Heavy bullets in a PTR-91/G3/CETME/etc

[HumptyDumpty]

I have the opportunity to get a large quantity of cheap 185 grain projectiles. Naturally, I do cast as well, but with how much I shoot this rifle, do enjoy the convenience and time-savings of a ready-made bullet. Does anyone here have stories of success or failure with heavier-than-NATO projectiles in one of these rifles?
P.S Mine is something of a Frankengun, built on a PTR receiver.

[Went2kck]

What r you shooting them in and caliber?

[HumptyDumpty]

It's basically an HK-91 at this point, in the standard .308, with a 1/10 twist, 18" barrel. As I understand it, the rounds should stabilize, but theory is not always reality. There is also the HK's somewhat unique operating mechanism to consider.

[HumptyDumpty]

Well, it looks like I'll be blazing the trail on this.

[Larry Gibson]

Cast or jacketed "projectiles"?

If cast; GC'd?

Twist of barrel?

Does your rifle have a gas adjustment?

[Texas by God]

I would use starting loads from the loading manual and see how the roller locked action responds. Does your rifle feature a fluted chamber? It should work ok with the heavier bullet as long as you don't tax the system with hot loads.

Sent from my SM-A716U using Tapatalk

[centershot]

As far as stabilizing a 185 gr. bullet, yes, it should. The 1:10 twist in most 30 cal barrels will stabilize 200-220 gr. bullets depending on velocity. Think 30-03 cartridge.

[bimus]

I saved some 180 and 190 grain reloading loads from a Survival magazine from the mid 80's for the HK 91 I just don't know if it's ok to post them here ?

[HumptyDumpty]

Bismus-
I'd be very interested to see read that magazine excerpt.

Jacketed projectiles. I've got a good load using 150 grain bullets, but the current opportunity is for several thousand of the 185 grain variety. I just wanted to see if anyone has had any first-hand experience with this particular rifle. This is for cheap high-volume practice, hopefully out to 200 yards, if the accuracy is there. Two or three MOA would work. I've got some known-accurate ammo for shooting beyond that. As for casting, I've not been able to get good results with my only 30 caliber mould, a 160 grain GC design, which I originally purchased for my 30-30 (the rifle was sold a while back). I'll eventually try another, but given the current situation, I don't want to pass up on the chance to stockpile some ready-made projectiles.

[HumptyDumpty]

Cast or jacketed "projectiles"?

If cast; GC'd?

Twist of barrel?

Does your rifle have a gas adjustment?

There is no gas-system. FMJ, 1/10. Given that it is a somewhat common military gun, I'm hoping someone has already tried it, and can share their experience.

[WinchesterM1]

This is the video I watched to help me with my CETME

https://m.youtube.com/watch?v=r5pji0J-eoY

[HumptyDumpty]

Ow, that's a good video!

[godzilla]

Should make for an interesting recoil impulse!

[Larry Gibson]

There is no gas-system. FMJ, 1/10. Given that it is a somewhat common military gun, I'm hoping someone has already tried it, and can share their experience.

My bad, was thinking of something else when I read the title. Delayed recoil operated thus the recoil impulse will be different with the heavier bullet. I have used 174 FMJs in Cetme/G3s. The old M118 Match (white box loaded with IMR4895) worked fine in them as did reloads with IMR4895 up to 40 - 41 gr. The later M118 SB (brown box loaded with ball powder to higher psi) gave significantly more recoil and much "harder" functioning.

With the 185 gr bullets I suggest using 4895 starting at 34 gr and working up to 38 gr.

[GONRA]

GONRA reminds ya'll that in BLOWBACK or MODIFIED BLOWBACK actions
(CETME is a ROLLER-CAM RETARDED BLOWBACK action)
bullet MUST leave barrel or gun BLOWS UP!

Easiest to design such a firearm where the barrel is short,
velocity is high and bullet is LIGHT.
I.e., RESIDENCE TIME IN BARREL IS MINIMIZED!

Safest for reloaders to not wander too much from
original ammo specs. Heavy Bullet reloaders BE CAREFUL!

PS: Don't get RETARDED blowback mixed up with DELAYED blowback!
Olde Remington Model 51 pistol and
modern Remington R51 pistols are
probably the only delayed blowbacks yer ever gonna see!

[HumptyDumpty]

Well, for the benefit of those who are intimately familiar with the rifle and reading this thread in the future, I will note that my rifle is outfitted with a #17/36 degree locking piece. This further retards the action, resulting in a more easily controlled recoil impulse and slowed cyclic rate (for those of you with giggle switches). If you share GONRA's concern, this may be a solution. I however, am not sure that there is an issue. I've watched a god deal of slow-motion video, and the bullet is well on its' way before that bolt cycles, even with the stock locking piece. Further, the PSG1 uses the exact same operating system, with a barrel in excess of 25 inches. I don't know what ammo the Germans typically issue for that rifle, however.

[bimus]

cast loads I have shot in my HK 91
190 grain lead 36.2 grains Win 748 1917 FPS 190 grain lead Win 748 2053 FPS
200 grain lead 37.3 grains Win 748 1868 FPS 200 grain lead Win 748 1990 FPS
None worked the action like it should and 2000 FPS is the fastest I would go with lead .

Loads from the past I never tried
Sierra 180 grain spitzer boat tail IMR 4064 41grains 2300 FPS
Hornady 190 grain soft point boat Winchester 748 42 grains 2300 FPS

My best all time load for my HK 91 Is 150 grain FMJ BT 44 grains IMR 4064 2544 FPS mil brass 2529 FPS federal brass
Winchester factory load 7.62 mm 147 grain FMJ 2539 FPS
Scout Squad M1A1
150 grain FMJ BT 44 grains 44 IMR 2640 FPS mil brass 2640 FPS federal brass
Winchester factory 7.62 mm 147 grain FMJ 2655 FPS

[Texas by God]

H&K P7/ M13 9mm pistols are delayed blowback with ported chambers. The roller locked action came from the WW2 German G43/ K43 8x57 semi auto rifles. The CZ 52 pistol is also roller locked.
I may be wrong, may be right. I agree that the ballistic window is important with the Cetme design; just as it is with the M1 Carbine, M1 Garand, and Romanian PSL.

[wyowillys46]

While roller locked, the CZ52 is recoil operated. It uses the same operation/action as the MG-42.

[bpatterson84]

Yes, that Kraut space majik gun eats that weight, its not even that heavy. Ive gone over 200gr with mine. It's delayed blowback, that's all.