Need some creative thinking outside the box

[Ernie]

Typically, I would have posted this in the Specialty Handgun Section, but I would like to tap into as many people as possible.
I need your help in coming up with a wildcat cartridge in 6.5 that will give me performance (stay supersonic and hopefully above transonic) out to and just beyond 2K. I seriously want to nail a PD @ this distance.

The challenge is to do this in an 18" barrel
This will be in a specialty handgun.
XP or Striker.
There is a possibility of a custom non-designated action or one sold as a handgun action.
For perspective I have 2 SP's, both are 17" barrels (1-8 Twist). One runs an 140 A-Max @ 2775 and the other a 142 SMK @ 2700 from the muzzle.
the A-Max load is in a XP and is warm even when using Lapua brass (slight ejection marks on the head).

Okay guys, let the creative juices flow

 

[Buffalobob]

Well, here is what you have to have.

A bullet with a BC of 0.700 and A muzzle velocity of 3000 fps
or
A bullet with a BC of 0.725 and A muzzle velocity of 2900 fps
or
A bullet with a BC of 0.75 and A muzzle velocity of 2800 fps



The BC of 0.7-0.75 is possible from Richard Graves, I expect, and the bullet would weigh about 155 grains I would guess.

In a 26 inch barrel this would be achievable with a case capacity somewhere around a 264 Win Mag to a 6.5-300 Wby. I do not know the dynamics of short barrels and fast powders so I have no opinion of case capacity for an XP.


My opinion is rather than going with the conventional approach of designing a cartridge to do the job, design a bullet to do the job.

 

[Len Backus]

Ernie

I assume those examples above are 6.5 somethings? What load and speed are you getting with your 7Dakota? Do I remember 176 at 2,800? How close to your goal would you get if you necked it down to 6.5 and used BB's bullet weight?

 

[Ernie]

My 7mm Dakota (18" barrel) has a MV of 2706 with the 200 grain Wildcat. I would like to do it with an 8T barrel, but that may not be a reality.

I have for sure considered Richard's bullets. That is the only bullet that has gone down the 7mm Dakota's bore.


Len,
Those are both 6.5-284's (MOA Maximum & XP)
What is the Cateruchio's BC?


Elevation will be between 4500 & 5000 feet.

Typically I will lose about 300 fps in a SP compared to the same cartridge chambered in a rifle

 

[Len Backus]

I am using .630 for his 141 grain VLD bullet.

 

[Fiftydriver]

I can not say for sure but you may be able to get a 200 gr ULD RBBT to stabilize in a 1-8 barrel. Best bet would be with something like a Rock thin land 5R(Good luck getting one in a timely manner) or possibly a Krieger 1-8 4 groove.

The reason I do not list Lilja, there is no 1-8 twist 7mm barrel option. The cut rifles barrels are best for odd ball twist rates.

The reason I feel that the 1-8 may stabilize the 200 gr ULD RBBT is because I am shooting them in 1-9 twist rifle barrels and for the most part have performed extremely well. All that said, I have not done it to prove it.

TO get to 2K, well, from my numbers, you already have the right idea, a 200 gr ULD RBBT at +2700 fps is about the only way I see it happening in a specialty handgun, at least with a level of recoil energy that the firearm design(stock) will handle longterm and in a relatively portable barrel length for a handgun(18").

Only way to improve this I see, getting an aluminum tipped 7mm bullet that is roughly the same length as the 200 gr ULD RBBT but with a bullet weight in the 175 gr range. This would offer at least as high of a BC but with another 100 fps velocity boost.

Now as you know, I do not believe velocity is the only way to get to extreme range, in this case however, your already using the ultimate bullet out there in the 200 gr ULD RBBT as far as accuracy and ballistic performance. Some of the solid VLD designs may run with this bullet but none will be as consistantly accurate over a variaty of barrel designs and bore diameters.

Unfotunately, this is a waiting game for Richard to get the jackets and tips imported and then finalize the design, will the new bullets offer anything over what we already have, from what I have seen with the 338 versions, DRAMATICALLY!!!!

Kirby Allen(50)

 

[Ernie]

Kirby,
I plan to get you some cash for a Rock for the Dakota after the first of the year given the known wait time.
totally agree with your conclusions in 7mm. I am waiting patitently/inpatiently for the alum-tipped WC's in 7mm.

What I am wanting to see what can be done in the 6.5 cal. I don't think it can excell the 7mm Dakota in a SP, but I do want to hear what you guys think as the most useable case in the 6.5.

Keep it coming guys!!!

 

[davewilson]

let me guess. you want 3000 rounds out of the barrel?

i'm guessing we'll be a tad in the overbore category!

 

[Steve Shelp]

All,
I've got some info from the 6.5 world that I think will help you figure out what can and can't be done. When Sierra came out with the 6.5 155 SMK bullet, I tried them in my 6.5-300 WWH with a 30" Hart barrel. The throat in this rifle was setup for the 139gr Norma bullets but it had burnt out enough that seating the 155s wasn't too bad. The body/boatail junction was seated approx .075" below the neck/shoulder junction of the case. It would have been nice to have a longer throat, but I was giving the 155s a quick evaluation to see how they shot and go from there. If they worked pretty good I would've throated it properly and let'um fly. But the accuracy of them never really worked for me so I stayed with the 140gr class bullets. Also the small BC change wasn't worth the effort/expense.

Anyway....through all of my testing with the 155s (a couple hundred rounds across the chrono and on paper) I never got them much over 3175fps at 10ft from the muzzle. Again that is with a full load of H870 and a 30" (8" and 9" twist) barrel in a 6.5-300 WWH. The 9" twist barrel was a shotgun with the long 155 grainers at 100yds.

So based on that and using the velocities pointed out by BuffaloBob to stay supersonic..... this is going to be cutting it rather thin and a lot of pressure for a 6.5 in a short barrel.

Good luck and hope these reference numbers help.

Steve

 

[davewilson]

some on here have posted getting over 3250 with a 140 gr with a 270wsm. the 6.5 is a bit smaller to push on(or maybe it's less bearing surface) don't want to start that debate again. but 3000 would be in reach, especially if you improved it a bit.

 

[Fiftydriver]

The Berger 140 gr VLD is one of the better BC 6.5 bullets out there. I know I can hit around 2700 fps in my 6.5mm WSM with the 15" Lilja barrel. I would thing with an 18" barrel you may be able to sneak out another 100 fps possibly. I have heard the new Norma 270 WSM cases are hell for stout and will take alot of pressure. I have not tested this personally and to be honest, most Norma brass is very soft but there have been enough reports that there must be something to it.

Basically, take a 270 WSM case, neck it down to 6.5mm and improve the crap out of it to get as much capacity as you can in that short case and see what you can get out it. You may be close but I do not know if you will get there or not.

Richard has a 168 gr bullet in 6.5mm but the nose forming die was sent wrong, something like a 10 ogive instead of the ULD. As such, BC is much lower then it could be.

Anyway, it will be a challange in the 6.5mm bore.

You could always take the 7mm Dakota and neck it down to 6.5mm. Overbore, yes, but usible, certainly. Heck, my small 6.5mm magnum, my 6.5mm Allen Xpress is based on the slightly longer 300 Dakota case and it works just fine, the full match of the 6.5mm STW.

Will the barrel life be limited, to some degree but it is certainly practical with todays ultra slow burning ball powders. Would you see much advantage over say a WSM in the short barrel, some but not much.

Kirby Allen(50)

 

[NDNorm]

been thinking about this

the top is a .243 and the bottom is a 7MM WSM. making a form cutter and rebating them to the small bolt face, then a barrel chambered to fit 180 Bergers set out long along the line presented here. don't know what that would do out of a 18 inch tube. only thinking.
Norm

 

[Wild_Bill]

6.5 Ultramag

Hi if you have a large muzzlebreak and muzzle blast isn't an issue try a 6.5 ultramag.

I know that it is a big case but it should get you there or the 338 ultramag necked to 6.5 would also get you there. I would also be looking to get Richard to make you a heavy alloy tipped 6.5 projectile it should be awsome.

Cheers Bill
Australia

 

[blygy]

I'm just getting the final pieces together for my 6.5X300 Win Mag (Not WSM) project.. I was talking to Richard and he mentioned the possibility of a 180gr 6.5mm Bullet... It would need a 1-7 twist he said..

This might what you need...