Ok I just bought a BCM Mk12 upper with rifle length gas. My current lower that I will be modifying for the Mk12 has the A5 with H2 buffer. Is this too heavy since dwell time will be lower than my middy upper that was previously on it? What buffer should I get for the Mk12?
Try out what you have first. If it functions fine, then I wouldn’t touch it.
I think you want to be in a different forum than the one you selected.
why would this be in the shot show forum?
The dwell time, barrel length, gas pressure and gas port size are all related.
Making an assumption based only on dwell time without knowing the other variables is poor practice.
The Mk12 should have an appropriately sized gas port to cycle a reasonable buffer.
The standard A5 works with most configurations.
Start with what you have.
Most likely it will work fine.
I have a 20" M16A5 that has an FN barrel (.093 port) and I have run it with the A5-3 and -4 buffers with 4 or 5 types of 5.56. I also use the green Springco spring as well.
You will be fine, I have the same barrel, it runs Tula on both an H3 and a rifle buffer just fine…(more than enough gas)
Same setup my MK 12 with .102" gas port runs perfect with Vltor A5 extension and A5h2 buffer…I did change the spring to a Tubbs Flat wire spring. I also run a M16 Carrier group.
Like others said you should be perfect!
That was almost a 1.5 years ago. He’s probably got it figured out by now. Probably should start paying attention to the post dates. Lotta necroposting going on.
Alaska is a different time zone. Threads post there later. :sarcastic:
He was just trying to help, not sure why you felt the need to be a dick, were you inconvenienced? 
Its easy to forget to check dates when you are reading search results or google hits…
On the contrary. Why bump an ancient thread while adding absolutely nothing to it? Most searches are because an individual is looking to receive information, not for giving any. Generally, it is frowned upon to necropost if you’re contributing absolutely nothing to the thread. Don’t believe me? Ask a staff member. The majority of his posts are necroposts & he’s been told before. It’s not hard to check dates, really… it’s not.
Also, apparently you didn’t know, but name calling is also frowned upon. There, now three people learned something in this thread: the OP, the gentleman I quoted, and yourself. What was it that you contributed?
I contributed exactly what you did, minus the rudeness, hypocrisy much? Where did I call you a name?
Let’s see…
Calling someone a “dick” IS rude and IS…
…wait for it…
…considered name calling.
But since you lack the mental capacity to wrap your head around that, I can see how you consider checking post dates as a challenge.
Happy holidays, Mall Ninja. This convo is over or take it to PM.
Sorry its not name calling, you are confusing nouns and verbs.
But since you lack the mental capacity to wrap your head around that, I can see how you consider the phrase “being a dick” as name calling.
Same to you sir!
We’ll just close it to stop the drive by bickering and the necroposting.
Alaska3006. As it has been mentioned before, please be mindful of posting and then ask yourself if posting in threads that are pretty old serve a purpose.