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Posted: 6/26/2003 9:25:32 AM EDT
I have heard the thin "pencil" barrels like the "A1 government" contour shift point of aim after 10 or so rounds have been fired. Another source (selling fluted barrels) says that a fluted mid weight barrel is nearly as light, but much more stable.

Can any of you personally verify this? I know the claims, but it it hype ot fact?
Link Posted: 6/29/2003 7:51:20 AM EDT
Part hype and part fact, in my opinion; since it depends on what you're using the piece for. If I fire a quick bunch of rounds thru either of my early barrels (one 20" A1 type and one SP1 Carbine barrel cut to 11.5" w/a XM177 type flash hider} and then sit down at a bench rest, the point of impact has moved up an inch or so at 100 yds, and the groups are usually a tad bigger than when I start cold and fire one every 2 or 3 minutes. On the other hand, I'm not looking for match or bench rest type groups out of either of these pieces, so I don't consider the change to be significant. A match or varmint shooter might though.[:D]
Link Posted: 6/30/2003 11:21:56 AM EDT
The reason I am inquiring is that I am planning a light weight scoped varmint rifle, seeking close to MOA accuracy AND would like the whole rig to be close to six pounds. I think the AR15 platform has a lot to offer with light-weight free float tubes and great accuracy potential. Actually this question is about barrels themselves, not the action type (auto-loader or bolt-action, etc). I have a bull barrel AR15 that is superbly accurate, but too heavy to carry for a casual stroll through prarrie dog land (which can be miles and take hours). I don't want to build another heavy rifle, nor do I want a light weight that shoots 6" somewhere else at 200 yards after 10 rounds. I will have a 2-7x or similar scope, so I will know if it is shifting.
Link Posted: 6/30/2003 5:24:50 PM EDT
The most accurate barrel I own is an old 20" Colt SP1 pencil barrel. The 1/12 twist LOVES anything near 55gr. It's IBZO'd at 50yds right now. Just need to verify and fine tune at 200m. :)
Link Posted: 6/30/2003 10:49:31 PM EDT
I've got a 16" superlight that shoots moa all day long. Yes there's some horizontal stringing during rapid fire but just about EVERY barrel will exhibit a shift in POI as it heats up.
Link Posted: 7/1/2003 2:31:41 PM EDT
In my opinion, and from the information that I've learned here at ar15.com., I would have to say that Tactus hit the nail on the head when he mentioned "rapid fire" POI shift. If you are varmint hunting, etc. such as a shot now and then, the barrel shouldn't be affected enough by heating up to affect accuracy very much at all, ecpecially if the barrel is free floated. I would estimate that the most advantage of a heavier barrel would be in the steadiness it would allow for the long shots. Harry
Link Posted: 7/3/2003 5:51:47 AM EDT
Originally Posted By HarryD: ...... I would have to say that Tactus hit the nail on the head when he mentioned "rapid fire" POI shift. If you are varmint hunting, etc. such as a shot now and then, the barrel shouldn't be affected enough by heating up to affect accuracy very much at all, ecpecially if the barrel is free floated... Harry
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Well I hope so, I just finished another project and this light varmint rig is next. I need at least 20" of barrel to keep the velocity up and a light free-float tube is definitely in the cards. I have a Calvary Arms (synthetic) lower that I may use, but it just feels too long. If they ever get their new standard length one in actual production I may "trade up" to it.
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