new to semi auto 8x57 (Zastava M76)

[WouterNL]

Hello to you all.

Maybe someone can help me to get on track at the right direction (in a safe way).

My current project is to get my Zastava M76 semi-auto shootable with lead boolits.
I managed to slug the barrel, and I took measurements of the lead pill :
bore .311" - .3115"'
groove .3235"

The rifle is designed for the 8x57mm mauser cartride.
The rifle is a kind of copy of kalasnikov's ak47.
The barrel lenght is 55cm (source wikipedia).

To get this rifle shoot, I have a saeco mould (081) which gives me boolits of ca 182,5 grain (hardness of the metal is ca 15brinell).
I give the boolits a hornady gascheck and put them through a lee .323"sizer.
at this moment I know that the boolits are sized maybe too small (given the groove diameter I measure) but I haven't got the sizer made a bit wider yet, this will happen in the future.

When I make a dummy of this boolit, the metal is hitting the lands a little bit at a case overall length of 73,65mm.

My first concern is to find a safe load which is capable of repeating the rifle after every shot.
dont want to use this rifle as a straight pull (I have a Swiss K31 for doing that)

For my other rifles I use the "Harris-load" of ca 16 grain alliant 2400.


This was my startingpoint at my M76 journy;
2 weeks ago I loaded up five rounds with increasing amount of powder (alliant 2400).
The powderloads were; 16,0 // 16,5 // 17,0 // 17,5 // 18,0 grain.
after boolit seating I putted the cartridges through a lee factory crimp die.

I loaded them from the magazine, the highest load first;
None of the shots was capable of repeating the rifle. But the 18 and 17,5gn load were capable to eject the case without problems. The 17gn load I cant remember, the lowest two loads needed a bit assistance from me as I remember it right.


I don't have experience with "developing my own" loaddata, therefore this post;

I can do two things.
1. I can increase the amount of alliant 2400 till the rifle is repeating fully (or till I see signs of high pressure)
2. Or I use another (slower) powder.

If I do path .1:
I can't find loaddata with alliant 2400 powrder in the 8x57 cartridge (for lead boolits). But is there anybody who has experience with this powder in this cartridge with (almost) the same weight of boolit?
How far can I go up with the powder without making it hazardous. Unfortunately I don't have quickload to find a theoretical calculated pressure...


if I do path .2:
In the lyman cast bullit handbook(number 3 of 1980), loaddata for the 8x57 is given at page 208 for a 181grain boolit.
The mentioned powder H335 is also mentioned at the burn-rate table of the Vitahuori reloadingbooklet (issue 2012).

In that vitha burn-rate table Hodgdon(?) H335 is at the same level of Vithauori N133 powder.
This is triggering me, because a bottle of VV-N133 is standing in my little reloadingroom....
What I don't know is;
can I use the1980 Lyman loaddata for the H335 but then with the N133 powder? (just based on a comparisation of burn-rate).

What would you (experienced reloader who is not taking any risks) do in my case?



Thanks in advance for a helpful reply.


Wouter

[1johnlb]

Drop the first idea #1, go with the 2cd. Slower powders is the way to go with a dacron fluff, 4895, 4064 range has proved excellent in most other semi autos. Your probably going to need a load that will produce between 1900 to 2100 fps for best accuracy.

[UBER7MM]

...bore .311" - .3115"'
groove .3235"....
I give the boolits a hornady gascheck and put them through a lee .323"sizer....

Standard accepted practice is to oversize your boolits by +.001-002". You might get better accuracy with a .325" sizer. Try out what you have, it might be acceptable. If not look into lapping out your sizer. You can find out how by searching this site.

I hope this helps,

[historicfirearms]

Also, its not a good idea to seat your boolit so long that it starts engaging the lands. This is a recipe for a slam fire in a semi auto.

[haak48]

Don't forget that the M76 has three gas regulator settings, 1,2,&3. If you have not already, try the largest hole (#3) before increasing the powder charges. JH

[WouterNL]

Hello,

thanks for the reply's
Especially the one from 'historicfirearms'
I will note this in my cartridge-recipe for sure.


The first test I did was already with the gas-regulator at setting no 3 (hole dia 2,20mm).


@ "'1johnlb'', the ''4895'' and "4064" powder you are writing about, is that IMR powder?
This powder (IMR) is according the burn rate table of the Vithauori almost the same as Vitha N133 powder I have.
But it is al little confusing, because in the same burn-rate table also a "H4895"powder is mentioned (Hodgdon) and a "4064" (Accurate) (the burn-rates are almost the same according the vithauori-table).

The old lyman cast bullet book I have (no 3) is giving a starting load of 29,8 gn "H4895"
Would this amount of powder be a safe startingload when using Vitha N133 (which is according to their burn-rate table a little bit faster than IMR4895 and H4895)?

[A pause for the COZ]

I have had real good luck with A5744 in 7.62x39, 223, and 305Win in Semi autos. It seems to give just a bit more gas to operate the actions in the same loads and RL-7 and some of the others.
I use it allot. Gets the same benefits of the faster powder with out having to move up to a slower powder and use a filler to get the pressure you need.

[mac60]

I don't know anything about this particular rifle. The advice given in post #5 is where I would head first. Since function is the first issue, I'd look at suitable powders overall and pick one sort of "in the middle" (burning rate wise) and try to work up as close to the max. recommended charge as I could. Once I had that ironed out and had it functioning well, I'd experiment with diameter. I'd expect .325" would give a better level of accuracy than the .323" you're using now.

[Gunnut 45/454]

WouterNL
IMR and H 4895 are pretty much the same powder. With H4895 is a tad faster. IMR 4064 is a powder for 8x57mm I use it for full load for cast boolits. If you use starting loads for Jwads and IMR 4064 you should be in the ballpark for function in your M76 with cast boolits. What boolit are you wanting to use? Flat nosed boolits might not feed well. A RN design should feed fine.

[CHeatermk3]

Wouter, what is the as-cast size on the driving bands of your boolits? Will an un-sized casting fit into a fired case?

[WouterNL]

The as-cast size on the driving-bands is .3255". I made a dummy round with a gascheck pressed on (with a .329"-push through sizer) but the gascheck is bigger then the boolit, so it's making the caseneck wider and I loose the neck-tension which i need to keep the boolit in place.

For now I don't use the boolits as -cast. When I've found a powdercharge which is capable to get the rifle funcioning as a semi-auto I will make my .323 sizer bigger.


The boolit ismade with a saeco 081 mould, it's a round nose type. With the boolit seated at 73,05mm (col) the boolit is making no contact with the lands as far I can see.

I found out that cases of 57,40mm are too long, when I put them in the chamber the diameter of the casemouth is shrinking, with a 57,2mm case this is not the case (so I guess the case-chamber length is somewhere in between.
For precautionary reasons I trimm all the cases with the lee-case trimmer-gauche to 56,62mm, this will do the job and will help me to get an uniform crimp on the caseneck after seating.

7 series a 3 loads are standing ready for testing (maybe tomorrow)


thanks for the advices so far, i will report back the results after testing.

[WouterNL]

The test-shooting is done.
I also measured the velocity.

powder / charge / velocity (m/sec)
Alliant 2400 / 19gn / 516
Alliant 2400 / 20gn / 553
Alliant 2400 / 21gn / 567
Vitha N133 / 30gn / 548
Vitha N133 / 31gn / 528
Vitha N133 / 32gn / 588
Vitha N133 / 33gn / 607

I did have some failure-measurements on the velocity, so the velocity-data is not very reliable.


The observations;
With all those powdercharges, the rifle did repeating very well.
I did not signs of over-pressure (no flattened primers / no cracks in the casing)

the cases with the alliant 2400 powder were coming clean out of the rifle, the cases with the Vithauori N133 powder were a little black.

and.... ca 3 or 4 times I observed the problem that the new round wasnt chambered properly, the boolit bumped to the beginning of the barrel.
In the meantime I made a dummy, adjusted the lips of the magazine, and this dummy is tested over 20times, and was fed properly into the chamber each time.



For about the accuracy, i tried to shoot over the chrony and didn't care much about accuracy.
The first card I shot (with the alliant charges) were ok, at the second card with the viha-powder I saw that the half of the holes were not round, but a little oval. I think the boolits werent flying straight through the paper....

next thing to try:
making the sizing-die bigger to .326 or so. then testing again....

[Buckshot]

............You might see if there's anyone here who has tried cast lead in a Hakim. It's a copy of the Swedish Ag42 Ljungman. The Swede in 6.5x55 and the Hakim (an Egyptian produced cousin) in 8x57.



I have one but have never tried cast lead in it.



The Hakim is a direct gas impingement system, where I bet your Zastava is a piston gun.

...............Buckshot

[WouterNL]

There is indeed a big piston-system in this Zastava, according to wikipedia is the Zastava a copy of the ak47, but then made a little bigger.


Within 2 a 3 weeks I'm able to make new rounds and test again, I have good hope that this thing is "shooting nice" with cast in the near future.

[WouterNL]

Never heard of the Hakim, but what I found in the I-net, i do like it also (there are not much rifles I don't like... )

[43PU]

I have a hakim and it really likes the Lee 175-323 PCed with a check over 32grn of IMR 3031. Now my gas port is seized all the way open so be careful!!

[WouterNL]

Yesterday was M76-testing-day again!!


The goal of the test: find out what kind of ''accuracy'' I have with the rifle ''as is'' at 100m.
(the inside of the barrel has a kind of deposit in the grooves at the last end of the barrel, i don't know yet how to get rid of this stuff).

At the last test I tried several powderloads in order to find out if the rifle was able to repeat properly. All the loads I tried were capable to repeat the rifle.
I had feeding problems, but adjusting the lips of the magazine solved this for 98%.
I shot the first test with .323" sized boolits. ca 50% of the shots of the first test with the vitha-N133 powder didn't go straight through the paper at50.
Now I opened up the sizer to .3245", and all the shots of this test (shot at 100m) went straight through the paper, nice round holes.


I shot the rifle with a 10x magnification scope. And supported the front end with a simple rifle-rest.
I only shot 10shot groups at 100m, the used powder was Vithauori N133, loads: 30,0 / 31,0 / 32,0 , 33,0 grain.

The best group was loaded with 30 grain powder. But the group-size (average spread of 36mm) was too big i think...



The next thing is to get the accuracy some better.

The current plan to proceed...:
* getting the deposit out of the barrel will help maybe, a brass-brush is used already and also soaking in ''millfoam'' and ''robla'', but the stuff is still inside, I don't know which options are left.... maybe someone can advise me something?

* I have to buy a new bottle of alliant 2400, I want to test this powder also for accuracy .

* maybe I try another setting of the gas-regulator (smaller setting)


Are there other ideas to improve the accuracy?


Thanks for replying!

[mac60]

Maybe I missed it, but I don't see a mention of what bullet lube you are using. If that is leading (lead build up) at the muzzle, maybe your lube is failing you. At any rate the leading can't be helping any. 36mm is about 1.4 inches. If the range to the target is 100 meters - that is very good accuracy in my book. If every rifle I had shot a cast boolit into a group of 1.5 inches at 100 yards I'd be thrilled.

[WouterNL]

The lube is a mixture of beeswax and partially hydrogenated palmoil.

The crud in end of the barrel was already there when i bought the rifle. I assume it's a result of not sufficient cleaning after shooting a lot (of corrosive ammo).
This week I want to try something else to get the crud out of the barrels end.
After that next tests will be done....

[Wayne Smith]

Couple of things not mentioned. You are shooting a gas gun, thus your critical measurement for functioning is gas pressure at the gas port - not anywhere else. Depending on where this is a fast powder like 2400 may not provide adequate pressure that far down the barrel. You will be better off with a powder that distributes pressure further down the barrel.
Secondly, your cleaning regimen needs to make sure the gas port and piston system is free.