30BR brass necks keep getting loose

[mwezell]

Ed, I turn for a .328 loaded round in a .330 chamber.-- M

[eww1350]

I am running into this problem of loose 30BR necks that have me stumped. I have a .330 neck 30BR rifle. After fire forming, I begin with using a .327 bushing, any smaller is too tight. After firing a couple of times, I have to go to a .325 bushing since things begin getting loose. After 2-3 more firings I am at .324 bushing. After one more firing it seems much looser then when I first used it. It seems that at this rate I will have to go to a .323 bushing soon.

I neck turn my brass to .0010. My mic measurement of a loaded cartridge is coming out to .330 even after using a .324 bushing.

What am I doing wrong? Should my necks be thinner?


Any help would be greatly appreciated.

Thanks,
Ed

Ed,...what you have written "flies in the face of conventional wisdom"...if you indeed have brass with .010" walls and are using a .325" bushing and have a rifle chambered with a .330" neck reamer by a competent gunsmith...you cannot have loose neck tension after sizing the brass for another firing...something is amiss in your data...take your reloading dies, brass and rifle to an experienced 30BR shooter or you gunsmith and let him look at the setup...taking wild guesses from your info posted on the internet is not likely to solve the problem...If I were taking one of those "wild guesses" I would say your bushing die is set up incorrectly and you are NOT even sizing the neck because your bushing is not held down in the bottom of the bushing recess in the die...get someone with experience to put some "eyes" on your die setup..

Eddie in Texas

[mturner]

My reply about clearance being "overly generous" did indeed come from losing the clarity offered by the original post.

That said, I still believe the answer to lie in "changing character of the brass," ie work hardening as others have so well explained.
al

Al,
I have followed your post for some time, and have no doubt about your knowledge. At the same time, the original post can be looked at two different ways. He says the loaded round measures .330", which would indicate almost no neck clearance. He also states (by accident) the he turns his brass to .0010" instead of .010". In that case we would have a loaded round of about .3105" at the pressure ring, or .0195" clearance which equals generous clearance.

Michael

[mwezell]

I don't see any bad advice here. I know what I have said is as true in my own and most shooter's experience as it can get. There are always exceptions. Maybe Charles knows more that he'd like to share, other than his opinion of who to listen to, which frankly, I've come to find pretty useless in short range. I see where speculation would come into play here because of the numbers being somewhat outside the norm, but I don't see any guesses either. Ed, find someone you trust to help put the pieces together. It's all verifiable and can leave no room for subjectivity except in what works best for you and your gun.

[RJM]

"30BR brass necks keep getting loose"

Have you annealed your case necks? If you didn't, they start out hard (springy) and only get more so. When they are too hard, you will get less neck tension.
Regards,
Ron

[Al Nyhus]

Whatever the method of necking up (expander or f-forming), annealing before the first 'real' firing cures a lot of ills.

You can also have varying neck tension in these 30BR's because of the fit of the neck i.d. to the turning mandrel. After necking up, the case neck i.d.'s are funnel shaped. About 10 seconds with a pin guage will show this. Making the neck i.d.'s round and straight before turning is something I've found to be critical.

Good shootin'. -Al

[Markhor]

Thanks Al, I do notice the funnel shape that you mention when the brass is first expanded, it seems to go away (at least to my inexperienced eye) when I begin the neck turning process.
what have you found to be the best method to insure that the neck I.d. is perfectly round? Also
What annealing setup are you using and what part of the cartridge are you heating I.e. the neck or the shoulder & neck junction?

Eddie; I appreciate your advice on having an experienced shooter look at my setup. My problem is not that the bushing is not engaging the cartridge neck, because it is and I can feel the tight neck when I load a bullet. The problem is that it does not remain tight for more then a few firings and I have to go to tighter bushing to archive the same tight fit.

Ed

[Dick Grosbier]

My load is a bit stiff at 34.8 grs of 4198, maybe that's taking a toll on the brass.

34.8 is not a bit stiff , it is a pooch load according to my friend Allie. And a normal load in my book.

[ConRich]

+1 what Dick G posted. I have loaded up to 36gr of H 4198, but my standard load is 35gr. As far as I'm concerned , you can't get too much H 4198 into a 30BR case.
IMHO,

Dick

[eww1350]

Markhor....Ed...the reason I have a hard time understanding your issue...is I have brass (100 pieces) for my 30BR that I made in 2007 and have shot over 3,500 bullets out of it and I use the same bushing today as I did in 2007 (a .325")...I did not anneal untill they had 5 or 6 firings...I still use the same bushing..we have a number of 30BR shooters in our club and I have never heard of necks thinning after a couple of firings..you have a very unique issue..I would like to get a few of your problem cases to inspect and test...

Eddie in Texas

[Charles E]

Slight apologies -- I don't see much bad advise on this thread -- save for Al's uncharacteristic "too quick" read -- It does happen, though, from both knowledgeable people like me (& Al) when we misunderstand, and from others, who, as I said, just repeat what some guy told them.

That out of the way, & why I seem to keep coming back to this thread, something just doesn't quite add up with the numbers. I'd add my encouragement to Mike & Michael to get a knowledgeable smith or shooter to take a look. I think some of your reported measurements might be wrong. Might not, too, but something just doesn't feel right.

BTW, for brass springback, here is a link to Varmint Al, well worth reading: http://www.varmintal.com/arelo.htm

(Here's the significant part to neck tension. Remember, he's using conventional dies, oversizing then expanding up with a mandrel or button...

ANNEALING AND NECK TENSION.... Uniform neck tension is another reason to anneal your case necks. Each time you neck size and then the expander ball opens the neck up to the correct diameter, the brass' yield strength increases. It is called strain hardening. As the yield stress increases, there is more spring-back (to a smaller neck ID) after the expander ball opens up the neck. This effect increases the neck tension. A new annealed neck will have less neck tension than a case that has been fired and neck sized a number of times. Cartridge brass is 70% copper and 30% zinc and its yield stress and strength is increased by cold working.


Annealed cartridge brass has a yield stress of 19,000 psi.
¼ hard cartridge brass has a yield stress of 40,000 psi.
½ hard cartridge brass has a yield stress of 52,000 psi.


So the neck tension on a ¼ hard neck will be twice that of a freshly annealed neck. If your rifle's chamber neck clearance is large, then you could easily get to the ¼ hard condition in 5 or 6 reloading cycles. It would take more cycles if your chamber neck is close fitting.

* * *

The funnel shape of necks that Al Nyhus remarks on seems to be a constant phenomena. I get it with necking down as well as necking up. One of my wildcats is an 8x68-S necked down to .30, with a longer neck. I believe that because the brass of the shoulder in some manner "supports" the brass in the neck it is closer to, I get the funnel shape.

Went so far as to set up my case forming workflow to include a step to inside ream the necks before final outside turning. I do get dead-straight necks, and even wall thickness but don't believe I can really shoot the difference. Maybe when it's dead calm...

It's just one of those things you have to go through & decide for yourself whether or not it's worth the effort.

One thing I *think* no one's mentioned -- Wilson bushings are tapered, and many dies only size a portion of the neck. the .30 BR has a long enough neck that if you're seating bullets so the pressure ring is quite deep, you may not be getting the sizing at the pressure ring that the number on the bushing reads.

But do take your cases, bullets, dies (esp. bushings) & esp, measuring tools to a smith or very knowledgeable shooter. As several have said, something just doesn't feel right.

[Pete Wass]

I have had great success on the 33g node but one's barrel will tell them what node it likes best. Always remember, the bullets we shoot aren't heavy enough to be able to beat the wind so one can not beat what the windflags are telling them. Less owder = less a lot of things good.