[ICL]

What are members experiences with shoulder angles?

When does neck thickening and case lengthening become less significant? I've read various claims thirty degrees, forty degrees, forty five degrees etc, but I have no direct experience.

what shoulder angles(or what increase in shoulder angles start to give feeding problems in bolt actions?


At what point does shoulder collapse during forming or sizing start to become a problem?

Many thanks in anticipation of your replies.

 

[chevwilliam]

OK, my Experience is with two "parent" Cartridges reforming into several "Children".

The first is .22 hornet.
i expand the Neck and Shoulder area to about .250" diameter, then Run the result into a .25ACP sizing die up to the Top of the Rim. the result is a Case of .276 Diameter and 1.38)" long; or about .020 shorter than the Parent case.

The second is 5.7x28mm FN.
I expand the Neck and Shoulder to about .250": then use three Steps to reduce the diameter form about .314" down to .276" which result sin the final case being between 1.215" to 1.260" in length compared to 1.137" of the Original.

The 5.7x28mm FN starts with a shoulder angle of 31 degrees and 24 minutes half angle.
The .22 hornet starts with a shoulder angle of 5 degrees and 38 minutes half angle.

Good Luck with your Quest.
Best Regards,
Chev. William

 

[nvshooter]

I kept it simple...

I kept it simple, and went with a tried-and-true angle: I took my angle from the .30-06 SpringBreak at 17 degrees 30 minutes. I have seen the angle shown here, there and around the web as 17 degrees 15 minutes. Dave Manson ground my reamer to that angle; so it reads on my reamer print. I saw on another website upon which I was a paying member (the opportunity to re-up was not offered; I was too much trouble) that one nutcase wildcatter did his at 32 degrees, and it required no fireforming. I think 32 degrees is pushing it. If I had my Desert Magnum and Sierra Stomper to do over again, I'd pay homage to the .308 Winchester and use twenty degrees. You should easily get that if I got 17.5 degrees. The 5.56mmNATO uses twenty-three degrees. That may be asking a lot for rounds not hydraulically-formed.

I chose the angle from the '06 because we fired-off bazillions of them in WWII. I figgered that was good enough proof under fire. I wanted a gentle angle to make sure the rounds would feed. So what if your shell has 89 degree 59 minute shoulders and holds a ton of powder? If it won't feed from a magazine, of what good is it? So I went gentle and easy on the angle. I know the buzz is all about 30-degree and 35-degree angles and even 40-degree angles on those ugly (my opinion) Ackley Improved cartridges, but my philosophy was to take it easy and go with something that has been so very well proven for over a hundred years. I must have done it right because Jason says my shells are "balanced" in their appearance. I value his word. He's a wildcatter from long before I started fooling with them. Member carpooler is another one who knows this game very well. Seek the counsel of these two before dropping the money on dies and things that may not do the job when crunch (or crush) time comes.

My rounds required no fireforming and no "false shoulder," whatever that is. I wanted to avoid burning-up time and money doing that. I formed mine from .375 Ruger Basic brass (Hornady p/n 8674), using three discrete forming dies custom-made by Hornady. The last step in forming is done with the custom-made resizing die. I found that by setting the die 0.004 inches above the shell-holder, I developed a very nice and barely-there crush fit. Setting the die 0.0035 inches above the shell-holder eliminates the crush fit but you know with the shoulder being just 0.0005 inches more toward the case head, there is very little slop between the bolt face and the case head to give you what looks like flattened primers with lower-powered loads. I had that problem...

I had a mile of open air (about 0.015 inches) between the bolt and head. You want about 0.002 inches. The firing pin pushed the case forward, the propellant combustion pushed it backward and the primers came out flat as a pancake because the primer was pushed out a bit and was then flattened by the pressure as the case moved rearward. There is a whole discussion about it in these pages from about four years ago when the .300 Nevada Desert Magnum sent its first bullets toward the heavens. MikeG solved it by explaining exactly above as to why I was seeing the problem. If you can generate a slight crush fit for your cases, you can avoid the problem I had.

Best of luck. Keep us informed...

 

[black mamba]

My 35 Whelen AI has the 40° shoulder, and I rarely if ever have to trim brass. Some people have had feeding problems with this steep angle, but mine feeds fine (a customized Mark X Mauser action).
If I were designing a new cartridge, I think something between 30 and 35 degrees would be the best combination of case capacity and case stretch.

 

[michelewerling5]

shoulder angle

ICL -

Howdy !

Not in necessary order....

IMHO -
Not all shooters select a sharp-shouldered case based on personal experience they've had w/ case stretching/lengthening.
Many pick such cases and $$$ to have a rifle chambered for them w/o having ever fired a sharp-shouldered case previously.
A lot of shooters go w/ a sharp-shouldered case simply because they like the "look".
Some times, there's really no point in applying a sharper shoulder angle; certainly for larger-calibre cases w/ minimum shoulders present to start with ( such as .35 Remington ).

P.O. Ackley himself didn't use a sharp shoulder on every last one of his designs.

If a wildcat's design can incoporate a moderate shoulder angle along w/ sufficient neck lg to keep the
" powder combustion turbulence point " located within the case neck, there's less need for a sharper shoulder angle to be used in the design.

Forming:
On a recent 6.5mm wildcat I worked on, that was based on .243Win fmaily brass and .455" shoulder diam; I was not able to form shoulder angles beyond 27*; when using traditional die(s).

Case neck and shoulder " thickening " on wildcats depends a lot on whether and how much
" shoulder shove " is being performed on the parent brass. This thickening itself can help retard case length growth that comes from successive firings of the cartridge ( IMHO ).
Shoulder thickening is not universally " bad ".


With regards,
357Mag

 

[jim love]

I have a 25-06 AI and a 280 AI both have 40 degree shoulders as most of of his were.With a little work both feed fine. I have had many Ackley rounds most were fine a couple had to be reworked until they would feed ok. I have had a few of the ICL's with the 45 degree shoulder but also needed to be reworked by someone that knows what they are doing.

 

[Bong Son Buck]

Actually, it's not the degree of shoulder, but the body taper that would cause feeding problems. Two different issues!

 

[std7mag]

Black Mamba,
If you have a 40 degree shoulder angle on your 35 Whelen, then it's an Ackley Improved.
One of the issues with the Whelen was the small shoulder.

ICL,
Are you attempting to create your own wildcat, or are you looking at doing one of the many "Ackley Improved" ?

Shoulder angle, and body taper can have an effect on loading from a magazine. If the lips on the magazine are too tight, the cartridge can't raise high enough for the bolt to get behind.
If the magazine is kinda on the short side, then a sharp shoulder angle can catch it also.

Neck thickening is usually associated with the shortening of a parent case. For example, if you wanted to make 308Win casings from 30-06 casings, then you would need to either ream the inside of the neck, or turn the outside of the neck.

 

[black mamba]

Black Mamba,
If you have a 40 degree shoulder angle on your 35 Whelen, then it's an Ackley Improved.

Re-read my post, that's what the AI stands for, Ackley Improved.

 

[ICL]

Many thanks for the replies so far
Hope to get to reply to each point over the next few days as work commitments allow.

ICL,
Are you attempting to create your own wildcat, or are you looking at doing one of the many "Ackley Improved" ?

I'm thinking about one or two of my own

My ideas are almost the opposite of the short fat stubby cartridges, I'm also looking for a compromise of easy feeding and solid headspacing in the larger calibres

I'm thinking about something approximately like a rimless 06 head sized version of the 7x75mmR vom Hoff super express as a way to chase the throat in shot out barrels chambered for 03 and 06 based calibres in long actions like the Rem 700.

and a longer case (probably about 55mm / 2 inches long) on a .222 head size, to give capacity and performance similar to say the 6.5X54 MS and .250 Savage, but that will safely work in a stretched Sako Vixen, CZ/Brno Fox diameter action and achieve velocities and energies required to be legal for deer in Britain.

for the small case, it would probably need a fairly wide and steep shoulder to achieve the necessary capacity and hence performance without going to brutal .223 pressure levels, and also to allow necking up to .30 with positive headspacing.

For the larger case, less body taper than the .308 would allow previous factory chambers to be cleaned out, but if it is only used for rechambering x57mm and x 06 chambered barrels, a smaller shoulder could be used, I'm also thinking about a long .30-03 / .270 win length neck, as I'm looking for both case length, loading density and ease of loading, rather than out and out powder capacity.

 

[jim love]

One of the smoothest feeding rifles I have ever owned was a Pre 64 Win in the 375 H&H,that old long taper case just was perfect,and a 300 H&H was so very smooth.

 

[HarryS]

i load for 43 rifle cases. Can't say that shoulder angle helps on feed nor neck thickening nor case stretching.

many shoulder angles I use including some ventur/radius Weatherby cases. Feeding is more problem with the specific action with most CRF having problems with cartridges other than the specific cartridge that the specific action was designed for. keep to push feed on wildcats and feed problems in turn bolt rifles will ne small if any.

Case stretching is usually a problem of high pressure with body taper contributing little to the effect. Most wildcats are unfortunately, loaded to way above Sammi pressure specs. that is why they look good at first glance.

Just my thoughts. During the first 20 years of reloading I went for max velocity, the next 35+ years I load for maximum accuracy. Lately I seem to be reloading heavy weight for caliber bullets; except for 22 CF where I'm going very light weight.. we all change with time.

 

[MagnumManiac]

Well, one of the slickest feeding cartridges I have ever used has a 45º shoulder and it isn't a wildcat!
In a properly designed rifle, the 416 Rigby feeds like butter, as do the 375 H&H, 404 Jeffrey & 505 Gibbs.
I have had many problems feeding cases like the 458WM & LOTT. With those it has always been bullet profile causing the issue.

Cheers.

 

[std7mag]

BlackMamba,

My appologies, somehow I missed that...

I did the Improved 40 on my 7mm-08. (since Ackley never actually worked with that cartridge).
Trimming is no less of a chore for me than with the standard 7mm-08.

 

[black mamba]

I did the Improved 40 on my 7mm-08. (since Ackley never actually worked with that cartridge).
Trimming is no less of a chore for me than with the standard 7mm-08.

Sorry to hear that. To me the lack of case trimming is the much better reason to have a 40° shoulder than a grain or two more powder capacity. I bet your 7-08 improved is a good looking cartridge, though!

 

[carpooler]

Go over to Target shooter, David Tubb's pages. He slowly worked up to steeper angles, until he got to 30 degrees. There the stretching stalled out, and that's what he uses. IN my 6mm wildcat's 300 RCM parent brass, the shoulders are already 30 degrees, but I went with 26, and when the shoulders blew out forwards, it cut down my neck lengths. What's left is basically a 243 Win.'s neck length. So now I've had a neck throat job, and will have to form some new wildcat cases from full length 375 Ruger Brass. This is a whole lotta work, for a little longer and thicker neck.

edit; but I can now make, per my CerroSafe chamber casting, a rimless 240 H & H Magnum, but do it in a short mag case.

 

[std7mag]

yes, they definitely draw attention at the range.

Definite lack of load data for it though.. And the load data that is out there is grossly overpressure!!!
With the 7mm-08AI case size, I can theoretically go about 1.4 gr. of powder higher than standard 7mm-08. However this doesn't happen.

On the plus side, somehow with the rechambering my rifle now has an accuracy node closer to maximum 7mm-08 loadings. Before my accuracy node was about mid load range.

On a side note, when fireforming, it does tend to shorten the casing. It isn't until about the 3rd reloading that I need to start trimming. I always check, but the 3rd is when metal is actually taken off.

 

[Ozarks]

I believe the .284 Winchester [35 degrees] has the steepest shoulder of any general commercial case. If the big gun and ammo makers wouldn't go any steeper I don't think I would either. One really gains very little capacity and rounds developed for military use where feeding is paramount will usually be 23-28 degrees.

 

[ICL]

... rounds developed for military use where feeding is paramount will usually be 23-28 degrees.

There seems to have been a blip in Britain around the nineteen teens, when some very steep shoulders appeared
and to a some popped up in Europe and America, but to a lesser extent.

I'm guessing that part of this may have been in answer to H&H's marketing claims and hype about putting patented belts on its cases

(after wwi, BSA and Kynoch even put belts on automatic pistol cases)

Westley Richards went the whole hog with 90 degree shouldered .318 cases for Mauser actioned rifles (it's very similar to an improved .338/06.)

The one which has me questioning the relationship between shoulder angle, body taper and good feeding and extraction in Mauser rifles is the .416 Rigby,

which still has a great reputation for slick and certain feeding in dangerous game rifles - even though it has minimal body taper and a big 45 degree shoulder.

 

[carpooler]

The Big Rigbys are at home in very large diameter receivers. Weight has become your best friend, with these boomers. This thread is more about what works in a standard diameter receiver, IMO.