308 MG42 Ammo Reloading

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easymoney
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308 MG42 Ammo Reloading

Postby easymoney » Wed Jan 31, 2018 8:52 pm

I started reloading once fired 7.62x51 military surplus brass for my 42 after 8mm got more expensive.

I immediately found that most sizing dies (including my new small base die) do not bring the cartridge cases down to a size that easily fits into a 7.62x51 barrel. I have several barrels and some fit OK but others don't fit the cartridge case when dropped into the chamber (I saw this from 42 manuals as a method to check ammo). The ones that don't fit well seem to be the newer/unused barrels. Resized cases seem to be about .005-inch or so too large around the case just above the cartridge base.

New military ammo all fits perfectly into all my barrels.

I would like to continue reloading to feed this beast but want to produce a factory spec round.

Should I check with custom reloading die makers?
Should I bore out the cartridge case portion of the new barrels a little?

What is a good course of action or advise?

Thanks

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Re: 308 MG42 Ammo Reloading

Postby JBaum » Wed Jan 31, 2018 9:23 pm

First off I'd make sure the chamber is clean. If you need to remove a few thousandths, use a stainless steel bore brush that fits the chamber, and some polishing compound. Spin it on an electric drill. Check frequently. If the factory round fits and your reload doesn't, I wouldn't polish the chamber, I'd look elsewhere for the problem first.

Did you check case length? If it's more than the minimum, shave it and see if that helps. It could be bottoming out on the bore step for the end of the cartridge. Semi guns are hard on brass, and often stretch it just a bit during extraction when pressure inside the cartridge hasn't fully bled off yet.

Make sure the dies are not only touching, but slightly compressing on the top of the cartridge to where there's a little resistance from the bottom of the die pressing against the plate on the base of the reloading machine. I have an AR10 that's very tight the way you mention, and that was the solution to the brass seeming to be oversized. Once I had it set to firmly contact the base plate, it wasn't a tiny bit too long anymore. And if the brass was more than minimum length on the new chamber of my AR10, it was too long and the bolt wouldn't close. Case lube is good, it will make re-shaping the brass easier. Slightly oversized brass worked ok in my worn MG42 chambers, but didn't like letting the bolt rollers go fully out in the new barrel.

A few thousandths here and a few more there makes just enough difference to cause a problem.
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Re: 308 MG42 Ammo Reloading

Postby easymoney » Thu Feb 01, 2018 2:05 pm

Thanks for the reply and information.

When I reload, all my reloaded rounds fit into the Lyman and RCBS 308 cartridge gauge as all should. However, they drop only partially into the barrel chamber; they miss about 3/8-inch going down all the way. When you compare military made (German or US) 7.62X51 ammo to my reloads they are a little larger (a few thousandths) near the base of the cartridge. There is no issue with the length of the cartridge as I have trimmed and measured.

I have been told that the Germans make their barrels a little tight. Don't know for sure if there is any truth to this.

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Re: 308 MG42 Ammo Reloading

Postby JBaum » Thu Feb 01, 2018 5:26 pm

If a factory round fits, it's not too tight. Like I said about my AR10 - factory fits, but I had to tighten up the dies to make reloads fit.
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Re: 308 MG42 Ammo Reloading

Postby Blanksguy » Thu Feb 01, 2018 9:05 pm

easymoney,
Some things that you might want to look at are:

1: SAMMI-Specs. for 7.62x51mm NATO Chambers vs. Commercial .308 Winchester Chambers. I think you will find out that the Military chambers are slightly larger.

2: When "sizing" rifle-brass (especially after being fired in a Military sized chamber........the area just above the extractor-groove will be larger. If your sizing-die will not bring this back down to SAMMI-Specs. Then you may want to look for a sizing-die that sizes this are of the cartridge-case back down to "factory-specs.".

3: Going back to that fired brass.........is this your fired brass or from a "bulk-dealer" in surplus 7.62x51mm brass fired from an M60 or m240 automatic weapon (?).......again, check the diameter of the fired case just above the extractor-groove before and after sizing. Sometimes you can "adjust" the height of the sizing-die....sometimes requires a different sizing-die or the trimming of the contact area between the die and shell-holder (** Remembering not to set back the location of the neck are of the case.). I believe that last resort would be to "adjust" the chamber......maybe just touching it with a 7.62x51mm chamber reamer. Remember.....dies and shell-holders are cheaper than "Barrels" and "Gunsmith's fitting-time.....

Note: We found a lot of the above out through trial-and-error from making "Blank" ammunition for reenactors/movie business for over 20-years and using a lot of fired cartridge-cases.......well over 1,000,000 made.

Regards, RichardS
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Re: 308 MG42 Ammo Reloading

Postby easymoney » Sun Feb 04, 2018 9:34 pm

Great responses; thanks to all.

I have been told that the German machine gun makes make the chambers a little tight because they heat up so quickly once firing begins.

There really does seem to be a difference between the size of brass coming out of a US made reloading die and the size of ammo made for military. All of the brass I have reloaded is Lake City mil surplus.

I have found a manufacturer in Nashville GA which has said they would make a custom made sizing die for $119. All I have to do is send them a couple of my barrels and they will make the die to produce military grade sized ammo.

Thanks

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Re: 308 MG42 Ammo Reloading

Postby Blanksguy » Mon Feb 05, 2018 3:06 pm

Easymoney,
The Military usually has their MG Barrel's Chambers reamed a little on the loose side to allow for dirt/powder-fowling during firing of many rounds under unknown conditions. This will usually show up as brass that shows expanded cases in the area just forward of the extractor-groove on the cartridge-case.

Again, I would look into small-base-dies for resizing the LC (Lake-City) cases that you have as it sounds like they were fired in an M60, or M240, or other Machinegun.......then look into a good case-resizing-lube.

Next......as you are firing these in a 308 MG42.........is the barrel that you are using one of the newly made MG42 Barrels that were sold on our MG42 Board some time ago (?). .....How tight is the chamber (?).

Last, I would ask over on several of the "Reloading-Forums" in their 7.62x51mm NATO Reloading and see what other reloaders will tell you about reloading this cartridge.

Regards, RichardS
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Re: 308 MG42 Ammo Reloading

Postby amafrank » Wed Feb 07, 2018 9:59 pm

easymoney wrote:Great responses; thanks to all.

I have been told that the German machine gun makes make the chambers a little tight because they heat up so quickly once firing begins.

There really does seem to be a difference between the size of brass coming out of a US made reloading die and the size of ammo made for military. All of the brass I have reloaded is Lake City mil surplus.

I have found a manufacturer in Nashville GA which has said they would make a custom made sizing die for $119. All I have to do is send them a couple of my barrels and they will make the die to produce military grade sized ammo.

Thanks



I've loaded for my MG42 in both 8mm and 308 and never had any issues using a variety of dies. If you are having issues it is likely your barrel and chamber.

As for the idea that the Germans make the chambers tight because they heat up fast I can tell you that it isn't true. Their chambers are pretty much standard for the NATO spec ammo. They don't heat up any faster than normal either.....the chamber really doesn't heat up that much. With a red hot barrel in an MG42 (machinegun) you can grab the barrel by the extension and it is only warm. You can touch the chamber and its not but not overly so. You touch the barrel and leave burned skin behind. This true in 8mm or 308.

If factory ammo fits and your reloads don't than there is a problem with your dies or technique. I don't use Lee dies because I frequently see little issues with them that create problems for me. Shoulders pushed back too far if you run them in far enough to size the head end of the case, necks sized too small or not enough.....if you can get dies made that make you happy have at it. I'd buy a set of Redding or one of the other quality dies first though.

Frank


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