accuracy problems with new barrels

More
14 years 7 months ago #3458 by PATRICKLANDRY
accuracy problems with new barrels was created by PATRICKLANDRY
I bought 2 ar10s, 308's. Had both rebarreled with broughton barrels,18 in. and 23 in. Heavy.
Went through the barrel breakin process.
Now have around 200 rounds through each.
Both rifles will only group 3 to 2.5 in.
After 125 rounds, I began to get a few 1.5 in groups, then back to larger groups. 5 shot groups.
many times first round hits dead on.
Sometimes the rounds group as if climbing a ladder? 3 to 5 inches.
Have tried 2 different high dollar scopes, no change.
Ammo, 3 different factory match ammo's plus many other factory ammo's, 165 to 175 gr.
Also, reloads. 175 / 168 HPBT with varget, different loads and bullet seating depths.
No matter the type of ammo, I still get the same results.
My thoughts might be the barrel is not torqued correctly???
Or, anything else???
Both rifles are doing the same thing, same gunsmith???

Please Log in or Create an account to join the conversation.

More
14 years 4 months ago - 14 years 4 months ago #4523 by lotoofla
Replied by lotoofla on topic Re:accuracy problems with new barrels
While I don't know how your barrels were made. I may have some info that you may not like. While reading ACCURIZING THE FACTORY RIFLE by M.L. McPherson, on page 38 he talks about grossly over tightening barrels, and how this causes tempature-sensitve strain responses will cause the barrel to bend differently (causing poor accuracy). He sites that the F class shooters take extra barrels to a match, and if they need to change the tube they can do so with out tools as the barrels are a little more than hand tight, and yet they shoot itty bitty groups at 600-1,000yds!! To your question, and my situation of making 2 uppers with barrel blanks. I think that when I put the barrel extention on that I'll tourque it to no more than 20 Foot Pounds, using accra glass to secure it. Since I'm using RECEIVER blocks, instead of BARREL blocks, this makes this possible, as when I mount the fore arm tube, I won't be straining the barrel/receiver extension relationship. As to your gunsmith, this is a loose-loose situation because you, nor I were there when they put the barrel together. We just know it does'nt shoot as good as it should. PS my FACTORY ArmaLite (T) with a 24" barrel does the same thing.

Tom
Last edit: 14 years 4 months ago by lotoofla. Reason: greater clairification

Please Log in or Create an account to join the conversation.

  • a Guest
  • Visitor
  • Visitor
14 years 4 months ago #4526 by a Guest
Replied by a Guest on topic Re:accuracy problems with new barrels
Pratrick 2 things come to mind 1st was the receiver squired. I sold the tool rights to Brownells for the AR15 tool. 2nd was the upper and lower properly beded and shimed to stop the toqure role. Was the gas transfer hole drilled burr free? How heavy are the barrels?MSH

Please Log in or Create an account to join the conversation.

More
14 years 4 months ago #4536 by PATRICKLANDRY
Replied by PATRICKLANDRY on topic Re:accuracy problems with new barrels
Thanks for the info.
I took the guns to a different gunsmith.
He called me 2 days later to tell me what he found.
1. The flash suppressor was on way to tight.
2. Crown on the barrels where terrible
3. Barrels where on way, way, way to tight.
He said the chamber was very tight, but should be no problem.
He also bore scoped the barrel and said it looks good.
I am out of country and should be back in 2 weeks.

Please Log in or Create an account to join the conversation.

More
14 years 4 months ago #4537 by PATRICKLANDRY
Replied by PATRICKLANDRY on topic Re:accuracy problems with new barrels
found 3 problems
1. flash suppressor on way to tight.
2. barrel crown was terrible. the worst he has ever seen.
3. barrel was on way, way, way, to tight !
chamber is tight, but ok.
bore scoped the barrel and looks good.
guns should be ready in a week or so.
will let you know how well they shoot, later.
thanks

Please Log in or Create an account to join the conversation.