Anyone cut down a SCAR20S barrel?  Thinking about either cutting down and having it profiled for an Allen Engineering suppressor, or cutting down where a suppressor will sit flush with the receiver.  Also, any experience with gas jet size?

Yes.

I did not reprofile mine but did cut to 16.1" with a target crown...threaded to 5/8-24 of course.

My smith did a great job timing the barrel where I do not have to use shims/shoulders...if you just cut it t 16" without a reprofile...the barrel has a ton of shoulder room...

Gas jet wise I am running a 1.3mm with a traditional baffle suppressor (YHM R2).

It is the best thing I have done to my SCAR 20...hands down...

I think an Allen suppressor would be sweet on there...

Thanks for the info.  I’m wondering if the barrel diameter is large enough to profile the taper in instead of using the AE collar.  Do you know approximately how much barrel you have sticking out of the receiver after the chop?

Total exposed is about 2.4"ish without a muzzle device...

I am pretty sure you'll have to profile the barrel to fit an AE collar...

Thank you.  I’m aware of the profile, but I’m thinking I’ll be able to have the taper profiled directly into the barrel rather than having a step for a collar.  The barrel diameter seems thick enough.

For sure and that would be sweet.

Not sure what length the collar requires so you might have to go 16.5”…

Either way I have zero regrets cutting my barrel.

I was thinking about profiling mine for my Ops Inc. 12th model, but after shooting it for a while with a SilencerCo Saker, I decided to go with a lower back pressure suppressor. Mine would not function 100% suppressed and I was seeing one or two FTF per magazine unsuppressed (depending on what load I was shooting) with the 1.3mm jet and that was the most reliable combination I was able to find.

On my 7.62 AR's the 12th model generates quite a bit more back pressure, to the point I run adjustable gas blocks and heavy buffers and I adjust the gas depending on whether I'm shooting suppressed or not.

The Ops Inc. suppressor is second to none for sound suppression, at the price of back pressure, which is one thing the SCAR 20 doesn't handle well.

I've since cut mine to 18" and I'm running the SureFire RC2 with a 1.4mm gas jet. It's been 100% reliable suppressed or unsuppressed with everything from 155gr. to 178gr. handloads. I went with 18" because I really like shooting out to 1000 yards and I won't be able to push my 175gr. loads fast enough with a 16" barrel. 18" gets me there, but barely.

1.3mm is the universal go-to with 16”…not sure where I’d start with 18”…

If you had FTF but not FTE … you didn’t have enough has with your loads…so maybe a 1.35 or 1.4 would have worked better…but it looks like the RC2 solved your problems…

I see you are in UT so a slightly more gas jet is probably needed…

My experience is with a YHM R2 at 1100’ altitude…

All of my issues were with the 20” barrel, running the Saker. I was seeing FTF and FTE, as well as last round hold open issues, depending on which jet I was using. Running suppressed with the stock 1.4mm jet gave me about a 50% function rate, going with a 1.45mm jet, thinking I needed more gas, reduced reliability even more. Working down to the 1.35mm jet improved reliability a little and going to 1.3mm jet saw a significant increase in reliability. Dropping to 1.25 gave me about about a 90% function rate suppressed, but about a 5% function rate unsuppressed. Anything less the 1.35mm gave me significant issues unsuppressed while anything more than 1.3mm gave me issues suppressed. I even tried a bunch of factory ammo, which didn’t help. All of this is what lead me to believe the Sakers increased back pressure was causing my problems.

Swapping to the RC2 with the 20” barrel and the 1.35mm jet functioned 100% suppressed and unsuppressed, that’s when I decided to chop the barrel to 18”. Going with the 1.4mm jet was my starting point, figuring that the shorter barrel would have about the same back pressure as the 20” with the 1.35mm. Once I get some time, I’ll test how it runs with the 1.35mm jet.

Just sent mine off to get cut and profiled for my surefire FA762SS

Nice!

Where did you send yours?

I cut mine down as well.  I agree with Hun- it is the best thing done to mine!  It just feels right now and cycles more smooth.  It is still amazingly accurate as well.  D Wilson did mine and pretty fast turnaround time.  I think it is 180.  I did not change my jets and it cycles everything 100% even shit Wolf steel cased, locks back on empty mag.  

https://imgur.com/a/WhGB4o5

This is the way.

I truly think this is the best configuration for a SCAR 20 in .308...but that is me.

It is also quite evident that many European units do not like the SSR stock and have swapped for either the fixed or folding UGG (as have I) and go for the PR designation vs the TPR...

The SSR stock to me doesn't offer much...it had more slop than I cared to have and it weighs just too dang much...it does look cool though...

Looks great - what length is that now? 16"?

Sent it to D Wilson

Talk to ADCO.  They did something similar for me and it turned out great. If I can ever find a 30cal AEM5 I'll do the same thing to my 20S

You won’t be able to do this, not nearly enough barrel diameter. The reason for the collar at all is because the suppressor has to screw on to the brake. The brake diameter is usually larger than the barrel diameter in most cases, so the collar is used to increase the barrel diameter at the rear and give the suppressor something to “stop” against.

Profiling the rear “stop” directly into a bolt action bull barrel is workable because the bull barrel is already wider than the brake threads and the barrel diameter likely would have to be reduced anyway in order for the suppressor to slip over.

Basically, your existing barrel profile would need to be wider than than the AE/OPSINC brake threads by a couple millimeters in order to forgo the collar and have the same collar shoulder diameter for the suppressor properly supported.

I wish I could explain with actual measurements, but  don’t have calibers to measure mine, unfortunately.

Thanks for the reply.  Yeah after looking at the barrel, I’m pretty sure the barrel diameter is .750, which is definitely not enough.

I’m still debating on whether to cut and profile for AEM5, or just cut and use an AAC can.

This is an AE30 on a 16" SCAR 17 barrel, so not quite as thick as the 20, but you get the idea: