shoulder angles

G

g n brezinski

Member
I was looking at a article about Tom Drummond a noted 1000 yard shooter from Williamsport area in the early 70s.his cartriges had a 60 degree shoulder on the on the weatherby cases.ackly used 40 degree and the ppc has a 30 degree .my ? is is there a perfect angle for the shoulder or is this a personal thing?
most factory cases are 25 degree.
gary b
 
angle

GN -

Howdy !

Ideally, the shoulder angle and neck lg together would combine to keep the powder combustion " turbulence point " inside the case' neck; according to former Savage Arms engineer Robert Greenleaf. I'm inclined to agree.

More modest shoulder angles or those in the " mid range " of usual choices can work just fine, if neck Lg and subsequent case / cartridge oal still fit the action/load port/magazine well..... IMHO.


With regards,
357Mag
 
Gary you kinda answered your own question. Good barrel, good bullets and good shooter Trumps everything. Pun intended.
 
Arguably the two most precision, and accurate chamberings are the 6PPC and the 30BR. The most common form of both have 30 degree shoulders.
 
I suspect that you might run into payback with regard to efficiency of case forming, case life & case prep down track with the more extreme shoulder angles.

Me, I'm kind of lazy & don't need another issue with my shooting, so ! won't bother to prove or disprove my thesis.
 
Ferris Pindell had a theory about shoulder angle and "turbulence effect", whatever that means. He tried to explain it to me....but..it never did click.

In 2000 I bought his 40 degree PPC tooling and for a few years I shot a couple of variants,the 6-40 dune and the 6-40 Tyger. The 6-40 dune held 3.5 more grains of water than the traditional PPC having a 40 degree shoulder 0.035 beyond the regular PPC neck/shoulder intersection. At a IBS 600 nationals it won a 2nd, 3rd, a 4th and a 5th.

The 6-40 Tyger had the 40 degree shoulder through the PPC body/shoulder intersection. That same year it shot a 0.1430 HV agg.

After Ferris passing when I inventoried his shop and shooting stuff I did not find a single piece of 30 degree brass in his PPC or BR inventory, but a local friend of his had already sold most of the brass for June.

The 40 degree chamberings I did, both with and without tuners, were interesting projects.

In competent hands and a drive to win, I feel the 40 degree PPC would out shoot the 30 degree version, but??

Near the end of that 10 year project a HOF friend told me "either shoot a PPC or get beat by a PPC". Well 99.98% shoot the 30 degree case. What if 99.98% were shooting a 40 degree case??

.
 
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35* is optimum for case life when dealing with long shoulders IME. By "long shoulders" I mean .243Win/22-250/PPC/BR/6CM etc sized cases. Also fat magnum cases in the 30's/338's

40 degrees is too steep for long shoulders as it'll bounce, shoving the s/b radius back before getting enough clearance. The result is casehead separation.

30 degrees works but it can be a pita. Some 30* setups benefit from lubing only the base so that the shoulder can stay locked....not slip. When shoulders slip-, cases grow, the result is casehead separation.

40 degrees works great for short shoulders like 308/30-06/338WinMag and will even hold on a PPC or a 223 but it's marginal...

If one is willing to anneal every reload one can shoot steep shoulders and get away with it for quite a few reloads (maybe 20???)

Anything under 30 degrees is not only poor use of cartridge length but leads to serious sizing problems.

TPE Theory is laughable IMO, a THEORY dreamed in an armchair and drawn on a drafting program......under actual TESTING it means nothing (Witness the WolfPup)

Ablation?-Yes

Abrasion?-Pahhh



opinionby




al
 
The 6PPC and the 30BR shoot pretty good...but it ain't about the shoulder angle any more than it is the barrel. the stock, the bedding, the scope, etc.... With all that stuff to worry about, why would anybody even think of the shoulder angle. I wish it was more simple, but it ain't.

OK, that said, if you had a rifle that shot well, the time, and the money to play around with a different shoulder angle, I suppose you would be doing a good thing.
 
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