Case conversion

[Nora]

I've got a pre-war ('36 S-237) Mauser that I've had for 15 years and never fired. It's just one that I've not loaded for yet. I've now got a set of Lee RGB dies on there way and should see them early next week. I'm not able to find brass at a price I can afford (part of the reason for not loading for it yet). However I've got more than a lifetimes worth of Win '06 brass, and about 200 rds of once fired PS-74 (Korean) mil-surp. I'm looking at using the mil-surp as donor brass for the Mauser.

I've not converted anything before and wouldn't mind some pointers. It seems that it should be fairly straight forward, push the shoulder back, enlarge the mouth, trim and fire form. But that just seems to easy to be true. So here are my Q's.

Should I anneal the cases before and or after I start / finish?

I'm planning on shortening the legnth in several steps, should I do the same with widening the mouth from .308 to 8mm?

How many times should I trim the cases before the finishes legnth?

If I've missed anything else feel free to critique my idea.

Thanks in advance
Nora

[madsenshooter]

You don't have much of a change to make there, I'd use Imperial sizing die wax, and anneal afterward, I've had trouble with shoulders collapsing when I annealed beforehand, but then I was reducing the diameter, and things might be easier for you if you do it beforehand. With a tapered expander you should be able to go from .308 to 8mm in one step, might lose a few cases with the necks splitting. You could trim the 06 cases either before or after, or both.

[mooman76]

I concer with Madsenshooter. Use a good sizing lube not the spray stuff. I find that the Lee or Imperial work well for this. I have never sized this from 308 as I don't get much 308 but have lots of .06. This is one of the easies caliber convertions to do and I too was sceptical but it's esier than you think. What I did was to cut the .06 to aproximate length using a dremal. Then lube and run up into the new die a few shot strokes at a time until I get it all the way up and sized. Then trim to length and the other brass prep you need to do. Some die brands seem to work better than others. If you are making a dramatic change in neck size (which you are not with this) it id better to neck size with a in between size so you don't do all at once and get colapsed sholders or folds in the brass. You don't have to trim first and I didn't once just to see but you have allot of brass to stretch for no real reason and your die may run out of room. You will need a lot of force doing this so a good press is needed and I did mine on my Lee challenger so that's good enough and don't use brass that is questionable or you'll end up with a stuck case.

[rockrat]

I usually use Hornady Unique lube. Only made a few cases, just lubed them and ran in full length sizing die in one pass, then trimmed. You can tell where the shoulder was, but should iron out with firing. Don't forget lube in case mouth when forming.

[Bullshop]

Bull Size case sizing lube the best I have ever found. Do a search here. I posted about sizing 30/06 to 257 Roberts in one pass.
Yes I sell it and yes I promote it but just the same yes it works great.
BIC/BS

[26Charlie]

I use the RCBS file-trim die for the 8mm; run an '06 case in, cut off excess with fine-tooth hacksaw, then file flush with die.
Then the cases are ready to deburr and FL size in 8mm dies.

The f-t die is so hard the file won't touch it.

[Gerry N.]

I've made hundreds of sundry Mauser military caliber cases from '06 brass. Simply lube the cases, I prefer Imperial Die Wax, run 'em into a full length die. For most Mauser military cases I then rough trim with an IMP tube cutter, following up with my Forster case trimmer and a de-burr. Not a particular problem. For longer lasting cases, annealing after the first firing and collet neck sizing where applicable will result in long lasting brass.

In the 60's the Army closed Ft. Lawton in Seattle. My Scoutmaster at the time was a Col. stationed there. He got me a 30 gal. fiber drum of (mostly) empty '06 brass. I'm now down to my last 5,000 or so cases.

Gerry N.

[Crash_Corrigan]

+1 on what Gerry said. When I was using my 98/22 I also shuddered at the cost of 8 mm brass. I found a guy locally {Brassmaster.com} here in Vegas and I bought 1000 cases for $75 a few years ago. He brought them over to the house in a plastic 5 gallon bucket. I sold off half to a buddy of mine who had a '06 and I converted about 250 into 8 x 57 mm'a. It was tedious but with a good single stage press, good lube and a motorized trimmer it took only a few evenings of work to end up with usable brass.

After the first firing I annealed all of them and only neck sized from then on. Some have over 20 firings and still are good to go. Loaded over 12 gr of Red Dot and a Lee 170 gr .324 boolit I got reasonable results.

[milsurp mike]

I lube my brass with Lee lube and remove the sizer decapper rod from the 8mm sizing die and size to 8mm in one pass.I then use a small tubing cutter that I got from the hardware store to trim to the proper length.I then replace the sizer decapper pin in the 8mm dies and size the mouth and deprime.A final trim and your ready to anneal the brass.I have resized 100's of these cases.Once you get the hang of it you will be able to fly right through them.Mike

[NickSS]

I have made hundreds of 8 and 7mm cases from 06 brass using RCBS size and trim dies. After firing them once or twice I anneal them. I have some 8mm cases that I have been using for 20 years with cast loads. The brass was originally 1936 Vintage Frankfort arsenal 30-06 match brass.

[jonk]

Lube, size, and trim. If you have a trim die, so much the better.

Very easy conversion.

[TAWILDCATT]

I have converted 06 to 8mm and trim them with the harbor freight mini cutoffsaw
$27.its a second to cut.the new one I saw yesterday is better than the one I have.