Some disappointing news, I couldn't get the SAG Mk3 to fit the KUSA

There is something about the barrel diameter near the trunnion that causes too much pressure on how the rail sits and some of the left side screws won't line up. The rail is slightly canted to the right and the screws hit the edge of the top rail after they pass through the trunnion base mount

The red screws won't index and seat properly but the yellow ones are fine. I messed with it for a couple of hours trying different orders of assembly and screws but couldn't find the right sweet spot to get it all together, so effectively I can't use the Mk3 on the KUSA. Yet, anyway


I had a lot of trouble with the gas tube binding with the KUSA piston even though the Mk3 has adjustment room to change the angle and get this right. I did have to follow their alternate instructions and not install the gas tube first because of variations in how the piston may meet the Mk3 gas tube. The alternate method leaves the Mk3 gas tube loose and then you have to do this wiggle dance screw driver lever pray to the AK goes nothing slips or falls out dance to get the gas tube connected to the top rail after the piston and carrier are installed in the rifle. Not a knock specifically on KUSA, SAG includes this alternate method for a reason (and I'll be trying the Mk3 on my 545 and 223 Saigas to get a larger sample size, as well as some Bulgarian guns and the PSA 103)


And I hate to say this but it took like 6 minutes to get the SAK Mk3 installed on the 7.62 Saiga. It all drops right in and is smooth as butter... except for the rear cover, which doesn't fit right. The charging handle binds up on the rear part of the Mk3 and won't go fully to the rear because the rear rail cover is sitting nose down where it meets the main rail, and it sits too high in the back where the recoil spring locks it in place. This could be a problem with the folding trunnion on the Saiga but I'm not sure yet
See the yellow line and how it looks to be misaligned with the front part of the rail
It binds up on the red circle by the charging handle and I think it's because of how it sits on the red circle in the back over the trunnion
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Big ol fat gap there between the front and rear rails. This is all Russian on Russian here, and when I was test fitting the Mk3 to the KUSA this problem did not happen, but I didn't have it all assembled and tightened down either


It does however look really sweet with PA 1/4




So just to be clear it won't currently fit the KUSA at all, and it has issues with the Saiga as well but it seems like the Saiga can be fixed if I tinker with the rear trunnion more and see where it's binding up

I kinda feel like the Mk3 isn't going to be able to fit the KUSA at all, which I genuinely hate to say. I want this to work

Great thread and pics. Thanks for taking the time to create this informative thread.

I would think that if the rings themselves were on the fixed front portion of the Mk3 rail that the rear removable section of the Mk3 would probably still be able to come off, unless the LPVO occular lens was super low and near the recoil spring button

Late to my own thread again I see , but I've been busy with work and whatnot

I'll try to make some time to get back on track this weekend. I still want to test the SAG Mk3 on a few more chassis and get good groups on the KUSA which has been zeroed with the PO 3.5x21P Venezula (bottom rifle and optic). So far during zeroing there was nothing special about the groups either good or bad

Polish Factory No 11 had some smooth mags that turned out to be crap.  Just saying.

Hate to say it but today was kind of disappointing with the KUSA 103 shooting groups. Maybe I'm spoiled by the AK74 and maybe the PSA 103 too, but I really was expecting a bit more to be honest, though I still have not suppressed it and am actually still optimistic I can cut group size down

I shot Federal Fusion, Hornady Black, the very last of my Yugo M67 and Barnaul red & green box FMJ

Seems like even with high quality ammo it struggles to hold 3 MOA and I had some surprising 7 inch groups at 100 yards with Barnaul, which is normally really consistent bulk ammo. There was also some wind from time to time at about 10-12 mph but I was shooting head-on into it so I do consider that as a factor, but I can't assign all the blame to the wind either



To eliminate me as the variable I kept a known good rifle next to me and would periodically cross check my groups with that rifle, and it performed as expected. In my opinion my trigger control was on point and there was zero shift of the reticule on target after each 5 or 6 round group when pulling the trigger on the empty mag. I was actually quite happy with how well I was dialed into the gun today. I had a really nice groove and felt like all my mechanics were on point. I also swapped in other optics with the same ammo type as a control group to be sure it wasn't PO 3.5x21P having problems, and it wasn't. All the optics grouped the same and my known good rifle was straight and true today as well. I'm going to get a couple friends to group it again next weekend to fully eliminate me as the variable, but right now I think I have a pretty solid baseline for unsuppressed shooting with the KUSA 103 brake mounted

I will say the stock trigger is pretty bad and to be fair I should probably swap to an ALG. I could feel a lot of grit during takeup and then a lot of resistance at the break. The reset wasn't much better unfortunately

I shot twenty to twenty five rounds in 5 or 6 round groups per type except Yugo because I only had 15 or 16 rounds left. I let the gun sit about 30 minutes between types and paused about 1 minute between shots


Overall it averaged almost exactly 4 MOA between all 4 ammo types, so not out of the norm for a typical AK. Barnaul was the worst at 5 MOA average and Federal Fusion was the best at 3 MOA average


Barnaul
4x 5 round groups
Average: Exactly 5 MOA
Best: 3.9
Worst: 7.3



Yugo M67
2x 5 round groups, 1x 6 round group
Average: 3.894 MOA
Best: 2.954
Worst: 4.7



Hornady Black 123 SST
4x 5 round, 1x 6 round group
Average: 3.87 MOA
Best: 2.6
Worst: 4.8




Federal Fusion
4x 5 round groups
Average 3.09 MOA
Best: 2.3
Worst: 4.8




I did shoot Wolf 123gr HP and some Golden Tiger 123gr HP here and there to get a rough idea of what they were doing as well, but I'll save them for the next outing. Overall they seem to be pretty close to Barnaul, meaning 4 to 5 MOA

As I said I still intend to suppress the KUSA because I do believe that will cut group sizes, but I'm going to do a little more testing with bulk ammo first


I was going to get all fancy and use shoot-n-Cs, but there was enough sporadic drizzle that it didn't look like they were going to hold up

It's almost drilled all the way through, but yes, I would consider it a really deep dimple on both sides