Shoulder angles

[Changeling]

It seems that most have settled on 30/40 degree shoulders when making up a wild cat or working with existing designs. I also realize that over 40 degrees it begins to give loading problems for those using repeaters if not sooner.
But, steeper angles reduce back pressure against the bolt and action, and possibly increase burn time in the cartridge case, at least these were P.O Ackley's feelings/findings.

So, with some of these small/midsize cases I have been wondering about running the angle on out to 45 degrees are further giving small increase in powder and possibly aid in very minutely slowing combustion time (in case) and maybe using a slower powder that had been on the edge of necessary case capacity/burn ratio.

I thought since most of you guys who answer the rifle related problems/questions on this website are usually directly involved with this forum it would be the best place to post this for responses. What do you think?

 

[fguffey]

I have been wondering about running the angle on out to 45 degrees are further giving small increase in powder

I am wondering, running the angle on out to 45 degrees? Increasing the angle shortens the neck. Then there is that part about the case body shoulder juncture. If the juncture stays the same and I increase the angle of the shoulder I reduce powder capacity.

F. Guffey

 

[WSnyder]

One problem when going over 40° is when brass work hardens a bit it becomes harder to size the shoulder back when re sizing without crushing the case.

What do you mean by under 40° can cause loading problems with repeaters? Am I reading that wrong? Less than 40° shoulders and less body taper are typically easier to get to feed.

 

[Ggmac]

Mondragon had designed something like that about 100 yrs ago . I know 40 deg angles start to get iffy on feeding . I wouldn't know for sure but at some point the funnel becomes a restriction which could , should cause problems .

 

[riflewoman]

There were a number of wildcats with 45 degree shoulders, but above 40 reaches diminishing returns while the other issues previously noted get worse.

 

[Changeling]

Well it seems this idea went South fast . I also received a PM from a friend that said past 40 deg some shoulders get dents and some collapse! Well that's nothing serious though : , yea right :'(

WSnyder, you are reading it wrong because I wrote it wrong, I meant "over" 40 deg, not under ;D.
I'll change it, good catch.
The brass does work harden some in the shoulder area from resizing however annealing would take care of that if it became a problem.



I

 

[Ggmac]

Anneal it most if not all shoulders would buckle .

 

[Greyghost]

Think it more depends on what you want to do.... look at the 22-250 Rem with its 56 deg., 22-250 Imp with 40 deg., and the 220 Swift with 42 deg.

Phil

 

[fguffey]

Well it seems this idea went South fast . I also received a PM from a friend that said past 40 deg some shoulders get dents and some collapse! Well that's nothing serious though : , yea right :'(

"Well it seems this idea went South fast" I do not agree, it has been suggested problems can be created. Some shoulders get dents? Some shoulders collapse?

When someone decides to go to a chamber with a sharp shoulder I wonder what were they trying to get away from?

F. Guffey

 

[savagedasher]

40 or 45 I don't think you can tell the difference. 30 to 40 their is a difference. 40 gives a shoulder for the brass to hit on and slows down the case stretch. Taking taper out of the case has the same effect. More shooting and Less trimming.
Larry

 

[Eddie Harren]

In my experience, it is very difficult to increase the shoulder angle, on a case, and not remove some of the body taper. The two processes seem to go hand in hand.

 

[LHSmith]

40 or 45 I don't think you can tell the difference. 30 to 40 their is a difference. 40 gives a shoulder for the brass to hit on and slows down the case stretch. Taking taper out of the case has the same effect. More shooting and Less trimming.
Larry

Gene Beggs simply made the radius sharper at the neck/ shoulder junction on the .220 Russian and created the .220 Beggs and 6mm Beggs and virtually eliminated case stretching which is common on the .220 Russian which has quite a bit of body taper and a 30 degree shoulder angle. These rival the accuracy of the .22 and 6 PPC cartridges in short range BR.

 

[Changeling]

[ Gene Beggs simply made the radius sharper at the neck/ shoulder junction on the .220 Russian and created the .220 Beggs and 6mm Beggs and virtually eliminated case stretching which is common on the .220 Russian which has quite a bit of body taper and a 30 degree shoulder angle. These rival the accuracy of the .22 and 6 PPC cartridges in short range BR.
[/quote]

Now that is interesting Mr. Smith. 8) Would you happen to know what radius Mr. Beggs used at the neck shoulder junction?

Any downside to sharpening the radius angle ? I would think not, but you never know.