Preparing for a first Grendel build

[wvmagnum]

All, interesting development in my build. As it turns out I only live about 45 minutes from the Precision Firearms showroom in Martinsburg. Looks like I will be taking a trip that way. Anyone have any personal dealings with them they would be willing to share?

[jim_bob]

@bob, I've seen great reviews of the MBT triggers.

@wvmagnum, I've dealt with Mark, owner of Precision Firearms, a few times. Everything I've gotten from them has been of the highest quality. Their products are in very high demand, so patience is a virtue when dealing with PF. I feel like every transaction was fair and will definitely do business with them in the future. (Really interested in their side charging uppers.)

[realtreehunter]

..

[bob4432]

Anybody?

[jim_bob]

I've used 243 on a few builds, looks like 246 would be even better.

[jcjarmon]

This is what i would do.
Surplus Arms and Ammo carry black hole 18 inch barrels for Grendel. They also have the 7.62x39 BCG for a good price, with the Grendel extractor. Get you a cheap 3 port 58x24 muzzle brake off eBay that will do the job. A cheap adjustable gas block from Primary Arms will may a big difference in the way it shoots. Grendel barrels have oversize gas ports(.125) that make a non-adjustable gas block a bad idea. but Primary has Seeking's adjustables as cheap as 20 bucks, and they work. A 15 inch free float hand guard of eBay for 50 bucks or less and your in business. I like Black Hole barrels a lot, but look into Spinta Precision as well. They were sold out last time i looked, but they may come back in stock any time. Last one I bought on sale was 170 bucks, and it shoots sub-moa. Make sure whatever you get uses a rifle length gas system. You loose a lot with a mid-length on an 18 inch barrel.

[jcjarmon]

I know this is going to fly in the face of almost everybody in this forum, but leave the loctite alone. If you need loctite, somethings out of spec. An Ar isn't like a bolt gun. You don't have to bed everything. Just make sure you upper is true, and everything else is within the mil-specs. Also, I found CMC 3.5 pound straight triggers today on eBay for 140 dollars.

[LRRPF52]

This is what i would do.
Surplus Arms and Ammo carry black hole 18 inch barrels for Grendel. They also have the 7.62x39 BCG for a good price, with the Grendel extractor. Get you a cheap 3 port 58x24 muzzle brake off eBay that will do the job. A cheap adjustable gas block from Primary Arms will may a big difference in the way it shoots. Grendel barrels have oversize gas ports(.125) that make a non-adjustable gas block a bad idea. but Primary has Seeking's adjustables as cheap as 20 bucks, and they work. A 15 inch free float hand guard of eBay for 50 bucks or less and your in business. I like Black Hole barrels a lot, but look into Spinta Precision as well. They were sold out last time i looked, but they may come back in stock any time. Last one I bought on sale was 170 bucks, and it shoots sub-moa. Make sure whatever you get uses a rifle length gas system. You loose a lot with a mid-length on an 18 inch barrel.

Again, this is incorrect.

A real 6.5 Grendel doesn't use ports anywhere near that large.

Also, I strongly recommend against cheap muzzle devices or gas blocks off Amazon.

The reason is that metallurgy and treatments are often so poor, you will blow them apart, especially muzzle devices.

The tines on cheap flash hiders or brakes will literally separate and peel open. Many of them are cheap Chinese copies made from garbage metal with no heat treating.

[LRRPF52]

I know this is going to fly in the face of almost everybody in this forum, but leave the loctite alone. If you need loctite, somethings out of spec. An Ar isn't like a bolt gun. You don't have to bed everything. Just make sure you upper is true, and everything else is within the mil-specs. Also, I found CMC 3.5 pound straight triggers today on eBay for 140 dollars.

It's also going to fly in the face of most of the precision AR15 shops, the Army Marksmanship Unit, and every reputable AR15 precision smith I know.

Read this if you don't believe me: http://bulletin.accurateshooter.com/...ffers-answers/

I'm not getting sub-MOA rapid-fired groups by accident, or ragged hole 10rd groups at 100yds.

My barrels all get bedded into the uppers, and I bed the gas blocks with Red Loctite. I also bed the tubes into the gas blocks, and I attach the muzzle devices with zero torque and some type of locking compound, whether it be Red LT or Rocksett per manufacturer's recommendations for their devices.

[bob4432]

@LRRPF52
Can you link me to a video of the approximate amount of loctite to use on the various parts, such as a video of a build so I can see how much runs out from various parts? Also, when bedding the gas tube into gas block, where and how is it exactly applied, don't want to have loctite of any sort go down the gas port on the barrel. Assuming the parts are easy to find, I was planning on using Loctite 246 for the Blue (High Temp / Medium Strength) and 272 for the Red (High Temp / High Strength). I would like to do this once and do it right.

@jcjarmon
If you can assemble a upper in a better way, why not? Barrel Making Tech has evolved (coatings, tolerances, materials), Bullets have evolved, Powders have evolved, why can't the assembly method evolve when from the vast majority it looks like bedding does make a difference in the positive?

Bob

[LRRPF52]

@LRRPF52
Can you link me to a video of the approximate amount of loctite to use on the various parts, such as a video of a build so I can see how much runs out from various parts? Also, when bedding the gas tube into gas block, where and how is it exactly applied, don't want to have loctite of any sort go down the gas port on the barrel. Assuming the parts are easy to find, I was planning on using Loctite 246 for the Blue (High Temp / Medium Strength) and 272 for the Red (High Temp / High Strength). I would like to do this once and do it right.

@jcjarmon
If you can assemble a upper in a better way, why not? Barrel Making Tech has evolved (coatings, tolerances, materials), Bullets have evolved, Powders have evolved, why can't the assembly method evolve when from the vast majority it looks like bedding does make a difference in the positive?

Bob

I only put a small amount on because we're talking about very tight-fitting tolerances. Keep in mind that the aviation industry uses a lot of adhesives, many of which are similar to Loctite. Coatings and skins are often held together with adhesives on airplanes, as well as certain fasteners.

On barrel extensions, I get the extension started in a tight upper, place a ring of Blue LT around it, then fully seat the barrel. I never have excess spilling out everywhere.

I do this on receivers after I square the face and Cerakote.

For the gas tube, I insert the tube about halfway, then place a small amount on, and fully seat the tube until alignment, this way no adhesive gets in the port, but Loctite is anaerobic anyway.

[bob4432]

I only put a small amount on because we're talking about very tight-fitting tolerances. Keep in mind that the aviation industry uses a lot of adhesives, many of which are similar to Loctite. Coatings and skins are often held together with adhesives on airplanes, as well as certain fasteners.

On barrel extensions, I get the extension started in a tight upper, place a ring of Blue LT around it, then fully seat the barrel. I never have excess spilling out everywhere.

I do this on receivers after I square the face and Cerakote.

For the gas tube, I insert the tube about halfway, then place a small amount on, and fully seat the tube until alignment, this way no adhesive gets in the port, but Loctite is anaerobic anyway.

Thx, some of the videos I have seen when people put the barrel in, the blue loctite just pours out.

Now with the gas tube, do I place the loctite on the top/sides of the tube and then let it set overnight w/ the upper in a armorers block w/ the 'gas tube alignment' upside down. Also, any issue using the high-temp versions of the loctite?
Thx as always,
Bob

[bob4432]

Also, it seems the consensus is to use Red LT on the gas block to barrel, is there anyway to use High Temp Blue LT as I don't want to marry any gas blocks to barrels since it would usually marry the barrel nut too. Or, is breaking the Red LT "grip" not that hard? Just don't want anything permanent as I would like the option of changing things around in the future. Please advise,
Bob

[A5BLASTER]

Yep there is a very easy way to get it off after useing the red locktite on it, a simple heat gun from a hardware store will work just fine.

Heat it up till it smokes and releases and then take the part off.

[bob4432]

Yep there is a very easy way to get it off after useing the red locktite on it, a simple heat gun from a hardware store will work just fine.

Heat it up till it smokes and releases and then take the part off.

Thanks, didn't realize it was that easy