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Brian S
06-11-2003, 09:47 AM
I have had some grouping problems on my 6.5/308 and was looking at the barrel last night. After giving it a real good cleaning I noticed some scratches about 1/4" into the barrel from the chamber. They go from one groove accross and nearly touch the next groove. I can see 2 of these and the rest of the barrel is fine. Would scratches so close to where the bulllet hits the barrel cause a problem for accuracy? The grooves seem to be a little shallower if thats a word. I would think thats just wear from years of shooting. I did the old try to put a bullet in backwards at the muzzle and its very tight. It didn't go in at all. Any tips? Is the old rcbs 6.5/308 the same as the modern .260 Remington. I have measured everything but the angle of the shoulder and they seem to be identical.
Thanks
Brian

DATUM
06-11-2003, 10:51 AM
Brian,
It sounds like the chamber reamer had a couple of metal chips on the reamer pilot when the chamber was made. Sometimes if youre not careful, the reamer will collect metal shavings (chips) while cutting. the machinist should flood the reamer with coolent or clean the reamer often while cutting. If a chip is stuck on the reamer pilot while the lathe is turning, you have a small groove going around the inside bore. The chip is harder than the barrel steel because the chip warms up during cutting (work hardens). Sometimes you can lapp the barrel to remove these markings but it depends on how deep they are. If the markings are too deep you can bring the barrel "back" rechamber till the marks are gone then re thread and set headspace.
A 6.5-308 is almost the same, it's a little bit tighter around the neck(.002) and brass should be trimmed about .020 shorter than the .260. Ref.JGS reamer prints.

Brian S
06-11-2003, 11:42 AM
Thanks Datum,
Sounds like that could be the cause of it or the cleaning rod beefing into it as it enters the barrel but they are usually aluminum. The barrel has been on the rifle for atleast 35 years so I wasn't around when they reamed it. How do you go about lapping it out. Firelap or put some compound on brush and work it. The chips we make at our shop are in the micron range so I get that work hardening chip problem, just messy grinding sludge.
I've actually shot factory .260's through this rifle with no problem and then just trimmed them all to the same o.a.l. before I reloaded. When I got the rifle all the brass was old cracking military .308's necked down to .264. So I measured the .260 factory round against the reloads and they were almost exactly the same. Now I have have headstamped .260 brass and they've been through 2 or 3 times at bat. This barrel is really tapered and I think it has some issues with heat after a couple shots. So if it comes to having to re-chamber I may just buy a new 22 or 24" barrel. Getting back to the accuracy part, do you think these scratches would effect accuracy or would they stabilize as they spin through the barrel.
Brian

DATUM
06-11-2003, 03:44 PM
Hi Brian,
The way I lapp a barrel is to take a old brush on a cleaning rod run up from breech to bore , keep the tip of the brush in the barrel about 3/8". if you like put a patch on the brush about 2/3s the way down, before you run it into the barrel. When you have the brush in position, pour hot lead into the muzzle, it should fill most of the brush and the 3/8 in front. After it cools, push it forward a little bit and cut the lead off that stops you from pulling the rod "back thru the barrel, it's like a mushroom of lead on the crown. After thats cut , push the lapp out the muzzle smear Clover compound ,I use about 1000grit.( some guys argue about what grit ) Carefully push the lapp into the bore aligning the rifling to the grooves in the lapp. Run rod back and forth about 10 times staying in contact with the rifling. Then push lapp out muzzle again and rotate lapp one rifling groove, insert into barrel lapp 10 times ,rotate ,do it again until you have rotated into every rifling groove. After all this clean it and take a look. Maybe do it all over again!!!
I have a brand new Remington 700 take off barrel if you want it you can have it Free just cover the shipping. If it's a Remington you have it should work but check headspace.
I sure hope all this helps!!!

AMMOe
06-11-2003, 05:45 PM
Brian: I don't think those scratches would effect accuracy to any degree. I hae shpt too many rifles with "imperfect" barrels to think that is your problem. A general condition of wear might be the problem. After alot of shooting and resultant wear, it's often necessary to rework old loads; from seating the bullet out a bit more to starting from scratch to see what shoots best.

And of course, if all else fails, there is the option of setting back the barrel a turn. Good luck! ~Andy

Brian S
06-12-2003, 07:28 AM
Well that makes sense Datum thanks for the explanation. I'll take you up on that barrel, I'll pm you with my info. Andy I guess thats all part of the hobby. "Dear I need to get more than one powder to find out which gets the best groups, no I'm not going to blow up the garage". Can you turn a model 700 down and re-thread to fit a small ring mauser such as the Turkish model 38?
Thanks
Brian

DATUM
06-12-2003, 08:03 AM
Brian,
The Remington 700 has 1 1/16 X 16 Threads with a minor dia. of .985 . The small ring has a .980 major dia. so you're good to go!
I received your message, and will call you today. I'm happy to help.