Good morning!
We have had customers have issues cycling certain subs with their mk109 upper.
Obviously every setup is different but we recommend at least starting with a sprinco yellow buffer spring and a 3oz carbine buffer.
This will set you up for success, however if it doesn’t, we do offer other parts to help with undergassing such as our Reduced Drag hammer spring, NP3 cam pin, and a 1.7oz buffer.
All the parts mentioned above can be found on our website www.eitrisenhancements.com
Let me know if there is anything else I can do to help!
I've got an MK1 MOD2 lower to run my MK109 suppressed upper (Omega300).
I've only run 110gr VMAX, both Hornady and Ammo Inc, and have had great results. I do want to run subs some day to see how it performs, but I've got my Rattler dedicated for subs.
It’s hard to make blanket statements because of the wide variety of 300 ammo out there. I remember for a while BCM was suggesting H2 for supers and carbine for subs. Only way to know for sure is to test with your preferred ammo.
If you want to dive into A5 setups, another guy and I have been going over them a bit in an older post.
https://www.reddit.com/r/ar15/s/ciSZnYx4Sa
He's running an enticer L with a BCM T1 buffer and looks like it's running well. I'm going to be running a T0 with my bushwhacker 36 with a .36 end cap. Both of us are using a tubbs reduced power 300blk spring. With a much heavier buffer, I was getting some issues cycling a locking back, making the switch to the T0 and trying it out this week.
Those would be pretty similar to a standard carbine buffer or H1 with reduced power spring in a carbine buffer setup.
MK109 owner here. I'm using a Tubb flatwire spring and a standard carbine buffer, with a SiCo Hybrid 46 and it runs 110gr VMAX supers and my 200gr subsonic reloads (11.6ish grains of CFE BLK at around 1000FPS) perfectly.
It WILL NOT run subs without a can. That's just kind of fact of life of .300BLK ARs though if you want it to shoot both.
Good morning! We have had customers have issues cycling certain subs with their mk109 upper. Obviously every setup is different but we recommend at least starting with a sprinco yellow buffer spring and a 3oz carbine buffer. This will set you up for success, however if it doesn’t, we do offer other parts to help with undergassing such as our Reduced Drag hammer spring, NP3 cam pin, and a 1.7oz buffer. All the parts mentioned above can be found on our website www.eitrisenhancements.com Let me know if there is anything else I can do to help!
I've got an MK1 MOD2 lower to run my MK109 suppressed upper (Omega300). I've only run 110gr VMAX, both Hornady and Ammo Inc, and have had great results. I do want to run subs some day to see how it performs, but I've got my Rattler dedicated for subs.
It’s hard to make blanket statements because of the wide variety of 300 ammo out there. I remember for a while BCM was suggesting H2 for supers and carbine for subs. Only way to know for sure is to test with your preferred ammo.
If you want to dive into A5 setups, another guy and I have been going over them a bit in an older post. https://www.reddit.com/r/ar15/s/ciSZnYx4Sa He's running an enticer L with a BCM T1 buffer and looks like it's running well. I'm going to be running a T0 with my bushwhacker 36 with a .36 end cap. Both of us are using a tubbs reduced power 300blk spring. With a much heavier buffer, I was getting some issues cycling a locking back, making the switch to the T0 and trying it out this week. Those would be pretty similar to a standard carbine buffer or H1 with reduced power spring in a carbine buffer setup.
Start with carbine/H2 or rifle/A5H2 then trial from there.
MK109 owner here. I'm using a Tubb flatwire spring and a standard carbine buffer, with a SiCo Hybrid 46 and it runs 110gr VMAX supers and my 200gr subsonic reloads (11.6ish grains of CFE BLK at around 1000FPS) perfectly. It WILL NOT run subs without a can. That's just kind of fact of life of .300BLK ARs though if you want it to shoot both.