Pronghorn cartridge in 6mm

[FLS]

What is the difference between the 6mm Creedmoor and the 243? I assume the 6mm Creedmoor is on the 6.5 Creedmoor case?

Correct. It’s on the 6.5 Creedmoor case, but it will come from factory with correct twist for high BC bullets.
It’s the only factory 6mm option if you want to use high BC bullets.
A fast twist 243 or 6mm Rem can surpass its performance on an action long enough to take advantage of case capacity, but it’s a custom build. $$$

 

[antelopedundee]

Don't need it. Just get some 30-06 brass and run it through the die. Take your pick on brand.

Except he wants the correct headstamp.

https://www.grafs.com/retail/catalog/category/categoryId/695?

I have several 6.5-06s and IMO it's preferable to neck up a .25-06 than to neck down a .30-06. I have also made cases from .270 Win brass.

I don't know about liability issues, but there's no good reason why any company making .25-06 cases can't make a 6.5-06 case. Just sayin.

 

[FLS]

6BR



Light
Handy
efficient

Holds all the long range bench rest records.

Just all around awesome.

Yes it is. When it’s time to rebarrel my match rifle, that’s the route I’m going.

 

[FLS]

Except he wants the correct headstamp.

https://www.grafs.com/retail/catalog/category/categoryId/695?

I have several 6.5-06s and IMO it's preferable to neck up a .25-06 than to neck down a .30-06. I have also made cases from .270 Win brass.

I don't know about liability issues, but there's no good reason why any company making .25-06 cases can't make a 6.5-06 case. Just sayin.

It seems a shame to have to run that crappy brass in a custom build.

 

[cahunter805]

I’m pretty well versed in reloading techniques. I have a 25-06, 270, 30-06. Just don’t want a similar sized case without the correct headstamp.

Could always go 6.5-280AI and size Nosler brass!! Would be a very fun setup!

 

[ImBillT]

What is the difference between the 6mm Creedmoor and the 243? I assume the 6mm Creedmoor is on the 6.5 Creedmoor case?

You can load long bullets to magazine length without giving up case capacity because it’s shorter than the .243Win, and factory rifles will come with a tighter twist than 1-10. Those are the primary reasons that the 6.5CM beats the .260Rem.

 

[ImBillT]

Could always go 6.5-280AI and size Nosler brass!! Would be a very fun setup!

Except 6.5-06AI dies are everywhere and 6.5-280AI does would have to be full custom, and the cartridges would be ALMOST identical.

 

[cahunter805]

Except 6.5-06AI dies are everywhere and 6.5-280AI does would have to be full custom, and the cartridges would be ALMOST identical.

You just use a 280AI bushing die and swap the expander to 6.5 and use the appropriate bushing size.
Also no fire forming needed.

 

[antelopedundee]

It seems a shame to have to run that crappy brass in a custom build.

In spite of those reviews I don't think it's crappy.

 

[ImBillT]

You just use a 280AI bushing die and swap the expander to 6.5 and use the appropriate bushing size.
Also no fire forming needed.

A) you’re gonna seat with what? Why not just go 6.5-06AI and use a real seater and die set?
B) you’re locked into .280AI brass, or having to build a special gauge to help you place the neck/shoulder junction at the correct location because necking an AI up or down places the neck shoulder junction in a different location than necking a standard cartridge up or down and then making it an AI. If you try to neck it with a bushing die other than a Forster, you won’t be able to get all the to the shoulder. You could probably use 30-06 brass if you sized it in a Forster bushing die. I haven’t used a Forster bushing die.
C) although the difference is minute, the 6.5-06AI is larger than a 6.5-280AI.
D) you’d have to pay for a custom reamer print.

^^^ Seems like a lot of hassle to avoid fire forming. If you don’t want to fireform, there are options that will yield practically identical performance and don’t require fireforming.

There’s not really any velocity to be gained by going from 6.5-06 to 6.5-06AI. You mostly just get better brass life and POSSIBLY a LITTLE less throat erosion. I have a 6.5-257Rob AI, with 130’s and 140’s I’ve chrono’d it running faster than most people ever get out of their 6.5-284’s, and that at 10% less powder capacity. Velocity from the 156gr EOL was unimpressive, but a powder change will likely fix that. I probably just got lucky with a fast barrel, but any 6.5-257Rob AI should match a 6.5-284, 6.5-06, 6.5-06AI of equal barrel length. You pretty much reach the maximum performance of a 6.5mm bore, with a case capacity of 60-65gr H2O. You can usually wring a little more pressure out of magnum cases, and of course, although there isn’t MUCH to be gained, doubling case capacity(think 26Nosler) does yield a LITTLE.

From my gun
130’s 3400fps
140’s 3300fps
156’s 2975fps

If I did it again, I’d lean heavily toward 6.5x55AI, 6.5x57(different from a 6.5x257Rob), 6.5-284, 6.5-06 or 6.5-06AI. All would be easier, yield almost the same velocity, and have minimal disadvantage.

 

[shb]

The Accurate, Long Range 6mm BR

The Accurate, Long Range 6mm BR © Glenn Burroughs Some years ago there was a company that developed a nearly perfect cartridge. And although it was intended for distances of less than five hundred yards, with the proper barrel twist and a...

www.longrangehunting.com

 

[Don Fischer]

You can load long bullets to magazine length without giving up case capacity because it’s shorter than the .243Win, and factory rifles will come with a tighter twist than 1-10. Those are the primary reasons that the 6.5CM beats the .260Rem.

So how long a bullet can you get in 6mm? All I'm aware of is 105gr and they are not very common around here. If I though I really needed more than a 87 to 100gr bullet in 6mm, I'd simply step up to 25 cal! BTW, about my 6.5x06. I to have used 270 Win and 280 Rem brass to reload. have never necked up a case for anything and in 6.5x06 using a 25-06 case, I also shoot a 25-06. Be somethig to use those case's to make 6.5x06's then have to neck something else down for 25-06!

 

[BuzzH]

Ain't no dust on the plain jane .243 either...brass is easy to come by, good velocity, available in all kinds of rifles and if semi-custom you can twist/throat to your liking.

If not for sentimental reasons, I would have re-barreled my ruger 6mm to .243 Winchester.

There reaches a point where messing with brass, AI this and that, wildcats, etc. that it just isn't worth it.

 

[cahunter805]

A) you’re gonna seat with what? Why not just go 6.5-06AI and use a real seater and die set?
B) you’re locked into .280AI brass, or having to build a special gauge to help you place the neck/shoulder junction at the correct location because necking an AI up or down places the neck shoulder junction in a different location than necking a standard cartridge up or down and then making it an AI. If you try to neck it with a bushing die other than a Forster, you won’t be able to get all the to the shoulder. You could probably use 30-06 brass if you sized it in a Forster bushing die. I haven’t used a Forster bushing die.
C) although the difference is minute, the 6.5-06AI is larger than a 6.5-280AI.
D) you’d have to pay for a custom reamer print.

^^^ Seems like a lot of hassle to avoid fire forming. If you don’t want to fireform, there are options that will yield practically identical performance and don’t require fireforming.

There’s not really any velocity to be gained by going from 6.5-06 to 6.5-06AI. You mostly just get better brass life and POSSIBLY a LITTLE less throat erosion. I have a 6.5-257Rob AI, with 130’s and 140’s I’ve chrono’d it running faster than most people ever get out of their 6.5-284’s, and that at 10% less powder capacity. Velocity from the 156gr EOL was unimpressive, but a powder change will likely fix that. I probably just got lucky with a fast barrel, but any 6.5-257Rob AI should match a 6.5-284, 6.5-06, 6.5-06AI of equal barrel length. You pretty much reach the maximum performance of a 6.5mm bore, with a case capacity of 60-65gr H2O. You can usually wring a little more pressure out of magnum cases, and of course, although there isn’t MUCH to be gained, doubling case capacity(think 26Nosler) does yield a LITTLE.

From my gun
130’s 3400fps
140’s 3300fps
156’s 2975fps

If I did it again, I’d lean heavily toward 6.5x55AI, 6.5x57(different from a 6.5x257Rob), 6.5-284, 6.5-06 or 6.5-06AI. All would be easier, yield almost the same velocity, and have minimal disadvantage.

A- Seat it with the 280AI seater with a 6.5mm stem.
B- You can still load 6.5-06 brass especially if you size it with a false shoulder and fire form if you want to.
C-The 6.5-280AI has the shoulder forward more and thus slight more capacity.
D-If you were gonna build a 6.5-280AI a custom reamer would be best anyway. I always like to spec my own reamer if buying new also. Usually longer freebore also.

As with any custom or wildcat there is a lot of prep/work sometimes for not much gain but that’s what rifle looneys live for!

 

[sbhooper]

You can load long bullets to magazine length without giving up case capacity because it’s shorter than the .243Win, and factory rifles will come with a tighter twist than 1-10. Those are the primary reasons that the 6.5CM beats the .260Rem.

I have not bought a factory 260, but I wonder if whoever still chambers it, does a 1/8? My barrels are Criterions that I put on Remington and Savage actions and they are 1/8.

 

[antelopedundee]

I’m pretty well versed in reloading techniques. I have a 25-06, 270, 30-06. Just don’t want a similar sized case without the correct headstamp.

Many years ago I had a .25-06 and wanted a 6.5-06 so I had a 6.5-06AI made so there would be NO CONFUSION as to what ammo went to which rifle. Right now I have Norma, Nosler, Prvi Partisan aka PPU and R - P nickel plated .25-06 cases and the the Qual Cart are as good as any of them.
Once I got them the first thing I did was to make sure they would chamber in the gun I have in my possession. I ended up running them thru a FL sizer [sans expander] and about .010 from the shellholder. Next item was to deburr the flash holes. The necks cleaned up easy enough.

 

[mtmuley]

Ain't no dust on the plain jane .243 either...brass is easy to come by, good velocity, available in all kinds of rifles and if semi-custom you can twist/throat to your liking.

If not for sentimental reasons, I would have re-barreled my ruger 6mm to .243 Winchester.

There reaches a point where messing with brass, AI this and that, wildcats, etc. that it just isn't worth it.

Truth this. Ain't hard to kill antelope. mtmuley

 

[noharleyyet]

Ain't no dust on the plain jane .243 either...brass is easy to come by, good velocity, available in all kinds of rifles and if semi-custom you can twist/throat to your liking.

If not for sentimental reasons, I would have re-barreled my ruger 6mm to .243 Winchester.

There reaches a point where messing with brass, AI this and that, wildcats, etc. that it just isn't worth it.

6mm's fun to shoot and performance's intersecting sweet spot.

 

[antelopedundee]

Ain't no dust on the plain jane .243 either...brass is easy to come by, good velocity, available in all kinds of rifles and if semi-custom you can twist/throat to your liking.

If not for sentimental reasons, I would have re-barreled my ruger 6mm to .243 Winchester.

There reaches a point where messing with brass, AI this and that, wildcats, etc. that it just isn't worth it.

If pragmatism ruled the day, the custom gun business would still be a gleam in someone's eye.

 

[ImBillT]

A- Seat it with the 280AI seater with a 6.5mm stem.
B- You can still load 6.5-06 brass especially if you size it with a false shoulder and fire form if you want to.
C-The 6.5-280AI has the shoulder forward more and thus slight more capacity.
D-If you were gonna build a 6.5-280AI a custom reamer would be best anyway. I always like to spec my own reamer if buying new also. Usually longer freebore also.

As with any custom or wildcat there is a lot of prep/work sometimes for not much gain but that’s what rifle looneys live for!

A) If you want a .020” oversized bullet channel in your seater, and a loose stem to boot, be my guest. Forster uses a .0005” oversized bullet channel. Wilson uses a thousandth or two, I don’t remember, but the seater stem itself has less than .0005” between itself and the bore and centers the bullet on its interface with a perfectly aligned stem. By screwing a 6.5mm seater stem into a die meant for a 7mm stem, the only thing aligning the stem is the is the threads, all you have to do to see the problem with that is wiggle your seater stem.

B) yes you can use a false shoulder, but doing so with proper headspace requires a lot more care and measurement than the average reloader wants to go through. I had to do it with my wildcat initially as I was originally using a die situation similar to what you’re describing, and I can tell you that it is an unnecessary pain in this situation.

C) you’re right. The 17.5 degree shoulder of the 6.5-06 means the neck shoulder junction moves about .044” forward of a 30-06, compared to moving forward about .015” necking a .280AI down, however, I hadn’t realized off the top of my head just how far forward of a 30-06 a 280Rem shoulder is. Still minimal.

D) I haven’t checked PTG, but they usually have quite a few variations of anything remotely standard. They almost certainly have a 6.5-06 reamer print that is a perfect fit for a no-turn neck after sizing down Lapua 30-06 brass with a couple different throat lengths, guaranteed to include a throat designed for the 140VLD. Talk to Dave Kiff and he’d set you up with which print they already have that works best depending on which brass and bullet you want to use. While you’d pay special order price, you wouldn’t have to pay custom price. It’s possible that you’d want something slightly different than what they had, and then you could go full custom. On the other hand, it’s unlikely that too many folks have done much necking down a .280AI, you’d almost certainly have to pay for a custom print.