6.5 Grendel

[Shane Lindsey]

Just picked up a Sanders armory 6.5 Grendel upper. Took it to the range and it would not shoot better than about 5 MOA with Hornady 123gr Black or the 123gr SST.

It seems a little undergassed, as it would not consistently lock or feed. Will this affect accuracy as well? Can usually diagnose a bolt gun. Not new to ARs (issued) but never had to trouble shoot them, jsut handed them to the armorers.

 

[WanderingGoatie]

What did the spent brass look like?

 

[Roughrice]

It sounds like its under gassed.
Sometimes it could be the gas block alignment...causing the port to be slightly closed
Sometimes it could be the gas port (too small)...but Sanders is usually set up correctly...unless a drilling bur is blocking the port.
Sometimes it could be the buffer/spring combination... if it was being used with a different barrel/cartridge configuration.
Even the bolt lugs fitting tight in the barrel extension may cause a delayed release.
I've hand cycled a tight one before 40-50 times, slamming it into battery to "break-in" the lug abatement.

 

[Ckgworks]

Typically my grendels have been over gassed and I've added adjustable gas blocks to tune them down......like Roughrice said check gas block alignment and other items he mentioned. Lube the heck out of it and cycle it till everything is moving nice. The last one i built was tight on lock up but it "wore in" with oil and hand cycling. I'm guessing it had a small burr on it. Not 100% sure on accuracy, but I'd say it affects me shooting accurately more than the gun.
Good luck

 

[Shane Lindsey]

What did the spent brass look like?

Case head didn't appear to have overpressure. Typical of what I see from most AR types. No super hard ehector print. They did have a bent case mouth, but firgured that is from ejection/hitting deck.

 

[Shane Lindsey]

It sounds like its under gassed.
Sometimes it could be the gas block alignment...causing the port to be slightly closed
Sometimes it could be the gas port (too small)...but Sanders is usually set up correctly...unless a drilling bur is blocking the port.
Sometimes it could be the buffer/spring combination... if it was being used with a different barrel/cartridge configuration.
Even the bolt lugs fitting tight in the barrel extension may cause a delayed release.
I've hand cycled a tight one before 40-50 times, slamming it into battery to "break-in" the lug abatement.

I did check the alignment of the gas block. Looked slightly off, so I re-centered it.

Would this affect accuracy like this though? It is the Type II Grendel, FWIW. 4-6" is just not acceptable though.

 

[Zen Archery]

Did you give it a good scrub down before shooting? Try different ammo/weight.

 

[BALLISTICJESUS]

At 5 MOA. I would be checking the scope and mounts first.

 

[cajun]

Have not seen gas problems cause accuracy issues.

 

[Mike D Texas]

I wouldn't waste any time with an upper with that many issues. Make the manufacturer figure it out.

None of that is acceptable on a factory assembled upper.

 

[lilharcher]

At 5 MOA. I would be checking the scope and mounts first.

This……5 MOA is way too much. Usually a bigger issue like untightened rings.

 

[Shane Lindsey]

Rings were torqued to 25"# per manufacturers recs. American Defense recon mount.

May put another scope on and aee it that is issue.

 

[Shane Lindsey]

I wouldn't waste any time with an upper with that many issues. Make the manufacturer figure it out.

None of that is acceptable on a factory assembled upper.

Have a note into Sanders. Waiting on reply.

 

[Shane Lindsey]

Did you give it a good scrub down before shooting? Try different ammo/weight.

Punched it with a few patches of Hoppes. Wasn't dirty so didn't scrub