Shoulder Angles .......What's good. What doesn't matter?

[350JR]

Ok. Probably a subject that's been beat to death but this forum is the only one (that I'm in that I know won't turn into a flaming war....like some.) I would ask for opinions.....so you are elected by default.

Ignoring the blown out wider shoulder diameters for increased capacity that go with most steeper shoulders ( AI stuff) what is so important about steeper shoulders other than hoping for less case stretch? Anything?

For decades 25 degrees was pretty much the standard on high pressure (magnums) cartridges and most are still in use. Too, there are several in the 17.5-20 degree range still flying off the shelves like the 30-06 and 308 families.

I kinda like the 30 degree angle but it's more "the look" than anything I can put my finger on that FOR SURE makes them any more desirable other than noticing A LOT of target/long range target rounds developed seem to lean in that direction. Kind of makes me go......hmmmm.

The 35 degree........eh, I'm undecided on looks alone and don't see a real technical advantage other than a higher, wider shoulder diameter.
The 40 degree, no offense to aficionados of such, I flat do not like. To me they look like the primer should be a charging socket to charge it up before giving it to a lonely female. ONLY my opinion. I realize they are promoted to stop/reduce case stretch but that's not enough for me to even think about it, no matter what combo of one and shoulder diameter increases capacity. It just won't be THAT much over a 30 degree shoulder, IMO.

It seems the shoulder angle changes and maybe the very small amount of body taper compared to the ol' timers in newer cartridges may just be combinations created to increase capacity........and convince possible buyers "they need one".

The body tapers and shoulder angles of past decades had reasons they were used then and perhaps ONE of the reasons why they survived the decades they have.

I just have to wonder how much of the changes is hype to draw buyers. Not saying it is.......but it does make one wonder.

Opinions are appreciated, pro or con.

God Bless
Steve

 

[SJB358]

Steve, I have no real basis in this, but I think some of the shoulder angle deal is to keep the combustion in the case vs in the throat. I believe some cartridges like the 243 and similar with relatively shallow shoulders will burn a throat faster than a steeper angled case such as the 6mm Rem, Creed and similar.

I have never shot enough rounds to have any of them make a difference. Case taper and positive headspace seem to control case growth for me. I think the sharper the shoulder, the easier it is to get a case to stop growing, but overall, minimally sizing helps with them all.

Not sure that answers the question, but it is my 2 cents.

 

[350JR]

A good point but like you mention, I don't shoot enough to worry about enough erosion to make a hunting rifle inefficient. Others may and target shooter do......but I guess I didn't specify I'm referring to hunting rounds.

Thanks
God Bless

 

[mjcmichigan]

The other thing that comes up is reliable feeding and extraction. I don’t have a strong opinion on that. The H&H, being an early magnum, the taper helped feed and extract. I believe the engineering is better nowadays, which seems to more that make up for the taper advantage on H&H. I don’t hear weatherby guys complaining about the shoulders on Wby cases.


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[truck driver]

No ballistiction here but the 30-06 with it's 17 degree shoulder is the only barrel I have ever shot the throat out of but then I only owned one rifle when I did it and shot the heck out of it.
Like Scotty I believe the sharper shoulders promote better powder burn helping with better ballistics.

 

[gbflyer]

I think, at its most primal level, you hit the nail on the head: increased case capacity.

 

[Dr. Vette]

I’m not home right now to check my latest issue, but I “think” it was Guns & Ammo that had an article on modern cartridge design that finally, to me, showed how some cartridges are “designed accurate” for lack of a better term.

I have never seen proof that a certain cartridge can be more “inherently accurate” than another, and the article showed how it is possible. Now, having said that, I still don’t believe that the majority of those deemed “accurate” by urban legend are’

I will see if I can find it when I’m back, since I can’t find it on the web.

 

[Blkram]

Shallower shoulder angles definitely made for smoother feeding and extraction, and I think that this was important for those cartridge that were destined for use in hotter climates like Africa and India (H&H family) and for military cartridges and firearms that would be fired fast and furiously.

Cartridges with steeper shoulder angles that have been around for awhile now, and are being introduced today touting that they have several benefits that today's shooters seem to be looking for (if memory serves correctly; hope I am getting these right??? I'm no ballistician either! LOL):
- increased case capacity (straighter cases walls and larger diameter cases at the shoulder) = more performance and improved efficiency without the need for longer cases (and actions)
- less case stretching during firing = improved case life and more energy transferred to bullet
- improved headspacing on the shoulder = reduced throat erosion
- improved chamber dimensions = improved bullet alignment from case through throat to rifling = improved accuracy
- improving inherent accuracy/consistency = decreasing the standard deviations in the ammunition thereby mitigating variables/variances in shot-to-shot performance, therefore leading to a more "accurate" cartridge
- enabling these newer cartridges to be chambered in shorter, stiffer actions that flex less during firing = improved accuracy

Definitely seeing feeding issues with some of the sharper shoulders, such as found on the short, fat cases, as encountered with the WSM's and WSSM's (the latter which were not manufactured for very long)

I think some of the other variables that have been improved are assisting in the overall accuracy:
- tighter manufacturing tolerances (quality control)
- improved steels and other materials
- improved powders
- improved bullets (higher BC's)
- improved use of barrel twist rates to better stabilize todays bullets
- improved triggers, action bedding and stock stiffness practices
- and as much as I am not a proponent of longrange hunting, the new fad of longrange shooting and PRS competitions and such, are getting more people to practice on improving shooting form,

And that is a good thing! It improves individuals' knowledge, experience, abilities and confidence, which will improve their marksmanship when hunting

 

[Anonymous]

I think that shoulder angles are largely overblown in the modern era...

Back in the days of long, sloping cartridges like the H&H- they feed smooth but they also extract easily. That was pretty important back in the days that they loaded cases with cordite and the methods for measuring chamber pressures were archaic (at best). With modern powder? Eh, not so much advantage anymore.

The steep angles help prevent case growth, probably a great benefit with 1920s and 1930s brass. Modern extrusion and annealing techniques are very good. Not sure it makes enough difference to worry about anymore.

Shooting hobbyists tend to be preoccupied with inconsequential elements. Quality brass and arms and sane loading practices probably have far more to do with brass life and loading performance than shoulder angle.

 

[30-338]

It hasn't been mentioned but we do have spec 280AI with 40 degree shoulders. We shouldn't have to defend what we shoot and it's shame it's come to that.

 

[SJB358]

It hasn't been mentioned but we do have spec 280AI with 40 degree shoulders. We shouldn't have to defend what we shoot and it's shame it's come to that.

That’s a fact!

 

[truck driver]

It hasn't been mentioned but we do have spec 280AI with 40 degree shoulders. We shouldn't have to defend what we shoot and it's shame it's come to that.

That’s a fact!

It sure is.

 

[350JR]

Arguing about each one is not now, nor was it ever intended to be part of the answers I was asking for. No one should feel any cartridge is being discredited.

We all have opinions on subjects and that's all that was being sought out. No one is attacking any round.

Food for thought though. While the 280 AI IS INDEED a fine round that alone does not indicate that the shoulder angle is directly proportional to anything other than part of HOW the increased capacity was acquired.

The difference in velocity another round would have with the same capacity shot at the same pressure is also moot, regardless of how the capacity was obtained.

There is NO way to quantify that two rifles with different chambers, throats, leades, rifling, lands are "all other things being equal" that is often quoted....... and it's pointless to say "they are loaded to the same pressure" .

SAAMI themselves states in the pages before the specs that other rifles are not guaranteed to have the same results as what they got in the test rounds sent to them to quantify, for those very reasons NOT TO FORGET they also have a list of "possible errors" that include, but are not limited to, machinery wear and human error.

It's not uncommon to read where a person has two rifles of the same SAAMI chamber and sometimes even by the same mfg........that do not and cannot produce duplicate loads with one showing high pressure considerably before the other.

With identical loads in 100 rifles, clinically tested with 100 different sets of equipment by 100 different technicians would not, and simply cannot all be identical.

It's common knowledge that all powders used vary lot to lot alone. Quickload puts a number on it at 10 percent plus or minus anything the program puts out.

That........is a lot. I personally view the results from QL......AND all load data published to be a "shotgun approach". While we are AIMING here......it can fall within a spread "from here........to here". My rifle, your rifle, ......brass, primers, powder, neck pressure......etc etc.......are unique within themselves. I consider to approach loading for a single rifle (RECALL.....if you will, that ALL load data was calculated for being safe in ALL rifles, EVER made, in ANY condition......of that cartridge.) as anything other than unique, almost makes handloading......pointless.

Each has their own opinion and this is a good thing. To indicate that one person's opinion is always correct is not, nor can it be so. Way too many things change velocities gotten let alone what we assume our chamber pressure may be.

Handloading ..........is a fickle beotch. Things can change with the slightest of reasons.
To ARGUE A is better than B....is pointless and moot as both are simply the opinion of each party.

Kind of like arguing about a certain wall in the news and the effectiveness of such should it come to be. :wink:

Please don't let this become anything but what my post was......a request for opinions and, if desired, why the poster believed that to be prevalent.

God Bless
Steve

 

[Blkram]

All I know for sure is that I like a cartridge and a rifle that feeds smoothly and reliably, at all times, under all conditions!
It is definitely frustrating when it doesn't, in the field, when you need it. I especially do not want it to happen when dealing with a problem bear, or large, tough game such as elk or bison, or a big, mad bull moose. If I need to make a follow up shot for any reason, it has to be there!

If a shallower shoulder angle assists in this regard, then I am all for it!
Had a Marlin 336 in 30-30 jam on me one time, and my Model 88 in 338 Federal is having feeding issues, but I believe both of these were related to the rifle and not the shoulder angle.
Turns out the feedrails are very different between the Model 88 308 and 358 Win, and we are currently looking to remedy this.

 

[lhsako]

It's mostly about marketing/sales.......

 

[preacher]

I've had feeding issues in Mod 700 short actions and in the Model 7 with the 40 deg Ackleys ( 6.5x284, 6mmx284, 22-250 AI) never with the LA in .375 Weatherby ( venturi radius helps I'm sure), 340W, 35 Whelen AI, 30-06 AI, .280 AI. I feel like the sharper shoulder "holds the powder column" in the case a Nano-second longer, resulting in a better burn...but I can't prove it! I also never had a problem with the Marlin 336 in 30-30 AI, and it was a shooter. Of course, all the "Improved" sharper shouldered rounds are loaded to higher pressure, usually.

 

[preacher]

I've also had ignition ( headspace issues) with only two sloping shoulder rounds...the .404 Jeff and the 9.3x62 (both with factory ammo, though of High Quality). Never with the 35 Whelen standard factory ammo ( as is often mentioned about it in writing) and only one .338 winmag in a Mark II Mod 77. Go figure.

 

[filmjunkie4ever]

My experience definitely pales in the face of many if not most here, though I do have much experience with a handful of cartridges and here is my $0.02:

I have found that accurate rifles can be built in virtually any action, cartridge or barrel length as long as the barrel is properly cut, throated and mounted, the bullets are concentric and the assembly of the cartridges is consistent.

I feel like the slope of the case and the shoulder is of little consequence as long as the three above mentioned variables are properly controlled.

I’ve fired rifles in virtually every case configuration, to wit: rimless, semi-rimmed, rebated rimless, rimmed, belted, straight wall, bottleneck, double radius, etc. and have seen winners and losers in all different shapes and sizes.

But whenever someone does a good enough job of marketing their reinvention of the wheel, it sells more guns and that’s a good thing!


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[Brinky72]

No expert but I’ve heard all sorts of reasons for both. I’ve heard that body taper and gentle shoulders have been better for function and feeding especially when in regards to under stress and in semi automatic and full automatic rifles. Oddly the 6.5 Creedmoor has been brought onboard by special operations with its sharper shoulders and lack of body taper. Also heard that sharp shoulders and minimal body taper helps with better bore alignment and resultant accuracy. I’ve seen some pretty darn accurate examples of the opposite. 300H&H comes to mind and the 338 Lapua doesn’t look like an improved case to me. I’ve owned a bunch of 30’06’s and they’ve all been accurate and needed little to no case trimming. I also have a Creedmoor and a 280 AI that I’ve ran rounds through as fast as physically possible without a hitch. Above my pay grade I guess.

 

[Blkram]

In the latest edition of Outdoor Life's The Adventure Issue, Dave Emery writes about this in the Shooting Column: Cartridge Design titled Elements of Modern Cartridge Design.
Interesting article.
Might help.