Zastava’s ZPAPM70 AK Derivative Part II

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02/04/2022 – My intention was to disassemble the ZPAPM70, displaying my mechanical prowess and illustrating my path to a simplified methodology. Unfortunately, the process is easy and I wanted to spend range time getting familiar with the rifle’s personality.

Air brakes and slanting compensators…

The difference between a muzzle brake and compensator is that a brake uses gas exiting the barrel to tamp down recoil. A compensator typically does not dampen recoil, but rather uses exiting gas pressure to provide a direction force to oppose muzzle rise and rotating bullet induced barrel torque. There are numerous hybrid designs that do both.

Neither brakes or compensators are of consequence when used with light cartridges and heavy rifles in non fully automatic operation. The 7.62x39mm and 8 lb ZPAPM70 rifle is a good illustration of  such a combination. How about when someone is a highly skilled marksman, like the guy on the adjacent shooting bench who won’t take a shot without first air sampling with a sling psychometric? Again, of no consequence, because the rifle is not as precision as the shooter.

The slant brake supplied with the semi automatic Zastava ZPAPM70 is a carry over from the selective fire AK. It performs no recoil reduction and it has little compensating effect on semi auto firing. Why is it there? Because Zastava, along with other AK derivative manufacturers, wants to retain as much of the parent firearm as possible. However, I had other plans for the rifle’s muzzle, so it had to go.

The detent pin that locked the slant brake in place was depressed, the slant brake was removed… yes, I know it is a compensator, but how can I argue against a 75 year old nomenclature… and a ridiculously over priced adapter was installed. Pictured next to the slant brake is a M14x1 female to 5/8×24 male adapter, which also provides a proper shoulder when mounting a 5/8×24 thread silencer.

No, I am not afraid of an out of flat barrel shoulder or a droopy silencer. The adapter’s smallest bore measures 0.355″, the SilencerCo’s Omega M36 has a 0.355″ end cap installed and a 0.355″ range rod is a slip fit from silencer end cap to rifle muzzle. The ZPAPM70 groove diameter measured 0.3115″.

On to 7.62x39mm M43 handloads

The 7.62x39mm is represented on Real Guns® in American standard versions, meaning 0.308″ barrel groove diameter as used in all Ruger products chambered for the cartridge. The handloads that follow are adjusted for the Zastava’s ZPAPM70’s 0.3115″ groove diameter, with one exception, with bullet diameters ranging from 0.308″ to 0.311″.

I view the 7.62x39mm in the same light at the 300 Blackout and 30-30 Winchester class cartridges. Subsequently, bullet weights have been bracketed between 123 and 150 grains that will expand at 7.62x39mm muzzle velocity. Which is generally an abstract criteria as impact velocity is what is important. So let’s put a pin in it at 150 yards for deer and similar size game… maybe a bit more.

Bullet Type Bullet
Diameter”
Weight
Grains
Bullet
Length “
COL
Length “
Net Case
Capacity
Grains
Hornady SP 0.310 123 0.870 2.190 31.5
Sierra SP 0.311 125 0.906 2.190 30.6
Sierra HPBT 0.308 135 1.056 2.190 29.4
Speer SP 0.311 150 1.005 2.190 28.7

 

Handload Data

Warning: Bullet selections are specific, and loads are not valid with substitutions of different bullets of the same weight. Variations in bullet length will alter net case capacity,  pressure and velocity. Primer selection is specific and primer types are not interchangeable. These are maximum loads in my firearms and may be excessive in others. All loads should be reduced by 5% as a starting point for development where cartridges have greater than 40 grains in capacity and 10% for cartridges with less than 40 grain capacity following safe handloading practices as represented in established mainstream reloading manuals. Presentation of these loads does not constitute a solicitation for their use, nor a recommendation.

7.62x39mm (M43)
Firearm Zastava ZPAPM70
Barrel Length 16.3″
Max Case Length 1.528″ +0.000″/-0.015″
Min – Max COL 2.150″ – 2.200″
Primer CCI 200 (LRP)
Bullet Diameter 0.311″ +0.000″/-0.0020″
Reloading Dies Lee Precision FL

 

Bullet Type Bullet
Weight

Grains
Net H2O
Grains
Capacity
COL” Powder Type Powder
Charge

Grains
Muzzle
Velocity

fps
Muzzle
Energy

ft/lbs
100 Yd
3 Shot
Group
Hornady SP 123 31.5 2.190 Re 7 28.0 2372 1537 3.6
Hornady SP 123 31.5 2.190 H4198 27.0 2335 1489 4.2
Hornady SP 123 31.5 2.190 IMR 4227 25.0 2350 1508 3.3
Sierra SP 125 30.6 2.190 Re 7 28.0 2395 1592 3.0
Sierra SP 125 30.6 2.190 H4198 27.0 2316 1489 2.4
Sierra SP 125 30.6 2.190 IMR 4227 24.5 2327 1503 3.4
Sierra Match 135 29.4 2.190 Re 7 26.0 2237 1500  3.7
Sierra Match 135 29.4 2.190 H4198 26.0 2240 1504  3.2
Sierra Match 135 29.4 2.190 IMR4227 23.5 2238 1501  4.3
Speer SP 150 28.7 2.190 Re 7 25.5 2168 1566  2.8
Speer SP 150 28.7 2.190 H4198 24.0 2051 1401  3.4
Speer SP 150 28.7 2.190 IMR4227 22.5 2115 1491  4.1

Adaptable shooting

The Zastava functioned reliably with supersonic loads. Subsonic loads were not on the bench. The noise reduction with silencer is enough to make a range session easier.

Most long guns I work with seem to have a GC around the location of the trigger. The ZPAPM70 balances mid handguard empty, rear handguard with a loaded magazine. Adding a silencer and scope actually did not shift balance very much.

I didn’t mind the forward weight. that balance made for a steady sight picture and it was easy to cradle carry. The short stock? The ZPAPM70 is fast handling, but I would like to mount a collapsible stock that would include an extra 1.25″ LOP within its adjustable range.

It felt like my noggin was too close to the receiver and the drop looked too much… until gaining some experience, at which point I realized optical sight alignment was very good…. but my head still felt too close to the receiver.

Applications

With a rail in place, rifle scopes and red dots are both options. Both useful configurations. I don’t care for this type of side rail as it it is…ungainly. So perhaps a dust cover with integrated rail, or a mount that replaces the standard rear sight. Maybe… maybe I would just leave the sights alone and use them as received?

 

Considering the ZPAPM70 family tree, it would difficult to suggest that it is not a good firearm for security applications. However, my personal circumstances favor handguns. On the other hand, hunting circumstances favor moderate range cartridges and moderate weight rifles. The ZPAPM70 is suitable for deer, coyote and black bear with the right bullets.

Overall

I don’t know. Usually I find myself tinkering with rifles that predictably shoot sub MOA groups. That level of accuracy is not really of consequence. Fun? The ZPAPM70 offers lots of it, but it is also a well made firearm that could provide a good deal of utility. Factory ammunition is probably the easiest way to go as handloading does not yield the typical reward of refined accuracy. Of the AK derivatives I have handled and shot, the Zastava is a good one.

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