Small base sizing die in 308 (M-14 accuracy woes)

I've read that all Lee rifle dies are small base dies and it seems to be true. I have a .308 with a really tight chamber and full length sized brass in either RCBS or Hornady dies wouldn't allow the chamber to close. I tried Lee dies and it worked. I don't know if they are true small base dies or just slightly smaller than normal but it worked for me.
 
My gun would close on a 308 go gauge but would not fully close on a case re-sized by a lee die, take that for what its worth.

Small base/ New Match dies should form the shoulders 0.003 shorter then SAAMI spec....newer dies will reduce the shoulders and circumference

From Lee

If you have the Lee Pacesetter die set with a full length-sizing die, you shouldn't need a small base die. Other manufacturers make small base dies on the premise that semi-autos require cases sized to the minimum allowable case dimension for reliable feeding, but in reality most semi-autos have chambers cut on the large side for that same purpose. The result is overworked brass and shortened case life. If you have any chambering problems with ammunition that has been sized with a Lee full length sizing die, return the die and a couple fired cases to the factory for free adjustment.

Lee's address is;

Lee Precision Inc,
4275 Hwy. U,
Hartford, WI 53027.
Click to expand...
 
An FL die will do the same job. An SB die just sizes a few thou smaller. 5 I think. A properly set up FL die will work just fine. It's not a one is better thing.
"...My gun would close on..." The case means nothing. It's not a guage.
"...all Lee rifle dies are..." Lee sells FL dies too. Don't think their stuff is all SB though.
 
Savage Model 10 PC.

Ran the brass through my Lee dies. Bolt wouldn't close. Checked the trim length, tweaked the die position, ran them through again, still no go.

Found a RCBS SB die at WSS, BINGO......life's good!!

(E) :cool:
 
Thanks for the info guys. My reason for this inquiery is a result of reading this:

h ttp://www.zediker.com/downloads/14_loading.pdf

On page 5 he explains loading for the M-14 platform. I have a Norc that I can't get below 3 MOA. I've put a USGI barrel, TRW bolt, match oprod, bedded USGI stock, shimmed and untized gas system in, and glassed it with a Leupold Rifleman on a CASM mount. I've decided my reloading practices for it must be the issue. I have no problems making sub minute loads for my 308 rem 700, but there seems to be more to loading for the M-14.
 
None at all.

I've been working on this rifle for years off and on. I haven't done that much as far as load work goes. I mostly blamed the rifle. Just tried a few 155 gr smk loads with 4895 recently, consistent 3 MOA. I was thinking about making some 110 gr and some 168 gr loads and seeing what happened. I just want to make sure I know the ins and outs of loading specifically for this platform first.
 
Go to M14forum under ammunition.
But I finally broke down and bought LC brass and IMR 4064. I loaded 41.7 grns with the 175 and 168SMK's, the168's were about 1 moa but the 175's were one holers or 1/2 MOA worst case. I have read numerous places that the 175 and 168 SMK take the same charge, based on the above results I think this might not be factn.
Click to expand...

First thing is to try the 4064

Make sure you use a chroney.
 
What loads have you tried so far?

I have been working on some 155 and 168 grain loads since the start of summer and just recently found a 168 grain load at the low end-of the 4859 range that works exceptionally well (just netted a 0.59" group). Other loads are grouping anything from 1.5" to 4".
 
My small base dies for .308 and .223/5.56 only make the base diameter of the case .0005 smaller. The real difference is the SB die sizes further down the case. A M14 type military chamber is .0025 larger in diameter and .0025 longer in chamber length. This means a standard FL .308 resizing die is for all practical purposes a "small base die" for the M14 chamber

183911.jpg


You need a good gauge to see how far you are bumping the shoulder back during resizing.

RCBSPM.jpg


If you don't already have a cartridge case headspace gauge I would buy the Hornady gauge in the top of the photo below. That way one gauge will fit all calibers and you only buy one gauge.

Picture009.jpg


If your having chambering problems make sure your die is making hard contact with the shell holder and the press cams over. Meaning adjust your die further down and push the shoulder of the case back further.

I normally use my small base dies "once" when buying once fired military cases to return the cases to minimum dimensions. This is added insurance if the ammunition may have been fired in larger machine gun chambers.

Bottom line, the majority of military chambers are "fatter and longer" and chambering problems are caused by the shoulder of the case not being bumped or pushed back far enough with standard sizing dies.
 
Pr589, I have tried other loads in the past but have dismissed their results as I have been modding the rifle up until very recently. Now that I have exhausted options for fine tuning the rifle itself I am working on loads. I've tried 42 and 43 gr of IMR 4895 under 155 gr SMK. Both with consistent 2.8-3 MOA results.

Bigedp51, You hit the nail on the head for what I was trying to understand from that article. Thanks for the heads up on the Hornady gauge. I was about to buy the RCBS one. So my rifle having no issues with chambering means I have no requirement for a small base die. I'm going to buy the gauge in any case to get an idea of what my chamber us doing to the brass.
 
Just for the record re Lee "small base dies"

With my jig the Clymer 308Win go gauge came out at 1.629
The S&B 308 Win ammo came out at 1.624
My fully resized 308 win cases using Lee press and dies came out at 1.634
 
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