98Z5V

Find as many replacement parts as you can - at this time. Stored said replacement parts. Run gun hard.

@AngelDeVille is the man, brother. No other explanation for it.

I like this one - it's perfect.

There are 5 Grendels. Both the Mk12 Mod 0 and Mk12 Mod 1 are 5.56 guns, though. The Mk12 Mod H is a Grendel. There's an M4 Grendel, 18" SPR-barreled SPR-ish Grendel (it's Mk12-ish in it's nature), a light(er) weight 18" Grendel, and the 12.5" Grendel. The Mod H is quite a ways from being finished (need more specific parts), but it fires, and is accurate as all hell. It's gonna be some time before that Mod H is done-done.

Check out the video. He brings up some very, very interesting comments, changes throughout the fielding of the rifle. Very good vid on the Mk12. We have stretched my two 5.56 Mk12s to 850 yards at shoots before, and we'll do it again. For 5.56, I love my Mod 0... it's the best. But I think I love my Mod 1 more... 🤩 EDIT - The Mod H, in 6.5 Grendel, is gonna be a completely different animal, and will overtake the other two, by far... I'm just sayin'...

I LOVE THAT!!!

It's in MIL-C-70559, and you're right - it IS gonna be hard to find a copy of that. You'll have to dig long and deep for it. Inside it, it will state 303 stainless for gas tubes, because 303 will never work-harden with heat. You can't heat-treat it. That's the exact reason it's the specified material. You see lots of manufacturers making 304 gas tubes - it's a hell of alot cheaper than 303. Ask a company "what's mil-spec about your gas tube?" Is it the shape, the bends? The OD or ID? If it's 304, it's not because it's made from the material that was specified in MIL-C-70559.

https://www.hornady.com/assets/site/hornady/files/load-data/6-5-creedmoor-147-153gr.pdf ^^^ There's the load data from Hornady on the newer 147s, and the brand new 153 A-Tip. Recommended COAL is 2.800", so magazine limits aren't going to be the problem.

It'll be accurate - it's just a very well thought-out cartridge, brother. When it comes time to reload them, get ahold of me. I've got a pretty good combination going with them, on Hornady 123 ELD-M projos.

Oh, hell no... That's some SERIOUSLY complicated shiit to use to complicate your shiit!!!...

Dug the targets back out - the little gong at 300 yards is John's so I don't have a pic of that one. At the end of the day, I got out the .300 Win Mag and got rid of my last box of 165gr softpoints for it. Only loading up the 225gr Hornady ELD-Ms for awhile into the future. Here's the 200 yard target. The Win Mag is zero'd for 225 yards, but not for these 165s. It's zero'd for the last load I had, and that was the 195 HPBTs. It did some damage to the steel at 200 yards - kinda surprising how much damage it did, really. Those 165s had to be screamin'! John mostly shot his .308 AR, and I was on the .260. It's easy to tell the difference between the .308 impacts and the .260 impacts. That .300, though... damn... Here's the 500 yard target. It took the most punishment. Lo and behold, I DID hit the 880 yard target! Right in the throat! I couldn't tell you which shot this was, but when we walked it the first time, that target was clean. Sometime between the walk, and pulling targets - I nailed that bastard. I wore up and down that there were several times that I hit it, chasing wind, then not seeing any dust - "Has to be a hit!" Yeah, not so much. One of them got in there though. Here's the 1000 yard target. It was clean when we walked it, and it was clean when we went to pull 'em - so it got hit with the pistol... Great day - BADASS setup for shooting distance! Very tough day with the full-value wind. Overall, still a great day.

Finally did the recon on "the farm" today. It's a dream for distance-only. Two straight, flat miles of nothing. This stretch was specifically designed by the farm owner, to shoot at distance. He disced the area to plant the targets. He build a 4-foot hill to shoot from. He cleared all vegetation. He was there to meet us when we showed up, and gave us a tour guide of the area, and his plan. It's pretty damn cool, what he did. He also zapped a coyote last week at 562 yards, off the top of his truck, with a .300 RUM. I like this guy... We got out there, and he had to leave - taking all his workers to a dinner, for everything that they've done in the past few weeks. It was just me and GP John. I took the .260, and the Win Mag (to get rid of 165gr soft points that I had). John took his .308AR and the 6.5 Creed. The 375 CheyTac was bought out from under us, so we were only there to recon the place, and get some decent distance. Temp was 82 degrees (unheard of in AZ in mid-May), very overcast with heavy cloud cover, but winds were 7~11mph directly from the west. We were set up shooting south, so that was a right-to-left wind, variable, and pretty high up there, for this shiit. We set up ISPC steel plates at 200, 500, 880 (half-mile, and "800 meters" for Mister Eddie), and 1000 yards. We set up a 6" gong at 300 yards. I started with the .260, single hits in the 200, 300 and 500. I couldn't hit that damn 880 for anything. Moved to the 1000, and couldn't hit that thing, either. John went up, and did the same thing, with his .308. He switched to the 6.5 Creed, and did the same thing... That 880 and 1000 weren't gonna be hit today. Not with the stupid wind we had. I'll get target "after" pics up later. It was a great day, and it was a tough wind. Not matter what, you always learn something...

Also, I don't know if this matters yet, but what BCG did you use? KVP has conflicting information on their website about BCG weights, between 9mm and .45ACP - and this is not one of those - it hits harder.

Larry, quite literally, got out of his truck, walked up to the firing line ("What are y'all shooting at?..."), and cleaned the 200-yard target with his first shot from a 1911....

You don't need a 24", no way. I have a 12.5" barreled Grendel that hits 850 yards with 10.6 mils of drop. There's not alot of velocity difference in the Grendel performance, per inch-of-barrel. Go with the 20", brother - it'll be able to handle any distance that you throw at it. No reason at all to go more. I'd even go 18", if it's available to you. Shiit, I have two 16" Grendels, two 18" of these things, and the 12.5. They're a damn sickness...

You have a close-up of that spacer you made? How much length did it add, in total? Got a pic of what it looks like installed on the spring end? I'm trying to figure this out...

Is that one marketed specifically for .40 cal? That's a pretty hard hitting pistol round - let alone in a blowback AR platform. What's that buffer sold as, man?

Ah, you got this. That pistol buffer is 7/8" longer than a 3.250" AR15 carbine buffer. You're on it.

You'll be able to find a copy of the TDP out there somewhere - it's still up in a few places. It's the actual document with all the specs, and it clearly lists 303 stainless for gas tube material.

Too much recoil timing - there's too much time allowed for the BCG to travel rearward, then forward. It's the 7 5/8" extension. These things were designed around the 7.000" extension. That extra 5/8" each way is another 1 1/4" of BCG travel - and time. You might need more than a 10oz buffer in there, too. Which buffer is it, exactly? It's gotta be pistol-specific, and longer than 3.250" carbine buffers are. .40 is a mean caliber, it's "10mm Lite..." I'm running 8oz pistol-specific buffers in the 9mm and .45AR, and the .45 used to double on me once in awhile because the buffer was too light (ran an H3 buffer and $1.75 in stacked quarters before), and the BCG was moving so fast. Blowback pistol caliber ARs are hard on hammer pins - get some KNS Precision anti-rotating pin sets in these things.

Nope, 303 stainless. It's the only thing that's ever been spec'd for the gas tube, once they came up with that.

303 is the mil-spec, because 303 doesn't work harden with heat, ever. That's why it was spec'd for gas tubes in DI ARs. 304 is what alot of guys make headers out of. 304 changes shape once it gets it's initial heat - which is why header-makers can "be off" once in awhile. No worries for them, because the headers will "conform" to where they should have been made in the first place. 303 is hard to get, but it's worth it, in the long run. I've blown out 304-stainless headers a few times, due to heat, right at the collector, both times. It can't handle the concentration of heat, long term. My $0.02.

This is for new member @Betanio - you've been viewing this topic all night, man. Send the question already. It's quite alright to post it right in this thread, zero fear of bringing up old threads. We're here to help, man.

You using 303 stainless or 304 stainless on your gas tubes? Very interested in the shooting results, man.

He's crafty, ain't he. We need to keep an eye on Doc, brother...