Mark Gale Posted January 24, 2015 Share Posted January 24, 2015 I can pull the barrel in minutes. Like I said in my first post, I have access to friends with machine shops/ lathes. Work would be cheap to free. Is the barrel chrome-moly or stainless steel? Turning one of their chrome-moly barrels is a bad idea. Link to comment Share on other sites More sharing options...
Thehotrodpig Posted January 24, 2015 Author Share Posted January 24, 2015 I can pull the barrel in minutes. Like I said in my first post, I have access to friends with machine shops/ lathes. Work would be cheap to free. Is the barrel chrome-moly or stainless steel? Turning one of their chrome-moly barrels is a bad idea. Chrome-moly. Please explain. Link to comment Share on other sites More sharing options...
dauntedfuture Posted January 31, 2015 Share Posted January 31, 2015 There is not an issue cutting down or turning or fluting a chrome molly barrel. There will be issues if you have one of the treated barrels like nitride. You can, but should not cut down a Chrome lined barrel as you cant put a crown on chrome and you will have what you have. You also cant re-chamber or throat a chrome lined barrel. Cutting down chrome lined barrels has been done and it will work, the rifle will go bang, it might just not be as accurate as it could be. Some PDs years ago cut down 20" M16 rifle barrels just past the FSB and they worked fine. Depending on how your barrel was made, you can induce or reduce stress in the barrel and alter the bore on the barrel if you turn, trim or file. Depending on how the barrel is made, most true match blanks are turned, then bored and rifled to keep the bores straight. with some barrels you always induce stress in the bore, like button rifleing (Douglas, Wilson, etc.. You get less to no stress when you cut rifle a barrel (Krieger). If your barrel is CHF I would not do anything to it. The barrel, contour and chamber are made together and not usually made in a traditional sense. Many of them are hammered to shape with the bore and chamber made together and finish cut at the end. Those barrels that are finished turned get inspected to make sure the bores are straight and actually straighten the bores when the barrels are finished on a big machine. As such, if you start turning or fluting your going to relieve stress and things might shift. There are no knows. I think that most of the time you will find that its not economically efficient to modify an existing barrel. You are going to spend 100 or so to turn the barrel and you can get a new one for 180 (Flaxon) to 250 (BHW, ranier etc). If you had a premium barrel (Krieger blanks are 350) you might think about it. Link to comment Share on other sites More sharing options...
kurtm Posted January 31, 2015 Share Posted January 31, 2015 The above post is one of the best I have read in a while. Good info, reliable and accurate! A learned man! Thanks DF! Link to comment Share on other sites More sharing options...
Shadowrider Posted January 31, 2015 Share Posted January 31, 2015 (edited) I've turned literally tons of 41xx heat treated alloy chips and dauntedfuture is spot on. Edited January 31, 2015 by Shadowrider Link to comment Share on other sites More sharing options...
mikeor70 Posted July 13, 2015 Share Posted July 13, 2015 OP, What was your final decision/outcome? I'm kind of in the same boat myself. No charge machine shop...18" Govt profile Bushmaster (cut from a 20") and thinking about fluting forward of the FSB. I haven't shot it yet, so no baseline on accuracy. I've got no other reason to do it, than just because I'm bored. Thoughts? Link to comment Share on other sites More sharing options...
wbear Posted July 13, 2015 Share Posted July 13, 2015 I had a 16" Bushmaster heavy barrel turned down to a pencil profile. When I got it back I had to readjust the sights of course but once done it has been just as accurate as it was before. Taking the weight off was well worth it. Link to comment Share on other sites More sharing options...
ccoker Posted July 13, 2015 Share Posted July 13, 2015 I would agree with the balance is more important than total weight of the gun. Link to comment Share on other sites More sharing options...
openclassterror Posted July 13, 2015 Share Posted July 13, 2015 OP, What was your final decision/outcome? I'm kind of in the same boat myself. No charge machine shop...18" Govt profile Bushmaster (cut from a 20") and thinking about fluting forward of the FSB. I haven't shot it yet, so no baseline on accuracy. I've got no other reason to do it, than just because I'm bored. Thoughts? The barrel dia forward of the gas block is less than .750 (usually about .720). Bore dia is .224, leaving about 1/4" total wall thickness. Anything less than 6 flutes is almost a waste of time, as the short distance between a rifle-length gas system and the end of an 18" barrel doesn't leave room to remove much material. Let's say you do 1/4" flutes, 1/8" deep, and they end up with an effective length of 3". Therefore: material removed = Pi (R^2) /2 x L (surface area of a circle with 1/8 rad, divided by two as the flute is a half circle, times length) (3.14 x (.125x.125) / 2) x 3" long = .0736 cu in per flute, times 6 flutes = .4415 cu in. removed by fluting. This is assuming the flutes are full depth all the way to the ends, which they are not. They get gradually shallower at both ends due to the radius of the fluting cutter. Weight of steel is approx. .29 lbs per cubic inch. Therefore, .4415 cu in x .29 lbs = .128lbs, or approx. 2oz. So, cutting 6 flutes 3" long ahead of the gas block will reduce total weight by less than 2oz. It is a measurable amount, but not a significant amount. Again, it is also not a good idea on a hammer forged barrel, as residual stresses may be released during fluting that could cause the barrel to warp. Hammer forged blanks start out several inches shorter than final length, and stretch as they are forged to shape, creating an elongated grain structure. Cutting slots along this axis can make the barrel spring badly. Not always, but often enough to make most gunsmiths shy away from the job for fear of scrapping the barrel. Link to comment Share on other sites More sharing options...
mikeor70 Posted July 13, 2015 Share Posted July 13, 2015 Dang Tom....getting all mathematical on me! You knowledge, advice and expertise is always on point. After giving it some thought, I'll probably forego the flutes and just shoot the dam thing. Link to comment Share on other sites More sharing options...
troupe Posted July 15, 2015 Share Posted July 15, 2015 What he said !! Flutes look cool out front, but you won't notice the difference. BUT, if in your mind, you like it better, that may make you shoot better. This game requires good mental being and you may shoot better because it looks better to you. Think about it, why do we all spend a lot of money on shooting shirts to look like Peacocks with companies that do nothing for the lower class shooters, other than take your money for using their equipment. We want to look good , and you may mentally shoot better. Your ahead of the game, since the work won't cost you a dime. Link to comment Share on other sites More sharing options...
fastshooter03 Posted July 18, 2015 Share Posted July 18, 2015 I too have turned down barrels for shooters who are unable to wield heavier ARs. Fortunately I have not heard of accuracy issues afterwards but I don't mess with the end of the barrel if it isn't required. Nick . Link to comment Share on other sites More sharing options...
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