Okay, this is one of those questions I probably should know since I've been reloading for a couple of years, but how thick should the brass be in a case neck? On a more practical basis, how do I know if the neck is too thick?

I've never worried about this before, but I just formed a bunch of 300 Savage brass from military 308 cases and miked the case necks, which measured .015". Since I didn't have any factory brass handy as a comparison I have no idea whether this is an acceptable thickness.

How do you know the neck is too thick - make a chamber cast from your rifle and measure the neck diameter, then make sure you have .002" clearance so the bullet can release cleanly when the cartridge is fired.

What thickness should your brass be - my Hodgdon reloading manual edition 26 lists the 300 Savage cartridge neck outside diameter as .3390", so subtract .308" to get .0310" and divide by two for a neck wall thickness of .0155".

Mostly we don't worry about neck wall thickness when doing our reloading because the factories leave a generous clearance when cutting chambers and drawing brass. But when we start making our own brass, or start benchrest shooting with very tight "match" chambers then neck wall thickness needs to be checked. If you don't and a bullet gets stuck in the case neck because the neck was wedged into the chamber; then pressures get really high, really fast.

Ok, .015" is probably a good average neck thickness measurement for the class cartridges we are discussing, however, let's think in terms of the rifle neck chamber diameter. Neck thickness can vary from one manufacturer to another and an individual case neck thickness can vary which is why benchrest shooters "turn necks" to get consistency. Therefore:

1. If you have some fired cases (cases fired two or three times and not annealed would be better because less spring-back) you can measure this case add .001" and get a fairly accurate measure of your rifle neck chamber.

2. Make up a "dummy" round and check neck diameter of dummy and compare to fired case. You are looking for .002"+ for a factory rifle.

3. Run your formed brass in standard sizing die and if the case does not fit that would indicate a problem in neck diameter.

4. Run dummy round in chamber and feel for drag or difficulity chambering which would indicate a problem in neck diameter.

5. If all looks well shoot mild loads and look for pressure signs.

6. A chamber cast will certainly give you specifics of your rifle chamber.

Hope this helps.

Hey belaw

I typically outside neck turn down to .013" plus or minus .0005" or so. Today bounty hunter and I were neck turning some brass with his new K & M turner and had to turn down to .013" to get down to the thinnest part on some WW brass.

I recently got some 280AI Nosler brass and it was fairly consistant from .0135" to .0145", so the brass you have is plenty thick. You definitely could outside neck turn .001" or so off it without any problem.

quote:

What thickness should your brass be - my Hodgdon reloading manual edition 26 lists the 300 Savage cartridge neck outside diameter as .3390", so subtract .308" to get .0310" and divide by two for a neck wall thickness of .0155".

Well, I was looking at this all wrong getting hung up on proper neck thickness when the critical measurement is the neck diameter of a loaded round.

I loaded up some dummy rounds when I go home this evening and then measured the necks.... which measured .3381, so I guess I'm good to go with my reformed brass without neck turning. Thanks for all the good advice.

You're welcome belaw. Glad we could help.

When you're prepping your brass before resizing, take a bullet and see if you can insert it into the neck of the fired case, if it slides in, you're good to go. Kinda K.I.S.S.

Most reloading manuals have the maximum cartridge dimensions at the top of the data or somewhere else in the book. If your manual doesn't, you should get another one that does!

Your micrometer will let you see if your loaded round exceends the maximum neck diameter. ??

Jim C.

He knows what reloading manuals have in them. And, he knows what a micrometer does. The question was about neck thickness. Does your reloading manual show case thickness????