2.3" or shorter cartridges made from 12mm/308 brass?

[Swampman]

Take a look at the .308 x 1.5 inch Barnes.
It was designed back in the early 60's by Frank C. Barnes (COTW author).

It can push a 150 grain bullet at 2540 fps (barrel length not specified).

As I see it, the problem with changing cartridges in an AK is likely to be in getting magazines to work.

It wouldn't be a problem for a major manufacturer, but for an individual, designing and constructing a reliable magazine would be very difficult, unless it was for a round that had similar diameter, overall length and case taper to something that's already chambered in the AK.

 

[justin22885]

i can design my own mags, may take some work getting things right, but i could come up with a simple sheet metal and spot weld magazine that should follow the taper of anything i need.. and given the design of the AK essentially having no magazine well, if its a little bulkier where where its welded it wont matter and if i used the 308x1.5 you mentioned, i could cut down .308 followers i bet.. so the spring would be the difficult component but a 7.62x39 spring should work

looking at that 308x1.5 barnes, it would appear the cartridge case is 38mm overall length but the overall length of the cartridge is 72mm same as the .308?.. this would mean it would have the appearance of a REALLY long bullet.. but if i take the COAL of a 308, subtract the case length to figure out how much space after the case is actually the bullet on a .308, and apply that to the 38mm cause then with bullets seated as deep on a .308, the 308x1.5 would come out to just under 2.3 inches... essentially exactly the cartridge i was looking for

my idea is to find something that can be used in lieu of 7.62x39 or 5.56, but maybe be made from more common reloading components than x39, but with more power than 5.56, so the 308x1.5 or 6.5BR are probably my best options though if i decide cartridge case commonality isnt nearly as important as common bullets then i may just abandon this whole idea and stick with 6.5 grendel, and convert some .308 rifles to 6.5 creedmor or 6.5x47 (whatever the difference between those may be)

 

[hatt]

I'm not getting where x39 reloading components are uncommon. You can buy new brass, once fired brass, brass ammo all day long. Probably for a similar price of .308 brass. Bullets are common as well.

 

[justin22885]

95% of the components you'll find for x39 are steel case, and .310 bullets, id rather have something that can be more readily made from domestic components which typically mean based on .308/30-06 or 223 brass and .308" bullets if not 7mm, 6.5, or one of the other fairly common projectiles

308x1.5/30BR and 6.5BR seem to be my options

 

[justin22885]

thinking about it more, i have decided to "adopt" one of these cartridges as a main chambering of mine simply because i will be able to make a bunch of it for dirt cheap out of once fired .308 brass.. my options are 308x1.5, 30 BR and 6.5 BR.. the difference between the 30BR and 308x1.5 is the 30BR has a 30 degree neck angle whereas the 308x1.5 has a 20 degree neck angle

considering the primary platform will be that of a semi automatic, and ammo will be made from .308 brass, between the 308x1.5 (20 degree neck), 30BR (30 degree neck), and the 6.5BR (which looks like a slightly fatter 6.5 grendel).. which do you think is the better choice, and why?

 

[axxxel]

What are your intended applications and from what rifles will you fire this cartridge?

For my needs, a 7 mm variant would be the ticket. There are heavy enough bullets for the tougher hunting applications, while there are lighter bullets for target/practice/small game. You don't have to go to 200 gr bullets to hit the really high BC. The 6.5 kinda lacks heavy hunting bullets and I suspect that it would be slightly less efficient out of a shorter barrel, but that's a guesstimation.

 

[justin22885]

well my goal is to get all my rifle calibers using the same diameter and same weight of bullet for long rifle actions, short rifle actions, and really short actions.. my second goal is for them to all share the same base diameter so i only need to pile up on one type of brass for all.. but for the BR cartridges their primary purpose will be in an autoloading rifle, most likely a modified AK as they can handle the bolt thrust and making a barrel is just a matter of turning one to contour, no threads, no extensions

im thinking since the 123 grain 6.5 bullets match the ballistic coefficients of the 150 grain .308 bullets, i could take 6.5mm BR and load those to 2800fps.. with the same velocity and ballistic coefficient as .308/7.62x51, id have an identical flight path in a lighter weapon with less recoil and all those 308 "tuned" optics that are set up for a specific bullet drop will match my new rifle load perfectly

 

[axxxel]

"well my goal is to get all my rifle calibers using the same diameter and same weight of bullet for long rifle actions, short rifle actions, and really short actions.. "

So basically you'll be using a 6.5 BR chambered AK and a .260 Creedmoor bolt action rifle/AR-10/Saiga? Sounds kinda funky to mem but perhaps you don't hunt large game the same way I do, and perhaps you don't shoot as large volumes with your AK as some people do. Won't it be a horrible chore making all that 308x1.5" brass? Or will you buy BR brass over the counter?


... but to stay on topic, I'd just go with the 6.5/.308x1.5" cartridge that is the easiest to get to feed in your home made mags. Ballistics will be similar from all options.

 

[justin22885]

ill have no problem making the brass (and im leaning toward 6.5 BR).. also, i have a few AKs and some extra parts kits so... ill still have at least one in 7.62x39 for cheap shooting and another in 5.56 for ammo commonality with all the 5.56 rifles out there

and no, i dont hunt, really dont have much interest in it to be honest, most my rifles are generally of the military type

 

[axxxel]

awesome! I'm looking forward to see what you'll use as mags!

 

[justin22885]

yeah.. mags could be a problem.. grendel mags might work though since the BR cartridges are really only SLIGHTLY wider than 6.5 grendel with the same taper and its not hard getting AR mags onto an AK.. so.. machining out the AK bolt face slightly, use an M76 extractor, have the appropriate barrel custom contoured for an AK, install and use grendel mags with an AR magazine adapter

though when you consider just how cheap the steel cased ammo is, to buy the bullets and the powder needed to achieve any level of commonality youre already paying as much if not more per round (not even including in the cost of brass) as if you were to load it from those stockpiled components.. so at this point about the only thing gained from something like 6.5mm BR vs 6.5 grendel (which in itself is only $0.37/rd) will be to achieve a similar flight path to .308 winchester.. is that worth it?.. probably not

so this whole idea is probably not the best one as itll be much cheaper and a hell of a lot easier to just stockpile already loaded steel case ammo and if i want better accuracy from that point i could always just pull the bullets, pour the powder into a container and re-load with a more accurate measure for better shot consistency