Minimum case taper

[buckbrush]

Is there a rule of thumb about minimum case taper?

We are trying to get the maxiumum capacity from a 300 RUM case with a 40° shoulder. If the base is 0.550' could the case diameter be 0.540' at the shoulder or is that pushing it?

Thanks.

 

[robbor]

I have no idea about the numbers but kirby allen over on long range hunting has developed his own line of high capacity wildcats and as i recall the origional was based on the rum case blown out with less taper than a 300 rum Ackley Improved.

 

[Robert]

Is there a rule of thumb about minimum case taper?

We are trying to get the maxiumum capacity from a 300 RUM case with a 40° shoulder. If the base is 0.550' could the case diameter be 0.540' at the shoulder or is that pushing it?

Thanks.

For what taper lenght? I think the angle of a taper or taper slope is more important than the diameters difference.

There is certainly no rule, as are also to consider:
-pressure deveopped will also have an influence in cones sticking together impairing primary extraction function,
-Primary extraction travel inherent to the action. The longer the priimary extration, the smaller the taper can be...

But is there really very much capacity to gain in reducung the taper???
R.G.C

 

[DaveTooley]

There is more to consider than just case capacity. A few thousands less in body taper will not get you much velocity but will create problems that will make shooting the rifle an ordeal. You have to be able to get the case in and out of the chamber. That requires a full length sizing die that works. I have designed and made dies for a lot of wildcats over the years. Straight cases and sharp shoulders compromise case sizing. I like .010' taper per inch. I have gone as straight as .008' per inch and it works OK. I don't like shoulder angles steeper than 30 degrees, particularly on large diameter cases. Steep shoulders and little body taper lead to separated cases because in the sizing process you're collapsing the side walls of the case.

Take a look at the 338 Edge. 338-300 RUM Reamers and dies are already available. If you want to go down a bumpy road and reinvent the wheel again I'll be glad to help.

Dave Tooley
Tooley Custom Rifles

 

[aitrble]

Dave
Lets do it!!! You saw a 17/224 Weatherby kill a rockchuck at over 900 yards. Its been a long time since I talked to you. The coyotes are 4 to 1 now, lets hunt. You need some more powder in your eyes.

 

[buckbrush]

I have no idea about the numbers but kirby allen over on long range hunting has developed his own line of high capacity wildcats and as i recall the origional was based on the rum case blown out with less taper than a 300 rum Ackley Improved.

Kirby Allen is building me a 338 Ultra Maxx which uses a blown out 300 RUM case and 338 bullet. This gun will be more of a pack gun and will remain a 30 cal to shoot the 240 gr SMK. He will probably just chamber a standard 300 RUM instead of making things too complicated.

Thanks to all that replied.