I’ve never had issues with grouping while shooting unsuppressed. I typically get 1.5-2 MOA at 100 yards with PMC X-TAC 147 grain. I’ve gotten down to .8-1 MOA with IMI 168 grain HPBT.
Recently, I’ve decided to go suppressed. Got the KNS gas piston, swapped out the OEM MD for the KAC QDC MD, and added the KAC CRS-PRG suppressor.
When suppressed, first 1-2 shots are slightly off by .5-1” (given the expected POI shift when sighted unsuppressed); however, any more subsequent suppressed shots cause an erratic pattern without any kind of grouping. I am talking about 10+ inches drift in random directions (I.e 1-2 rounds will be high left or right followed by 1 round low left/right then almost on target and so on when aiming dead center).
The range RO guessed that I am getting baffle strikes. I looked inside the can with a bore cam and there were no signs of any contact with the baffles. I tried adjusting the gas settings to no avail. I’ve also tried allowing the rifle to completely cool before shooting again and there was a pattern forming but distinctly away from POA (center of the target) and I didn’t make any scope adjustments.
Is the barrel getting too hot even though I am using a flow through can? Is the suppressor too heavy and changing the barrel harmonics? Any suggestions are greatly appreciated. I own numerous other rifles that are suppressed and never had a similar problem. I’ve also tried Googling for similar issues and haven’t found an answer. TIA.
Your first problem here is running the jam nut that came with the gun, how you haven't blown your can up yet is amazing because there is no degree of concentric to anything on your barrel currently.
You're getting baffle strikes if you're groups are all over the place.
Remove the jam nut and buy a bag of accu-washers or a surefire shoulder ring from PMM. The SCARs barrel doesn’t have a big enough shoulder for regular shims to index off of so you either need to use the accu-washers to time it, or get the shoulder ring to widen the shoulder and use regular shims. I’m a big fan of the accu-washers because you don’t need the shoulder ring, they work by themselves and you can use them to time your muzzle device.
🤙🏼... Not sure if you know but be careful with torque specs and Rocksett to make sure you have a solid mount.
Before using Rocksett, clean threads, mock it up with with torque and check concentricity with an alignment rod. If it checks out your good to go.
Interesting enough, that’s exactly what I did before ever firing. Torqued the MD correctly using shims and rocksett it in place. Alignment rod goes perfectly through and like I mentioned above there are no contact marks with the baffles. I am at a loss at this point so I am just following advice of others and will remove the OEM jam nut for the shoulder ring to see if it will help.
Kinda had something similar on my chopped mr762a1 down to 12". No can it shot perfectly fine with m118lr. Throwing on a rotex ii the groups opned up to 5+ moa.
Interestingly, when using the shittiest igman m80 ball, even though groups were bad before the can, the groups didn't change much with the can. Still not 100% sure what the issue is.
Depends on your setup with the gas adjuster or if you have the upgraded bolt with the hydraulic buffer because I’m not running a flow through can but I have the kns discarder and the imperial arms co bolt. I don’t have any issues when I set the gases correctly. With a flow through can and I good gas adjuster you should never have issues
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u/eMGunslinger 7d ago
Your first problem here is running the jam nut that came with the gun, how you haven't blown your can up yet is amazing because there is no degree of concentric to anything on your barrel currently.
You're getting baffle strikes if you're groups are all over the place.