The Last (?) Grail Gun - 12G FRT

[strobro32]

Y'all are not going to believe this. I was going to test the 10 rd mags with 5 rds to see if the spring force was making them not run. I thought I would clean the mags so I took the 3- 10 rd box mags apart and all 3 mag springs were in backwards. I switched the plate retainers and follower around so the high point of the spring was pointing to the front of the mags and they all work flawlessly during 50 rds today. Flawlessly with #8 fed wally shot. They were 2x as easy to load after the fix. 615 RPM.

https://flic.kr/p/2suSqH4

 

[Alaska_Shooter]

That’s a beautiful thing to see 😀

 

[strobro32]

It feels good as my head thrashes under recoil. I'm a head banger again.

 

[arch stanton]

It does work as advertised. It took around 60 rounds for the break in. It does fire trap loads they have to be over 1200 fps. The gun is junk and rough but what do you want for dirt cheap. I would for sure use some lapping compound and work the gun in and also deburr the gas holes

 

[strobro32]

I experimented this morning.

JRC = Just Right Carbine buffer tube- about an inch shorter than OEM. Used to put some preload on the bolt and carrier.
2 quarters are used to keep the cam pin from hitting the lower.

JRC + OEM buffer and spring, #8-2 3/4 = 615 RPM
JRC + 2 quarters + OEM spring + Kynshot 308 RB5030 hydraulic buffer + #8-2 3/4 = 527 RPM
JRC + 2 quarters + Tubb 556 flat wire spring + Kynshot 308 RB5030 hydraulic buffer + #8-2 3/4 = 461 RPM

461 RPM is close to AA12 speed but with more bounce.

 

[ericthered]

I experimented this morning.

JRC = Just Right Carbine buffer tube- about an inch shorter than OEM. Used to put some preload on the bolt and carrier.
2 quarters are used to keep the cam pin from hitting the lower.

JRC + OEM buffer and spring, #8-2 3/4 = 615 RPM
JRC + 2 quarters + OEM spring + Kynshot 308 RB5030 hydraulic buffer + #8-2 3/4 = 527 RPM
JRC + 2 quarters + Tubb 556 flat wire spring + Kynshot 308 RB5030 hydraulic buffer + #8-2 3/4 = 461 RPM

461 RPM is close to AA12 speed but with more bounce.

 

[strobro32]

After today, I'm ready to say 460 RPM is too dang bouncy. I much prefer the ROF to be 550-600 RP.

 

[Alaska_Shooter]

Does anyone know what size replacement buffer tubes will work? Can I swap out to a carbine buffer tube?

I haven’t taken the time to look at how far the carrier has to move into the buffer tube but maybe someone already has checked it out

 

[Alaska_Shooter]

Bummer



I emailed them to ask if they’ve seen this before

 

[strobro32]

Dang. My rear take down pin is crazy loose. Seems like the detent spring is dead.

 

[strobro32]

Does anyone know what size replacement buffer tubes will work?

I was using an A5 to keep preload on the carrier.

 

[arch stanton]

Bummer

View attachment 43999

I emailed them to ask if they’ve seen this before

I figured this would happen it needs to be made of steel for sure

 

[strobro32]

How many rounds through it before it broke?

I've shot about 500 rounds and my aluminum lever extender is beat up. I'm going to contact Tharpe and ask it he plans on making a steel one. It will probably need a steel carrier extension too.

I also had to replace the rear take down detent spring. It was about 2/3 the size than when I put it in.

 

[arch stanton]

How many rounds through it before it broke?

I've shot about 500 rounds and my aluminum lever extender is beat up. I'm going to contact Tharpe and ask it he plans on making a steel one. It will probably need a steel carrier extension too.

I also had to replace the rear take down detent spring. It was about 2/3 the size than when I put it in.

I have 200 through mine and had to reshape the large gouges out of the lever already. I dont see this lasting. The carrier piece still looks like new in mine and he also now includes the yellow rubber piece for the lower trigger pocket to eliminate over travel.

 

[Alaska_Shooter]

As a guess, 400 or so rounds. The aluminum face on mine was also beat up. The washer on the carrier part also takes a real beating. Did you reconfigure yours for the roll pin retainer using a drill press or hand drill? I need to do that

He responded almost immediately and will have the warranty part in the mail tmw. Great guy! I also just asked him if he’d make them out of steel. Maybe if a few people ask? 😀

What a really fun time to be into fast guns. We’re living in another golden age

 

[Alaska_Shooter]

He said that he profiles the thinner part of the extension by hand and that mine was the first failure. He said he’ll make sure to leave that area thicker in the future

 

[strobro32]

I used a drill press to cut the 1/8 hole. Sorry. I took a quick pic for another person and forgot to post it here.

 

[Alaska_Shooter]

Thanks for the pic!