The Last (?) Grail Gun - 12G FRT

[strobro32]

I took it apart to clean it last night and that regulator did not want to come out. This thing is a beast. I'm not a piston or AK guy but the sound and smell of it's operation is not smooth like an AR. It feels like a steam pole driver. Not slick like my Beretta 1301.

 

[ericthered]

Have you lubed the ever loving snot out of every single moving part? I use gun grease. Before breakin mine had a slightly "crunchy" feel. While not very refined feeling, mine is the lowest recoiling12ga I have shot.
You running all factory with the weird spring buffer and weird spec spring? Mine worked with those fine.
Gas system was a little rough to take apart the first time. It gets kinda gummy. The short stroke piston should slide pretty smoothly without the bolt installed. Maybe check it for straightness, it is high grade chinesium.
Is your ftf in regular semi, or ss? Is the hammer dropped when it malfunctions? If the hammer is dropped/primer dent could be bolt bounce. I havent ever had it with mine. You can throw a h2 buffer in to fix that. I think that was the weight I was messing with. May have been h3. I would throw in a decent spring then as well. Recoil will be slightly more then what it should have been. But it sounds like your recoil is way to much right now.
I had talked to the original designer of the conversion. I wonder if he is associated with this product. I had wondered if manufacturing out of metal would add to much awkward weight to the operating system. Seems weird that your were sold a shoe for the lever instead of a modified lever as both files were released in his file drop. His channel is minishcap on odysee.
Have you established an operational baseline without the SS installed?

 

[Alaska_Shooter]

I learned on my first outing that the gas plug (?) can be assembled backwards 😀

My gun has smoothed out over a couple hundred shells. It’s still not liking the light loads but runs on heavy upland loads and up.

 

[mak91]

Got the 2 halves and tower printed. Rotor is next, got 3 different designs for it. Depending upon which one works out it should hold between 25 and 40 rounds.

 

[strobro32]

Have you lubed the ever loving snot out of every single moving part?

Yes Sir!

You running all factory with the weird spring buffer and weird spec spring?

Yes

Is your ftf in regular semi, or ss?

Have not tried to install the SS yet. I wanted to break it in first. Many people recommended that.

Is the hammer dropped when it malfunctions?

No. Most of the problem is failure to completely feed so far. I will try different ammo next.

I had talked to the original designer of the conversion. I wonder if he is associated with this product. I had wondered if manufacturing out of metal would add to much awkward weight to the operating system. Seems weird that your were sold a shoe for the lever instead of a modified lever as both files were released in his file drop. His channel is minishcap on odysee.

I got both M12 FRT versions from Tharpe Gunworks. I have the SS and Arc fire conversions. Just trying to get the OEM working before I try them.

 

[strobro32]

I'm reading a lot about canted gas tubes on the M12. I think mine may be. The regulator or spring loaded piston does not like going in or coming out. I have to knock out the piston with a brass cleaning rod from inside the upper. I'm not sure what to do about it.

I checked but I cant be sure. I cleaned the snot out of it again, slathered it on Mobil 1.

 

[ericthered]

Sorry, I read FTF as failure to fire. Feeding makes more sense to try to turn the gas up to fix.
Wont be near that gun until this weekend to mess with it, but if I remember, the gas block was a little annoying to get off. The piston should slide easily however. If your piston tube is canted, there should be a wear mark on your piston where it is binding. If not, I would paint the piston with a paint marker or whatever, and see if you can get a wear mark.

 

[strobro32]

The piston does not slide down under it's own weight, maybe it's just the oil. I removed the forearm and tried to see if the piston tube was bent, dinged or ovaled but I just can't be sure. A straight edge says that the gas tube is not straight from front to back and the regulator tube is smaller than the gas block but the gap is even on both sides from side to side.

I bought some different 00 buck to see if that is better.

 

[Alaska_Shooter]

Buckshot has been hit or miss with mine. It depends on how hot it’s loaded.

Slugs have all worked

 

[strobro32]

I will try them. Setting 1 or 2?

 

[ericthered]

I will try them. Setting 1 or 2?

Slugs setting one. Buckshot should be one as well, but some may need to be two.

 

[Alaska_Shooter]

My slugs work on setting 2. I’m able to dial gas down now that the gun has smoothed out. It’s much less crunchy to work the action on

If you don’t have anti-walk pins for the hammer and trigger, this gun needs them. The gun ships with weird clips on those pins that are impossible to reinstall once removed to install the FRT

 

[strobro32]

Thanks for the pins tip.

Today's progress:

I shot 115 rds of 00, 000 buck and slugs for a total of 211 rounds shot of buck and slugs . Started on #1 but switched to #2 because the rounds ejected quite close and I had a few failures to return to battery. The forward assist does work.

4 rds failed to feed as the front of the hull got crushed into the chamber. All with 10 rd mags. 10 rd box mags seem to have more slop than the 5 rd but if they were held forward in the magwell they worked better so I guess we will try to shim them for future testing.

The action seemed to smooth out as well, metallic crunch.

I turned the gas to 3# and tried Wally Federal 8 from the 5 rd box mag. 20 rds worked flawlessly. I tried 5 from the 10 rd but they had feeding problems as well so I shot them from the 5 rd box mag. They were much easier on the shoulder.

This SG will not be my first choice for personal defense so I'd like it to function with Wally ammo for fun. I look forward to installing the SS and bringing it to skeet to hear the serious shooters grumble.

 

[strobro32]

If you don’t have anti-walk pins for the hammer and trigger, this gun needs them. The gun ships with weird clips on those pins that are impossible to reinstall once removed to install the FRT

I took apart the FCG but did not see any "clips". The parts look identical to an AR except weird hammer.

 

[Alaska_Shooter]

I almost didn’t notice mine. The clips looked like one coil off a spring.

“The JTS M12AR uses small, single-coil spring clips/keepers inside the receiver to retain the hammer and trigger pins instead of standard mil-spec hammer pin notches. These factory wire clips are notoriously difficult to reinstall, prompting many users to replace them entirely with standard aftermarket anti-walk/anti-rotation pins.”

I needed to loctite the anti walk pins and also the super safety trip that goes in the bolt carrier

The recoil really likes loosening things up

 

[strobro32]

Found them! Left side of the trigger and left side of the hammer,

 

[strobro32]

The recoil really likes loosening things up

Yes. The upper and lower rattle now.

 

[strobro32]

The bolt at the end of the carrier won't let the upper close. What was your solution?

I just talked with Tharpe. He said to get constant pressure on the buffer, assemble the upper using both pins.

 

[Alaska_Shooter]

I (slightly) slide the upper on from the front to get the bolt into the buffer tube. Then I push both pins in.

 

[strobro32]

I ran a 25 rd box of Wally Fed 8 today with the SS. ROF was 597 RPM. Flawless with 5 rd mags. I must have a drum and a SBS stamp.

I did have an issue with the super safety, the M12AR selector detent pin hole is drilled about 1/32" too far to the left in the lower. It just means I can quickly slide the cam to the right or it may not engage in the semi. I opened up the slot in the SS cam so now we can reliably be super safe.

https://flic.kr/p/2styrnT