Will Shortening my barrel cause issues?

Hi all, I have a Zastava Mini Mauser in 7.62x39, I load my own Subsonic rounds and would like to get a suppressor to suit, an overbarrel suppressor adds 100mm roughly in total length so i was thinking about having it cut down 100mm at the same time as getting a suppressor fitted, but im worried with doing so the accuracy will be effected, my loaded sub rounds run lead 151gr projectiles, im not sure if having a much slower projectile in a cut down barrel will suit the twist rate of my barrel or not, has anyone had experience in doing this. Cheers

Shouldn't do if any the barrel will be stiffer and you could improve the crown. I have shortened barrels on most of my rifle and all shoot very well.

I own 2 zastavas...one in .223 and another in .308...also own a 7.62x39mm norinco. ...will accuracy be affected???? probably not if anything it COULD improove as barrel may be stiffer. is it worth doing??? if dedicated bush rifle yeah why not ,it sure makes them nice to carry BUT you will loose a little of the little bit of speed you have(or not)...the crappy stock on mine had a crack at tip forend so I cut it off square and got barrel cut back to sit suppressor flush with that...downside is no way in hell will I fire it without can fitted.....my other rifles I will do so ,they are loud but not ear splittingly so...
I have theory on the subsonic loads ..... based on what happens with a .22lr ..you MIGHT accually GAIN speed with your current subsonic load..... because if you look at trials where people have cut .22lr barrels progressively shorter the velocity goes UP UNTILL it reaches certain length then goes down....I believe this is where powder no longer has any "push" left on projectile so from that point onwards...or point where it stops accelerating anyway.... the resistance against barrel starts slowing it.
your 151s will be just fine I believe..they are great projectiles.

The twist rate is the twist rate barrel length isnt an issue as far as stabilization or accuracy is concerned especially as you are all ready running subsonic.

Have you shot any animals with the 151g yet?interested to see how they go I have some subs loaded for my .308 but hesitant to try them on deer,kill hares and possums well tho.

15/16 inches is heaps for the 7.62x39 but expect a bit more blast with high powered military loads. If subs are stabilized OK now I cant see your proposed shortening doing any harm to accuracy.

You shouldn’t lose any accuracy only a little speed 7.62x39 is a small round with a we relatively small amount of powder to burn
This means that you can get away with a short barrel without loosing to much speed the moment you cut your barrel down to the point where the powder hasn’t finished burning before the bullet leaves the barrel is when you will start seeing dramatic losses in speed
When the Russian’s we’re testing the sks rifles they found that the Difference between a 20inch barrel and 16 inch barrel was almost nothing but if they went to 14 inches they started seeing A lot of Diminishing performance

Id chop your barrel to 16 inches and suppressor fitted

What you are descibing (shortening the barrel so its overall length is the same after the suppressor is fitted) is a fairly standard practise with most suppressor makers. For a short bush rifle it is common to go shorter still. Velocity will dropp slightly with the same loads but as you are loading your own (subs) then you will simply need to adjust the charge slightly to get the full burn and the speed that you want. Go for it.

Most of the powder should be burnt in the first 9 inches of barrel. I used to run a Subsonic .303 No4 with 14 inch barrel. A mate sent his Ruger 44 mag to have a suppressor fitted for a over barrel and the gunsmith cut the barrel back to 9 inches without telling my mate what they were about to do to his new rifle. Still shoots straight, but he was and still is a bit pissed about it.

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Originally Posted by Tasbay

gunsmith cut the barrel back to 9 inches without telling my mate what they were about to do to his new rifle. Still shoots straight, but he was and still is a bit pissed about it.

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yeah that would piss me off also.

What percentage ratio do you shoot subs to supers? and how far you shoot with supers?

I run a 12” 300 blackout barrel or 305mm, mostly shooting subs and dropping red deer with 125gr BT supers doing 2005fps out to 200m. So cutting a 7.62x39 barrel shouldn’t be a problem and way easier stalking with a short barrel in the bush.

My 9 year old daughter is the only one who has shot an animal with my subs so far, was a nice size nanny goat about 40m distance, it dropped instantly, was a nice frontal shot, im yet to try them out more to get a more conclusive answer though

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Originally Posted by tikka

What percentage ratio do you shoot subs to supers? and how far you shoot with supers?

I run a 12” 300 blackout barrel or 305mm, mostly shooting subs and dropping red deer with 125gr BT supers doing 2005fps out to 200m. So cutting a 7.62x39 barrel shouldn’t be a problem and way easier stalking with a short barrel in the bush.

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I plan to only shoot subs from this rifle, thanks all some interesting points made indeed,

IMHO If you wanted less than 14.5" go 300 blackout as it uses shotgun powder. But 15-16"inch will be fine for 7.62 for both supers and subs. I have a 14.5 inch 7.62 and it makes quite a flash and bang with supers. My testing of an sks 20" vs Type 56 16" was a drop of about 150 -200 fps with chicom ammo.

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Originally Posted by Tasbay

Most of the powder should be burnt in the first 9 inches of barrel. I used to run a Subsonic .303 No4 with 14 inch barrel. A mate sent his Ruger 44 mag to have a suppressor fitted for a over barrel and the gunsmith cut the barrel back to 9 inches without telling my mate what they were about to do to his new rifle. Still shoots straight, but he was and still is a bit pissed about it.

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Personally i would be slighly more than "pissed" about something like that, some one be buying me a new barrel

For subs in my izzie 18mh i use blue dot 9 grains barrels 15 inches barkie and like a flashbomb with supers thought. With supers It looses 300 fps compared to the sks. Much fun though for a cheap as gun.