243-06?

My thoughts is that if I build a custom rifle it would be a 6.5-06 over a 6mm-06. I've read that the 6.5's fly better.
 
Extreme overbore. A 6.5-06 gives you 87-140gr bullets with extreme ballistic coefficients. Example, a 120gr Nosler can be pushed faster than the 24 could push a 100.
 
It will launch a 6mm 115 gr bullet at 3300 fps, a 243 would be doing good to hit 2800 fps with that bullet.
Click to expand...

Scorch while I have no reason to doubt you I have no experience with the 6mm-06. I built a fast twist .243 Win last year and am able to break 3000 fps with the 105 A-Max and 107 SMK I have backed them down to a little below 3000 though. I haven't tried the DTAC or Berger 115's yet but my 1:7 twist barrel can shoot them.

Here is some sample load data that I used when I started building loads for my .243 win. I found some load data for the 6mm-06 as well. Work up to these loads if anyone is going to try the as they may not be safe in your rifles.

243vs6mm06data.jpg



.243 Win & .243 AI
6MM-06
 
Most wildcaters I know are pretty knowledgeable about what their building and that includes me. I haven't met anyone yet that their sole goal is velocity but that is one thing to consider on selecting a case.

My 243AI is lot different that the one taylorce1 posted from the 6br site so is my reloading data and velocity along with my Kreiger barrel 243.

My 284 reloading data did come from the 6br site gun of the week and I pretty much match his and our rifles were real close.

I've had couple 6x284 build got little better than 240Wby velocity without the belt case and the 284 case has appr 3gr more H20 capacity.

The 30-06 has appr 68gr H20 capacity if you compare that to the 243 @ 53grH20 that's a big difference, My 243AI has 56gr H20 capacity appr.

Based on the case capacity of the 30-06 and if I build a 6x06 I would expect better than 240Wby velocity. If you look at the Nolser manual they have a load for the 240Wby using a Lilja barrel 1/10 twist @ 26" with 95/100gr bullets @3352fps and that's a max load and that was with 53gr/IMR-4831. worse thing that could happen if you only got the 240Wby velocity good part is you build a 240Wby without the belted case.
 
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Hmmm lets think another way......About a 50 by 20MM? Take a 20MM and neck it down to .50. This should be a barn burner.:eek: Might even be a little over bore.
 
I own a .243 I hardly shoot it in fact I couldnt even tell you what twist the barrel is. However one day I got the smart idea to do some handloads for it and a buddy of mine had good success with this load so I tried some. I believe it clocked in at around 3100 fps. So in short the .243 win is a great cartridge. If your looking for something faster I would go with the 220 swift AI a gunsmith told me once that he had chambered several Rem 700 actions for this cartridge and that it is extremly fast somewhere in the 4000's. Due to it being an AI it is a little nicer to your barrel life. (JUST A LITTLE)
 
thank you all for your posts. it's been an informative couple of days. I am probably going to just nail the coffin shut on this "Hairbrained Idear of the Day".

any ballistic improvement over a 243 hot load is minimal at best and would offer no noticable advantage in the way of either long range target shooting or big game hunting. I think I'll just load up some +ps and let the old 243 do what it does best.
 
Take a look at the case dimensions for the .240 Weatherby. Very close with the capacity higher in the Wby case due to the double radii shoulder/neck and shorter neck over the .30-06

It takes a lot more powder for a small gain in velocity, and in some cases less than equal velocities according to my Nosler book. I doubt the gains would be worth the expense. The .243 is a really efficient cartridge as-is.
 
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I just remembered that I was going to add a caveat about the 243-06 probably having slightly less volume than the 30-06 due to being sized down. ;) I couldn't find an actual reference to the 243-06 capacity...
 
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