From TFB:

The M17 has an AR-style charging handle, rather than the conventional AK handle, it has a monolithic dust cover/gas tube cover with a full-length top Picatinny rail. The rifle also has an adjustable folding ACR/SCAR style stock. Zoran M Susic, Zastava’s marketing and research manager, told Jane’s that “the base for the modular M17 modular AR is the Zastava M05 in the calibre 7.62×39 mm, the system of the Kalashnikov, which is the standard calibre of the Serbian Army and many other countries”

The new rifle also has a quick-change barrel mechanism with Susic noting that the barrel can be “replaced in less than 60 seconds" ....It uses at present a 20-round magazine, but that this is expected to be replaced by a 30-round magazine in the future.

In addition to the AR-style charging handle the rifle’s controls are ambidextrous with safety/selector switches on both sides of the receiver. Previous photos, dating back to 2017, show a forend with MLOK points and a 6 o’clock Picatinny rail, the new photos show the rifle with a ribbed rail cover.

The M17 has been developed to use a proprietary cartridge - 6.5×38.7mm, rather than the original 6.5×39 mm Grendel cartridge. The new round has been developed by Serbia’s Prvi Partizan, an ammunition manufacturer. The new round reportedly has better ballistic characteristics, with a flatter trajectory and more kinetic energy on target out to 800m, according to the Serbian Ministry of Defense.

Anyone know more?

There is no reason that the Serbs would need to stick to the exact parameters of the 6.5 Grendel.  The Grendel was designed for retrofit into the AR15 platform, so the maximum pressure was limited by the existing bolt design and the OAL limited by the existing magazine well.    The development of the M17 gave the Serbs more flexibility, so the "  flatter trajectory and more kinetic energy on target out to 800m" certainly sounds like they increased at least one of the following: operating pressure; overall length of cartridge; or case diameter.

Makes sense. Waiting for the civilian export version!

Upon doing more research, it seems like the press releases for the past several years have often referred to the 6.5 Grendel.  The changes to the cartridge might be less than I originally thought, especially if the  " flatter trajectory and more kinetic energy on target out to 800m" is in reference to the 7.62x39 rather than the Grendel.

"The 6.5×38.7 mm round, developed by Serbia's Prvi Partizan, leverages work on the company's 6.5×39 mm Grendel cartridge, but it has been optimised to be fired from automatic and semi-automatic weapons."

https://www.janes.com/article/90088/zastava-arms-develops-new-modular-assault-rifle

I'm still surprised they don't make it 6.5x39 - just a 7.62x39 necked down to 6.5 so it can run out of 30rd AK mags. 

gatnerd said...

I'm still surprised they don't make it 6.5x39 - just a 7.62x39 necked down to 6.5 so it can run out of 30rd AK mags. 

Because they aren't stupid? Having a 7.62x39 chamber by accident would be far too exciting.

Red7272 said...

gatnerd said...

I'm still surprised they don't make it 6.5x39 - just a 7.62x39 necked down to 6.5 so it can run out of 30rd AK mags. 

Because they aren't stupid? Having a 7.62x39 chamber by accident would be far too exciting.

Considering that 6.5x39 would have 0.293 neck diameter and 0.264 bullet diameter, I have to question if a 7.62x39 round would go into a 6.5x39 chamber far enough to fire.

However, it might cause a difficult-to-clear stoppage, if the .311 bullet were to get stuck in the 6.5x39 chamber neck.

gatnerd said...

I'm still surprised they don't make it 6.5x39 - just a 7.62x39 necked down to 6.5 so it can run out of 30rd AK mags.

That idea has some merit, but using a case with less taper significantly increases powder capacity, with correspondingly improved performance.

                                                                  6.5 Grendel                                  6.5 PPC                                        6.5x39

stancrist said...

Considering that 6.5x39 would have 0.293 neck diameter and 0.264 bullet diameter, I have to question if a 7.62x39 round would go into a 6.5x39 chamber far enough to fire.

New gun, steel case and steel core probably not. Old gun with a worn throat, lead core or brass case very much so. Locally there is a famous case of a guy who lost an eye when he cambered 30-06 in a 25-06.