BAD groups----need help

[One Shot]

I've got a AR in .300 Whisper and can't get good groups. I was shooting Matchking 220 gr with 9.1 gr H110. I bought some Nosler spitzer in 200 gr and tried 9 gr H110. I'm still getting 6-8 inch groups. Any ideas?
Thanks

[i8asquirrel]

What is your barrel twist rate? I have found better accuracy with 1680 powder and 4227..

[One Shot]

I think it's a 8

[Hoser]

Is your can on tight?

Have you tried shooting any groups without the can?

I am assuming you have some sort of muzzle device.

[One Shot]

I haven't tried it without the can.

[buffetdestroyer]

If using any sort of sighting device or optic, check that first to make sure that it is on tight.

Clean the weapon thoroughly and take the suppressor off. Tighten down any sighting systems (base, rings, etc.). See what kind of accuracy you are getting after this.

If you are getting good accuracy with the suppressor off, then you may have misaligned threads and you may be getting baffle strikes.

If accuracy is still crappy, inspect the rifling and crown for burrs and visible imperfections. If after all this, and you still are nowhere, try 150-175 grain bullets to see if it is a twist rate issue.

I would say that if you are getting 2-3 MOA, it is likely a load problem, but with 6-8 inch groups, it is likely something functionally wrong with the weapon (assuming a capable shooter in a benchrest situation and a reasonable sighting system).
________
Hero honda hunk specifications

[Rikky Lee]

Try it without the can first and report back.

[One Shot]

Thanks I tried some diferent loads last weekend with only slight improvement. I'm planning on doing more testing tomorrow ( Wed ) and I'll try with the can off and see what happens.
thanks for the input.

[One Shot]

I tried without the can. Still using 9.2 of H110 and one box with .220 gr RN, and one with 200 gr Spitzer. I still got one with 4 inch groups ond one with 8 inch groups. I had just fininhed shooting 1/2 in groups with my .223, so I don't think it's me.
Any other suggestions? I did buy some different power, but I wouldn't think it would make that much difference. I have a new Nikon Buckmaster on the gun and would think that shouldn't be the problem.
Thanks again for the help.
Doc

[Rikky Lee]

Hmmm

Time to try a few different things. Both with and without the can on.

Can you get any factory ammunition?

Also try some supersonic loads if you can - and get some 220 and 240 Matchkings.

Finally, just to confirm, you have checked the barrel twist is 1/8?