Any Good 7mm Options I Should Know About?

[barnbwt]

I'm considering diving into an (ugh) AK build, though I hate the thought of it (just can't stand the guns, if you can't tell). There's a twist which would make it more appealing to me, though; it will be built upside down and dressed up to look like a ZB30-series LMG --only little, maybe



Details of the build concept so far:

For those who don't know, the ZB30 is the direct progenitor of the BREN LMG used by the Tommies during WWII, designed by Czech weapons genius. It locked with a tilting bolt rather than a rotating one, but was operated by a long piston fixed into massive bolt carrier that rode on rails; just like the AK

I sourced a 7mm barrel that will work (an old Madsen LMG barrel with the chamber cut off, and cooling rings down its length), but obviously that bore diameter isn't something normally associated with an AK. So I'm wondering if there are any good 7mm wildcats I should check out.

The ZB30 shot 8mm Mauser originally, and had straight 20rnd magazines unlike the BREN's ginormous swoopy ones. So any straight mag would work here; FAL/M1A for 308-sized rounds, or even 20rnd AR15 mags for smaller ones. I suppose AK mags could be used, but I think a long, curved mag wouldn't look right (maybe for a Madsen or BREN MK II lookalike)

The dial sight knob on the left side will be the safety, since that's where it will be when flipped (this is a lookalike, not a copy/clone). Sights would probably be fixed or even adjusted with a drum on the same axle as the safety (that'd be slicker)

Gas tube would be stretched, as would the piston by necessity. The barrel is like 20" long IIRC, so probably 6 or so inches further out would get the look right. With an aluminum piston keeping the weight down, it seems like it should be doable (though it might not be as overgassed as a stock AK)

Trigger group might be relocated, but it might be just as easy to trim off the trigger spur and use an internal linkage

Tapered dust cover (now on the bottom) will be made into a box, and will have the grip/trigger attached to it

Carve up a stock, grip, and carry handle from some walnut and steel laying around, slap on an RPK bipod, and Bob's your uncle!

Back to the subject of the thread:

-I presume 7mm Mauser would work for a more 'full size' build, provided I find a PSL/M76/SVD kit that doesn't break the bank (seems like a poor proposition, though). Suitable magazines might be tough to locate, though (might BAR's be close enough?)
-7mm-06 would work for sure with BAR mags (does it use Mauser bullet diameter?) but might have issues with the action, being so long
-7mm-08 would keep the power up there with the real-deal, while keeping a slightly smaller magazine profile that would fit nicer with the scaled-down proportions of the receiver. As before, this requires a PSL-size kit (or does it?) which may limit my options
-7TCU (223-blown out to 7mm) is comparable to Blackout, so should be closer to a match for typical AKM parts (or 74 parts, rather). AR15 20rounders would match the actual ZB30 capacity and look.

I don't expect this to be my go-to gun, but a pure range toy, so ammo obscurity doesn't bother me hugely. The main thing is bullet diameters that match the 7mm Mauser bore, and the ability to fit into available magazines (the mag-catch might be modifiable, but the body is the part I can't make myself too easily). I'm mostly torn between 7-08 and 7TCU, but am open to others in the 308/223 size ranges if there are any good ones I've missed (I don't know much about 7mm caliber offerings, if you can't tell )

TCB

[barnbwt]

280 Brit might be cool; the round NATO should have shoved down our throats post WWII . Also the whole British/BREN connection. Sadly, it's like 1/4" or so longer than 223, so I doubt there's a mag out particularly suited for it (could always use a 308-length mag, though). I'll have do some more digging to see if there's a case head it could be based upon (ooh, it apparently shares one with 308 Win! )


Who knows, with a lighter and more sane bullet ogive, I could see it fitting in an AR mag (a bit lower capacity, of course). Funny, it's basically a 7-08 but fun-sized, and I assume it would be very close in performance to 6.8SPC. Interesting. I actually like that much more than 7TCU, which is practically a straight-wall case (i.e. pretty inefficient for a rifle cartridge). Bonus benefit of being able to use cheaper AKM-pattern action parts, probably.

So, 308 brass cut back & necked down to a 7mm-ish projectile (I gather there's a zillion bullet diameters right around here for some reason, all within a thousandth of two of eachother ). Probably use the neck and shoulder dimensions of 7-08, but with 308's taper, and set the case length to match the cannelure of whatever bullet I choose to go with. For a wildcat/custom cartridge, that actually doesn't sound totally unfeasible.

TCB

[unknwn]

An MG-13 magazine was originally made to accommodate the 8mm Mauser and is routinely modified to supply cartridges to FN49 in 7mm (not removable though) and an Egyptian Hakim in the normal 8mm
They aren't svelte by any means, but are capable of feeding the 7x57 like you outlined.

[5.56RifleGuy]

Just curious, why not build a zb 30 parts kit?

[barnbwt]

Because they're 1500$, and I'm trying for like 1/3rd or that...

As far as MG13 mags, that's not a bad idea, since I happen to have a couple (thought I'd mod them for my FN49, but apparently FNH bothered to make a different mag/receiver for the slightly longer 30-06 ).

I'm thinking more and more to do a short-action lookalike as opposed to a full size rifle cartridge. Reasons being; cost of a rifle-length AK or other parts kit is pretty steep, and I recently scored a nice BREN MKI kit. It'd also be cute next to the larger ones . So I won't be messing with a PSL or M76 kit, especially since I've found how pricey those are, although I do find myself lusting after an M76, now.

I'll wait a few months and see if AK kit prices drop any; they seem to be holding steady at a around 300$ for no reason.

TCB