Recently I picked up my SilencerCo Specwar 762. I hadn't ever shot my 17s with a suppressor before. Presently, the gun probably has around 2200-2300rds on it since buying it new in 2012. the last 200 or so rounds were using the suppressor.

Initially, I purchased a 1.35 and a 1.40 Gas Jet from Jarrod at Parker Mountain. I installed the 1.40 and off I went to the range. I put about 180rds through the rifle with the 1.40 gas jet, and of course on the suppressor setting which I verified multiple times. As I was about to wrap up, I thought I'd put another 20 rounds through the gun, I picked it up and I noticed the bolt carrier seemed sluggish, and didn't want to unlock smoothly. I took the gun apart, noticed that the bolt seemed stiff in the gun. I figured initially maybe some debris had gotten in there. I put it back together and I fired the last 20 round magazine without the suppressor on, it fired and fed the entire magazine without issue and locked back upon being empty

One thing I'll point out is with the 1.40 gas get, the rifle would cycle and lock back on the suppressed or unsuppressed setting without the silencer mounted to the gun. This should have been a clue, but considering I had never shot the gun suppressed, I didn't know that. The gun was still cycling hard in the suppressed setting without the can.

So I get home and take the weapon apart and start looking at whats going on. I took a fat Sharpie and painted the entire bolt with it and inserted it into the carrier looking to see if there were any drag marks on the bolt.





My goal was to determine where the burr had formed, or what had stopped it up.



The bolt stops right where the cam pin slot starts. A small burr, barely able to be felt had formed there. Whether it's peening, or what I don't know. Either way, this seems to have happened due to running the suppressor as it has been flawless prior to this. This gun was purchased new in November of 2012. After lengthy discussion with Jarrod at PMM, he has stated he's seen this before and this is probably the early stages of this. He would run the gun until is explodes, I however will not. It seems bolt carriers are in short supply.





I was able to remove the burr using 220grit and some ceramic hones and it no longer hangs up, however, at this point, I question whether to keep stepping the gas jets down until the gun chokes and then find the happy medium, or do I quit shooting the rifle with a suppressor.

Keep an eye on yours.

Your suppressor is fairly high back pressure, so you can almost certainly go to a smaller gas jet. For instance, I run a 1.35mm and I'm using a surefire socom 762 mini 2, which is practically a moderator. My rifle shoots softer with the suppressor than without.

Right. I had a long discussion with Todd Magee from a Dead Air and we discussed this matter particular pertaining to the SCAR and it's bolt speed issues. I think my game plan is actually to start with a 1.20 and work my way up from there. I want to make the gun choke and then find that happy medium where it works with a variety of different loading.

Long reads but this is a great place to know why this is happening. Even if you are not a fan of the final answer, these articles pass on ALOT of info. Understand if you run a suppressor, you have to tune it. FN knows where to look on a BCG to determine if its been run suppressed.

https://www.handldefense.com/2018/06/suppressors-and-the-scar-part1/

https://www.handldefense.com/2018/07/suppressors-and-the-scar-part2/

https://www.handldefense.com/2018/08/suppressors-and-the-scar-part-3/

Check your cam pin for signs of deformation as well.

There wasn't any deformation, per say, but there was a bit more wear than normal. I'm going to replace the cam pin.

I had read this the other day before I made this post. I had the exact same wear he talked about it Part 1, and removed the burr like he did. It's quote unfortunate that having owned this gun since 2012, and having shot it a lot without a suppressor, mounting a suppressor on the firearm has made me not trust it, and that sucks.

Definitely start with your gas screw. If you're running it with the 1.4 and it runs in both modes WITHOUT the suppressor attached then you are definitely over gassed and of course adding the suppressor only amplifies that. You're on the right track by going way down in jet size and working up. I think I'm running Jarod's 1.35 right now myself in both of mine and that seems to be good for me. I'm using the TBAC Ultra 7 and 9. When suppressed the rifles get dirty but I've not had the issue you are.

Good luck.

Just to give a brief update to this, I installed a 1.35mm gas screw the other day. The rifle would cycle on the non-suppressed setting just fine. On the suppressed setting the rifle would not lock back, or pick up the next round in the magazine. I mounted the Specwar 762 and fired several rounds while in the suppressed position and the rifle cycled fine. I feel I could in fact go to a smaller gas screw, perhaps 1.30mm.

After firing about ten rounds, I disassembled the rifle and took a look at the BCG. The burr has popped back up, albeit smaller and not causing much of an issue, but at this point, I think I'm going to discontinue using a suppressor on my 17s. Perhaps down the road I will buy a Surefire 762RC-2, but it's just not in the cards right now. Disappointing.

maxflo low backpressure supressor?

Unlikely to be added to my lineup.

That last group of shots you fired, was that with the 1.30 or still the 1.35?

1.35 - I do not have a 1.30 gas jet.

You should keep an eye on that location on your carrier while shooting without a suppressor for awhile. The wear point you indicated in your original post is under stress when the bolt is closing, not opening. A severely over gassed gun would still increase the cycling speed on both the back and forward movement of the carrier because it would bounce off the end plate, but the cam pin is always hitting that spot as the carrier goes forward, regardless.

In my 17 I find that the cam pin usually ends up with flat spots where the main contact is made during both directions of movement.

My cam pin has some flat spots as well. I have a new one in bound. I removed the suppressor mount tonight. I'm done shooting it with a can. I'm not going to blow it up and have to buy a $380.00 bolt carrier that is impossible to find. Just not worth it to me.

It's normal to see wear on the cam pin. When you have two pieces of steel slamming into each other one has to give, and in this case it's the cheaper of the two that you want this happening to.

Right. I'm aware that some wear is normal. I've been shooting AR's long enough to know that you're going to see wear on a cam pin, so it can be assumed it would happen on the SCAR. It seems to have been further aggravated by the use of a suppressor.

I put maybe 40 rounds through mine with either a 1.35 or 1.3 gas jet and a can on...I need to go back and check. It barely cycled without a can on and with it in suppressed mode; I don't think it locked back on an empty mag without the can. Again - this is by rote memory and I could be mis-remembering. I haven't really had a chance to wring it out with a can on it.

FWIW, my can is a Dead Air Sandman-L.

I'll check when I get home, which gas jet I have installed.

FWIW my SCAR17 is an early one I think, I bought it in very early 2011. They didn't add the extra lug to the bolt until after I bought mine.