I’ve assembled 3 lowers before but not ever an upper, this will be the first. With the previous rifles I bought a barreled upper, complete upper, and had a gunsmith assemble one.
Here is a list of parts I have already purchased
Geissele 15" MK16 Blem
Geissele 16" CHF barrel
LMT forged upper receiver
LMT BCG
LMT Buffer and Tube
My questions: Do I need to pin the gas block? If I just use 2 screws with locktite, do I need to put another dimple in the barrel? It only comes with one dimple. I almost got a Daniel Defense barrel because it comes pre pinned with gas block for the same price as the stripped Geissele barrel, But I like the contour on the tapered Geissele better that the DD barrel. The DD barrel looks like it has more weight out towards the muzzle.
Also I have an H buffer, any recommendations on which spring to buy?
If I get a LMT MARS stripped lower can I use a Sionics Enhanced LPK. I understand there are some proprietary parts that I think would come on the lower. Thanks in advance for any advice.
You can use the two screws and blue Loctite with just one dimple. I’d recommend finding screws that have the little teeth on the end, if not already equipped. That would be adequately attached. You can also pin it for increased peace of mind. You already have a gas block and tube, and pins?
I’d try a regular Colt spring from Brownells, or wherever.
I think you need an extra bolt release and pin with the MARS, don’t remember for sure.
I don’t have a gas block and tube yet. If I do pin the gas block I would have a gunsmith do it, but I would prefer to just use the screws if that’s a solid connection. I think I can put another dimple myself if that would make it better than one dimple.
One dimple is best, because different brands of blocks use different spacing. Of course, if thats not important to you, you could use a dimpling jig to place a second dimple, but at that point you could pin it just as easily.
With the Mk16 rail, you’ll want a very small gas block.
Ok thanks. Any suggestions for which brand of gas block would be good? BTW I just got the blem G rail and I am so happy. The only thing wrong with it, is the T mark numbers on the top of the rail are not white. Atleast that’s the only thing I can see wrong with it. Other than that it looks perfect and paid half price for it.
My G handrails came with one of their gas blocks. As mentioned above, one dimple opposite the gas port is what you want to do. If you need knurled set screws PM me your shipping address, I have more than I’ll ever use and can spare a few. Degrease everything and use red Loctite. I’d go with and H2 but an H will work, Colt action spring or Sprinco Blue spring, is what I use on my non-A5 guns.
These are the parts in an ELPK
1- SIONICS Enhanced Trigger
1- Semi Auto Disconnect
1- SIONICS Enhanced Hammer
2- Hammer / Trigger Pin
1- Trigger Spring
1- Hammer Spring
1- Disconnector Spring
1- Ambidextrous Safety Selector Long on left side and Short on right side.
1- Safety Detent
1- Safety Detent Spring
1- Standard Bolt Catch
1- Bolt Catch Plunger
1- Bolt Catch Roll Pin
1- Bolt Catch Spring
2- Takedown / Pivot Spring
2- Takedown / Pivot Detent
1- Takedown Pin
1- Pivot Pin
1- Mag Catch
1- Mag Release Button
1- Magazine Catch Spring
1- Buffer Retainer Pin
1- Buffer Retainer Spring
You can see by crossing off the FCG, TD/pivot pin and proprietary parts not much is left.
I have a BCM gas block under a MK8 and a Geissele under a MK4, and they both leave plenty of clearance. Once a gas block is installed, I see absolutely no reason to replace it with another brand’s block…so any barrel that uses set screws has 2 dimples.
If you’re mechanically inclined and buy a block with BCM spacing, I’ll let you borrow my BRD dimple jig.
I agree that $80.00 might be a little steep, but they are foolproof to install.
Back when ALGDefense had a separate site, she sold a carbon steel Super Gas Block for less and that is what I have always used. (ALG stands for Alice L. Geissele in case you didn’t know)
Here are the instructions so you can see how simply it is:
Spikes, of all people, sell a nice dimple jig that is set up to take set screw spacing from any variation out there. It has come in handy on more than one occasion. Only complaint is the bit that comes with it dies a quick death
I’ve only used a handful of brands gas blocks, but BRT is the smallest, and IIRC, Ballistic Advantage is small, too. The G model is fairly large, but I’d imagine it works. BRT and G pin easily with a drill press, although I haven’t tried the nitrided G version, only the stainless. If the barrel comes with a gas block, I’d test fit it with the rail before buying or drilling anything.
If you buy the BRD jig to pin your own gas block, you’ll also need to buy a taper reamer to fit the taper pins. I believe the correct size is a number 2 taper reamer.
If you want to pin your gas block, I would recommend the Geissele gas block. It uses a straight coil pin, and is pretty simple to do, you just need a decent drill press.
As others have said, one set screw in a dimple with adhesive is sufficient. I wouldn’t use blue loctite, though, as it is not heat resistant. Red loctite handles heat better but can be difficult to remove. Rockett has been my preference because it’s resistant to heat but can still be easily removed.
From BRD
“5/32” is the standard pin for the Geissele gas block. #31 provides a base hole to ream to fit 1/8" diameter coiled roll pins, 1/8" dowel pins or 2/0 taper pins"
The BCM block comes with a #31 bit and bushing for an 1/8" coil pin
The universal comes with both bits and bushings.
Both will need to be reamed to size, straight and tapered.
BRD has those as well.
BRD Universal demonstration, using a cordless drill.
Looks like the end mill bit he mentions at the start will be needed also.
Some simple math and a steady hand gets it done, looks easy enough.
[video=youtube_share;E2n5wrc73fQ]https://youtu.be/E2n5wrc73fQ[/video]
Primary Arms where I got it says manganese phosphate CHF 1/7. It did not come with a gas block. I still need to purchase one. I really am so happy with the G rail blem. No dings or scratches at all.