Well guys this is my first post here, its good to find people that love the big bores like I do. I hope my post will be up to the standards of what you expect.

OK first off lets talk about the round I designed. After much conversation with Ed Huble settled on what I wanted to do. The case starts as a 50BMG that I cut the neck off of then expand or fire forum. The nice thing is that it does not need to be expanded a whole lot so I can use my hand expander I made. I am not using a belt on the case as I wanted to be able to make brass very easily. The case has a capacity of about 263gr/H2O. Right now i'm loading it with paper patched bullets that I cast. The bullets weigh 1132gr and are backed with 185grs of W748. I have not reached top end yet as im still working up loads. but according to QuickLoads I should be pushing that bullet around 2100fps and that's not factoring in that i'm using a 50bmg primer. Its nice having that large primer to get a good burn with the short barrel I have. I have made a reloading die set that can fit in a pack and be taken in the field if needed. Im expecting to stop my load work up when I hit around 2300fps, but we will see.

Now onto the gun that fires this round. the gun was completely built by me. I did not make the barrel I bought a krieger, thy make some very fine barrels. The gun weighs around 15lbs with the brake and It's 16.25" barrel. It is a dream to shoot and the recoil is not bad. In the field the brake could be removed and it would save some weight and reduce the amazing amount of blast and back pressure you feel. I don't mind brakes so I leave it installed. The gun is designed to be able to switch calibers by just removing the barrel assembly and screwing in a 50bmg barrel. I am a machinist and started this project about 1 year ago. Its been a long road but its done and is everything I wanted. I did install a Aimpoint comp M4 red dot as the optic. I had to make my own mounting rail system with recoil lugs. The original mounting system with the aluminum rail failed rather quickly. The gun handles and points very nicely. well, enough talk, time for pictures.

This is a loaded round next to my 45 colt vaquero


Here is a picture i took before it got all painted up


This is the new scope rail I designed to handle the heavy recoil


Here is the view of the optic


Here she is all painted up




I did make/install another brake for it. the same style used on alot of 50BMG rifles. It cuts the recoil by about 50% more then the other brake








After realizing I spaced out painting the scope rail I finely took it apart and painted it the other day. Looks much better now.





You might have noticed that its a shell holder bolt. That actually works to my advantage because I use the bolt to head space the cartage. The shell holder holds the case in tight enough tolerances that it was just the easiest way to head space this round. I am currently working on building a repeating bolt action version and will let you know how that turns out. Thanks for checking out my hair brain idea.

I have one thing to say:



Do you have video of you firing that beast?

George

quote:

Originally posted by GeorgeS:
I have one thing to say:



Do you have video of you firing that beast?

George

What he said!

WTF is right, and I'll throw in a Holy Shit for good measure...

Looks like an interesting design. I like the shell holder bolt face. You have thought it out well. I am like the others. Would you like to share a video with us of it being shot?

As the Mexican said in Blazing Saddles, Santa Maria!!!

Nice job of machining and welcome to the group. Kinda looks like a better designed Maadi-griffin shell-holder with some nice mods.
Why did you design a case that headspaces off of the case Mouth? Be very very carefull with that as if you get a case too long, and you are able to cam that bolt over on it, Your pressures are going to skyrocket. Honestly, thats dangerous if you have a chamber with a tight throat. I have seen guns blow-up for that exact reason. Thats why no commercial rifle cartridges are designed that way. You need to trim each and every case to exact length and watch them like a hawk. Correspondingly too short and you have induced headspace. Maybe you can get away with it on a .50 case due to the wall thickness, but be careful. We are not talking about pistol cartridge pressures here. A 55Kpsi rifle cartridge suddenly going over 100K Psi is bad news. At the very least make sure the neck and throat of the chamber are not tight and very generous.
I have a .700 RLG on the FL .50BMG case, with a shoulder to headspace from that has done over 3200fps with a 1000gr bullet so I see no issues with your 2100fps other than a frankly dangerous case design. I don't mean to Dis your efforts in any way, just be very careful. If you want to borrow a reamer to fix that PM me. There is no reason your action and barrel would not work fine with the bigger cartridge and you would be a lot safer.-Rob

Starting off with a bang.
Thanks for sharing
Be safe!

He made chamber so no danger of crunching the
mouth and \with tight shellholder bolt the
case won't move. Like my 700 Short HE if it was
in a shellholder bolt. JT also clued me in on
the tubing caps for making jacketed bullets.

As far a that action, it is the best looking
shellholder bolt gun ever.It would be great for
bigger like Rob's or my 700s. A little bigger
do hopped up 8ga. Ed

Would be cool to turn that action into CNC code. Sell or share the CNC code for other gun nuts to make their own.

That thing will kill anything in front of it and with that brake, anything alongside it also!

pretty darn cool

JT has some videos on Youtube of this beast.
When you see them I think you will agree, JT is in the running for the smallest, most controllable, monster gun ever built.
I thought his 50 Razorback was great, but this is no contest.

Welcome to the board JT, I'm glad you came over.

Cheers, John

Its a good thing you put that cinder block on the end of the barrel! or you might be in a body cast with a tube for your pecker that got stuck in the dirt...

25 yeas ago a friend of mine designed a somehat similar cartridge. He refused to listen to me about head spacing off the case mouth. everything was fine till one day he chambered a round that required smacking the bolt down. He lost an eye and part of his face to the kaboom. I would not ever shoot such a cartride ever.
To be clear, I am not personally dissing the builder. I'm commenting on the design. Obviously a talented guy. but I don't want anyone to think this is an ok cartridge design. It isn't period.-Rob

Hey Rob,
Since this rifle is of the shell holder type would it be logical to say that it could be headspaced a little long and avoid the problem all together???

Cheers, John

Maybe add a rim like the 12gfh
Could be a small cottage industry selling 12gfh cases.

Add a rim, belt or shoulder doesn't really matter. You need a reliable method of head spacing. a rim isn't even necessary for a .700 just add a small shoulder. .030 works. I go to a rim when there are no other options. The case mouth on a big bore is a no no. Period. I would not ever shoot that gun set up this way! It's a recipe for a disaster or law suite . Period.
Look the guy is really talented and I really dont want to start a pissing contest , but this is a very bad idea! I'm trying to be constructive here, and the issue is readily fixed. again , no disrespect to the person, a critique only of the cartridge. A .700 BMG short with a shoulder is still a new design.Neither I nor anyone else would have any objections to such a design. not sure it's worth the effort but no safety issues.
Headspacing too long is a recipe for a case separation. Don't want to even think about that on a .50 BMG case.Bad Karma.
the only way to do this is with a really sloppy chamber, With nothing other than the shell holder rim to hold the case it will stretch forward untill it hits the chamber edge. You'll see a ring or a complete separation. You need a sloppy neck, throat and perfectly trimmed cases to make this work. This raises the next issue of how to assure adequate neck tension on the bullet? All in all, why? -Rob

JT,
To be clear - Rob loves your firearm design. He's had a bad personal experience with a giant case headspaced off the mouth.

Rob is an experienced designer of big carts, as well.. and he's not saying anything about you as a person. just providing peer review on the round.

Personally, i'd like to see the drawing on the firearm... a friend of my has a bmg of a sim. design.. but i THINK its a griffen maddi ..

i'd love to make one of these, in BMG, with a different arrangement to allow for a 24-26" barrel, bullpup

15 pounds, 16" barrel, single shot:

What is the practical purpose of this thing?

quote:

Originally posted by Indy:
15 pounds, 16" barrel, single shot:

What is the practical purpose of this thing?

hunting ..
mastadons? but hunting..

rob the case does not head space on the mouth. it head spaces on the rear of the case on the rim. the case locks into the shell holder bolt and that's what controls the head spacing. there is also no caming of the bolt on close so you can't force the bolt closed I'm a long case. when I designed the chamber I set the sholder/throat a little bit forward so there is no chance for the case to touch the step at the end of the chamber. I would really like to see your .700 case.

JT,

Do the folks around Provo cringe when you squeeze off a few rounds from that beast?

If you're ever down this way, bring that bad boy with you. Please.

George

Thy shure do when I show up at the local range lol

Can you post a closeup of the bolt face & one with a round held in place?

here are some more pictures. i wil try and get one of the shell in the bolt

here are some loaded rounds on my belt


we will just call this a proofing load lol


here is a picture of the chamber. i did not ream it. i turned it on a CNC lathe.



here are some photos of the shell holder part of the bolt

O i thought i would let you know that the shell holder is nice and tight to the rim of the case. if you put a piece of paper on top of the bolt face you can not even force a case into the shell holder. there is only a few .001 of play to allow the case to easily slip in. I will have to look at my drawing to see what the space is form the end of the case to the throat.

Ok, I see what your doing. Thanks for the pictures. I have to say, I've never seen anyone headspace off of a shellholder alone before. You basically have a case supported only by the rim of your shellholder in your chamber. From your bolt design I believe you have a coned breech. How much unsupported case head is there?Did you just screw the barrel in, then back it out once you had bolt clearance? I'm amazed it works frankly. All my .50 BMG shellholder actions use the case shoulder for headspacing not just the outer rim of the shellholder itself. How much do the cases stretch after each firing? Make sure you have lots of room between the end of the chamber and the throat. I thought you were headspacing off the mouth of the case and the most dangerous situation is when that case mouth and bullet get crimped if a case is just a little too long. Your headspace will also be a function of the case rim thickness and that varies from lot to lot.-Rob

Just like shellholder bolt on my Vulcan, that I have
my long 700HE in. The Rim fits tight and would
work to hold case for proper headspace for firing
even if no belt. The 700HE 3.87" cases in picture.
Now I have it chambered in PH,So soon will have the 4.3"
700HE extra long in Vulcan. Good for 34-3500.Ed

right now I'm making a thread protector for the barrel out of titanium. I am going to try it with out the brake and see how it is. Any tips?

Hold on tight, keep it pulled hard
to the shoulder, and do a dozen real
fast, of the good stiff loads,
then you will go with 28 inch
barrel.HaHah.. As you know I'm no fan of
short barrels and the length and
weight of a brake migh just as well
be all barrel. Adds couple hundred fps...Ed

Hey JT,
I just saw your Big Bore video and the problems you were having with Brake Blast in the face.
Some of the old anti-tank rifles had a blast deflector welded onto the brake. You might want to try this. If it causes excessive muzzle rise then simply drill a hole in the top of the bake to compensate.
I love that gun.

Cheers, John

thats why im going to try it with out the brake. with the brake is a dream to shoot but having that much weigh hanging out there really puts a strain on the arms. I finished the titanium thread protector and it looks bad ass. most likley i will shoot mild loads with the brake removed as im wanting to take an antelope with it next year. i used my 50 RazorBack this year and lets just say thy did not even kick lol. so next year will be the 700. i think if the round was loaded to around 1500fps it would do a great job on an elk lol.

I use a huge Vias style muzzel brake same diameter as the barrel with none of the holes pointing rearward. With 4 axis CNC you can actually create internal baffles during the drilling process. Probably reduces recoil by 40%. The most effective brake I ever tried was a titanium clamshell style on my 700 RLG, although it did increase the rearward blast a bit over the Vias style, nevertheless recoil reduction was about 50%. I'll post the cartridge specs on my .700RLG when I find em. My .700RLG was built on a McMillan repeater action and full power loads. I moved away from
Shell holder actions because of problems extracting cases particularilybwhen loaded hot and too slow to load in
Competition. Never tried your approach of headspacing off the shellholder rim.Frankly not excited about it but better than the case mouth approach I thought you were using.Again, critiquing the idea not the person. -Rob

Is ther any reason why you can not make a brake out of aluminum and have steel inserts in the areas with the most stress?????

Might not even need the steel parts.

Cheers, John

so you like the Vias brake style. do you think it works better then the brake you see on my gun before i installed the clam hell brake? I catch a lot of crap for having brakes on my guns. i say ok i will take it off and shoot it if you shoot it after me. no one has excepted the chalange lol.

The clamshells are more effective breaks but dump a lot of gas back at the shooter. I used 32 inch barrels on my competition .50's and 26 inch barrels on my .600 and .700 RLG.Backblast was a pain. I built my gun on a McMillan action and Tac .50 stock. Thus, I tried the Vias style and it didn't have the backblast problem and was pretty effective at recoil reduction. The Vias style was also a lot easier to make than the clamshell and looked pretty cool too. -Rob

The SWAT rifle for taking circus elephants out in tight corners in downtown is now made

I had thought about showing up at the local zoo with ol Bessie here and asking where thy keep there elephants . utah is an open carry state, meaning i can legally open carry a rifle and not get arrested, that does not mean i will not get stopped and questioned lol. Even though we also have another law that says just having a gun visible is not reason enough to stop some one for questioning. but you know cops. I think i will make one of those brakes and try it out.

the shell holder providing the headspace.. that's just clever as all get out.. make the chamber a bit long, and never worry about trimming more than usual...

pretty neat!