7.62x39 CZ 527

[garryc]

I finally finished my load development with my CZ 527 7.62x39
First I tried Olympic ammo and found two things. its dispertion was a 7inch verticle string, straight up. When I tried to resize the cases there was a ring left at the bottom of the web. I also found, upon pulling some bullets, that the crimping severly distorted the bullet. Save those for ratteling in the AK.
Then I tried winchester white box FMJ's, they had a .311 bullet. 2.75inch group. Then winchester SP's, 2.25 group. I was beginning to think something was wrong with the gun. No problem resizing the cases.
Then I loaded Sierra 110gr .308 HP's with 26.5 grains of R7. 2 inch wide x 3 inch high group. When shooting at a water filled milk jug at 100yrds it showed no sign of expansion. (Neither did any other bullet)
I tried Hornady 123gr .310 with 25.5 grains of R7. It gave a round 2 inch group.
I then loaded Sierra .311 SP bullets with 25.5 grains of R7. Groups ran 1 to 1.25 inch. Now I was getting somewhere.
I loaded Sierra 150gr .311 bullets with 24.8 grains of R7. The first group went into one .75 inch hole!! Of 6 groups the largest was 1.25 inch.
Now the question,
The 150 arrives at 150yrds with more KE than the 125, like 175ft pounds more. But will the bullet expand at the 1750 aprox (calculated) velocity? Would the 125, having less energy and near the same velocity, expand better?

[Leftoverdj]

Garry, the performance of the milspec ammo can be improved a lot by calling CZ and requesting an overpower firing pin spring. The stock spring is marginal on hard primers and gives inconsistent ignition. The milspec ammo still ain't very good, but changing springs and graphiting the spring, firing pin, and bolt interior more than halved my groups.

I went through much the same process you did, and got the same results. The 150 grain Sierra .311s give the best accuracy and the most downrange energy. Sierra can tell you the remaining velocity needed for expansion, but my best guess is that it is marginal at 150 yards. I'd expect some expansion on a shoulder shot and none on a ribcage shot.

The bullets built specifically as game bullets for the 7.62x39 are a lot more likely to expand, but I have my doubts about their pentration at 150 yards.

Interestingly, I am getting superb cast bullet performance from my CZ 527. Lee's C312-155-2R weighs 159 grains with my alloy and gives about 1.5 MOA at 2200 fps. I'm strongly tempted to use that bullet with annealed noses on any hunting I do.

[Unclenick]

Call the bullet maker. Expansion velocities in different media depend upon the jacket and nose construction. All else being equal, the heavier bullet will do better since it will maintain velocity and therefore expansion forces on the bullet nose for a longer period of time after entry.

You accuracy variations suggest you have a lot of harmonic vibration (the vertical stringing) and have barrel times landing in the unfavorable portion of the pressure wave in the barrel. I suggest you look at Dan Newberry's web site for information on developing optimal charge weight loads. If you are more technically inclined and own the QuickLOAD program, you can also make use of Chris Long's Optimum Barrel Time calculator.

Nick

[garryc]

I called sierra and was told that 1700fps, which is what I speculate the bullet will have at 150yrds, is too slow to cause expansion. They said the stiking speed should be over 2000. Oh well, the sierra 125 is made specifically for deer at a maximunm of 150 yards from a 7.62x39. Its not like I need another deer gun anyway with my Remmy classics in 8mm and 7mm mauser. What I really need is a V-Max, I've heard that graf has a special run of them.

[Unclenick]

Garry,

I ran your 125 grain Sierra bullet in an external ballistics program and found it requires 2450 fps at the muzzle to stay up to 2000 fps at 150 yards. I then ran a load table for different powders in QuickLOAD to find those that would achieve that velocity from your 18.5" barrel without exceeding safe pressure. A caveat here: The capacity of your brand of case expanded into your chamber affects pressure greatly as you near maximum loads. If you take a fired case (fired but NOT resized) that was correctly trimmed before the last firing, weigh it, then use an eyedropper to fill it with water just exactly level with the case mouth (no positive or negative meniscus above or below the mouth—just flat level with the mouth), then weigh it again, then take the difference in weights to arrive at the case water capacity, I can adjust the guesses below for your gun.

Be aware that the computer results are just guesses because powders can vary several percent in performance from lot-to-lot. For example, the W296 load below calculated a grain higher for H110, even though these are the same powder from the same factory with different labels (I verified that information by speaking with a Hodgdon tech). The program powder data comes from Russian lab measurements of samples that reflect just one lot of each powder, and not from worst case allowances or mean performance, which would be more useful. They presume the wimpiest primer you can get.

Using the default case capacity (usually low) of 35.5 grains for the 7.62 x 39 (M43) Russian, none of the powders in the QuickLOAD library manage to stay in the totally safe (starting load) pressure range except one European powder not commonly available here (SF-033 fl). The powders we get here all fall in between starting and maximum loads, so they may not be suitable in your rifle. CAUTION: REDUCE 10% THEN WORK UP TO THESE LOADS GRADUALLY, WATCHING FOR PRESSURE SIGNS:

Available space 2450 fps from 18.5” barrel loads:

• Alliant Reloader 7: 26.4 grains — Caution, Near Maximum Load!

• Winchester 296: 24 grains — Caution, Near Maximum Load (but lowest pressure of all loads listed here)!

Compressed loads:

• Alliant Reloader 10X: 28.6 grains, 101.4% compressed, — Caution, Near Maximum Load!

• Norma 200: 28.7 grains, 101.7% compressed — Caution, Near Maximum Load!

• Vhitavuori N120: 27.2 grains, 102% compressed — Caution, Near Maximum Load!

• IMR 4198: 27.0 grains, 103.7% compressed — Caution, Near Maximum Load!

I also tried the Sierra 150 grain bullet. The external ballistics program says it must have a muzzle velocity of 2360 fps to keep up at 2000 fps at 150 yards. This proved too much for the short barrel and no safe load could be calculated to achieve it without additional barrel length.

Incidentally, borrowing from Cooper, if you achieve 2450 fps with the 125 grain bullet, sight the rifle to impact 2.0” high at 100 yards (160 yard zero with this loading) and its POI will be +/- 2 inches from point blank to 190 yards; within the deer kill zone without having to hold off or allow for bullet drop at all.

I know you don't feel you need another deer rifle, but I expect that light, short combination will have some of the advantages of a scout rifle in terms of pointability and portability. Better for making snap shots. In woodlands, 150 yards is plenty of range. I seldom see a clear shot much over 75 yards within woods in Ohio; good thing, since we have to use slug guns and muzzle loaders here.

Nick

[Leftoverdj]

The 125 grain bullet is designed for the 7.62x39 and is not going to need 2000 fps to expand. The 150 was designed for deer sized game from far larger cartridges with an mv of 2700 fps or more.

Getting 2500 fps with 125 is easy even with the CZ's barrel. AA-1680 or the surplus WC 680 will do it nicely. So will H322. The limit for the 150 is about 2200 fps.

To my knowlege, there is no ideal bullet for the 7.62x39 as a deer rifle. The 135 varmint bullets would come close in a rifle with a .308 barrel, and will give adequate accuracy in .310-.311 barrels. A swager could reform 150 grain .30-30 bullets to .311 spitzers which would expand at far lower velocities than the .311 Sierra.

[garryc]

Empty case is 127.5gr. water is 161.6gr. Making capacity 34.1 grains. I'm abandoning the 150gr

[steve4102]

To my knowlege, there is no ideal bullet for the 7.62x39 as a deer rifle. The 135 varmint bullets would come close in a rifle with a .308 barrel, and will give adequate accuracy in .310-.311 barrels. A swager could reform 150 grain .30-30 bullets to .311 spitzers which would expand at far lower velocities than the .311 Sierra.

I am also in search of a ideal hunting bullet for my 7.62x39. I would like your opinions on a couple of bullets.

The Speer 150gr FN and 150 RN.
Sierra 150gr Pro Hunter and 135gr SSP
Remington 150gr Bronze Pt.

Thanks

[Leftoverdj]

Some 7.62x39s will shoot .308 diameter bullets pretty good. Some won't. It's probably worth the $20 to find out if yours will shoot accurately with the 135 grain SST. That bullet is designed to expand at lower velocities although I don't know how low. The .30-30 bullets will also expand at lower velocities, but RN and FN lose velocity so fast you would gain nothing in yardage.

The situation is dismal if you need .310 or .311 diameter bullets. There are 123 and 125 grain bullets designed for deer sized animals in the 7.62x39 or varmints from the full sized rifle cartridge. The 150s I know of are intended for full sized rifle cartridges. There is factory loaded 150 grain ammo for the baby Russian and one may hope that it is loaded with suitable bullets, but those bullets are not available to handloaders.

Fortunately, this does not ordinarily matter. It's only when you start pushing the range limits that the 123-125 grain bullets start getting iffie.

[Frogmouth]

My CZ 527 gave problems at the start. The ignition was erratic and non-existant on full length resized cartridges. According to our local gunsmith the problem was that many CZ 527's in 7.62x39 had chambers that were incorrectly reamed out. The answer (which worked) was to take a full turn off the barrel thread and rebore the chamber correctly. However, since then I have always used Federal 210 primers because I am told that they will still ignite with light firing pin hits. After fireforming the Winchester brass I have never done a complete full length resize. Only a partial resize, without the bore expander, to take the shoulder back a little. Then the cartridge neck gets redimensioned with a Lee Collet die. I don't get failures to fire anymore.

Projectiles???? My current favorite comes from Australia made by Taipan http://www.bulletmaker.com/Jret.htm , 135gn .312" JHP. At a loaded length of 2.248" it sits about 32 thou off the rifling and fits the magazine. Taipan also has a 150gn JHP .312" which works quite well with the right powder. Taipan's 124gn JHP is OK but needs seating a very long way off the rifling and has a cannelure where you don't want it.

I'm still experimenting with powders but ADI's AR2207 (Hodgden H4198) at 25.2 gn behind the 135gn projectile gives 1" groups at 100m. I will chronograph this and see how she goes on porkers.

DISCLAIMER. This information is provided in good faith and is given without liability for loss or damage suffered as the result of its application.

Regards: Frogmouth

[Lawyer Daggit]

Frogmouth, The problem is not the incorrect reaming of the barrels. Winchester Australia (agents for CZ in Australia) stopped marketing the little CZ in 7.62x39 here because the carbine apparently has been built to eastern block specs for the round and not SAAMI specs. Apparently SAAMI chose to deviate from the Russian measurements when developing their specs.

This is not a problem in a semi auto that has a sloppy chamber anyway, but is a big problem in a bolt action.

The remedy your gunsmith suggested would work because it would alter the headspace. I take it you have removed the factory sights- I am in a quandry about what to do about mine as I rather like the factory sights.

[Lawyer Daggit]

Frogmouth, The problem is not the incorrect reaming of the barrels. Winchester Australia (agents for CZ in Australia) stopped marketing the little CZ in 7.62x39 here because the carbine apparently has been built to eastern block specs for the round and not SAAMI specs. Apparently SAAMI chose to deviate from the Russian measurements when developing their specs.

This is not a problem in a semi auto that has a sloppy chamber anyway, but is a big problem in a bolt action.

The remedy your gunsmith suggested would work because it would alter the headspace. I take it you have removed the factory sights- I am in a quandry about what to do about mine as I rather like the factory sights.

[joneb]

How about fire forming cases and neck size only ?? I would if it were me there could be a bit of slop in there causen trouble. Could the taperd case also be a problem ?

[Frogmouth]

Lawyer Daggit

I appreciate what you say about the SAAMI chambering. It's probably unfortunate that we have a hyperabundance of the El Cheapo Chinese cooking M43 ammo knocking around which does not work reliably with the SAAMI chambering. Anyway my re-reamed CZ 527 works well now!

Yes, I was in two minds about the iron sights on the CZ until I rationalised that I was never going to use them whilst I had a scope attached. Ergo, I knocked out the rearsight and then eventually, with some effort, managed to remove the bag snagging foresight.

Whilst in the mood, I also deactivated the set trigger ... it was just too
tempting to use on the range, but a potential hazard if applied outdoors.

Frankly for a 18.5" non match grade barreled rifle the CZ 527 shoots extremely well ... into less than 1" at 100 metres.

However, if 6.5 Grendel bits and pieces become readily available in Oz, I would be very tempted to convert over.

Regards: Frogmouth

[NFACurious]

Well I know this topic is a few months old, but here is my quesion.

I too have one of those wonderful mini-mauser actioned rifles, and have been trying the Sierra "303 British" .311 dia. 150gr sp bullets to develop an accurate load. In my quest for information, someone mentioned using Greenhill's formula to find the optimal bullet length of bullet for the rifle. I determined with the manufacturers website and using the old measuring the cleaning rod meathod that my barrel has a 9in twist. According to Greenhill's formula, a 9in twist with velocities under 2800 requires a bullet with an approx. length of 1.5''. The closest thing i have found that meets that requirement so far is Sierra's 303 british 174gr. HPBT. It has an overall legnth of 1.22''. Has anyone tried to develope a load off of this projectile?

[RareBrit]

Hi chaps,

Interesting question ... hope people are still reading this thread.

I'm currently using a CZ527 in 7.62x39 my pet-load is straight out of the viht catalogue. Their suggested loading is 27.3gr of n120 under a lapua 123gr FMJ. I'm using beautiful Lapua brass, seems a bit thicker than the average stuff. Out of a 16" barrel the book claims around 2361fps, which is going some for this cartridge. The load is MOA accurate, maybe a bit less if I allow time for cooling.

Anyone know what this load is doing out of a 18.5" barrel ... I suspect MV is going to a be up good amount because 16" to 18.5" is a fair jump.

Cheers

RareBrit

[NFACurious]

Rarebrit,

Yes sir i am still reading this thread seeing if someone will answer my question, but in the mean time, maybe we can work together. So you have a 16'' barrel? What twist rate does it have? I'm pretty sure my barrel is an 18.5 but i'll have to ceck on that, so tell me what i need to cook up the same round you are shooting. I'm always interested in a MOA to subMOA load for my 527.
Thanks,

-Curious

[RareBrit]

Hi NFACurious

My carbine is a stock CZ527, 18.5" barrel, don't see the point in playing with a rifle if it works ... might stick HS stock on it though. The load is Lapua brass, straight out of the box. Lapua 123gr FMJ spitzer, 27.3gr of viht n120, CCI primers. Exactly as it is in the Lapua online reloading manual. Full length resize every-time using Lee dies and a single-stage press, use the Lee crimp as well. Not sure what OAL is, I just bullet seat half-way up the canular.

I'm just curious to see if anyone has a muzzle velocity for this load through a stock CZ527 carbine? There's a legal requirement in the England for rifles used for deer to produce a minimum of 1700ft/lbs ... and I reckon this load is going to be pretty close on that.

Of course ... Hornady do a really nice 123gr soft-point spitzer that'd be an interesting alternative bullet for this load...

ttfn

RareBrit

[NFACurious]

Rarebrit,

Ok i should be able to replicate your load, and I have access to a Chronograph sometimes so once i get the load built up the way you have it and then i'll take it out to the chrono and see what its doin. Tell me out of curiosity what twist rated does your barrel have? Mine as a 1-9in twist rate which according to a few twist rate calulators to properly stableize the bullet i need either a bullet 1.5'' long or atleast 174gr. so anyways lemme know if you want me to try to get some chrono data for you.

-Curious

[steve4102]

Lapua 123gr FMJ spitzer, 27.3gr of viht n120, CCI primers. Exactly as it is in the Lapua online reloading manual.

There's a legal requirement in the England for rifles used for deer to produce a minimum of 1700ft/lbs ...

Is there also a requirement in England on what type of bullet can be used on deer. Here in MN it is illegal to hunt deer with FMJ bullets. If not, why would you chose a FMJ bullet for hunting? Getting a bullet to expand properly at 7.62x39 velocities is hard enough without using a FMJ bullet. I would try the Sierra 125 for deer.

[RareBrit]

Hi,

Yep, UK laws are that only expanding ammunition are to be used on game, can't think of any exceptions. This usually means a soft-point or premium hunting bullet. Problem is ranges only generally allow 'non-expanding' ammunition to be used, so accuracy loads are usually worked up with FMJ. Strangely, most ranges allow gas-checked cast bullets, which seems like a bit of a contradiction to me...

RareBrit

p.s. Curious, I've had a brief peek down the bore of my carbine, looks fairly quick, so probably a 1 in 9.5" as well, CZ tend to stick to a winning formula when they've found one, I think it's called 'engineering' . Seems to stabilise 125gr bullets fine, which is what the 7.62x39 is designed for.

[RareBrit]

Hi Curious ... you tried that load yet?

[aimlesslee44]

Just found this, a bit late but here my two cents worth.

My son and I both have CZ 527 7.62x39's, his a 2001 model, mine a 2008 model, his is decidely smoother and better finished than my later model. Mine has yet to be tested having only just obtained it. (they stopped importing this rifle in this cal years ago because of the european chamber specs causing trouble with the cheap chinese ammo thats been dumped on the market out here) however I tried all manner of loads and projectiles when we bought my sons one and the projectile that shoots by far the best is the Speer 130gr Hollow, now I know this is made as a 'varmint' bullet however we have not lost an animal with this projectile and our main species here is the red deer, I shot my biggest stag (over 200lb dressed) with one shot behind the shoulder with these projectiles out of a 7.62x39, have also shot a lot of deer with these in a 308 Winchester although there is a lot of meat damage. I know they're .308 and the 527 is .311 but in ours they shoot well (1" to 1 1/2" consistantly)and they kill. Chronographed the load we use posts just over 2000 fps, the load is Remington Case (small primer) Federal primer, Speer 130gr Hollow and 25.5 gr of ADI 2207.
Velocity doesn't sound impressive I know but the results speak for themselves, I just hope mine will handle these as good as his, out here in NZ, (the 130 Speer Hollow) a 'varmint' bullet they aint! a game bullet they most certainly are!

[Unclenick]

Welcome to the forum.

Those Speer HP's are a varmint bullet when they're going fast enough. What you've done is succeed in tuning it down below its catastrophic expansion impact velocity, and thereby made it serve another purpose well. Congratulations on that! It's appropriate application of technology for your intended purpose. Put it out at 3000+fps, though, and it will pretty much explode.