VZ 58 Pistol SBR Project - what do I need to know?

[MeatAxe]

Yeah, with the 7" barrel, I'd also be worried about blowing my hand off in a stress situation, so I prefer 11" to 12" or thereabouts. I have a Mini Draco with a @ 7" barrel that manages to singe my eyebrows when shooting -- not so pleasant. Also, (at least the M193) 5.56 bullets need to be hitting the target at 2400 fps or above in order to fragment, which is where that round shines ballistically for self defense.

MAC did a similar test with AKs using 7.62x39:

https://www.youtube.com/watch?v=lbgAh9-sCDQ

With a 11 - 12" barrel, the 7.62x39 loses @ 300 fps in velocity to a 16" barrel, which is about the same as adding another 100 yards of distance compared to a 16" barrel. Basically, the 7.62x39 loses about 300 fps of velocity every 100 yards it travels out to 200 - 300 yards. So, with a 11 - 12" barrel, the 7.62x39 should still be effective for self defense out to 150 - 200 yards.

[RSR]

Good video -- I posted earlier regarding Jim Fuller finding effectively the same and also the demigod link earlier in this thread too regarding SBRing 7.62x39, but yeah, anything below 10" isn't a good idea in 7.62x39 and 12" actually seems fairly ideal (the weight of 4 piece brake on my 10.5" M92 PAP @ 8oz and length at over 3" might as well have extra barrel length).  And MAC's findings reflect that.

Jim Fuller of Rifle Dynamics at one point had a video on youtube, now deleted or made private, on the Krink and how he doesn't recommend less than 10" barrels due to insufficient penetration.  Rifle Dynamics' website listing for the Yugo Krink goes into that at least briefly.

In the video, he was basically clearing some kind of misfire or jam out of a Romanian or similar 7.62x39 Krink  w/ 8" barrel.  The weapon was on his tailgate of a newer model truck (thinner sheet metal) and somehow fired towards the cab.  He was expecting all sorts of damage to the cab and engine compartment too...  In brief, the round penetrated his bed steel in full, but just dented the cab steel and didn't penetrate into the cab. 
Since a lot of Rifle Dynamics customers at the time were private military contractors in the Middle East (this video was at least 4 years old and I believe older), Fuller decided in good conscience and further testing that the 10" Yugo Krink barrel is the shortest that makes sense and he could accordingly sell in 7.62x39.  The smaller diameter 5.45x39 he stated did have sufficient penetration out of an 8" barrel to be serviceable.

If you want to go w/ a shorter barrel than 10" -- IMO, you're better suited w/ something in 300 blk or 9mm (or other pistol).  The pistol powders are designed to burn quickly which mitigates muzzle blast and flash, which put simply is the physical manifestation of a substantial amount of wasted energy and ballistic potential (should you have shot from a longer barrel)...

[PorterN]

I wrote this up for another social media post elsewhere about a month ago, but it kind of relates to this topic and I got good pictures of my muzzle flash with a brake and blast shield I still haven't gotten to the range with the new SiCo ASR Brake, so I still haven't updated this review:

While the VZ58 doesn?t really need a brake, I figured it would be fun since it is a short barrel and the 7.62x39 isn?t quite as soft-shooting as an AR. I knew it would also have a pretty impressive fireball, regardless of the muzzle device on the gun. Initially, I shot it with the factory ?flash hider? which did mitigate the flash, but only to a degree - it also seemed like it was more sporadic and less uniform of a flash - sometimes it would be off to the side, sometimes it would be straight up in the shooter?s vision, sometimes I didn?t notice a flash at all.



Left photo: After that initial range session, I tossed an extra 30 cal ASR Muzzle brake on it so I could mount the SilencerCo Omega300 can I have. That turned the random fireball into two concentrated, consistent fireball breaths out the side of the brake, as intended. The brake made it a very soft-shooting gun, but holy bleep was the concussion bad throughout shooting line on the range. I think it was even worse in the two neighboring stalls than it was in my own stall. Even back behind the line, it was loud as hell, and rocked you pretty good. Definitely not making any friends, but getting lots of looks, and smiles from those who shot it.

Right photo: I got the ASR Blast Shield on a trade - it came with another gun. I tossed it on the VZ58, and went to the range. While my brother was shooting it on the line, I felt like the report was more of a low base boom bouncing off the back of the indoor range, and less like a concussive shockwave. It was definitely better. However, when I shot it, I realized quickly that the one giant fireball out the front was popping right up in my line of sight to the target, and interfering with my shots. While I wasn?t timing anything, I feel like the flash probably would?ve slowed me down, and it would definitely ruin night vision - probably more than the blasts going out to the side on the bare brake, since it?s right in your face instead of in the peripheries.

Fast forward to today, I bought an ?ASR BRAKE.? SilencerCo really failed hard on the naming of this one, since the ?ASR MUZZLE BRAKE? typically is what comes up in searches, and there?s very little info on this thing. Anyway, the ASR Brake is another ASR Muzzle Brake attachment that looks like the blast shield, but with holes and their ?Anchor Brake? on the end - it?s on the right here in the photo:



The hypothetical questions of the day include:
- how much of that concussive blast and lateral flame/shockwave the ASR Brake thing will actually give me, how much the Anchor Brake will help me, and
- how much vertical fireball i will still get.
ALSO, do y?all think there?d be much of a difference, benefit, or drawback in tossing on an ASR Flash Hider instead of the Muzzle Brake to work in conjunction with either of these other devices.

I am kind of hoping for a happy medium between the Blast Shield and the ASR Brake over the bare muzzle brake, but I?ll definitely be trying this out soonish.

I do want to add, of course, that in a perfect world, I?d just have the suppressor mounted on it at all times. but that?s not always doable, logical, or even really needed. Also, I may try some of these on my AR pistol or Tavor, too, since I have ASR brakes/hiders for those as well, but for now - it?s just a 30 cal thing.

[MeatAxe]

^ On 7.62x39 AK pistols(10" to 12" barrels), I've noticed that they don't really even need a muzzle brake since the mv is reduced @ 300 fps coming out of the shorter barrel. However,  the muzzle flash and blast is intense with a muzzle brake.

I've found that the Manticore Eclipse flash hider does a great job with minimal recoil. It's light, but requires a 14x1RH to LH adaptor.

Czechpoint sells the Phantom flash hider threaded to 14x1RH, which is pretty light weight.

[RSR]

The hypothetical questions of the day include:
- how much of that concussive blast and lateral flame/shockwave the ASR Brake thing will actually give me, how much the Anchor Brake will help me, and
- how much vertical fireball i will still get.
ALSO, do y?all think there?d be much of a difference, benefit, or drawback in tossing on an ASR Flash Hider instead of the Muzzle Brake to work in conjunction with either of these other devices.

I am kind of hoping for a happy medium between the Blast Shield and the ASR Brake over the bare muzzle brake, but I?ll definitely be trying this out soonish.

I do want to add, of course, that in a perfect world, I?d just have the suppressor mounted on it at all times. but that?s not always doable, logical, or even really needed. Also, I may try some of these on my AR pistol or Tavor, too, since I have ASR brakes/hiders for those as well, but for now - it?s just a 30 cal thing.

I think you should try the ASR Flash Hider w/ the ASR Brake shroud.  Should both reduce flash and provide some muzzle control.  The Czech SF Brakes work similarly.

Curious how much the muzzle extension, muzzle device, and shroud weigh in combination.

[PorterN]

I'm thinking that as well.

I went to the range yesterday, and got the lane against the wall. That seemed to make all the flash bounce right back into my face, reflecting a lot of light back at me, too. made it so bad, I maybe shot 5 rounds and quit shooting the VZ. I tried it with the suppressor, but it felt like it was increasing bolt velocity too much and even caused one malfunction.

I'm thinking I may just ditch the ASR mounts and quit trying to suppress the VZ and get a good flash hider for it. but first, I do want to try the ASR Flash hider coupled with both the ASR Brake and the ASR Blast Shield to see which is better - if I like one of them, I'll stick with that.