Glockcomma Posted June 13, 2009 Share Posted June 13, 2009 I dropped off a stainless 20" heavy barrel at a gunsmith yesterday to be lightened and shortened. He plans on turning the rear portion of the barrel from the gas port area to the rear shoulder to .800, is that to thin? I've been looking everywhere I can think of on line and can't get an outside dimension at the chamber anywhere except AR15 Barrels.com they show .980 for the first 2.5". I don't want to second guess this guy he has been a gunsmith/machinist for a long time, but I don't want to flinch every time I pull the trigger either. Link to comment Share on other sites More sharing options...
kgunz11 Posted June 13, 2009 Share Posted June 13, 2009 .800 is way more than enough meat under the hand guard. I've seen .650 plenty of times. Never thought to measure the OD of a class III M-16 bbl, but it probably isn't more than .800. Link to comment Share on other sites More sharing options...
kgunz11 Posted June 13, 2009 Share Posted June 13, 2009 BTW, the finished OD wouldn't bother me as much as the turning down and what it does stress wise to a barrel. Contouring should be done before the barrel is rifled for utmost accuracy potential. Then again, I have to remind myself most folks are happy with 1.5MOA out of an AR. Link to comment Share on other sites More sharing options...
Glockcomma Posted June 13, 2009 Author Share Posted June 13, 2009 That's a relief about the dia. thanks. But now I'm stressed about the accuracy, this barrel is a 1/2 moa barrel and that's with me behind it. It's a sweet shooting rifle but just so damn heavy, I guess I'll just keep my fingers crossed. Link to comment Share on other sites More sharing options...
kgunz11 Posted June 13, 2009 Share Posted June 13, 2009 If your smith goes REALLY slow and removes very little material in each pass it might not hurt much, but it's going to take a long time to do. You don't want the bbl to get above room temperature, so he should use lots of coolant. Even then, you're not out of the dark, the bbl might have stress in it waiting to happen. The safest bet is to sell what you have to someone that doesn't mind the heavier bbl and get one the size you want. AR barrels aren't as hard to get as people think. Link to comment Share on other sites More sharing options...
benny hill Posted June 13, 2009 Share Posted June 13, 2009 AS long as he uses plenty of coolent to keep it cold, it does'nt matter. Link to comment Share on other sites More sharing options...
Glockcomma Posted June 14, 2009 Author Share Posted June 14, 2009 I emailed him this morning before I took off to shoot a match in Albany OR. and told him to pass on the lightening, when I got home he had left a message that it was already done. Where is crappy service when you want it. I'll find out if he kept it cool and try to get out and shoot it before to long and report back. Thanks guys for your help, Tim Link to comment Share on other sites More sharing options...
larry cazes Posted June 14, 2009 Share Posted June 14, 2009 Should be fine. I have had more than one barrel turned down like this with Zero loss of accuracy. Link to comment Share on other sites More sharing options...
Glockcomma Posted June 14, 2009 Author Share Posted June 14, 2009 Thanks Larry yours and Benny's post makes me fell better. I just hope that he kept it cool, it's not this guys first rodeo he has been doing this for a long time I think I'll be O.K. Does anybody know how short of a barrel you can run with a rifle length gas system? Link to comment Share on other sites More sharing options...
warpspeed Posted June 14, 2009 Share Posted June 14, 2009 I would not worry. I had a HBAR profile turned down to 0.75 under the hand guard. It was 1.5" before and now shoots < 0.5". Link to comment Share on other sites More sharing options...
00bullitt Posted June 14, 2009 Share Posted June 14, 2009 Assuming he kept it cool and turned it properly.....you won't have any trouble. I've had barrels lightened and fluted that came back shooting better than before. I've never had one come back shooting worse. My smith uses a mist type cooling system which keeps the barrel very very cool. I've turned them down to .700 under the handguards and fluted it as well. JP used to do a barrel that was .500 under the handguards. I prefer somewhere between .680-.720 under the handguards with flutes and .740 in front of the block with more flutes. I like my barrels fairly light. The one I shoot in competition now is a Noveske 18" that was fluted after the fact and it shoots 1/2 moa after 5500 rounds. Link to comment Share on other sites More sharing options...
gotm4 Posted June 14, 2009 Share Posted June 14, 2009 Mine is really heavy near the barrel extension for about the first 2.5" or so about .900", forward of that to the gas block I had turned to .650". My barrel is a 18" rifle gas White Oak 1x7 and was SPR profile. On my wifes I went down to .630", hers is a 18" midlength gas White Oak 1x7 and was SPR profile. Link to comment Share on other sites More sharing options...
Sudden Death Posted June 14, 2009 Share Posted June 14, 2009 Don't worry about accuracy. I turn them down all the time to .625 under the hand guard, everyone that I have done it for has been more than happy with it. Link to comment Share on other sites More sharing options...
Dan Sierpina Posted June 14, 2009 Share Posted June 14, 2009 Turning the barrel will be fine. Material is removed equally around the bore. Problems arise from metal removal in an unequal manner. Flat bar steel will curve if material is removed from one side only. Link to comment Share on other sites More sharing options...
Glockcomma Posted June 15, 2009 Author Share Posted June 15, 2009 I just picked up my barrel, my man does not use a cooling system he just takes it real slow .0020 cuts he said it never gets hot. It is exactly one pound lighter and the gun feels way better. It's 18" now threaded and crowned, I'll post again after I get a chance to shoot it. Link to comment Share on other sites More sharing options...
mike cyrwus Posted June 16, 2009 Share Posted June 16, 2009 (edited) AS long as he uses plenty of coolent to keep it cold, it does'nt matter. Benny turned down my hbar to .660 or so and it was just as accurate as before. thank you again, sir! Edited June 16, 2009 by mike cyrwus Link to comment Share on other sites More sharing options...
UW Mitch Posted June 16, 2009 Share Posted June 16, 2009 With 0.002" cuts it must've taken forever! As I read this thread I was thinking - flood coolant would be nice! Give us a range report. ~Mitch Link to comment Share on other sites More sharing options...
grywlfbg Posted June 16, 2009 Share Posted June 16, 2009 Assuming he kept it cool and turned it properly.....you won't have any trouble. I've had barrels lightened and fluted that came back shooting better than before. I've never had one come back shooting worse. My smith uses a mist type cooling system which keeps the barrel very very cool. I've turned them down to .700 under the handguards and fluted it as well. JP used to do a barrel that was .500 under the handguards. I prefer somewhere between .680-.720 under the handguards with flutes and .740 in front of the block with more flutes. I like my barrels fairly light. The one I shoot in competition now is a Noveske 18" that was fluted after the fact and it shoots 1/2 moa after 5500 rounds. JP still does - their Ultra-light 18" is .5 under handguard and .745 in front of gas block. But they do lower the rifling to 1:9 I assume to keep heat build-up down. Link to comment Share on other sites More sharing options...
Religious Shooter Posted June 16, 2009 Share Posted June 16, 2009 I think the real test of accuracy for 3 gun is to shoot off 30-40 rounds quickly and then shoot 2-3 5 shot groups. See what it does then when it is hot. Link to comment Share on other sites More sharing options...
Glockcomma Posted June 17, 2009 Author Share Posted June 17, 2009 Mitch last night at work I was thinking about my last post a realized I put 2 thousandths I meant 20 thousandths. Link to comment Share on other sites More sharing options...
UW Mitch Posted June 17, 2009 Share Posted June 17, 2009 ah...0.020" sounds like a much more reasonable depth of cut Thought maybe your guy REALLY wasn't into taking big cuts. When I'm working titanium for my rings and pens, my big bites are 0.020" deep. ~Mitch Link to comment Share on other sites More sharing options...
kellyn Posted June 18, 2009 Share Posted June 18, 2009 If you see rifling you went to far. Link to comment Share on other sites More sharing options...
RAZZ Posted June 18, 2009 Share Posted June 18, 2009 I realize we are talking about 5.56 barrels here, but does anybody have a suggestion for a minimum acceptable diameter for a 6.8 spc barrel? I have a Bison Armory 20" 6.8 barrel on order, and it has a .840 diameter out to gas block, then .750 at the block, followed by .720 to the FH. As it is going to be a 3-gun 'toy' rifle, I am on the fence as to whether or not to get it lightened under the hand guard. I want it light and quick, but I don't want to ruin my new barrel. Link to comment Share on other sites More sharing options...
Glockcomma Posted June 19, 2009 Author Share Posted June 19, 2009 I just got back from the woods where I shot my rifle with the newly lightened barrel, and I'm relieved to say I still have a 1/2 moa gun. Thanks all for your insight Tim Link to comment Share on other sites More sharing options...
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