Mega AR15 MML vs Seekins SP3R upper for precision?

R

RemoteDoc

Private
Minuteman
Nov 28, 2023
11
9
Willow, AK.
#1
I'm looking to build a more precision oriented 6MMARC. I've read through several forums. I found a lot of useful insight. I had narrowed my choices to the Larue Stealth 2.0, Mega AR15 MML and the Seekins Sp3R upper/rail combos. I ruled out the Larue due to it is limited to 13 inch hand guard.
I'm not sure if the triangle shape of the Seekins will cause any issues with gas blocks. I know their triangle shaped AGB will work. But, I usually prefer the Superlative Arms bleed-off type. I also considered buying the Seekins 22" 6mmARC rifle. But, I'd prefer to stay at 20"; and I thought it odd that Seekins went with a rifle length gas and a 1:8 twist. So, I'll build a rifle using a Proof Research, 20", Rifle +1, stainless barrel.
Between the Seekins SP3R and the Mega Arms MML upper/rail combos, which would you recommend; and why?
Thank you for your insights.
 
#2
I’m gathering parts for a 6.5 Grendel and went with the Seekins SP3R,mainly because of the way they free float the barrel. The SP3R handguard has plenty of room for the superlative arms has block.
 
#6
#11
I just sold a rifle with the SP3R handguards that housed an .875 SLR gas block. It fit with no issues.
IMG_6030.jpeg
 
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#12
I'd vote Seekins, I have an older (pre-Zev) Mega Arms AR15 MML with a JP Supermatch barrel and I can't say I'm impressed there's a lot of flex in the handguard compared to other options I've ran including the Seekins SP3. The only thing I'd caution on the Seekins SP3 is be really careful of how tight you get the screws, especially the top 4, there's almost no thread engagement on those 4 (probably because of the cut in angle and proximity to the barrel nut, and they are easy to strip.

My JP Mk III, White Oak TR, Seekins SP3R, all have much less flex than my MML does. Worse yet, if you don't like it, you have no option to run another handguard. What I really like about the White Oak is it's stiff, but it's cut at lengths so the gas block is exposed. Some folks feel strongly about not having an exposed gas block but after doing it on a few builds for awhile I wouldn't' do it under the handguard again unless I was building a real hard use option and in that case I probably wouldn't run an adjustable gas block anyway.

All that said I'm a big fan of the BCM upper, they are known to be undersized and of all the uppers I've tried (which admittedly is not dozens/hundreds etc.) they've been the tightest fitting and still allow use of basically any handguard. If you don't mind being locked into a handguard like the SP3, then I'd probably go with the seekins IRMT with the SP3

It's really too bad most all of the monolithic options have gone away, but at the end of the day for 99.9% of AR buyers precision is not the top priority, modularity likely is and you lose that with monolithic.
 
Last edited:
#13
ToddM said:
I'd vote Seekins, I have an older (pre-Zev) Mega Arms AR15 MML with a JP Supermatch barrel and I can't say I'm impressed there's a lot of flex in the handguard compared to other options I've ran including the Seekins SP3. The only thing I'd caution on the Seekins SP3 is be really careful of how tight you get the screws, especially the top 4, there's almost no thread engagement on those 4 (probably because of the cut in angle and proximity to the barrel nut, and they are easy to strip.

My JP Mk III, White Oak TR, Seekins SP3R, all have much less flex than my MML does. Worse yet, if you don't like it, you have no option to run another handguard. What I really like about the White Oak is it's stiff, but it's cut at lengths so the gas block is exposed. Some folks feel strongly about not having an exposed gas block but after doing it on a few builds for awhile I wouldn't' do it under the handguard again unless I was building a real hard use option and in that case I probably wouldn't run an adjustable gas block anyway.

All that said I'm a big fan of the BCM upper, they are known to be undersized and of all the uppers I've tried (which admittedly is not dozens/hundreds etc.) they've been the tightest fitting and still allow use of basically any handguard. If you don't mind being locked into a handguard like the SP3, then I'd probably go with the seekins IRMT with the SP3
Click to expand...
Thank you for your insights. I have a few BCM receivers and a few DD hand guards.. I might just do that.
 
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