looks likea half moon shape or is in any way not completely concentric with the bore yoursuppressor is probably not mounted correctly.

Once you have a square shoulder it should pull your POI together somewhat butyou will still have some POI drift, hopefully it will be more repeatable foryou. To my knowledge Thunder Beast Armsdoes not make a SCAR specific break to mount your can to.

Youronly other alternative would be to have a gunsmith/machinist fabricate you acustom adapter for mounting your suppressor.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #4 ·
Thank you sir for the advice. I believe I mounted the 30BA brake per TBAC's instruction; I tightened the jam nut all the way down on the barrel (bottomed out), then installed the proper peel washers in order to time the brake, then applied a bit of lock tight and tightened/timed the brake. Looking down the bore, it appears concentric . I just don't if having the peel washers is a bad thing? Is it better to disregard the washers and go untimed?

you are correct, TBAC does not offer a SCAR specific brake, but I've heard others using similar procedures successfully.

As Sten stated POI shift happens with all suppressors and some makes/models havefewer shifts than others.
A commonissue with the 17S is that it does not have a proper shoulder behind thethreads. This causes a problem becausethere isn't the mechanical interface required to ensure alignment.
Theissue is that the shoulder is what keeps the muzzle device straight and keepsthe can from moving during firing. Witha shoulder of insufficient diameter there is nothing to mechanically keep themuzzle device in line with the bore. Youhave to use the SCAR factory jam nut as the barrel shoulder.
(1)Screw the jam nut all the way back (towards the action) until it bottoms out("shoulders") on the shoulderon the SCAR barrel and make sure it's tight.

(2) Screw on your can using the normal precautions until it bottoms out (“shoulders”)directly against the jam nut.

(3) THIS IS CRITICAL, CHECK ALIGNMENT. In the instructions that came with your 30BA,there should be instructions on how to verify the suppressor is mountedstraight on the barrel. This involvesremoving the bolt (more involved on some semi-auto rifles like the SCAR) andlooking down the barrel from the breech (chamber) end. You should see the shiny barrel and then aperfectly concentric shadow from the suppressor. If the shadow from the suppressor looks likea half moon shape or is in any way not completely concentric with the bore yoursuppressor is probably not mounted correctly.

Once you have a square shoulder it should pull your POI together somewhat butyou will still have some POI drift, hopefully it will be more repeatable foryou. To my knowledge Thunder Beast Armsdoes not make a SCAR specific break to mount your can to.

Youronly other alternative would be to have a gunsmith/machinist fabricate you acustom adapter for mounting your suppressor.
 

·
Registered
Joined
·
1,699 Posts
You've got an odd problem. I've use my 30P-1 on my SCAR several times, each time using the jam nut as the "barrel shoulder" and it's worked well. I would IM Zack at TBAC, he's always got a great answer for anything TBAC.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #6 ·
Thank you, I've got an email into Zac. I think it has to do with the peel washers I'm using between the nut and brake. I reevaluated my suppressor alignment and I am second guessing whether or not it's concentric.
 

·
Registered
Joined
·
418 Posts
Assuming your POI shift is vertical?
I think I would not use the peel washers if you can time the can directly to the SCAR jam nut without a baffle strike. The extra peel washer sandwiched up against the SCAR jam nut might be compounding your shoulder alignment issue.
 

·
Registered
Joined
·
148 Posts
As Sten stated POI shift happens with all suppressors and some makes/models havefewer shifts than others.
A commonissue with the 17S is that it does not have a proper shoulder behind thethreads. This causes a problem becausethere isn't the mechanical interface required to ensure alignment.
Theissue is that the shoulder is what keeps the muzzle device straight and keepsthe can from moving during firing. Witha shoulder of insufficient diameter there is nothing to mechanically keep themuzzle device in line with the bore. Youhave to use the SCAR factory jam nut as the barrel shoulder.
(1)Screw the jam nut all the way back (towards the action) until it bottoms out("shoulders") on the shoulderon the SCAR barrel and make sure it's tight.

(2) Screw on your can using the normal precautions until it bottoms out (“shoulders”)directly against the jam nut.

(3) THIS IS CRITICAL, CHECK ALIGNMENT. In the instructions that came with your 30BA,there should be instructions on how to verify the suppressor is mountedstraight on the barrel. This involvesremoving the bolt (more involved on some semi-auto rifles like the SCAR) andlooking down the barrel from the breech (chamber) end. You should see the shiny barrel and then aperfectly concentric shadow from the suppressor. If the shadow from the suppressor looks likea half moon shape or is in any way not completely concentric with the bore yoursuppressor is probably not mounted correctly.

Once you have a square shoulder it should pull your POI together somewhat butyou will still have some POI drift, hopefully it will be more repeatable foryou. To my knowledge Thunder Beast Armsdoes not make a SCAR specific break to mount your can to.

Youronly other alternative would be to have a gunsmith/machinist fabricate you acustom adapter for mounting your suppressor.
Tagging this post for future reference. Thank you for this info.
 

·
Registered
Joined
·
508 Posts
I know it's what the suppressor manufacturer instructs one to do in this case and that some folks get by with it... but I thought using the jam nut as a shoulder for a suppressor mount was a big no-no on the SCAR? For my Specwar 762, I tightened the flash hider directly against the shoulder and it works perfectly and increases accuracy if anything. Is the muzzle device for the TBA designed in such a way that this is not possible?
 

·
Registered
Joined
·
1,024 Posts
Thank you, I've got an email into Zac. I think it has to do with the peel washers I'm using between the nut and brake. I reevaluated my suppressor alignment and I am second guessing whether or not it's concentric.
I think it has to do with the tiny shoulder on the SCAR barrel. It's like the little deformed hand of the butler in Scary Movie...

giphy.gif
 

·
Registered
Joined
·
16 Posts
I'm supprised there is no real clear answer or custom made jam nut for this problem. I have the same issues with mine. I picked up my direct thread can from Greentop Sporting Goods last month. You can read about it in a thread further down the list titled "TBA Suppressors ?". My experience had all the fun taken out of it, and I now have a can permanently Rock set onto the barrel. Thanks TBA and Greentop !
 

·
Registered
Joined
·
3,286 Posts
Ok, .... Maybe this will help. I had an issue several years ago with my YHM QD adapter. No one could say for sure what was causing my POI shift into unrepeatability.... it " ghosted " me for quite a while. What I did to lose my repeatability with only attaching the QD.... it was... (the solution ) I over torqued it..... and it was just enough to tweak the rifle's accuracy.
Sometimes the smallest thing causes grief... when I explained what was happening with my rifle everyone ( YHM ) ( FN ) wanted me to send in the weapon.... !
Hope this is of some help.

mjk1

I guess to add FN really has a niche in the market with the pencil thin barrels and the super accuracy....! It may not be surprising that even the little thing would effect it.
 

·
Registered
Joined
·
1,423 Posts
I would recommend reading Silencer Shop's Sticky , " SCAR 17 Muzzle Devise Compatibility List " their a forum sponsor with sound advice, it would be worth a read. Sorry I can't post a link I'm stupid.
 

·
Registered
Joined
·
757 Posts
I can't imagine why any manufacturer would recommend keeping the jam nut, there is no way it will provide a consistent shoulder. This is your problem. It's gotta be. If I were you, I'd remove it and remount the brake with the washers and check with an S.A.R. Or if I understood their website correctly-get one of the new FH and avoid the washer adventure altogether--still check with SAR.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
2 Posts
Does anyone have any accuracy information for the SCAR Heavy/17 with an SBR / 13" barrel. With standard brake and suppressed. Mostly used CQB & Suppressed but need to know how far out I could hit the bad guys accurately.
 

·
Registered
Joined
·
418 Posts
The 13" barrel was designed for CQC operations and you can expect it to perform well at ranges of 800m and less with the 175gr. M118LR and Mk316 Mod0 cartridges.

The reduction of barrel length will not in and of its self affect accuracy. Shorter barrels benefit from increased rigidity. You do lose velocity which affects drop and drift.

You will find that lighter rounds will go transonic earlier.
 

·
Registered
Joined
·
2 Posts
The 13" barrel was designed for CQC operations and you can expect it to perform well at ranges of 800m and less with the 175gr. M118LR and Mk316 Mod0 cartridges.

The reduction of barrel length will not in and of its self affect accuracy. Shorter barrels benefit from increased rigidity. You do lose velocity which affects drop and drift.

You will find that lighter rounds will go transonic earlier.
I wouldn't have expected it to perform "well" out to 800m. If i can get accuracy 200-250m that would work. We run 168gr so if anyone has any hard numbers it would be appreciated. Preferably in the SCAR. Have heard 20-25fps loss per inch. Velocity does matter but with only 3" difference how much would this loss affect accuracy out to 250m?
 
1 - 19 of 19 Posts
Top