Tight neck vs. No turn .308 win
- Thread starter potatoe
- Start date
Keith Glasscock
Gold $$ Contributor
What brand of brass do you want to use? With Winchester, a .335 is a good neck diameter for just skimmed (.333 loaded round), but can also fire factory Winchester brass without turning (assuming you mic the necks just in case).
I don't have any Lapua to measure, so hopefully someone that uses it can chime in.
I don't have any Lapua to measure, so hopefully someone that uses it can chime in.
Keith Glasscock
Gold $$ Contributor
Here is the info on Lapua brass:
http://forum.accurateshooter.com/index.php?topic=3787358.msg36072794#msg36072794
http://forum.accurateshooter.com/index.php?topic=3787358.msg36072794#msg36072794
XTR
F-TR obssessed shooting junkie
potatoe said:
My last barrel was a "no turn, tight neck" if you used WW brass. The neck was .339, too tight for Lake City or Federal but just right if you reloaded in WW. (you want a .442 if you want to be able to shoot pretty much anything)
I don't know what kind of shooting you are doing, but for applications other than bench rest I think turning is a bit much. Try a Lee collet die, they are only $28 which is a whole lot cheaper than the equipment for turning and tons less time.
effendude
Gold $$ Contributor
I am breaking in the new F-TR barrel and these are the dimensions I am coming up with. Skim turning new Lapua brass to what I would guess is 60-70%. Loaded rounds measure .337 and fired rounds measure .3415. I don't have a ball micrometer to measure neck thickness.
I truly believe uniforming the case neck wall thickness helps the uniform release of the bullet.
Scott
I truly believe uniforming the case neck wall thickness helps the uniform release of the bullet.
Scott
I need to order a reamer and have been measuring some stuff. Lapua seems to be around .339" or so. Interestingly enough, Fed GM brass is a full .342" when loaded.
I think I will get a .342 neck unless I someone talks me out of it. I want to be able to shoot factory ammo too.
I need to find some GM loaded ammo and see if it is as thick as my box of brass.
I think I will get a .342 neck unless I someone talks me out of it. I want to be able to shoot factory ammo too.
I need to find some GM loaded ammo and see if it is as thick as my box of brass.
DennisH
Life Time NRA member
Neck consistancy seemed to help my scores!
Again, I skim turn the necks and run about .002 neck tension. I always check concentricty!
As one person put it to me: I may make the difference between a 9 or 10!
I will have to note I shoot with two people who just load their bullets. Both have shot perfect 600 scores! Both were shooting BRX's and not 308's. OPINIONS?
Again, I skim turn the necks and run about .002 neck tension. I always check concentricty!
As one person put it to me: I may make the difference between a 9 or 10!
I will have to note I shoot with two people who just load their bullets. Both have shot perfect 600 scores! Both were shooting BRX's and not 308's. OPINIONS?
I've ordered about 8 reamers in 4 different cartridges and gone back and forth with neck dimensions. I think the simplest and most broadly acceptable answer is to get a SAAMI minimum neck. I spoke to Gary O'Cock about this a few years back and he said that many top benchrest shooters were completely re-thinking tight-neck guns and he thought .003-.004" of neck clearance had no negative impact on accuracy for 6mm cartridges. Add in German Salazar's comments about .006" or more being acceptable for 30cal cartridges and a picture starts to develop: ample clearance is not detrimental to accuracy and certainly enhances safety and function. If I had just gone with SAAMI minimum neck dimensions, I would have ordered only 4 reamers instead of 8 and I'm sure I would not have dropped a single point in competition (F-Class).
PS. that's a .343 neck in 308WIN and if you use Lapua brass that gives you .006-.007 of clearance.
PS. that's a .343 neck in 308WIN and if you use Lapua brass that gives you .006-.007 of clearance.
If using bushing dies you can have the best of both worlds.
Use a no-turn neck chamber or turn for .003+ clearance, then set your die so you size the brass and bump the shoulder the way you want it, but set the bushing so it only sizes the top 75% of the neck. This gives plenty of clearance for good release but the unsized portion of the neck allows for a snug fit which helps center and support the cartridge in the chamber. I turn my brass anyway to make it all the same even with a no-turn chamber.
Use a no-turn neck chamber or turn for .003+ clearance, then set your die so you size the brass and bump the shoulder the way you want it, but set the bushing so it only sizes the top 75% of the neck. This gives plenty of clearance for good release but the unsized portion of the neck allows for a snug fit which helps center and support the cartridge in the chamber. I turn my brass anyway to make it all the same even with a no-turn chamber.
300 RUM
Gene Nowaczyk
Turning the necks nice and symmetrical only makes sense, it really does give a edge to bullet release, but exactly how much?
I shoot F-t/r and I can hold less then 1/2 MOA all day long shooting better then 1/2 MOA groups, doesn't mean I win though. At 200 yards I can produce 1/4 MOA or better at times with un-turned necks and averaging .35"-.47" groups. At three hundred yards .9"-1.25" groups are fairly common, 600 yards & 1000 yards the wind can kill those numbers very quick, .65 to .9 MOA is what I hope for and what I get 50% of the time is 1 - 1.5 MOA.
So I figured I would turn the necks and see if I could get some advantage from it. Well at 0-300 yards I see maybe a .05" - .1" difference at times, but no real difference in my averages and no difference at 600-1000 yards.
Over the years I have become a better shooter averaging .6-.9 MOA and if I get a break reading the wind .5 MOA at 600 and 1000 yards only due to practice not to any magical reloading process. On the same note, I do FL size, clean primer pockets, trime etc, it does make a difference.
So what do you shoot and can you read the wind, that will tell you if you need to neck turn?
PS. My personal best group at 600 yards: 20 shots @ 1.96" (4 INCHES BELOW THE X RING) A perfect 180 ain't that the shit. "If only I could of trimmed off the mirage that day"
I shoot F-t/r and I can hold less then 1/2 MOA all day long shooting better then 1/2 MOA groups, doesn't mean I win though. At 200 yards I can produce 1/4 MOA or better at times with un-turned necks and averaging .35"-.47" groups. At three hundred yards .9"-1.25" groups are fairly common, 600 yards & 1000 yards the wind can kill those numbers very quick, .65 to .9 MOA is what I hope for and what I get 50% of the time is 1 - 1.5 MOA.
So I figured I would turn the necks and see if I could get some advantage from it. Well at 0-300 yards I see maybe a .05" - .1" difference at times, but no real difference in my averages and no difference at 600-1000 yards.
Over the years I have become a better shooter averaging .6-.9 MOA and if I get a break reading the wind .5 MOA at 600 and 1000 yards only due to practice not to any magical reloading process. On the same note, I do FL size, clean primer pockets, trime etc, it does make a difference.
So what do you shoot and can you read the wind, that will tell you if you need to neck turn?
PS. My personal best group at 600 yards: 20 shots @ 1.96" (4 INCHES BELOW THE X RING) A perfect 180 ain't that the shit. "If only I could of trimmed off the mirage that day"
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