Looking for some advice here.  I've had a Stag Arms Model 2 for about five years, and it has been nearly flawless.  Using just an Aimpoint PRO RDS, from a bipod I am able to shoot fairly tight groups at 50 and 100 yards, and am mostly able to hit a 12" circle at 200 yards.  Recently, I have been unable to hit a 6" target at 50 yards with any consistency.  

Could the likely cause be barrel fouling?  Generally, all I do is shoot some Breakfree CLP down the barrel and run a bore snake through once or twice.  Recently, I poured some Hoppes down there, ran the snake through, and got a really tight group for my first few shots, but then the group opened up again (mostly high and right, FWIW).  

Would it be worth investing in a barrel cleaning rod, and/or taking it in for a professional cleaning?  Any thoughts or suggestions would be most appreciated.

Check your optics and mounts first. If all appears tight, take it off and shoot with irons to see if you get the same result - then chase your barrel demon.

Adios,

Pizza Bob

Definitely start with checking the optics mount first like Bob said. If that's not the problem then I'd maybe take the handguard off and check to see if the barrel nut may becoming loose

3 minutes ago, Pizza Bob said:

Check your optics and mounts first. If all appears tight, take it off and shoot with irons to see if you get the same result - then chase your barrel demon.

Adios,

Pizza Bob

I agree with this.. I had a slightly loose mount once that was barely detectable at being loose.. coincidently it was a PRO.. I don't think that had anything to do with it.. in that I don't think the PRO has any issues.. just coincidence.. but tiny shifts at the RDS were amplified downrange.. and consistency sucked.. 

dirty barrel? no way.. I put metric tons of ammo through my ARs.. rarely clean them.. and have never experienced anything like that.. I think for your barrel to be fowled enough to produce what you are experiencing.. your BC would be so fowled it would barely move.. 

Do not shoot with chronic hiccups. [emoji6]


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1) get target where you shot like poop but still have hits. Is anything keyholing? (easiest check for doing at the time). 

2) When shooting for groups, how are you mounting the gun? It's not free floated, and applying variable pressure to the barrel/hand guard can result in deflection of the barrel and shifted pint of impact. If you sighted it in with no sling and are now wrenching on it national match style as a fully veste member of team push it harder, you can wind up with some serious changes in POI vs POA. 

3) Check your optic mount. Is it tight and properly installed. For something like the pro I would remove and reinstall as suggested in the directions.  Check the pic rail for undue wear, gouges, shiny marks, etc. (this is easy any time, but you can have issues even if it seems tight. But if it seems loose, it'll definitely cause problems)

4) Have someone else shoot it who you know can shoot. Are they getting groups? 

5) Inspect bore. Is it fouled. 22 conversion kits can leave a barrel leaded and underperforming. Getting it clean can be a giant PITA. 

6) Check the muzzle device for a baffle strike, or serious build up that might be upsetting the bullet on exit, damaging the jacket, etc. Impacted foreign matter, etc. will also do it. 

7) Check your gas key and gas tube. Is there uneven wear that is not radially symmetrical/concentric? Gas tube may not have been properly aligned and the gas tube affects barrel harmonics and POI during operation. If you zeroed it while it was mating up under tension, and it has warn significantly lopsided and is no longer under tension, it can cause issues with accuracy and repeatability. Usually this will jsut cause reliability issues as it wears, but it it was bad to begin with and creating tension, it cna change shooting dynamics. Probably not >6" at 50 yards though. 

The above shouldn't require tools or anything special. 

8) check barrel nut and barrel to upper mating. If it wiggles or clicks with the upper mounted to a vise and you wiggling the barrel, it's probably not too solid a connection. Torque to spec to fix. If it's at spec it may be a poor mating from day one that has gotten worse. You can disassemble and shim possibly in that case. Also, of course, check the upper and barrel nut for visible damage. If a defect has caused a crack in either, I'd expect it to behave poorly. 

9)If volume of fire is high, throat erosion could be an issue, at that point you need a bore gauge/scope. Tools will probably cost you more than a barrel though so..

Not comprehensive of all steps, but should give you ammo for google etc.