Terrible accuracy on new build

[Captk]

I took my new 6.5 Grendel to the range today after having function tested it at an indoor range to see what kind of accuracy I would get. The upper is Anderson, the barrel is a Brownells 5r 24" cut back to 21" and recrowned. I lapped the upper receiver to make sure it was square before assembly. The rifle functions great accept for the accuracy.
It started out stringing 5 shots, each next shot was 1 - 1 1/2" higher then the previous in a mostly straight up and very slightly to the right, maybe a 1:30 position. I went through 70 rnds (hornady AMAX/SST) before I gave up. It would scatter shots sometimes next to each other but usually a few inches apart, no pattern except the time when it was stringing.
I have a Simmons 6x24 Predator scope on the rifle and it seemed tight.
Any suggestions?

Thanks, Ken

[rabiddawg]

Has the scope been on a different gun and performed well?

Are you sure your crosshairs are level to the gun?

Are your ring and base screws torqued equally and properly?

I would change scopes, level the scope properly, retorque everything and try again.

[customcutter]

You said new build, are the barrel and upper both new. Are you sure the barrel was properly crowned? Don't mean to question your's or anyone else's abilities, but it only takes a smidgin.

[37L1]

Could be the barrel nut, over or under tight, might need a shim for timing?

Is the gas block tight? Look for powder marks nearby.

Not a lot to go on here. Good luck!

[LRRPF52]

Is the barrel bedded to the upper?

What kind of torque was applied to the barrel nut?

I also wouldn't trust a Simmons scope to hold up to a semi-auto recoil and reciprocating masses. I wouldn't be surprised if the erector tube is being moved with each shot.

[Captk]

Has the scope been on a different gun and performed well?

Are you sure your crosshairs are level to the gun?

Are your ring and base screws torqued equally and properly?

I would change scopes, level the scope properly, retorque everything and try again.

I had the scope on another rifle for 1 outing where I had issues sighting in. I will try another scope.

Ken

[Captk]

Could be the barrel nut, over or under tight, might need a shim for timing?

Is the gas block tight? Look for powder marks nearby.

Not a lot to go on here. Good luck!

Will recheck torque on barrel nut, it was very tight. No issue with gas block, no leakage and it functions great outside of accuracy.

[Captk]

You said new build, are the barrel and upper both new. Are you sure the barrel was properly crowned? Don't mean to question your's or anyone else's abilities, but it only takes a smidgin.

The crown looks fine and I have recrowned several barrels before with no issues.

[Captk]

Is the barrel bedded to the upper?

What kind of torque was applied to the barrel nut?

I also wouldn't trust a Simmons scope to hold up to a semi-auto recoil and reciprocating masses. I wouldn't be surprised if the erector tube is being moved with each shot.

The barrel is not bedded to the upper. I will try another scope and check the torque on the barrel nut. I have a Nikon 3x9 that I will try, the scope has been very reliable.
Thanks, Ken

[ricsmall]

If you've had a bad outing with that same scope, I would try that before changing anything else. Change one thing at the time. Shoot a five round group and reevaluate. I'd bet on the scope if it was me.

Richard

[Mesa1978]

If you are going to swap scopes a lot, it might be better to get a once piece QD mount and keep the scope in it, swapping mount and scope as a unit. Swapping scopes in and out of ringsets is riskier, just one over torque and the scope can be damaged.

[sneaky one]

CapKt.,Get at least a Leupold scope, and Same quality rings- quick take off units- they hold their zero just fine. Check torque specs. in

Inch lbs.

[Captk]

I put a new Redfield Revenge 6-18 scope on the rifle and returned to the range. Groups much better and it appears the issue was the scope. I was using PPU to get it sighted in and then 10 rnd of Hornady. Unfortunately since I am in NY and want a detachable mag I put a spur grip in place of the pistol grip. Next trip out I will bring a rear bag and front rest to see how accurate the rifle(I am) is.

ken

[gpsman007]

Run a dry patch through barrel see if anything is there

[wraith1516]

Could be worse you could live in new jersy I feel sorry for all the people living behind enemy lines