lost in all the 243 variations

[kevwil]

I'm starting a target rifle project and I think I want to go with an will be chambering it in some improved variant of the 243 Win cartridge. I'm confused by the vast variety of variants which seem to be the same.

What's the difference between "243Win Improved 30Ëš" and "243 BR-K" and "6mm Super X" and "6mm Super LR" and "6SLR"?

They all seem to be a 243 Win case with a 30Ëš shoulder, the only difference I can see is that the 243 BR-K seems to have a shorter neck.

Thanks!

Edit: clarify what's in question and what's not

 

[jonbearman]

Go to the home page and have a look at the 6xc. It has less powder capacity than the .243 but reaches the same velocity only using less powder and it has a 30 degree shoulder to impede brass growth like the .243 AI. I would look at both but the 6xc to me is very interesting.

 

[tonysnoo]

There is a lot of data at 6mmAR.com on most that you mentioned except the BRK?

The 6xc is a great choice too. My buddy shoots one. We are always comparing notes. He has to run his pretty hot to get the speed my 6slr gets loafing along. I do burn about 3 more grains but generally get 100+ more fps too. I suspect the shorter neck 6cm or 243 improved 30 is another step above mine.

 

[kevwil]

I'm sure the 6XC is great and all, but it has nothing to do with my question.

http://bulletin.accurateshooter.com/2013/10/hot-243-based-wildcats-the-243-br-k-and-6mm-super-x/
http://6mmar.com/Super_LR.html
http://6mmar.com/243_Imp_30_.php

How do you tell these apart? 243 case with a 30Ëš shoulder - that applies to each one.

 

[MrMajestic]

I'm sure the 6XC is great and all, but it has nothing to do with my question.

How does a Newbie win friends and influence people? ;D

 

[Dgd6mm]

What kind of target shooting? Will it be single feed or repeater? There are other 6mm's that may meet your needs better then what yo have listed.

 

[kevwil]

I'm sure the 6XC is great and all, but it has nothing to do with my question.

How does a Newbie win friends and influence people? ;D

You know what I really like is the iPhone. It's so fantastic, it's like 5-6 devices all in one. And so easy to use! You should go check it out, I'm sure you'll love it.

 

[kevwil]

What kind of target shooting? Will it be single feed or repeater? There are other 6mm's that may meet your needs better then what yo have listed.

Paper and steel, from 100 yards to as far as it will go. This will be single feed. One of my needs is to put all this 243 brass I have lying around to good use.

 

[jsthntn247]

I'm sure the 6XC is great and all, but it has nothing to do with my question.

How does a Newbie win friends and influence people? ;D

Looks like he couldn't firgure out the new format on snipershide so he came over here to be a smart---. Kev, a little humility goes a long way over for getting answers to your questions. Not many jerks over here so no need to be one.

 

[kevwil]

I'm sure the 6XC is great and all, but it has nothing to do with my question.

How does a Newbie win friends and influence people? ;D

Looks like he couldn't firgure out the new format on snipershide so he came over here to be a smart---. Kev, a little humility goes a long way over for getting answers to your questions. Not many jerks over here so no need to be one.

Seriously? I asked a very direct question about 243 Win variants, and received completely unrelated praises for 6XC. I attempted to keep the thread on-topic by providing links to details of what I'm referring to, and I politely stated that I agree that 6XC probably a great caliber but those responses are not related to my question. Please explain how that is not a correct statement and is somehow a smartass comment. I only made smartass replies to smartass comments, in a very tongue-in-cheek sarcastic style, with a smiley and everything. Now you're escalating things with name-calling?

 

[kevwil]

kevwil said: What's the difference between "243Win Improved 30Ëš" and "243 BR-K" and "6mm Super X" and "6mm Super LR" and "6SLR"?

Here we again,
.243 AI has 40 degree shoulder. You take a .243 round you fire it and it comes out as .243AI case. Some have reported difficulty feeding from a magazine.
6mm Competition Match (6CM) is same as above but with 31 degree shoulder. Designed to feed from magazine.
243Win Improved 30Ëš is the same as above but with a 30 degree shoulder. Don't know how it feeds from a magazine.
6mm SLR the brass has to be sized before it can be fired and has less case capacity then above. But has longer neck.

I don't know anything about 243 BR-K and 6mm Super X. The main thing to is get enough case capacity to burn slow powder (extends barrel file) to get to 1K yards. I believe that it is very difficult to do with the 6XC, 6SLR and 6Creedmoor. They can with faster powder.

Below is an article that you may find interesting.

I searched the forums for answers before posing my question and didn't find anything, apologies if it seems redundant. Thanks for the info!

 

[357Mag]

kevwil -

Howdy !

Ideally, one would have drawings showing each case's dimenions to use in comparison.

For those cases .243 ( Win family ) based that have a 30* shoulder angle and the same shoulder diam; the 2 remaining differing dimensions would be neck length.... and the " base-to-shoulder " dimension; the latter having a significant impact on case capacity.

In some aspects, these different cases arise as wildcatters finesse' case capacity, or perhaps more to the point.... " expansion ratio ".
If nothing else, shooters can use the various case specs when making a down-select to a final case capacity.
One shooter wanting perhaps the minimum practical capacity for shooting heavy 6mm bullets @ 1,0000. Another shooter wanting maybe to
come--up with his idea of an ideal 600yd rifle.

Larger case capacities that would adversely affect the rifles' " expansion ratio " also may imply lowered barrel life.

If you can put your hands on case' specs for all the varying cases under consideration, it could only help.


With regards,
357Mag

 

[jonbearman]

The only way to tell them apart from each other is to measure each case and note the difference. Some of the subtle changes are body taper ,shortened case with a heavier shoulder angle. Etc. If you have a lot of .243 brass already why not make the simple choice which would lead me to the .243AI. You can shoot a standard .243 in it providing both are no turn necks and then by firing the standard case you now have the wildcat. I guess the real part of the question about how to tell them apart leads me to believe you may suspect some of your brass really isn't .243 win anymore? Please elaborate sir.

 

[kevwil]

If you can put your hands on case' specs for all the varying cases under consideration, it could only help.

From those links I provided, there are diagrams for 243 BRK, 6mm Super LR, and 243 Imp 30Ëš. There's a photo of the 6mm Super X next to a standard 243Win - the base-to-shoulder length looks the same to me but could easily be a few thousandths off and I couldn't tell. The neck is quite noticeably longer than the standard 243Win.

The diagrams on 6mmar.com are chamber sizes, so it won't be a direct comparison.

Base-to-shoulder lengths:

• 243 Win = 1.5598
• 243 BRK = 1.566
• 6mm Super LR (chamber) = 1.5707
• 243 Imp 30Ëš (chamber) = 1.6366

Neck lengths:

• 243 Win = 0.2406
• 243 BRK = 0.3305
• 6mm Super LR (chamber) = 0.4753
• 243 Imp 30Ëš (chamber) = 0.2643

You mentioned barrel life, and that is one thing I'm considering as part of this process. The 6mm Comp Match seems to have been designed with long barrel life in mind, and is easily fire formed, but I haven't found any case diagrams yet.

For what it's worth, availability of barrel work and quality dies will also factor into my final choice. This will be going on a Savage large shank target action, if that makes any difference.

Edit: I just saw on this article that "6mm Super LR" is the new name for the 6mm Super X I linked to earlier. One point of confusion eliminated!

Edit 2: There seems to be a limitation with 6mm Super LR in that fire forming some brands of brass will result in donuts in the neck.

 

[kevwil]

The only way to tell them apart from each other is to measure each case and note the difference. Some of the subtle changes are body taper ,shortened case with a heavier shoulder angle. Etc. If you have a lot of .243 brass already why not make the simple choice which would lead me to the .243AI. You can shoot a standard .243 in it providing both are no turn necks and then by firing the standard case you now have the wildcat. I guess the real part of the question about how to tell them apart leads me to believe you may suspect some of your brass really isn't .243 win anymore? Please elaborate sir.

Well, I guess I'm confused why that's the simple choice. At least two or three of the others are no-turn necks and can fire-form using existing 243Win loads, so the 243AI has no benefit over the others there. And many of the articles I linked to make it seem like a 30-ishËš shoulder is "optimum" or somehow better than 40Ëš. On the flip side, would the 243AI have better availability of dies and barrel work?

I have 20 once-fired cases, 20 unfired loads, and an unopened box of 50 Nosler brass, from when I had a Tikka T3 Lite in 243Win last year.

 

[jsthntn247]

Personally I'm thinking about having a SLR made because of the longer neck and 30 degree shoulder. That way I can use the 200 pieces of once fired Lapua brass I have left over from my stolen 243.

 

[XTR]

The 6 CM and the 6 SLR accomplish basically the same thing at opposite ends of the shoulder.

The 6SLR you use a die to push the shoulder of a 243 back to 30* and make the neck longer, the body/shoulder junction does not move. You gain a longer neck and lose a small bit of capacity. No fire forming. This case has been reported to have doughnut problems when formed from Lapua brass because you are forcing the thicker neck shoulder brass up into the neck.

The 6CM you fire form the shoulder out to 30* in the fashion similar to an AI. The neck shoulder junction does not move, the body/shoulder junction moves forward slightly. You keep the short neck of the parent case and you gain some capacity. Cant imagine this is a problem for the Lapua brass

Both of the above cartridges keep the basic body taper of the 308 based parent, which isn't very much.

The 243AI the case body loses some of the taper and the shoulder is pushed out to 40*. This gives you pretty much the max capacity that you can get in a 308 based case. It's not that much of an improvement, certainly not what PO Ackley got blowing the shoulders of the 30-40 Krag out 100 yrs ago

The 6-47L uses the 6.5x47 Lapua case and necks it down to 6 keeping the rest of the dimensions of the parent case unchanged. Slightly less capacity than any of the 243 based cases, but you can get small primer Lapua brass if that's your preference.

Then there is the 6 Creedmore that uses the 6.5 Creedmore case and necks it down to 6mm. As cases go this would be my choice if I didn't have to use Hornady brass.

Personally I like W-W brass, because the 6 Creedmore brass is only available from Hornady (and only through GAP if you actually want 6 Creedmore headstamps) I'm going to build a 6SLR. For my purposes I'm sure it will get a 105 to the velocities I need (3000 to 3100), and the longer neck will probably result in better barrel life, no fire forming you size new brass with a die, which means I don't have to have to have one load for shooting new brass and another for the rest of the time.

 

[Dgd6mm]

The 6MM Competition Match's neck is .020 longer then a .243. You will get donuts in Lapua brass with the 6CM and the SLR. I run WW brass. I also inside neck ream. I did try Lapua brass but the base is a little bigger then Winchester and you need to small base die size it everyother time. Dave Kiff now has a reamer for the 6CM and Lapua brass.

 

[Dgd6mm]

You will spend x amount on dies no matter which cartridge you choose. For what you are going to do you have some good cartridges to choose from. If you choose the .243 30 degree or the 6CM you will have to fireform. The 6SLR you will use the die o form the brass. When you make your mind up on whatever one it may be, I'd like to know. Please post your decision, I know it may even be some other 6MM.

 

[kevwil]

When you make your mind up on whatever one it may be, I'd like to know. Please post your decision, I know it may even be some other 6MM.

Will do. I'm currently leaning toward the 243 Imp 30Ëš over 6CM due to no donuts in the neck and working with a wider variety of brass.

If I weren't looking to use 243 brass I already have, I might be interested in 6 Dasher or 6x47L. I also like the logic from the 6CM description where barrel life is extended by not running hot loads all the time yet still getting 3000fps.