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We got a heavy ar barrel that weighs too much at 2 and a half pounds. It is the H bar type of heavy, not the straight profile. Can I take some material off this barrel with out upsetting the stress of the barrel. I would rather have a heavy accurate barrel then a slimmer barrel but minute of barn in accuracy. Any advice from the A-men corner?
Not a problem as long as your 'smith doesn't try to turn it hard and fast.
A sharp HSS cobalt tool ran slow with a good flow of coolant over it will do well. Avoid generating heat when cutting. Small passes with a sharp cutter.
Another option is to flute the barrel this helps maintain the stiffness of the heavy contour and lightens the barrel weight. Another plus is the increase in surface area which aids in cooling. The barrel on my wifes AR Match rifle is fluted both sides of the gas port to get the weight down to where she could handle it. I had Kriegers do the fluting when they made the barrel.
Another thing to consider that helps a lot with this type of modification is while the barrel is off the rifle and been re contoured send it out and have it stress relieved again to remove any stress put in the barrel from machining.
For what the machining and stress relief would cost if done corrrectly, you could just go out and buy a new, lighter barrel and then sell the one you have and be money ahead.
True that. AR barrels are relatively cheap - unless you're buying top shelf.Quote:
Originally Posted by Outpost75
I'm not a benchrest competitor, but those guys & their rifles always fascinated me & indeed they were pioneers in moving rifle/cartridge accuracy to greater levels. On another website, I met a shooter that had a Shilen premium SS match barrel for sale in 6mm PPC. It was a take-off from his 40X rifle with about 3,000 rounds through it. I bought the massive barrel for $80 shipped. I had a local gunsmith cut for a recoil lug & install/headspce it on an untrued Rem 700 short-action. I put together a "poor-man's" bench rifle to fun shoot. Boy does it shoot! Groups in the teen's & low 2's are the norm! Having a rifle that reveals every flaw I make has been very helpful to improving my shooting technique.
This got me to thinking (a dangerous thing), these premium take-off barrels are fairly common as benchrest shooters think they no longer have the "accuracy-edge" or want something new. They are not too hard to find & at really cheap prices. These big massive barrels have plenty of "meat" & length left on them to be turned down into AR barrels. I always wondered if the effort to re-contour would be overly prohibited & what equipment would be required.
unless you have your own lathe and just want to kill time, it is more economical to buy a decent barrel in the profile you want.
A used barrel isn't a disadvantage most of the time. A benchresters used barrel ( especially one of the top competitors) will have plenty of service left in it for most shooters. I had 3 guys at work waiting for my 243 take of barrels when I was competing in NRA High Power. I shot hart barrels OTC contour at 26" long 1-7 twist. I changed out when X count started dropping at 600 yds. Threads could be removed and recut chamber refreshed and fitted up. Depending on caliber and chambering a used barrel from a top competitor isn't a issue for most.
My match rifles in this order were Krieger, Hart, Lilja and Pac Nor barrels ( always wanted an Obermeyer 5R for my M1A ). I have a Douglas on a garand and a shillen on a martini cadet.
A lot of home smiths built cadets and other rifles in 22 hornet 218 bee using take of 22 rimfire barrels from WIN REM and other target rifles ( why sierra still makes .222 22 cal bullets) with very good results.
I would trade you a PSA Freedom stainless light weight barrel!
I will do the work. I never thought of flutes and I have the cutter for flutes in a box of other goodies. Gosh, I like the idea of flutes!
I've turned down AR15 barrels and also fluted them. Usually one or the other but did both to one about 12 years ago or so for a lighter coyote barrel. Wasn't fantastically accurate before but would usually hover just under to about an inch. Shot the same afterwards and was much nicer to carry around. For fluting, unless your machine is very ridged use a horizontal mill radius cutter.
Cut fins in it ala Thompson. ;-)
If your working in a mill to flute an issue to watch out for is the Table rocking going from one side to the other as weight changes from table movement. As the table travels from start its weight ****s from one side of the knee to the other causing a rock in the tables movement. On a bridge port style or knee mill this can be several thousandths each way or a little more when the play shifts from X axis gibs ( table) y axis gibs ( in and out) and z axis gibs ( knee or up down) from side to side. The locks will help but not stop this from occurring. This is a job the old horizontal mill shined at since the rock was in the bottom of the flutes it didn't show as much.
Working with a ball mill in the Bridgeport has the same effect but the radius left dosnt look as good as the bigger diameter cutter does.