6mm-06, 6mm-06AI, 240 Gibbs, 243 Super Rockchucker...?

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double gun

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I got a bug to build a super 6, but cant decide which version. Any suggestions from first hand experience would be great. I would like to avoid any of the lesser known versions if possible.
 
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First fact: 243 Winchester has ample case capacity to launch a 105gr VLD at 3000 fps from a 24" barrel.
Second fact: With a 27" barrel and using faster burning powder, a smaller capacity case (6XC) can achieve 3000fps with a 115gr VLD and 3100+ fps with a 105gr VLD.
http://www.6mmbr.com/6XC.html

I want accuracy ,a case that feeds well in a repeater and long barrel life.
My custom 6mm SuperRifle will be built with:
NOTE: I'm using a Remington action to save money, a better choice would be a Stiller or Surgeon repeater action.
  • action taken from my very accurate Remington 700 243 Win SA
  • barrel 27" Krieger 1-7.5" twist which can stabilise 6mm 115gr VLD
  • cartridge 6XC which can feed using normal Accuracy International 10rounds magazines
  • Accuracy Internationol AICS stage 2.0 stock green
  • Jewell HVR trigger

This rifle will launch 6mm 115gr VLD at 3000 fps with an accurate barrel life of 2600-3000 rounds (20% better than 243 Win).
The ballistics will be almost as good as a 6.5-284 launching a 142gr SMK at 2900fps with half the the recoil of a 308 Win 168 SMK load.

Alex
 
No interested in the 243, or the 6mm. I have had both and still have a 6mm. The 6-284 gets denied aswell, my donor action is a long action I want to build off the '06 case. (And it gets nowhere near 4000 with 100grs.)

Thanks for the reply Dan, this rifle will be only used for hunting, wolf/coyote primarily - perhaps the odd antelope or deer. What kind of velocity are you getting from 100gr pills? how long is the barrel?
 
I just received a build last week that is a .257AI which should keep up with the 25-06. It's going to be my coyote gun. Maybe some 80 or 100gr TTSX for deer too.
 
double gun, IMHO the 6mm-06 is bordering on and may just be over bore capacity.

Unless you're going to go to a 29-30 inch bbl, you probably won't be able to generate the velocities you are looking for.

The rule of diminishing returns really starts to hit home with the small diameter bores.

Just IMHO of course.

If you want to do it, just because it might be fun as well as interesting, go for it.

It would really shine with the heaviest bullets you can find and a 1-8 twist rate.
 
The man wants a "Super 6" and already knows all about "Overbore" and "Barrel-Burner", so let's stop the finger wagging.

I run in 6.5mm circles and have, against all unsolicited advice, progressed from 6.5X55 to 264 Win Mag, to 6.5-300 Win Mag and now to 6.5 RUM. I did it because I wanted it, not for someone else. I shoot perhaps 50 rounds a year, so will only get perhaps 25 years of fun out of them before I lose extreme accuracy, which is long after I will have been bored by them and moved on to something else. There are powders that work well with even "extremely overbore" chamberings, but they are naturally few in number: US869; 20N29 and the like. In chamberings like these, Retumbo is considered "fast".

Maybe you want to stick with a standard bolt face, but if not, why not skip to where you really want to be and try a "6mm Win Mag" (aka 6mm Atlas - it's ALL been done before)- a necked-down 264 Win Mag? I know it has that bad belt, but smart people figured that out long ago and it still works. If it must be based on the '06, then you've already pretty much answered your own question - 6mm-06 AI. If the 6mm Win Mag, 264 Win Mag (or 7mm Rem Mag) brass is easy to find, and dies for the 6mm Win Mag are easy and inexpensive: you need a set of 264 Win Mag dies (with the sizing plunger removed) for full-length sizing and bullet seating; and a 243 WSSM sizer for neck sizing.

Finally, it won't "need" an extra long barrel. All chamberings "get the most" out of themselves, the longer the barrel. If you "need" to get 4000 fps out of a 100 gr bullet, but need a 24" barrel for the situations in which you will be using it, only something along the lines of a 6mm STW and up can do that - maybe. A 24" barrelled 6mm Win Mag does not become a 243 Win because the barrel's too short, as some would have you believe.
 
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Andy said:
The man wants a "Super 6" and already knows all about "Overbore" and "Barrel-Burner", so let's stop the finger wagging.

I run in 6.5mm circles and have, against all unsolicited advice, progressed from 6.5X55 to 264 Win Mag, to 6.5-300 Win Mag and now to 6.5 RUM. I did it because I wanted it, not for someone else. I shoot perhaps 50 rounds a year, so will only get perhaps 25 years of fun out of them before I lose extreme accuracy, which is long after I will have been bored by them and moved on to something else. There are powders that work well with even "extremely overbore" chamberings, but they are naturally few in number: US869; 20N29 and the like. In chamberings like these, Retumbo is considered "fast".

Maybe you want to stick with a standard bolt face, but if not, why not skip to where you really want to be and try a "6mm Win Mag" (aka 6mm Atlas - it's ALL been done before)- a necked-down 264 Win Mag? I know it has that bad belt, but smart people figured that out long ago and it still works. If it must be based on the '06, then you've already pretty much answered your own question - 6mm-06 AI. If the 6mm Win Mag, 264 Win Mag (or 7mm Rem Mag) brass is easy to find, and dies for the 6mm Win Mag are easy and inexpensive: you need a set of 264 Win Mag dies (with the sizing plunger removed) for full-length sizing and bullet seating; and a 243 WSSM sizer for neck sizing.

Finally, it won't "need" an extra long barrel. All chamberings "get the most" out of themselves, the longer the barrel. If you "need" to get 4000 fps out of a 100 gr bullet, but need a 24" barrel for the situations in which you will be using it, only something along the lines of a 6mm STW and up can do that - maybe. A 24" barrelled 6mm Win Mag does not become a 243 Win because the barrel's too short, as some would have you believe.
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Thanks for the input Andy! The action I have has the standard bolt face, so yes it IS going to be based on the '06. I am not hoping for unrealistic velocities either, I would like to get 240WM speeds or a touch more if I am lucky. The thing is there are a bunch of 6's based on the '06 - I was just hoping for someone to tell me one is the best of the lot.... :) wishful thinking on my part I guess. Each one claims to be the king.
 
The performance (speed) is basically going to be determined by case volume.

Other factors might make a particular cartridge more or less convenient:
- a long-ish neck can allow for a greater range of bullet and seating depth choices
- the brass might be from a cartridge family for which very high quality brass is available (for example a 6mm-06 and a 6mm-.284 have essentially the same case capacity, but for the latter you have the luxury of using Lapua 6.5-.284 brass)
- more or less case taper, more or less should angle have their pluses and minuses

Were you thinking of making it a light-bullet gun (e.g. 70 varmint bullets, or even 55 varmints), or were you going to use the heavier bullets (105/107/115)? I think with a top-end gun like this it is worthwhile designing it around the bullet you want to shoot.

Are you sure that you are stuck with a standard size bolt face? (I know that's what you have, but do you have good reason to rule out changing that?)
 
rnbra-shooter said:
The performance (speed) is basically going to be determined by case volume.

Other factors might make a particular cartridge more or less convenient:
- a long-ish neck can allow for a greater range of bullet and seating depth choices
- the brass might be from a cartridge family for which very high quality brass is available (for example a 6mm-06 and a 6mm-.284 have essentially the same case capacity, but for the latter you have the luxury of using Lapua 6.5-.284 brass)
- more or less case taper, more or less should angle have their pluses and minuses

Were you thinking of making it a light-bullet gun (e.g. 70 varmint bullets, or even 55 varmints), or were you going to use the heavier bullets (105/107/115)? I think with a top-end gun like this it is worthwhile designing it around the bullet you want to shoot.

Are you sure that you are stuck with a standard size bolt face? (I know that's what you have, but do you have good reason to rule out changing that?)
Click to expand...

The action is a must (as is the bolt face)because the model is no longer made, and my personal favorite - Sako 75. I plan to shoot 90-105gr bullets 99% of the time. Absolute maximum speed is not my #1 priority.... I would gladly give up a grain or two of capacity for a case thats easier to form. I am strongly leaning towards the plain old 6mm-06 right now.
 
rnbra-shooter said:
- a long-ish neck can allow for a greater range of bullet and seating depth choices
- the brass might be from a cartridge family for which very high quality brass is available
Click to expand...

so 6mm-270 AI ? use lapua 30-06 brass (neck turned) .

I had considered the 270 neck when I setup my 6.5-06 but ended going for standard chambering.
 
double gun said:
No interested in the 243, or the 6mm. I have had both and still have a 6mm. The 6-284 gets denied aswell, my donor action is a long action I want to build off the '06 case. (And it gets nowhere near 4000 with 100grs.)

Thanks for the reply Dan, this rifle will be only used for hunting, wolf/coyote primarily - perhaps the odd antelope or deer. What kind of velocity are you getting from 100gr pills? how long is the barrel?
Click to expand...

The bbl is a 26", stainless, fluted, varmint weight, gain twist RKS. Doing this from memory on my bb, but I believe I was pushing 100 gr bullets around 3400 fps. For the 6mm-06, just look at data from the 240 wby, they have the same case capacity. The Gibbs will push the same weight bullets about 75-100 fps faster. To go faster then that, I built a 6mm Mach IV a while back. That's a 7 Rem mag case necked down with the shoulder blown forward and improved. No real good powders for it at the time (T-bird 20mm powder was the only one I found that gave me the velocities I wanted and the accuracy I needed).
Built the whole gun around the 85 gr X bullet (got the idea from a series of Ross Seyfried articles in Handloader), and I could get that bullet up to 4000 fps. Now that there are more ultra slow powders out there, I may dig it out again. - dan
 
I have a 240 weatherby with a 26" barrel and it will shoot 54 grains of imr7828ssc and a 100 grain bullet safely at 3450 fps. 87 grain bullet at 3645 with 56 grains of imr7828. Anything more is uncomfortably (for the case) too much. 4000 fps with aa 100 grain bullet would be quite impressive! I do know that the 100 grain bullet is quite lethal on whitetails and wolves and the 87 grainer absolutely eats coyotes up at long distances.

That being said, the 240 is very finnicky to load for (mine and 2 others that i know of are anyway), and the cases are really expensive, since they are proprietary. Case life does seem good though, I am on the 6th loading on some of mine and they are in great shape yet.

I know a guy with a 257 weatherby that can get a 100 grain bullet going 4000 fps+, and thats with 10 or 12 grains more powder. the 4000 fps 100 grain 6mm is really going to be something special......
 
normanrd said:
... the 240 is very finnicky to load for (mine and 2 others that i know of are anyway), and the cases are really expensive, since they are proprietary...
Click to expand...

Thats one of the main reasons the 240 is off the list, sweet little round - but I hate buying weatherby brass.
 
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