I recently purchased a 300 blackout upper 8.5 inch (it was a blem) and paired it with a PSA JAKL lower. I changed out the muzzle device (dead air brake), grip, trigger guard, and trigger. Added eotech 512 and took it to the range to sight in today.
Started with 125 grain super sonics. I reloaded 20 grains of CFE BLK and SMK 125 grain bullets to 2.24. Without the suppressor, they ran great. I was able to adjust the gas block and they were shooting out at 3 o’clock. I want to say I was in the 3rd or 4th position. Next I tried my subsonic loads (220 berrys with 12 grains of CFE BLK). I opened the gas all the way up and they either dropped out or didn’t pick up the next round. No big deal, they are subsonic and i expected this. I was mainly testing to make sure they didn’t keyhole before putting on my suppressor.
Added my dead air sandman-s to the end and ran the subsonic through. They ran perfectly, ejected where i wanted them. Worked in the 6 and 5 gas position (had to use 6 as i worked backwards down to 11.2 charge)
Now the issue - I try the supersonic loads and i turn the gas down to the second position. Brass ejects straight forward. Very gassy. ‘Smoke’ coming out of the action, magazines, everywhere. Next, i turn it down to the 1 position and it opens the action 3/4 to full and sometimes ejects the brass. So i feel like there is no position that will cycle the supersonic loads correctly with the suppressor attached. Shouldn’t the position 1 gas also keep the bolt closed? No gas should be coming through right?
Is there too much back pressure with my suppressor? Do i need to try a different powder for the supersonic loads to function correctly with the suppressor?
Could there be an issue with the adjustable gas block? Just looking for some insight to help troubleshoot the issue. I really liked how the gun felt and shot, but i dont want to worry about taking my suppressor on and off. I want 2 loads, super and subsonic where all i have to do is go to the right gas setting.
Yes all hand loads. The subsonic are true “handloads” in the sense that its new starline brass, The supers are using once fired brass, but im splitting hairs.
Try using some factory ammo. I have noticed hand loads that work in regular ARs don’t play as nicely in a Jakl due to the way the gas system works. You may need to develop an independent/jakl only load.
I think i read that CFE BLK is smoky in general, so i may try some supers with the H110 that i have. I will also buy a 20 pack of supers from the store to see if that changes anything.
But do you think the adjustable gas block is working correctly?
I’m very disappointed with the new 8-position gas knob (new listing). Not only is it overpriced for what it is, but the product page is an exercise in vagueness. No compatibility info, no specs, nothing. Naturally, I assumed it was ‘universal’ for all Jakls—because how hard is it to communicate otherwise?
Then it arrives. Stamped 5.56? Great, I think. I’ve got a 5.56 10.5 upper from January 2023. Pop out the old ‘S’ stamped knob (and by the way, swapping these is a colossal pain in the field—if I wanted this level of gas system headache, I’d have just stuck with my SCAR). Go to install the new knob… and it doesn’t fit.
Why? The outer diameter is too large for the gas block, and the rail section with the detent notches is too thick to even fit into the channel it’s supposed to ride in.
Here’s the thing: you don’t need to reinvent the wheel here. Put some engineering specs and compatibility info on your product page. Feed the details through an LLM if that’s what it takes to get clarity. Just don’t leave customers fumbling with expensive, ill-fitting parts and wishing they’d stuck with simpler systems.
Until then, back to swapping out my old limited-adjustment knobs. Please, do better. @palmettostatearmory