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Author Topic: 243 to 6mm  (Read 692 times)

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Offline Curt Dawson

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243 to 6mm
« on: March 11, 2006, 04:32:00 PM »
Would it be very difficult to ream the chamber of a 243 win. NEF barrel to 6mm rem.?
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Offline Mac11700

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Re: 243 to 6mm
« Reply #1 on: March 11, 2006, 04:45:10 PM »
Quote from: Curt Dawson
Would it be very difficult to ream the chamber of a 243 win. NEF barrel to 6mm rem.?






Looks like the 243 is too big in the shoulder area to me...I don't think you can taper it down to .429" from .454" in .165"...I might be wrong though...

Mac
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Offline cheatermk3

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243 to 6mm
« Reply #2 on: March 11, 2006, 06:00:09 PM »
Welcome to the forum, Curt.  

I should refrain from answering your question directly here because it really belongs in one of the reloading forums;  Having said that, it is my OPINION that there is not enough of a performance gain in the 244 rem over the 243 win to justify trying to go from one to the other even if you could get around the difference in body taper.  You could get by reaming to 244AI but your setup costs for dies could set you back a bunch of $$.

In any event you might get a better answer in a reloading venue.
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Offline Mac11700

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243 to 6mm
« Reply #3 on: March 11, 2006, 08:20:37 PM »
It's ok to ask here Curt..even though it's not the Gunsmithing forum :D It's still dealing with Handi-rifles...and that makes it ok...

And by the way..Welcome.. :toast:

I think you'll find the 243 is a pretty good choice all by it self..without trying to stretch it out..The bull barrels are real good shooters...while the Superlites can be real finiky on what you feed them.


Mac
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Offline Curt Dawson

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243 to 6mm
« Reply #4 on: March 12, 2006, 02:23:24 AM »
The reason I asked was because of an aricle in "Petersons Rifle Shooter" and in the latest edition of "Cartridges of the World".Both made reference to pressure spikes in the 243 and sometimes eratic behavior with handloads that are not expierenced with the 6mm.The ammunition designers and balistians believe this is due to shoulder angle partly but mainly the shorter neck on the 243.
Sorry,if placed this in the wrong forum. :-)
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Offline Mac11700

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243 to 6mm
« Reply #5 on: March 12, 2006, 04:26:04 AM »
Curt:

You didn't ask in the wrong forum for doing this on a Handi..although you could also ask it on the Gunsmithing forum as well..Questions like yours get asked all the time here and we do our best to answer them..and we do have some pretty smart folks who post here who have a-lot of experiance with many cartridges..so don't worry about it.. :D

Like I said..the 243 bull barrel is a real good one to have...I liked mine a-lot..it shoots the 95 grainers under an inch..hot or cold..and the 55 grainers for mitchell under 1/2"...so accuracy wise it is a good one..very consistant..

Mac
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Offline Paul5388

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243 to 6mm
« Reply #6 on: March 12, 2006, 06:04:40 PM »
According to Accurate Powder, you need a 6mm Rem if you want a 55 gr bullet to go 4000+ fps!  The .243 won't even make 3900 fps with the same bullet.  :eek:
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Offline quickdtoo

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243 to 6mm
« Reply #7 on: March 12, 2006, 06:44:59 PM »
You don't need a 6mm, you need to change powder in the .243, several Hodgdon powders will exceed 4kfps with the 55gr NBT!!  :wink:

Tim

http://www.hodgdon.com/data/rifle/243win.php

EDIT: Whether that velocity will happen in a .243 Ultra with their notorious freebore is an entirely different matter, tho. :cry:
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Offline Paul5388

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243 to 6mm
« Reply #8 on: March 13, 2006, 03:43:09 AM »
Tim,

Had Hodgdon chosen to post some data for the 6mm with a 55 gr bullet I suppose we would have seen a H4895 load at over 4100 fps (Modern Reloading, page 273)!  :lol:
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Offline quickdtoo

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243 to 6mm
« Reply #9 on: March 13, 2006, 05:25:37 AM »
:lol:
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Offline mt3030

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243 to 6mm
« Reply #10 on: March 13, 2006, 10:31:14 AM »
I have reloaded/shot both 243s and 6mms. I have always been able to find better (more accurate and faster) loads with less work for my 6mms. Maybe the "pressure spikes" do have something to them. I had not heard of this factor until now. I've had good luck with Remingtons, Rugers and Parker Hales.
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Offline Paul5388

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243 to 6mm
« Reply #11 on: March 13, 2006, 12:11:02 PM »
The infamous SEE (Secondary Explosion Effect) was originally demonstrated with a .243 and reduced loads of Norma N205.
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It is not the case length but a case shape, and it's volume compared with bore volume, which makes a cartridge prone to give nasty surprises. A .243 Winchester is especially notorious. In Germany it was produced a deliberated Secondary Explosion Effect, wrecking a sturdy pressure-test barrel. I'll never give reduced charge loading instructions for .243 W. without asking: "Do you really know the risk you're running ?!" I presume, some kind of "Improved" .243 cartridge with a more abrupt case shoulder (say 25 degrees of angle) may lessen the liability to S.E.E. or detonation, but better safe than sorry!  source
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