Has anybody ever heard of a 308 Win modified with a longer neck?

[JasonT]

Hey all,

I was thinking about other "hyper-accuracy" case designs, and the predominant features are <0.02" body taper, 30-35 degree shoulder, and longer case neck (Cal x 1.5+/-).

Is there a design like that for a 308-like cartridge that keeps the case capacity in the 55-60gr H2O range, but extends the neck to 0.4"+, reduces taper to 5 or 6 thou, and blows the shoulder up to 30-35 deg?

Something like a "308-Imp35-long-neck"?

I'll draw one up in solidworks and post a pdf of the sketch for anyone who cares to look. Please let me know if anybody has heard of anything like it.

 

[savagedasher]

30.06 with the shoulder set back that would be the only case I know of .
Years ago I made plent of 6mm Remington cases that way
You could do the same with any 473 bolt faces cases . Larry

 

[JasonT]

Good point Larry - that's certainly a time investment, but it could be worth it. I'm imagining that using Lapua brass with only 308 capacity, sharp shoulder, and longer neck would certainly bring the cost per round down when factoring in barrel wear, brass flow, etc..

 

[XTR]

I think that the problem with that for a 308 is the number of competitive classes out there that require a 308 that there isn't a lot of interest in a modified version.

There was some concern on the part of the Canadians that there may be someone tinkering with their 308 chambers to the point that they were talking about having two sets of go/no-go tests at the F class worlds, one to ensure you chamber was not too large, an another to prove that your fired brass didn't have a higher than spec shoulder angle.

You could get a 308SLR type reamer/die setup and make them pretty easily.(Like my 6SLR a lot)

 

[JasonT]

That's some interesting info XTR - Does the SLR die bump the shoulder back and create a longer neck that way? I've only heard positive things about the 6 and 6.5 slr, so maybe there's a +20% 30-cal variant in the works here

 

[Medium rare]

30x284 win?

 

[BoydAllen]

A couple of things:
First of all a longer neck has nothing to do with improving accuracy. That is more about being able to use a variety of bullets and still being able to seat them into the rifling and with their shanks above the neck shoulder junction...that and something called the turbulence point, which again is not strictly speaking about accuracy.
Then there is the matter of the distance that you are building for. What distance? We know that for shorter distances slow twists and short bullets rule, with cases that are a lot smaller than any form of .308, and for longer distances the .308 has not been particularly competitive of late, and I seriously doubt that a sharper shoulder will magically remedy that. Last point is a question. What experience do you have with super accurate rifles? I ask this because absent that experience your musings would seem to have the requisite background experience for you to steer them in the right direction. IMO, gaining this experience should be a lot of fun, and which you would choose would depend entirely on the distance requirements. Currently the short range champ is the 6PPC and for long range the Dasher. There are others, but these will have an excellent chance of exposing you to top accuracy at their respective distances.

 

[Ggmac]

Look at the OLD 7.65 mauser rifle cartridge. Blow out the case and use 308 bullets .
There are a few older wildcats like that in the book Wildcat Cartridges 1&2
By Wolfe

 

[Laurie]

Absolutely agree with Boyd on this. Fine cartridge though the 308 Win is, it's uncompetitive in any and every discipline I can think of ..... other than those such as Target Rifle, Match Rifle, Palma Rifle and FTR whose rules restrict competitors to using .223 Rem and .308 Win rifles.

Having what is in effect a .308 SLR wouldn't affect this situation materially - but its mid and long-range external ballistics will be much poorer than those of the 6mm and 6.5mm versions. For short-range BR and suchlike, the extra recoil / torque / rifle disturbance inject a major disadvantage compared to smaller cartridges with lighter bullets. The one and only plus would be extended barrel life.

To make 30 calibre competitive, one has to go to a much smaller cartridge (.30BR) or significantly larger (.30-284 or bigger as in the short magnums).

 

[Liven The Dream]

.308 Gibbs ?????

 

[Spook]

300 rsaum or wsm

 

[Yote Hunter]

Basically a 30 TC.

 

[Laurie]

Basically a 30 TC.

True ... except the OP is looking for a longer neck too.

If the 308 Win didn't exist, the TC would maybe have been a great success. In the real world where it was up against the 308 with millions of rifles and scores of ammunition products already in existence ... why on earth would anybody imagine it would sell? Still, we should be grateful as its existence was a key factor in persuading Hornady (who designed and produced the .30TC for Thompson-Center) to develop the 6.5mm Creedmoor from it as most of the design work and tooling was already done.

 

[Yote Hunter]

Right you are Laurie. I was thinking the 30 TC had a slightly longer neck but in fact it is shorter but only a few thousandths. But it's does have a 30 degree shoulder with on .006" taper where as the 308 has .016 +/- body taper and 20 degree shoulder.

 

[RonS]

PM sent

 

[JasonT]

Wow guys thank you so much for all of the help!! I've had to be away from the computer for a while, so I'll respond to the statements and PMs as I can get to them!

 

[joshb]

I keep this on file. I bought a rifle chambered in 30x51 .

 

[JasonT]

Josh that's awesome!! I think the 30x51 looks remarkably like what I just designed in solidworks...

 

[Ggmac]

I guess no one reads books anymore .

 

[IdahoSharpshooter]

I still own dies for a wildcat I played with many years ago. 308 ZTSS.

Zero Taper Square Shoulder. I was curious as to how little taper and how sharp a shoulder I could get away with for HBR. If you ran an 8x57 in it would make your long neck.