New upper build accuracy???

Discussion about rifles in 300 AAC BLACKOUT (7.62x35mm), hosted by the creator of the cartridge.

Moderators: gds, bakerjw, renegade

User avatar
smustian
Silent But Deadly
Posts: 3433
Joined: Thu Aug 08, 2013 5:55 pm
Location: Central Virginia

Re: New upper build accuracy???

Post by smustian »

bdill wrote:So basically my rifle is shooting normal sized groups? If I just did 3 round shots then it stacks them under an inch I had one 3 shot group that was under a half inch and a 4 round that was right at .75 but my 5 round and 8 round groups suck. My 50 yard tests are great but the 75 yard tests are where I start seeing issues
The more shots you shoot at a given target trying to group the more chance of inducing shooter error. Sounds like your rifle is shooting fine and the thrown shot is caused by you. The farther away the target is the more minute the change has to be at the muzzle to have a shot to be off. That is why you have someone shoot 3-5 shot groups to check accuracy.
bdill
Silent Operator
Posts: 56
Joined: Mon Aug 25, 2014 8:32 pm

Re: New upper build accuracy???

Post by bdill »

It's possible it could be me but I had the rifle in a Caldwell lead sled.
User avatar
JeffWard
Silent But Deadly
Posts: 237
Joined: Tue Jul 15, 2014 12:13 pm
Location: St Pete, FL
Contact:

Re: New upper build accuracy???

Post by JeffWard »

bdill wrote:So basically my rifle is shooting normal sized groups? If I just did 3 round shots then it stacks them under an inch I had one 3 shot group that was under a half inch and a 4 round that was right at .75 but my 5 round and 8 round groups suck. My 50 yard tests are great but the 75 yard tests are where I start seeing issues
I'm guessing you're just getting barrel heat dispersion. If the first 3-4 go into sub-MOA, then the last few start to climb, or shift rt/lft, it's likely the barrel. Try shooting with a good minute to 2 minutes cool down between shots. Leave the bolt open, and let the chamber and barrel cool down. I bet you'll stack 10 shots inside an inch.

Shooting an AR with a 30-round mag tempts you to shoot too fast. Bench-rest shooters with bolt guns take a LONG time to shoot great groups. And as a hunting gun, it's really ONLY the first shot that counts with a dead cold bore.

JW
Guns are tools designed for dirty work both competitive and defensive. If I meet someone with a well worn gun, I hope their barrel is pointed the same direction as mine if the lead starts flying...
bdill
Silent Operator
Posts: 56
Joined: Mon Aug 25, 2014 8:32 pm

Re: New upper build accuracy???

Post by bdill »

Thanks for all the great tips. My confidence in this gun is now renewed lol
bdill
Silent Operator
Posts: 56
Joined: Mon Aug 25, 2014 8:32 pm

Re: New upper build accuracy???

Post by bdill »

Just to update the problem was the ammo. I got some more 125 gr remington match and it stacked 4 rounds just about on top of each other again. My largest group was about 1.2 inches in a 5 shot group. I also shot it slower to make sure it wasn't heating up. My best group was .86 inches at 100 yards. I think I'm still gonna sell it though and buy a noveske or Wilson combat 16 inch barrel. I just really like the look of stainless barrels.
DoubleJ
Silent But Deadly
Posts: 1045
Joined: Tue Jun 03, 2014 1:51 pm

Re: New upper build accuracy???

Post by DoubleJ »

I don't know about all that tightening and loosening of the barrel nut though. It's my understanding that every time you install/remove a barrel you're shortening the life of the upper. When I started building ARs, the procedure as I understand it is to tighten the nut to 30ft/lb, then continue until the next notch lines up. Sometimes you'll go above 80, but as long as it's once it shouldn't be an issue.
I do not reply to posts with horrific grammar errors.

I do not reply to posts concerning the case mouth dent.
bdill
Silent Operator
Posts: 56
Joined: Mon Aug 25, 2014 8:32 pm

Re: New upper build accuracy???

Post by bdill »

I don't see how could shorten the lifespan when you're really only doing it to seat the barrel but correct me if I'm wrong...
User avatar
smustian
Silent But Deadly
Posts: 3433
Joined: Thu Aug 08, 2013 5:55 pm
Location: Central Virginia

Re: New upper build accuracy???

Post by smustian »

DoubleJ wrote:I don't know about all that tightening and loosening of the barrel nut though. It's my understanding that every time you install/remove a barrel you're shortening the life of the upper. When I started building ARs, the procedure as I understand it is to tighten the nut to 30ft/lb, then continue until the next notch lines up. Sometimes you'll go above 80, but as long as it's once it shouldn't be an issue.
Tightening 3 times then going for final tightening is actually mating the threads for a more solid mount. If not mated, then with every shot, there is a slight bounce which will over time become larger and larger resulting in a loose barrel. Might be 10,000 rounds but it will happen.
User avatar
rebel
Silent But Deadly
Posts: 7285
Joined: Mon Apr 22, 2013 2:01 pm
Location: Moonshine Country

Re: New upper build accuracy???

Post by rebel »

You are tightening steel into aluminum. Thus the anti seize. I wouldn't want to swap barrels a lot but one time won't hurt. But your changing a good shooting barrel for a look? My 2 cents, leave it be and impress with the groups as opposed to "the look". Nothing wrong with a pretty gun, but ugly ones can shoot damn good to.
You can't beat the mountain, pilgrim. Mountains got its own way.
DoubleJ
Silent But Deadly
Posts: 1045
Joined: Tue Jun 03, 2014 1:51 pm

Re: New upper build accuracy???

Post by DoubleJ »

bdill wrote:I don't see how could shorten the lifespan when you're really only doing it to seat the barrel but correct me if I'm wrong...
Something to do with the fact that the aluminum doesn't stretch the same as steel fasteners do, so it applies some different type of force. I'm no metalurgist, and it was years ago that I was doing the research to begin my builds, so I've forgotten the reason. It's also my understanding that graphite based anti-seize isn't the best bet for aluminum. I think the TDP (sp?) recommends regular old Moly grease on all AR threaded parts. I use Mobile 1.

If you jump over to M4carbine, and can deal with the insane level of child-like abuse heaped on anyone that asks a question, you'll find more info then you ever wanted to know about the proper way to build an AR.
I do not reply to posts with horrific grammar errors.

I do not reply to posts concerning the case mouth dent.
Post Reply

Who is online

Users browsing this forum: No registered users and 155 guests