Thoughts on 11.5" barrel options, or, should I re-build this?

[Clusterfrack]

That's really interesting. If I'm understanding the data correctly the same Mk18's were shot suppressed and unsuppressed. Here's my read:

• Average group size increases as round count increases.
• Rate of increase in group size is independent of suppression up to 1200 rounds.
• At 2400 rounds, there is a large increase in group size with a suppressor.
• From 2400-4800 rounds group size declines with a suppressor, while group size continues to increase at a steady rate without a suppressor.
• Above 4800 rounds, group size increases at a stead rate, but groups from suppressed guns are about 1" smaller

I'd like to know what the standard error of group size is within each data point. Is this pattern observed in all guns? Or just one gun acting wonky? I'm having a hard time coming up with a universal mechanism that explains this pattern.

My personal experience is from using a LMT Mk18 with a T1 at carbine matches for a year. I had a casual bet (which I won) about the viability of this gun out to 400+ yds. The Mk18 seemed noticeably more accurate with a Surefire Mini. Obviously, that's totally subjective and anecdotal.

Yup! That's it! That's awesome you have it, thanks for posting it up. Would you be willing to email it to me? I just searched even using its title and couldn't find it, it must've been taken down.

Can you also post up the section on accuracy for @Clusterfrack? What started the interest was the increased precision noted when suppressed.

https://www.warriorsunited.org/s/CRA...-Data-Mk18.pdf

[ASH556]

@ASH556

I haven't read the whole thread yet... but I am pretty sure the OP, will enjoy the info and velocities in this thread.

All suppressed, 10.5", 11.5", 12.5", and 14.5" chrono info with popular SD ammo. ( Much easier to read if you are a member )

https://www.ar15.com/forums/AR-15/Su...714088/?page=1

Those velocity numbers are different than another thread I read. Based on that, with a minimum expansion velocity of 1,800 FPS, my setup is good to 300.

[wolf76]

@Default, thanks for posting the link to the Mk18 PDF. When I made my previous post, I was unable to find the link using the title.

For those who shoot their Mk18 (with the .070 gas ports) suppressed, approximately how much increase in cyclic rate is there when using the Surefire SOCOM suppressor?

[Caballoflaco]

Slight aside, sorry Ash, but that paper also made me like my old idea of replacing the foward assist with some kind of replaceable quick dump lube cartridge. Just lock the bolt back, roll the rifle on its side and smash that lube button.

Something I had thought about after hearing Pressburg talk about running dry guns to make cleaning easier and then adding lube if it looked like it was going to be a long day.

[SLUZENE]

Mucho want. Wish they posted velocity and groups.

In this video or another one, it appears to be a Proof carbon, not steel.

The SBR that lives in my head is a 11.5 proof carbon, can and a LVPO.

[DiscipulusArmorum]

I had big plans for a heavy profile 11.5 Colt barrel, but when the prices got stupid, I sold and used the money toward an 11.5 URG-I clone upper built by John Thomas with an 11.5 DD barrel, though I think those barrels have been tough to find of late too. I'm still optic shopping so no performance data yet, but I have high expectations based on my previous DD experience.

[ASH556]

Thanks to a PM from a very helpful forum member I am now down this path!

[TOTS]

Slight aside, sorry Ash, but that paper also made me like my old idea of replacing the foward assist with some kind of replaceable quick dump lube cartridge. Just lock the bolt back, roll the rifle on its side and smash that lube button.

Something I had thought about after hearing Pressburg talk about running dry guns to make cleaning easier and then adding lube if it looked like it was going to be a long day.

I remember that discussion. Just for clarification, I think his experience was specifically regarding the HK416 and it’s ability to get through a mag completely dry and then cleaned with compressed air unless they were in a no-shit gunfight. Then all the lube after taking cover.

[ASH556]

[ASH556]