"best" 308 dies to minimize runnout/maximize accuracy

[z7]

i know i know. . .

Not looking for "redding because i don't like my money" type answers but here we go

I am buying a really nice 308 bolt gun, custom barrel etc. discussing today with the gunsmith the specs, but i want to make sure my reloads are made to maximize the gun, not limit it.

i have RCBS small base sizer, and lee full length sizer, forster micrometer seating die (i really like it and don't want to change)

to maximize my accuracy, brass life, joy of shooting while minimizing runnout and ammunition based flyers, what is your favorite way to resize?

Lee collet neck sizer?
forster/redding neck sizer? bushings?
forster full length sizer?

or try what I have, if it shoots good don't worry about it?

I will, at least at first, just use what I have. if I want to try something new/new process like neck sizing the lee neck sizer is a tempting option for the price.

factors (as i understand) that need to be controlled for accuracy when reloading:
propellant (powder and primers) case volume, seating depth, bullet dimensions (inconsistent length, weight, bearing surface), neck tension, and runnout. it is the last two I would like to make sure I don't screw up with my current dies. i can control powder charge, i can buy good primers and make a combo my rifle agrees too. I can sort bullets and cases and buy better stuff like lapua brass, match bullets etc, but my equipment establishes neck tension and runnout. what is the best way to control those factors?

 

[stoky]

I think you will need to trim the necks to make the thickness uniform, for concentrically.
Sinclair (and others) make trimmers for this.
Match barrels are oft made with tight necks. It can be a PIA getting to where you don't get stuck rounds and or cases.

 

[Walkalong]

to maximize my accuracy, brass life

RCBS or Redding full length bushing die. Forster FL sizer with neck honed to your chosen dimension.

Competition seater of your choice. Several excellent choices.

 

[Nature Boy]

I started a thread a while back that might be helpful

http://www.thehighroad.org/showthread.php?t=801054&page=3

 

[z7]

I would rather buy expensive brass like lapua than trim necks. one of this items I will discuss with the the guy building it will be "i don't want to need to trim case necks" he builds a lot of guns for guys shooting PRS matches where they don't get to keep their brass, so I don't think it will be a problem.

walkalong, do you not like neck sizing? i realize i will have to full length resize periodically, but i noticed all the dies you mentioned were full length dies.

thanks again.

 

[Bart B.]

I agree with Walkalong except for the full bushing dies. They let the bushing slop around a thousandth or more and end up with case necks a smidgen out of line with the case body axis; but they're a lot better than standard full length sizing dies with expander balls bending unsupported case necks.

Redding claims that last 1/32 inch of the case neck that's not sized down in their bushing dies helps center the case neck in the chamber but the diameter of the neck at that point is smaller than the chamber neck so how in the dickens can it help center it? Bottleneck cases headspacing on their shoulders center up front in the chamber by their shoulder centering in the chamber shoulder when fired. When the primer fires the round, the case body doesn't touch the chamber wall anyplace except at its pressure ring where it may be pressed against the chamber wall opposite the extractor. And the case head's a few thousandths inch away from the bolt face. There can be several thousandths clearance between case neck and chamber neck. A .243 Win round centers its bullets in a .308 Win chamber when fired just as precise as a .308 Win round.

I've used RCBS and Bonanza full length sizing dies with necks honed out a couple thousandths less than loaded round diameters. No other die type ends up making the sized down case neck well aligned with the case body axis; they keep both body and neck aligned when sizing. I've got better accuracy with brand new .308 Win cases compared to any neck only sizing method.

These are the types of dies benchresters began using not too long ago. The smallest groups pretty much stayed the same size, but the largest ones shrunk quite a bit. Sierra Bullets figured this out back in the 1950's and have full length sized their test cases since then.

Once the case neck's properly sized and straight on the case, a ball peen hammer can seat bullets almost as straight as any standard seating die will, which is all you'll need with cases correctly sized.

You don't need tight neck chambers to shoot with best accuracy. But they may let you get a little more case life. I've got dozens of reloads with full length sized cases in SAAMI spec .308 Win loose neck chambers. Sierra uses SAAMI spec chambers in their test barrels shooting their stuff as accurate as anybody can.

 

[Walkalong]

These are the types of dies benchresters began using not too long ago.

Most still use FL bushing dies, but the honed out dies are very popular and probably are the best way to go, but not as cheap as chasing the right diameter with bushings though. Some just measure a loaded round and subtract .001 or .002 from it though. This works best with neck turned brass and custom chambers with tight necks. For a standard chamber I am not so sure. When I bought them for my .308 FL bushing sizer I just bought three different bushings, with the middle one the diameter I thought I would need. Even then, it will only work with the brass I am using. If I change and the neck thickness is different, I'll need a different bushing. Of course I could neck turn and stick with one bushing regardless of the brass used, but I have chosen not to neck turn and use Lapua brass which is uniform enough to make me happy with it as is.

 

[z7]

awesome gents, thanks for the help. i will probably go with what I have for now until i get the gun broken in/figure out some stuff, then I will probably pick up a forster full length sizer, and if i get set on one brand of brass, i might get it custom reamed.

 

[Bart B.]

I don't think you need to break in a good barrel; it just wears them out sooner. I've never had a good barrel not shoot very accurate from the first to last shot of their lives. If you start out with the best reloading tools, you'll sooner start out with the best ammo.

What "stuff" do you want to figure out?

If you want to try different makes of brass, then a Redding or RCBS full length bushing die may be the best to use. Get a few bushings with different sizing diameters. Brass with neck wall thickness with a spread of .001" or less is good enough. Bullets seated in such case necks won't be more than .0005" off center from the neck axis and have no measureable effect on accuracy.

Put a ring of .001" to .002" shim stock around the bushings so they'll have a tight slip fit in the die's bushing chamber and stay well centered which ends up making case necks best aligned with case bodys. Full bushing dies have the bushing chamber a couple thousandths larger than the bushing's outside diameter of .500".

 

[Dave P]

Terminology: maybe I am wrong, but "trimming" a neck is used to make the case length consistent in all the rounds.

Neck "turning" is using a tool (hand lathe) to make the neck thickness more consistent

 

[Sunray]

Sounds like you're over thinking the whole thing. Loading match grade ammo doesn't require any special tools. It's how the loading is done that matters. Primarily meticulously consistent technique. Match grade bullets make a difference too but those are not suitable for hunting if that's the plan.
"...have RCBS small base sizer, and lee full length sizer..." It's one or the other, not both. A bolt action will very likely never require SB dies anyway. Mostly just some semi-autos like 'em. You absolutely do not need multiple brands of the same thing either.
Anyway, the brand or type of dies set doesn't affect accuracy.
Case life is dependant on the load used. Not so much the dies.
While you can neck size only for a bolt action, using only cases fired out of your rifle, sooner or later you'll have to FL size 'em anyway. Neck sizing does extend case life a bit, but not enough to make much difference. Especially with a .308. Its brass is easily found and isn't expensive.

 

[Walkalong]

Terminology: maybe I am wrong, but "trimming" a neck is used to make the case length consistent in all the rounds.

Neck "turning" is using a tool (hand lathe) to make the neck thickness more consistent

Correct.

 

[Bart B.]

the brand or type of dies set doesn't affect accuracy.

People getting the best accuracy know otherwise. Only a few die makes and types properly set up and used get best accuracy.

Case life is dependant on the load used. Not so much the dies.

People getting the longest case life know the die type and how it's set in the press for the cases to be resized think otherwise; even with maximum loads. Some have got near 100 reloads per .308 Win case using full length sizing dies with necks sized 1 or 2 thousandths under loaded round neck diameters shooting maximum loads.

That said, those quoted remarks are commonplace amongst reloaders. The Lee collet die that sizes case necks is a good example of what's popular but not what's used to get best accuracy.

 

[30Cal]

People getting the best accuracy know otherwise. Only a few die makes and types properly set up and used get best accuracy.
...

Certainly. If you are shooting at the highest levels of competition. But you can still amaze your friends and shoot some very nice groups with the cheapest set of dies out there, and without all of the extra case prep. If you start with good brass, good bullets, and tune that, you should be able to duplicate factory match ammo (and usually exceed it).

 

[tcook90]

In this video, he's sizing .243 cases, but the .308 works the same.

Plus, a cool accent!!

https://www.youtube.com/watch?v=RZEas38vkKg

 

[243winxb]

Bushing - neck- center round

Bart B. <> Redding claims that last 1/32 inch of the case neck that's not sized down in their bushing dies helps center the case neck in the chamber but the diameter of the neck at that point is smaller than the chamber neck so how in the dickens can it help center it?

The unsided neck area fire forms to the chamber. May take 3 firings to fully expand. The amount left unsided has a direct effect on accuracy in my testing. If i size more of the neck then shown in my photo, groups open. Shooting a single shot doesnt require a lot*of neck tension or bullet bearing surface incontact with the case neck.

[/URL][/IMG]

 

[Bart B.]

Are you sizing fired .243 Win cases such that their shoulders are set back a couple thousandths?

Does the chamber neck have the same diameter as the unsized portion of those sized cases; to the nearest .0001 inch?

What's the size of a circle (in MOA) that contains all fired test shots with such setup with your die?

I ask because those cases look like they're only partially full length sized, not totally full length sized.

 

[redfir223]

I read somewhere that whoever wrote the article said that he got better results pushing the expander ball into the case than pulling it through. At first I didn't get what he was saying but then it made sense. I have Redding dies with an expander stem which unscrews. I sized several cases the way you normally would, and checked the runout and made notes on each case. I then took the stem out, sized the case again then putting the stem back in and raising the case into the die until the neck was expanded but not far enough to size the neck again. I found that pushing the case over the ball instead of pulling it through decreased runout measurably. On those which had the same amount of runout after this, it made sense to me that that particular case may have had a thicker spot in the case neck which got pushed to the outside upon expanding. A case like that will always be off center, so it is also a good way to find your most consistent cases as well. Has anyone tried this to verify my findings?

 

[Reloadron]

Case Gauge? I would talk to your smith about making you a case gauge using the same reamer they cut your chamber with as well as turning you a neck gauge using that reamer. A really good smith could turn you sizing dies also but if you go commercial I like the RCBS Competition FL die sets, especially for bullet seating.

Ron