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Neck sizing for .308

20 Mar 2012
@ 11:06 pm (GMT)

Matt Reid

Hi there,

I am currently working on my shooting skills using a Rem .308 and have been reloading for a little bit. Ideal goal would be confident of taking deer out to 600m with it.

I am running Norma brass, with 2208 and 210 primers and 168amax, going around 2700. I initially started neck sizing only but ran into chambering issues. I later found this was related to a slightly dodgy extractor that was 'crimping' the case rim when bolt was closed. Since then I have been FL sizing but accuracy doesn't seem as good (may just be me).

Am I better neck sizing only if possible? Will this likely reduce runout ?

Cheers, Matt


22 Mar 2012
@ 03:07 pm (GMT)

Nathan Foster

Re: Neck sizing for .308
Hi Matt, I thoroughly suggest you get True-Flite to fit a Sako style extractor to your bolt and end the extractor problems. The trouble is, now that the extractor is gimpy, it will eventually break so it needs to be replaced soon (you can tell your wife that Nathan said you had to do it).

I can't tell for sure whether you are better off neck sizing etc without seeing the rifle first hand but as trends go, the head space on the Remington .308's is usually a great deal looser than other rifle brands (which is fine). This can mean that neck sizing will be potentially helpful, increasing accuracy (but usually only marginally- if barely noticeable) along with increased case life (not over working the brass). I believe the case life factor is the biggie with loose spec Rem chambers.

I also find that neck sizing is faster and easier than FL sizing, I simply dip my cases in graphite and run them through the neck sizer. I go through a great deal of .308 ammo due to the tutorials so speed is important, as is a non finicky platform (non fussy rifle and hand loads), I don't have time to be mucking around with batching cases and projectiles.

Every now and then I will come across a rifle that prefers to be FL sized for best accuracy, showing a difference of say 1 MOA neck sized versus a .5 MOA when FL sized. In your rifle, it may simply be that some measure of concentricity (bullet to bore alignment) is lost by a bent extractor forcing the cases to one side of the chamber, forcing the case off centre. Of course, I am only guessing here.

Get that extractor fixed, thats the first step.

23 Mar 2012
@ 03:00 pm (GMT)

Matt Reid

Re: Neck sizing for .308
Hi Nathan,

Thanks for the reply. Seems a few people have had a similar issues with the rem extractor, bit of a weak point in the design maybe? The rifle is only a few months old, new via Reloaders. Initially I thought I was having headspacing issues, so went back to FL sizing, but may try neck sizing again.

It does however seem to take considerable effort FL sizing maybe indicating the brass is taking a hammering?

Great site by the way. Followed a few of your posts over at LRH also.


26 Mar 2012
@ 01:24 pm (GMT)

Nathan Foster

Re: Neck sizing for .308
Thanks Matt.

Yes, the M700 extractor can be a weak point. They seem to either break down after the first few weeks of use or last forever. I considered the extractor the sole Achilles heel of the M700 up until the introduction of the Mark X trigger. Now we also have quality control issues to take into consideration. Fortunately the platform is still of a sound design and great to work with.

If the cases are difficult to FL size, there may be a few factors at play. If the rifle has generous head space, FL sizing can be a bit difficult but the main concern is that the brass is being overworked and will eventually split at the case head. This incipient case head separation is usually gradual so you can catch it before a full rupture occurs. Ofcourse you are in a catch 22 situation where if you do not FL size, chambering is difficult due to the extractor protrusion. I believe it is important for you to replace the extractor asap.

Make sure you use lots of lube, that is always important. I use lee lube but sometimes use Snow seal wax but only on the outside of the cases as Snow seal has a strong petroleum smell which makes me suspicious of its potential reaction with powder. I lube cases by hand, spinning them in my fingers. Some folk use industrial silicon spray, seems to work well.

Ideally, when FL sizing, the die should not be touching the shell holder unless absolutely necessary. It is best to back the die off a couple of turns, size your case, see how it chambers, if it is tight, then turn the die down a quarter turn and try again- and so forth until the case is brought just undersize. One trap however, is that some dies will extrude the case, either on the down stroke via tight body dimensions which push the shoulder forwards, or, on the upstroke, the expander button stretching the case.

If the die body dimensions are tight, there is sometimes no option but to size to the shell holder. If the button is too tight, this can be remedied one of two ways. The user can apply more lube (via a cotton bud) to the inside of the case necks or polish the button by spinning the expander assembly in a drill and honing the button with fine emery. Some caution must be exercised with sanding the button because if it is made too small, in some instances (depending on die dimensions), tight case necks can mar projectiles during seating. On the other hand, a tight case neck can help lower ES.



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