Case neck thickness for .50 BMG brass. - Shooters Forum
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  #1  
Old 02-08-2017, 03:45 PM
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Case neck thickness for .50 BMG brass.


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Would anyone here have the details for case neck thickness for the 50BMG case? I have asked a manufacturer, they responded that .024"-.006" I took this to mean that.024 was the maximum, and the minus.006" (.018") was the minimum thickness. Does this sound copacetic?
I'm using an L.A.R. Grizzly Big boar with Match Chambering. (I didn't know it had that, but apparently it does. )
One more thing, is it easily done to trim the field grade 50 BMG cases to function in the tighter chamber, has anyone here done it ?
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Old 02-08-2017, 05:02 PM
rg1 rg1 is offline
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Not familiar with Grizzly Match Chambers. My loaded rounds vary with neck diameters that vary from .550" to .553". Different manufacturers have slightly thicker or thinner neck walls. So mine I measured have about 20 to 22 thousands neck walls. I'd say your manufacturers .048 minus .006 is about right but they run a little thinner too. Just make sure your cases are trimmed to 3.910" or less. There are outside neck turners if your chambers neck is too tight plus 50 bmg case length trimmers.
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Old 02-08-2017, 06:05 PM
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The tolerance is actually .024 +0 - .006. I just measured a dozen once fired cases and got .022 on all.

You need to know EXACTLY what chamber you have. You do that by casting and measuring. "Match chamber" is a marketing term more than a set of measurements.
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Old 02-08-2017, 09:58 PM
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If in fact that "Match chamber" is tighter tolerance, as in minimum SAAMi spec. you're going to positively need to do a chamber cast. If neck relief isn't adequate, pressures can go through the roof, dangerously so.

If it turns out that you do need to turn necks, K&M Precision has everything you'll need to accomplish that task. You'll also need a way to measure neck wall thickness, so for your sake I hope you don't need to turn necks, it's an expensive tooling up process, and even more so for 50 cal..

Trimming is a given, all bottle neck cases must be measured and trimmed accordingly.

SMOA
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Old 02-09-2017, 05:58 AM
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Quote:
Originally Posted by Submoa View Post
If in fact that "Match chamber" is tighter tolerance, as in minimum SAAMi spec. you're going to positively need to do a chamber cast. If neck relief isn't adequate, pressures can go through the roof, dangerously so.

If it turns out that you do need to turn necks, K&M Precision has everything you'll need to accomplish that task. You'll also need a way to measure neck wall thickness, so for your sake I hope you don't need to turn necks, it's an expensive tooling up process, and even more so for 50 cal..

Trimming is a given, all bottle neck cases must be measured and trimmed accordingly.

SMOA
The Rifle is/was offered in 2 chamberings, a generic "Field Grade" and a "Match Grade" The Match grade would only accept Match grade ammo. I tried to use L.C. ammo, but the Cartridges would stick in the chamber, making removal difficult, and this without firing. The Match ammo from Hornady had no problems at all. fed, and extracted easily as could be. I measured the length of both cases, the L.C. was at 3.910, and the Hornady was 3.900. Neck thickness of L.C. was .022, and the Hornady was .018 . I will be using the Hornady Brass only from now on.
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Old 02-09-2017, 06:06 AM
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Quote:
Originally Posted by JBelk View Post
The tolerance is actually .024 +0 - .006. I just measured a dozen once fired cases and got .022 on all.

You need to know EXACTLY what chamber you have. You do that by casting and measuring. "Match chamber" is a marketing term more than a set of measurements.
I contacted Hornady about neck thickness specs, and their reply omitted the +0 part, but the info was clear enough. The L.C. Brass I have measures .022, and the Hornady at .018 I feel that the difficult extraction was due to the L.C. being at the Max. length, so sized a case, trimmed to 3.900, and it also chambered, and extracted without effort. I'll just avoid the L.C. brass in this Rifle. I appreciate the help you all have posted! Thanks !

Last edited by Androclese's; 02-09-2017 at 06:18 AM.
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Old 02-09-2017, 06:09 AM
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If you don't have a sizing die to restore whatever measurements the Hornady brass has you're still stuck.

WHERE is the LC brass sticking? Does your sizing die correct it?
HOW does the dimensions of the chamber compare to the two kinds of brass? How does the re-sizing die compare?

I would be MOST uncomfortable until I had some real answers from the equipment instead of the seller.
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Old 02-09-2017, 09:25 AM
rg1 rg1 is offline
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Shame to not be able to use LC 50 BMG brass as it's most plentiful and cheaper. Plus it's great reloading brass. I'd look into a case neck turner.
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Old 02-09-2017, 06:09 PM
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I believe that the L.C. Brass was sticking at the case mouth, I smoked a case, and while it did stick, there was no mark in the smudge to indicate the neck was dragging in the Chamber. Since I've trimmed the L.C. to the minimum length of 3.900 it doesn't stick at all, and is easily removed. The neck O.D. of the loaded L.C. ammo is (on the one I measured) .5535 On the Hornady loaded round the Neck O.D. measured .5515 . I noticed that the L.C. case has a taper in the crimp area, the hornady does not. My thought is that this taper is what is sticking at the end of the chamber.
I will be investing in a neck turning device, as i'll need it for other cartridges as well as the 50 BMG. Some further research supports the need for Match only ammunition in the Match Chamber. I have 30 pieces of hornady Brass, so will use them. and not the L.C. The Big Boar doesn't get a lot of use as no local ranges will allow them, so I have to take it to a relative's Cabin up in northern Wisconsin to fire it, which I do a couple times a year.
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Old 02-09-2017, 10:42 PM
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Well heck, if you're going to tool up to turn necks anyway, there's no good reason to not turn and use those LC cases, it's very good brass and at the cost of 50 BMG brass like Hornady, I'd be all over the opportunity to use that LC brass.

I've always wanted to get into the "50", lucky you, I'm envious.

SMOA
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Old 02-10-2017, 09:20 AM
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Originally Posted by Submoa View Post
Well heck, if you're going to tool up to turn necks anyway, there's no good reason to not turn and use those LC cases, it's very good brass and at the cost of 50 BMG brass like Hornady, I'd be all over the opportunity to use that LC brass.

I've always wanted to get into the "50", lucky you, I'm envious.

SMOA
All in good time, I hate to let good materials go to waste, and if I can't get them to work for me, then i'll have some useful stuff to pass along to others who can use it. Funny thing is, right now, 20 rds of Hornady Match BMG ammo costs $108.00 . 20 pieces of the Brass alone cost $99.00 . so, for $9.00 more I get loaded ammo and still have the Brass afterwards. Can't make this stuff up.. I do enjoy shooting the LAR, as does my extended Family, it's not so bad in recoil, and everybody wants to get some braggin' rights. Since experiences are all we get to take along to the great beyond, I'm going to have as many as I can manage. They also like my little Re. 700 in 300 Blackout, no recoil much at all, good for the newer shooters among us. Next thing is to source some munitions for my 20 mm A.T. Rifle, the surplus stuff is getting so old it's not reliable anymore.

Last edited by Androclese's; 02-10-2017 at 08:26 PM.
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  #12  
Old 02-12-2017, 01:17 PM
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Originally Posted by Submoa View Post
If in fact that "Match chamber" is tighter tolerance, as in minimum SAAMi spec. you're going to positively need to do a chamber cast. If neck relief isn't adequate, pressures can go through the roof, dangerously so.

If it turns out that you do need to turn necks, K&M Precision has everything you'll need to accomplish that task. You'll also need a way to measure neck wall thickness, so for your sake I hope you don't need to turn necks, it's an expensive tooling up process, and even more so for 50 cal..

Trimming is a given, all bottle neck cases must be measured and trimmed accordingly.

SMOA
Just noticedthe part about measuring the neck thickness, I have a Ball Micrometer for that, (a vestigial part of my Machine shop years) I do not trust most calipers to do that job as well as I'd like it to be done. I use the Lyman 50 BMG accutrimmer for case length,set to 3.900" and measure each with a 3-4 " standard micrometer as well, to be certain. Have the Primer crimp problem solved, so on to preliminary loading. I have a K&M neck turning tool coming for the L.C. Brass, see if it does the trick. (I got a bit lucky in that a local shop had some H50BMG powder on the shelf )
You are all good people, and I thank you all very much for your insights, and shared experience. (But don't worry, I wont let your secret out)

Last edited by Androclese's; 02-14-2017 at 08:56 PM.
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