Brass shortages - options for serious wild cat conversions ?

Advice, comments and suggestions welcome.
In these times of restricted component availability and often no idea of when supplies might come thru I’ve been brainstorming some creative ideas to wild cat re-size brass that is available. I’ve got a 7mm BLaser Mag and while I have some brass in my stash it won’t last forever. The recent release of 7mm PRC got my hopes up that this might be a source of brass easily converted to 7BM. But alas the 7mmPRC brass is shorter OAL and to shoulder by about 2mm according to specs published. Bugger !
So got to thinking about all the various 7mm and 30 cal derivatives of the parent case, 375 RCM. Plenty of them- 7mmBM, 7 LRM, 28 Nosler, 7-375 and the latest addition to the family, 7PRC. And similar range of 30 cals.
Google & YouTube searches turned up a few guys doing some “extreme wildcat” sizing, some with very flash gear, others with fairly basic set up’s, so decided to give it a whirl. I have a pretty basic reload set up.
Have some 28Nosler 2x fired brass so thought I’d experiment with that to see what damage I could do in trying to resize to 7mm Blaser Mag. Quite a big reduction of about 6mm in COL as you can see in pics below.
Used a 7mm BM FL body die for most of the work, went in small increments 1/2 then 1/3 then 1/4 turn on die to progressively reduce the 28Nosler down to BM. YouTube and Google info said go real slow on the press strokes to avoid collapsing the case, which I did (real slow). Used Imperial sizing wax on body and neck but not too much . Series of photos below shows progress & end result not too shabby for first attempt & certainly seems to suggest it’s do-able if you have time. Have yet to neck turn & FL size.
HiAttachment 210188
28N on the left , case being re-sized in middle & 7BM at right. This is after 5-6 cycles

Attachment 210189
After another 6 or cycles

Attachment 210190
Almost there, neck trimmed to length

Annealed and neck sized
Attachment 210191

Be interested on any suggestions or feed back on this approach from you reloading gurus or engineers.
Starting with N28 is probably not ideal, the 300PRC or 300 BM on paper look like easier options.

How much shorter is the PRC overall? Can't just fireform it out,push the shoulder forward and live with a slightly shorter neck?

The PRC is ~ 2mm shorter & can’t imagine that can that could be safely chambered for fire forming ? But would be happy to be proved wrong

You would have to either seat to a firm jam or safer method expand the neck up then size back down creating a small false shoulder to headspace on.

Yeah you definitely want to check the neck thickness on those. The new neck is going to be made from a lot of the old shoulder material of the 28N and that could be a fair bit thicker than the original neck was.

This could cause a problem once you seat a bullet. It either won't chamber, or worse, it just about chambers but leaves insufficient clearance to let go of the bullet and causes a pressure spike.

If they are too thick, or if you have donuts, neck turning is the fix. I've messed around with case forming for wildcats a fair bit and am a fair ways down the rabbit hole on that one :O_O:

Thanks @Pommy, you are right - the neck thickness is next on the list to fix. Measures about 10 thou thicker after this re-sizing process. Will neck turn then check the brass will chamber.

there is a book/chart or more than likely many of them out there that list what you can make out of what....a must have for obscure rounds.

Talk to Bruce Bertram in Australia

He will make you any amount, of any brass you want

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Originally Posted by 7mmsaum

Talk to Bruce Bertram in Australia

He will make you any amount, of any brass you want

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thanks @7mmsaum. That would be brilliant. Contact details ? Just "Bertram brass" ?

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Originally Posted by 7mmsaum

Talk to Bruce Bertram in Australia

He will make you any amount, of any brass you want

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but..but..but...can he "SHIP IT" out of Ozzie so you can use it???????

I’d thought about the same thing in recent weeks @chainsaw my thoughts were 7LRM might be the one to resize so far have not confirmed with looking at any drawings though

the shoulders look to be different lengths in third photo.... eg one looks to have longer sloping bit .if it chambers Im sure it will sort itself out it just looks different to the other one,could be the light.

Yes hard to get an accurate photo, but also not the finished product yet. I’m going to neck turn it first then use FL die with recapping rod to give it a final tweak. Then we’ll see how it chambers. The N28 starting case is 35deg shoulders where was the 7BM and most of the other 375 RCM derivatives are 30 degrees.

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Originally Posted by chainsaw

thanks @7mmsaum. That would be brilliant. Contact details ? Just "Bertram brass" ?

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Bruce replied to say this is not one they’ve done

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Originally Posted by veitnamcam

You would have to either seat to a firm jam or safer method expand the neck up then size back down creating a small false shoulder to headspace on.

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This above is what I would do. The case headspaces from the false shoulder / ring on the neck back to the case head. Totally safe and reliable so even if the result is not what you wanted, it will be safe and straight forward to test. Use a starting load of powder a normal projectile and go hunting, no cream of wheat or other nonsense

At this stage no 7mm PRC brass in NZ, otherwise I’d give it a try. :thumbsup:

Neck turned and final? FL size. Might need to bump shoulder slightly further ?
Attachment 210221

will it chamber??? will answer that question...

Looking good

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Originally Posted by Micky Duck

will it chamber??? will answer that question...

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Not quite & don’t want to force it. I have FL sized using my normal FL die settings which I’ve used for regular Norma 7BM brass but feels like I need to wind the die down another 1/4 turn or so, and bump the shoulder back a tad more. Thicker brass in the shoulder area now given I’m well into what was the case body walls of the original 28N case.

Thought about starting with a LRM case?

Yes, thought about lots of different 375 RCM derivatives. Had N28 in hand so thought I’d give it a whirl to see what I could learn and achieve with a basic reload set up. Ideally I’d start with something closer to the 7BM dimensions. Any one got some 300 PRC or 300BM brass I could get a case to try?

https://www.nzhuntingandshooting.co....um-info-42743/

That’s the image I had burnt in my brain in terms of LRM to BM being fairly close in size I don’t have any of those 30s to send sorry I’m sure someone will chime in who has one

Thanks @Kelton, the 7 LRM looks like a good candidate & so does 300 Norma.

Good work Chainsaw.

Even after neck trimming I expect you will get doughnuts, requiring inside neck reaming. I think you will also need to trim neck length every time as there is a lot of brass to flow in the neck and shoulder.

Hope you get it going.

From memory 7LRM is a derivative of 7-375 Ruger, but the resizing is also a multi-stage job.

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Originally Posted by chainsaw

Thanks @Kelton, the 7 LRM looks like a good candidate & so does 300 Norma.

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300 Norma is lapua bolt face from memory mate if you want to try a piece of LRM brass sing out

Yep,you’re right. 300Norma is a 338 LM bolt face which I realised once I checked the Saami specs. bugger ! But hey a 300Norma necked down to 7mm would make one very interesting wildcat.:thumbsup:
If you have a 7LRM case or two to spare I’d love to have a go at resizing that.

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Originally Posted by chainsaw

Yep,you’re right. 300Norma is a 338 LM bolt face which I realised once I checked the Saami specs. bugger ! But hey a 300Norma necked down to 7mm would make one very interesting wildcat.:thumbsup:
If you have a 7LRM case or two to spare I’d love to have a go at resizing that.

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7mm long range hunter and the improved versions were Duleys 7mm FX and Abe’s 7mm screamer it was lightning 3400fps with 180vld from memory il flick me a pm re brass

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Originally Posted by chainsaw

At this stage no 7mm PRC brass in NZ, otherwise I’d give it a try. :thumbsup:

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Might be some :)

https://hosting.photobucket.com/imag...720&fit=bounds

I still have some Norma 7BM brass, the price is quite :oh noes:

The price of anything these days is farkn :XD:

Ok, further update on my attempts to get a Nosler28 cartridge down to 7BlaserMag. As mentioned above while I got very close to needed results the re-sized 7BM would not chamber. So out with the calipers to troubleshoot the problem. I was thinking it would be neck/shoulder region but turns out the problem is bottom area of case just at & above the head/case wall area and rim rebate. According to published specs N28 should be 0.534 vs 7BM at 0.535.
My reSized N28 to 7BM measured 0.550 on my calipers and an original 7BM 0.542. So 8thou difference. Also measuring about 5-6mm below the rebate rim there was 6-8 thou difference. See pic below. Then went back and measured another N28 case ….. it showed same larger dimensions as the re-sized “N28 to 7BM”. These were once fired N28 brass FL sized.
At first I thought it was my BM dies or re-sizing techniques causing that area just above the rim rebate to expand. But then checking another N28 case I realise the mis-match in case dimensions was there all along. Bugger !
Still a worthwhile excercise and some good learnings. One of which is don’t assume your brass is an exact match for SAAMI specs!?
Appreciate any others comments, critique and insights.
Attachment 210508

A solution is available as you know @chainsaw

https://www.nzhuntingandshooting.co....7/#post1385414