Thread: Wilcats and Pressure

I want to make the point in starting this thread that its intention is to not turn into a brawl or a dick waving comp as to whos right and wrong, but to discuss a topic that comes up on occasion with 'he said, she saids' more than actual facts

SAAMI pressures are set from loads submitted to them for approval as to ascertain standards for safety, interchangeability, reliability and quality.

The issue comes when new wildcat calibers are formed, either on new cases and less so on existing designs that have been necked down or up etc
What is the max pressure?

You can use DIY or 'laboratory' gear like strain gauges to obtain a number -we've had the discussion of the downfalls of the units before - and I will draw note to the fact that the Oehler that 'some' hold as the be all and end all - isnt even made anymore - also given the fact there is no way to calibrate the unit and also inputting the correct data as to tensile strength of the material as to get a accurate hoop strain leaves room for many errors (bead blasting a barrel will change the SURFACE hardness but not the true tensile of the material) the whole system leaves alot to be desired.

We are then drawn to the fact that 2 very similar guns, Mr A can get XXX out of it, and Mr B cant
Mr A keeps his mouth shut as to what, how etc he is doing to get XXX, but B will state the pressure is too high based on his results, which is entirely fine.
Mr B has hit the limit with his combo, but Mr A still has room to move for more powder if needed.
Thus a pressure of 'Max ZZZ' is quoted - yes maybe for Mr B, but given that there is NO SAAMI pressure, these are custom cases, in great big thick actions etc, is THAT the pressure, and how do you quantify it given the fact the Mr A is 'maybe' higher, or 'maybe' lower and just doing something different that everyone else hasnt picked up on.
Where do you call it quits and Max? when primers puke, brass is trashed, bolt has to be hammered open, or you pick a number like 87654 psi?

I spent a few hours the other week, measuring, cutting open cases, firing etc a caliber/load that is said to be 'way over pressure' by someone else shooting it.
5 firings on a cases that hadnt been full length sized EVER, and would still chamber, brass that had no measurable differences from virgin other than 2 1/10s of a thou as to be expected (I can drive a mic) no extractor or ejector signs, perfect primers - without pressure gear, if you were loading any run of the mill case - you would say was PERFECT.
The shooting of this caliber at range, using 2 different ballistic programs show the projectile was actually a little faster and or better in BC than already expected

If I build an action out of 4" round a run a custom case with meat in all the right places; which has no SAAMI data, and achieve results that dont hurt the brass, primers etc and the gear says (to make it simple) 100,000psi for eg, is that too high, or is that now an acceptable pressure for this new caliber?
The action isnt ever going to fail and the brass is built like a tank - so where do we stand now?

When you;re pioneering something new, who is right, the guy at the front of the pack with the best results/performance or the guy that hits a brick wall?
Maybe those at the front of the pack have a few tricks up their sleeve? I know that I learnt a few in the time I played around for my own interest - things that I would have never have considered, thought of or expected, but were proven in black in white behind the butt.

I came across something very similar recently online on another caliber I have interest in (big bricks out of an AR). Astronomical performance, and those that cant get there.

Soooo... you invent some new fangdangle case - whats the limit??

Is it me or reading that you just want a arguement??

If you're getting a speed you're happy with, and not piercing/flattening primers or have "sticky" bolt lift, destroying cases, stretching primer pockets etc, then that's enough

Who cares what the "actual" pressure is at that level? There's no downside to it if none of those things are happening

Originally Posted by Spanners

Soooo... you invent some new fangdangle case - whats the limit??

So for me, the limit (on anything, not wildcats 'cos fuck them) is where shit that is inconvenient to me starts happening, ie, the above things.


Different in a semi-auto or lever action - I'll just stick with book max to be sure.

Read the 1st paragraph and the last 2 lines

I have a genuine interest in all things guns and especially old ball stuff and the point is with odd ball stuff what is right and wrong, how and why is this conclusion come to?

I'd be more concerned about bolt locking lugs under excessive pressure and possible damage to the bolt or action from lug set back.

Plenty of articles floating around on the subject by reputable people.

no point spending big $$$ on custom actions and action blue printing if after 100 shots the bolt lugs are not engaging evenly.

Note that I'm not saying that this is likely to happen to any particular rifle or load discussed on this forum.

Simply saying in response to your post above that it's well documented and as bolt lugs are typicaly harder than an action, it's an easy way to kill an expensive new rifle. (if you believe the experts )

On standard action yes - but what about a big fuck off custom action ?

I'd pick that the bigger harder lugs will make bigger fuck off marks?

Yes I'd say 100k pressure is very safe in a big fuck off Barnard PChey action.

If you've got high enough pressure to do that, surely your brass is going to be showing signs first

100k was just a number that was even and plucked out of the air. orgianlly had 200k but is fantasy numbers. NOT saying anyone is shooting it but who/how do we/they/anyone ascertain what is safe or acceptable in an action and case combo that there is no standard for?
What if I soak projectiles in goat piss for a week and it makes them shoot 100fps faster than anyone else due to some chemical reaction - thus bar is raised.
Is it now unsafe because the speed I get is faster than the norm?
The bar is now raised as I have a secret sauce ....

Originally Posted by gimp

If you've got high enough pressure to do that, surely your brass is going to be showing signs first

You would think so but according to the articles apparently not.

well there you go


just another great reason not to bother with wildcats!

Simple mechanics says low tensile will fail before higher.

which = brass


What if the brass is held by the action so it can't fail


stronger action, less elastic deformation, brass can take more pressure??? I don't know anything about this.

Pressures, Case Strength and Back Thrust