Hoot, Al,
Thanks for the fast response! I'm in Texas, mostly shooting in rural west Texas, with a very solid folding table and a Lead Sled for dialing in. It was clean. I'm also shooting harder-bucking calibers, e.g., 300 WSM on the last trip. 'Next trip will be to a city range with fancy shooting tables, but I've shot there before in the various attempts with this rifle. The thumper was the 5th of 6 AR builds, which have all come out very nice. My home-built 6.5 Grendel is as accurate as most of my bolt action hunting rifles, at about half an inch at 100 yards.
Tell us more about the setup on the bench that you're using for accuracy testing. A steady rest setup or a Lead Sled is pretty important for cutting down the MOA number, not to mention a steady shooting table- At the local club, ours are precast concrete sitting on cinder blocks. IE "Rocks of Gibraltar".
* For this last exercise, Lead Sled with 3 lead bags on a strong folding table, on firm sandy soil. Other rifles, including harder recoiling calibers, are predictable, <1 MOA performers with the sled.
Also, besides switching out the scope, did you also try different mounts? They're not all created equal.
* I've been using American Defense Manufacturing "Recon" mounts for 2 out of three, the third is an EOTech XPS2 / doubler with integrated quick release mounts. I'll see if I can find something simpler in the drawer.
If you were local to the Twin Cities, we could go to my local range and try a few things.
* Thanks! I'm getting desperate, and with the price of fuel being low...
I don't think the headspace, if awry, would affect groups that much.
* Great, I don't want to buy 450 gauges
Are you using a muzzle brake or flash hider. If so, have you tried shooting with them off?
Muzzles sometimes can be set to just the worst possible spot. There are certain lengths of barrel/muzzle device combination that can leave the barrel whipping up and down.
* Great idea! It's a flash hider thing, I haven't tried with it off, but I'll do that next. It has plenty of clearance to the bore. The crown looks OK, but other than trying with the flash hider off, having the crown redone might the the cheapest thing to try at this point...
Speaking of which, are your groups opened up just vertically or just horizontally or both??
* Both windage and elevation.
I use a lot of muzzle devices and personally have never seen a muzzle device turn a 1 MOA rifle at 100 yds into a 5 MOA rifle.
Is this your only AR rig? They don't handle like any bolt action I've ever shot, especially in this thumper caliber.
* I got my first AR in Marine Corps boot camp in 1980, I have 5 ARs in 4 calibers these days.
It took a little while when I first got my 450b upper, to get used to the necessary bench presentation to milk all the accuracy out of it.
Not at all like shooting a bolt action. Not to insult you but I assume you have shot other caliber rifles for accuracy with success?
* I've wrung great performance out of every rifle I have, except one of those famous mid 80s Mini 14s that I wish I didn't buy
Looking forward to getting this one figured out!
Thanks Again,