6mmbr-338lapua

[brandonbc]

Okay here is something to ponder about.
Rite we all know short stubby cartridges have the most potential for accuracy. Now to get more speed you need to lengthen the cartridge rite?
What if you went even wider than the usual shell diameter that we use now, and kept it as long as a say a 6mmbr or 6PPC.

Ok in short take 338 lapuas shell cut it and fire form it to say a 6mmbr length and shoulder angel.
It will look like a 6mmbr that put on some weight.
Has it been done and can it be done and has anybody got one of those programs that build it in theory and gives you and estimate of its potential.

I think it would run a 115gr DTAC bullets in 6mm very fast and 140gr+ in 6.5mm at whopping speeds with the inherent accuracy of a 6mmbr

 

[mikecr]

Your crazy. But here it is:
Basically, a few grains shy of 243wssm.

 

[brandonbc]

Thanks for the pick

Well it can even be shorter I was thinking of having it just long enough to shoot the 115gr 6mm and the 140gr-6.5mm on the 3000fps par but not wasting case capacity.
Its like 6.5-284 people shoot 140gr at 2950 not to burn out the barrels any more but what about the rest of that capacity that was wasted.
Lapua came up with what I think is a optimum cartridge 6.5x47 they wanted a 123gr bullet at 3000-3100fps so they kept on cutting until it was optimum. So the 6mmbr was designed for shooting in the 80-100gr class for 100-300 benchrest competitions. But now that longer and heavier bullets are coming into the sport for long range people are going long cartridges again. I want short and stubby to shove the heavy 6mm and 6.5 at 3000fps but at a optimal proficient level and possibly fit in a short magazine for the varmint hunters and tactical short actions.

243wssm what is the accuracy on it? It looks very close to the 6mmbr but does it have its accuracy too? I found this picture below at http://www.gunsandammomag.com/reloads/gar0504/ I don’t know if it’s a 3 or 5 shot group if its 5 at 100 then im grinning. And the 107 grain only runs at 3040fps what will happen to 115 DTAC bullets you need 3000 comfortably.

With a 6.5wssm I need 139gr+ to run comfortably at the 3000 mark without pressures and I can back it off a little 2950 but the case runs at optimal level. I read a lot that they say run it hot and drop a grain and you get the optimum proficientsy out of it. And ive tried it and it’s true so far.
So in short a cartridge that will handle all those bullets to good effect run in a short action and feed out of a magazine with a smile.

So shoot! I’m all ears.

 

[mikecr]

It's overkill in 24cal as drawn above. With a 35deg shoulder or more, it would meet your performance criteria in 26cal.

I don't know if you've formed similar cartridges, but in case you haven't, I'll mention lessons learned to consider.

One issue with wssm brass is thickness. Looks to me that Winchester cut & formed the wssm from the wsm case. With this, we get ridiculously thick brass. Capacity is not as high as you might think, and it must be neck turned for accuracy and low ES.
Not a big deal? Well super thick brass isn't easy to fit to turning mandrels. It springs back like hell after expansion. Final turning mandrel fitting has to be done with neck sizing bushings, down from a higher cal. With my 26wssm, I anneal, then expand up to 27cal, from 25cal. Then I rough turn,a couple times) to ~13thou neck thickness. Then I size down to 26cal, and final turn it to desired 13thou thickness again. I anneal again.. Alot of work..

When you form this brass, it will end up very, very thick. You can use a forming die offered by Six enterprises. But you'll need to get them to make 2 steps larger in bushings. I had to have a single step larger to make a similar 6BR-284,just for fun). Let them know that you intend to use a 338Lapua case, so they know to verify the die body is large enough.
and order plenty of Redding neck bushings.

Sounds like fun. You can choose your capacity. But multi-cals do not mix well with a single case. It's one cal or the other for peak performance. Winchester should have known this, and really made a fool of themselves with 22/24/25wssm.

 

[brandonbc]

Ok Ok you beat sense into me. I thought it will be easy enough so maybe I should wait a little till somebody makes better brass with more space. Well I see the 25wsm necked to 6.5 and used mildly. So maybe ill look more to that or just shelve the project till someone does it rite.

 

[6Dasher]

I think I saw a 6mm stuck on a shortened 50BMG case,6mm thermosbottle as it was called I believe).

 

[6Dasher]

Here's a photo

 

[2RECON]

Okay here is something to ponder about.
Rite we all know short stubby cartridges have the most potential for accuracy. Now to get more speed you need to lengthen the cartridge rite?
What if you went even wider than the usual shell diameter that we use now, and kept it as long as a say a 6mmbr or 6PPC.

Ok in short take 338 lapuas shell cut it and fire form it to say a 6mmbr length and shoulder angel.
It will look like a 6mmbr that put on some weight.
Has it been done and can it be done and has anybody got one of those programs that build it in theory and gives you and estimate of its potential.

I think it would run a 115gr DTAC bullets in 6mm very fast and 140gr+ in 6.5mm at whopping speeds with the inherent accuracy of a 6mmbr

If you are going to form a Lapua Case that way you´ll need a lot of tooling and a tough press.... I´ve made a short .30Cal based on that case, and it was a lot of work...i know that there´s a 6,5mm/.338Lap. made by a german Tooling Company named TRIEBEL

Keep shooting

 

[JimmyO]

Hey just noticed your post. I've been dreaming of shortening and necking the .338 down to a 7mm that will throw a 180gn @ 3000-3200FPS kinda like a better 7WSM.

 

[2RECON]

Hi Jimmy,

i´m getting 3125fps using 190grs.SierraMK moly Bullets, 25"Barrel)and 3240fps,27" Barrel) from my .30Cal....mayby forming a stiffer shoulder and neck it down to 7mm you´ll get about 3300 with that 180grs Bullet....

Best