6.5x55 SLR

[chalkeye]

I'm interested in what it would take to make a wildcat based on the 6.5x55 cartridge, using the same philosophy as the 6.5x55 SLR: www.6mmar.com/65_SuperLR.php

I'm interested in an alternative to 6.5x55 AI that wouldn't require fire forming, and isn't so close to the 6.5-284 in geometry:

Basically, using the same base to shoulder height, and push the neck down to a 30 degree angle and reduce the taper at the shoulder.

This follows the 6.5SLR philosophy of a (slightly) longer neck to protect the throat, similar parent case volume, but more modern geometry (reduced taper, 30 degree shoulder) to reduce case growth and hopefully improve efficiency - but applied to a medium length parent cartridge.

My understanding is that this would require a custom reamer, and custom dies - but I can't get the dies made from formed brass (e.g. whidden's standard process) - would I have to get the dies made up with the reamer?

Is this a dumb idea? I'm obviously OK with the extra tinkering involved with a wildcat, I think it would be a fun experiment. Probably my main concern is that there wouldn't be significant improvement over the parent case.

Let me know your thoughts!

 

[Rust]

A few thoughts.

You might consider basing you design concept on the X 57 family of chamberings. Depending on your choice of donor actions the standard cartridge base of .473 would make more sense. Since the X 57 based chamberings include 6mm Rem, .257 Roberts, 7 X 57 brass availability is not an issue.

The X 57 family has been extensively wildcatted in the past and there may be very close matches to your concept utilized. There may be existing prints with reamer and die makers for both X 55 and X57 based designs.

I know a variety of both are covered in P. O. Ackleys Handbook, which unfortunately I seem to have misplaced.

 

[1shot]

Do a search for the 6.5 GWI.
A 30* shouldered Swede with most of the body taper taken out. It's a very easy accurate cartridge to form, designed by Greg Walley from Kelbly's.
I hope this helps,

Lloyd

 

[rardoin]

Or the 6.5 x55 BJAI

 

[chalkeye]

Why x57 when the x55 is already so close? Or are you suggesting applying the "SLR" method of pushing the shoulder back (but steeper) to the x57 case - which looks (to me) like half way between a 6.5x55 AI & a 6.5-284.

 

[ireload2]

If you want to reduce case growth
1. Start out with a chamber that is a perfect fit for your new brass so the brass does not have to expand or stretch.
2. Don't size the case anymore than necessary which means the FL die only sizes the case .002 to .003 on the diameter when you touch the shoulder.

When such a round is fired the case does not stretch diametrally and when it is FL sized it is not squeezed forward toward the case mouth.

 

[Sheldon N]

I like the idea. The main upsides seem be cheap Lapua brass, less trimming due to 30 degree shoulder, and convenient case creation with no fireforming needed. My worry though is that you'd end up in a scenario where forming the longer neck out of the thicker shoulder material may create donuts, forcing you to neck turn and eliminating the convenience factor.

 

[chalkeye]

Do a search for the 6.5 GWI.
A 30* shouldered Swede with most of the body taper taken out. It's a very easy accurate cartridge to form, designed by Greg Walley from Kelbly's.
I hope this helps,

Lloyd

Thanks Lloyd - this is almost the exact geometry I'm after, but I want the shoulder pushed back a little so it forms with a die, rather than fireforming.

 

[Rust]

Why x57 when the x55 is already so close? Or are you suggesting applying the "SLR" method of pushing the shoulder back (but steeper) to the x57 case - which looks (to me) like half way between a 6.5x55 AI & a 6.5-284.

Lets see, the 6.5 X 55 is the Swedish Mauser and has a .489 rim diameter, a .480 base diameter, is .435 at the shoulder, length from bottom of rim to shoulder 1.856, and a .311 neck length It is pretty much a unique case.

The X 57 family has a .473 rim diameter, a .472 base diameter, a .458 shoulder diameter, length from bottom of rim to shoulder 1.886 and a .323 neck length.

The 6.5 X 284 has a .473 rim diameter and the rim is rebated, a .500 base diameter, a .475 shoulder diameter, length from bottom of rim to shoulder 1.901 and a .269 neck length. Starts with a 35 degree shoulder too.

Not a lot of difference between the X 55 and X 57 with the exception of the slightly larger rim diameter of the X55. This possibly may require a little work on a tight bolt face, likely not. But there is more brass available for X 57 and if you can find RUAG or RWS even better, great brass. And the X 57 can give you slightly more powder capacity when improved, emphasis in the slightly part.

6.5 X 284 is another story. I have a fast and long barrel, and hit 2950 fps using 140 gr match bullets with a lighter load than some folks are using. I can hit the next node up from there but the load is a little stiff and 2950 is such a nice node so no need to push hard. The improved X 55 and X 57 along with the .260 AI can reach 2950 but they are maxed out there. At that velocity with 140s, barrel life won't be much greater with the X 55 or X 57 than the 6.5 X 284 either, maybe a couple of hundred rounds at best. But either should be a great chambering with the newer 130 gr match bullets

 

[1shot]

I can hit the next node up from there but the load is a little stiff and 2950 is such a nice node so no need to push hard. The improved X 55 and X 57 along with the .260 AI can reach 2950 but they are maxed out there.

I have had 3 6.5x55 GWI barrels, 30" long.
2 8.5 twist and an 8 twist. All were cut rifled and all would run in the 3,050 to 3,070 fps. range with 1,300-1,500 rounds of barrel life. If I did anything special at all, I maintained a good throat maintenance regime.
I hope this helps,

Lloyd

 

[chalkeye]

But there is more brass available for X 57

Rust, I disagree about brass options, but you are correct that the x57 is closer to the case I am trying to form - just longer. Thanks! Please see amended geometry below

3,050 to 3,070 fps. range with 1,300-1,500 rounds of barrel life

Lloyd, I actually expected both faster speed and better barrel life from that cartridge in that length barrel. I reached 2850 fairly comfortably with a standard swede in a 20" barrel (though I can't comment on it's life - only probably 500 rounds through it).

Guys, I'd appreciate your input on my revised idea - using a 7x57mm parent case, trimmed, neck down and push the shoulder back. No / little messing with the body taper.

Compared against 6.5x55 (shown in purple) - note, same OAL, same shoulder height:

Compared against 6.5x57 (shown in purple) - note 2mm trimming required.
- Is this too much material to push back?
- Will this be complicated when also necking down from 7mm?

And for reference, compared against 6.5-284 (again shown in purple) - note difference in taper, and much longer neck:

My main concern is that I'd be trying to move too much material pushing the x57 shoulder back as well as reducing the neck size.

 

[1shot]

Chalkeye,
I should have been more clear as to what I expect from a barrel in terms of accuracy. When it won't give me a 30%+ "X" count on demand and unexplained shots show up "off call" it's time for a new tube.
As far as hunting accuracy, it's still great, but I'm not lugging a 32" med. Palma taper through the woods!

Lloyd

 

[chalkeye]

Fair point!

 

[Tommie]

I like where you're taking this but keep in mind that the x57 case has considerable body taper. Even with the 30* shoulder you'll probably have some forward brass flow.

 

[DocDoc]

Why not the AI version? It already has a long neck for the x57, standard 7x57 fireforms without effort and the case would be stable.

 

[chalkeye]

I like where you're taking this but keep in mind that the x57 case has considerable body taper. Even with the 30* shoulder you'll probably have some forward brass flow.

The body taper doesn't seem too excessive to me (bear in mind, I'm coming from 6.5x55!), but fair point. My issue is that I want to form the case with a die (not fireforming), and I don't know if a wider shoulder diameter would form this way?

Why not the AI version? It already has a long neck for the x57, standard 7x57 fireforms without effort and the case would be stable.

The AI requires fire forming (which I want to avoid), and by my guess would be practically the same as 6.5-284 (with a slightly longer neck).

 

[kyreloader]

.284 Win on the right (6.5x284 necked up), 6.5x55 BJAI in the left

 

[perry42]

I bought a 6.5x55AI reamer from PT&G. Works great in my Bartlien barreled Mauser, not as accurate as my 6br but damn close.

perry42

 

[kyreloader]

Lapua brass would make me choose x55 brass over x57 brass to wildcat.

 

[Catfur]

As far as hunting accuracy, it's still great, but I'm not lugging a 32" med. Palma taper through the woods!
Lloyd

I'm not lugging anything through the woods, I don't know where the woods are.

If it kills deer, go with it (note, I can't find a deer to save my life), but I can tote a lot.