Preparing 30BR brass

[artbosco]

One other thing that puzzles me is that the 30 Cal tools I used to determine the chamber length were .335 in diameter but my chamber neck diameter is .333 (which is stamped on the barrel). How does the tool fit into the neck chamber? It fits with no problem. I bought two of them and sanded one down to .332 in my drill press because I did not think it would fit. I then used them both (one at .335 and the other at .332) and came up with the same measurement of 1.567. After I fire formed the 10 cases they measure .333 neck diameter.

If you got both of the tools to fit in your chamber, the .332" and more importantly the .335", chances are your chamber diameter might very well be .335" or even greater since you stated that you had no problem inserting it.

I'd go back to the smith that did the barrel work/chambering to ascertain for sure, what the actual diameter of the chamber is.

Sometimes, and I know this from actual experience, that all notations stamped on the barrel aren't always correct. Gunsmiths can make unintentional mistakes too.

You also might want to go back to the person or company you purchased the rifle from, inform them of the problem and ask if they'll correct it, sans charge.

 

[25AI260]

in my neck length.. i'm .009 - .0095 off the end of the chamber looks like i'm good to go... i may get to the range tomorrow instead of thurs.. yippie !
_-_
something wrong in that math...?

[.0384" bullet diameter + .0098" brass + .0098" brass = .3280"]

 

[mk_gram]

I measured the bullet diameter and they are .309 (Berger 115 grain). Your formula would give me (.309 + .012 + .012) .333 which is what my barrel is stamped. I also measured the case necks after fire-forming and they were exactly .333. It seems that I could turn them another .001 or .002 and be okay.

The barrel is a new barrel which was built and fitted by Hart Rifle Barrels. They also did the bolt when I switch from 6mmPPC to 30 BR.

Thanks again for the information!

Mark G.

 

[artbosco]

something wrong in that math...? [.0384" bullet diameter + .0098" brass + .0098" brass = .3280"]

The 0 and the 3 were transposed. Got it corrected above. Thanks.
.3084 + .0098 + .0098 = .3280

 

[artbosco]

I measured the bullet diameter and they are .309 (Berger 115 grain). Your formula would give me (.309 + .012 + .012) .333 which is what my barrel is stamped. I also measured the case necks after fire-forming and they were exactly .333.

It seems that I could turn them another .001 or .002 and be okay.

Sounds like a wise or judicious plan. Just remember, every time you change bullets, recalculate. Good shooting.

 

[AlNyhus]

I measured the bullet diameter and they are .309 (Berger 115 grain).

Mark, you may want to remeasure those bullets. The 115 Begers normally run about .3082 on the shank and barely .3083 over the pressure ring. Are you using a good quality micrometer that reads to .0001's or a hand held caliper? Most hand held calipers...even digital ones...will measure close to .001 'big' when used on round objects.

For cutting the necks, I really don't know how thick my necks are. I simply set the cutter a bit big, turn the neck, seat a bullet, check it over the pressure ring, adjust the neck turner as needed and repeat until it's where I want it.

For what it's worth..... -Al

 

[artbosco]

I measured the bullet diameter and they are .309 (Berger 115 grain).

For cutting the necks, I really don't know how thick my necks are. I simply set the cutter a bit big, turn the neck, seat a bullet, check it over the pressure ring, adjust the neck turner as needed and repeat until it's where I want it. For what it's worth..... -Al

Mark, Be it known, I do it the same way Al does it, and the way one of my mentors taught me to do it. It's a lot easier.

I have three dedicated turners, two for my 6PPC and one for my 30BR. One of the 6PPC turners is set for the initial pass [in and out once] and the other for the final pass [in and out "twice"]. The 30BR turner is set for one complete pass [in and out "twice"]. (Doing the final turn "twice" ensures that tiny high spots are removed.) Once my turners are set, I leave them alone.

Every time I turn 15 necks, I seat a bullet into the empty case and measure the neck OD as part of my quality control procedures.

To get the brass thickness dimension mathematically, if you really want to know what it is, you just work backwards. In my case, for the 30BR, it's .3280"-.3084"=.0196" divided by 2= .0098".

 

[mk_gram]

Al,

My digital caliper has graduations of .0005 (that may not be the correct terminology). What kind do you use that measures down to .0001? I have checked on-line for Starrett digital calipers and could not find one that would measure that precise.

I did remeasure the bullets and if I measure with the flat of the caliper jaw they are .309 but when I measured with the sharp nose of the caliper jaw it was .3085.

 

[AlNyhus]

Mark you really need to use a micrometer...rather than a caliper...for measuring round stuff.

Mitutoyo makes some darn good .0001 manual micrometers that won't break the bank, like the 193-211 unit. It reads the .001's in the window and the .0001's on the micrometer barrel. Mine when new was around $100, but there's always a bunch of similar used ones on ebay for decent prices. With a little shopping, they can normally be had for under $50. You want flat anvils and preferably carbide faces.

There's one on ebay right now that would be a good one:
http://cgi.ebay.com/Mitutoyo-193-211-Digit-Outside-Micrometer-0-1-NICE-/180614566531?pt=LH_DefaultDomain_0&hash=item2a0d779283

There's also the battery powered digitals....but I'm old school when it comes to micrometers. The manual ones let you develop a feel for what you're measuring.

Brown and Sharpe, Starrett and others all have good units.

Hope this helps. -Al

 

[artbosco]

My digital caliper has graduations of .0005 (that may not be the correct terminology). What kind do you use that measures down to .0001? I have checked on-line for Starrett digital calipers and could not find one that would measure that precise.

The Fowler IP54 0-1": http://www.fvfowler.com/pdf/2304/2304_21-22.pdf will take you down to decimal places you may never need to go, but at $96.50 shipped from Monty @ http://www.gaging.com/ , Toll-Free 800.497.5218, it does an excellent job. For ease of use, I added the Fowler #S52-247-005 Micrometer Stand for $27.75 shipped.

In addition, the use of a Mitutoyo .050" Gage Block similar to this: http://www.amazon.com/Mitutoyo-611105-531-Rectangular-Steel-Block/dp/B001OBSGAA , used regularly as a calibrating tool, will ensure the Fowler keeps its measurements exact.

These two tools are the most important ones that I possess.

 

[25AI260]

Howdy y'all
wondering.. how often do you or 'need to' turn necks on cases that were fire formed... cases that were turned for the first firing

 

[artbosco]

how often do you or 'need to' turn necks on cases that were fire formed.

I turn before I fire form to get them to seat in a very tight necked chamber because I have to, or they won't fit.

I turn the second time after trimming to my "trim to" dimension which takes place after the second fire forming.

After that, I monitor neck diameter growth and overall length growth, and then turn and trim accordingly.

 

[25AI260]

Ok... good i noticed that the neck has grown at the base of neck at the shoulder top
i didn't take much to fix an wondered if that was normal
i can fell a tightness from the inside where what you call the 'donut' mite be
thought i'd check with you all...

 

[AlNyhus]

Rich, it's not uncommon for necks to thicken up a bit over time. How much and in how many firings depends on many things...case length, shoulder angle, how far the shoulder is set back during sizing, how much of the neck length is resized, etc, etc.

This thickening can take the form of 'the dreaded donut' (it can be on the inside, outside or both) and be primarily at the base of the neck. It can also be a gradual thickening along the entire length of the neck.

The main thing is being aware of your particular rigs characteristics so you stay on top of these areas before they cause trouble.

Good shootin'. -Al

 

[25AI260]

thanks Al..

i guess i'm having the normal... its good to hear nothing strange is going on

thats a load off my mind .. < pun