revolver excessive pressure signs

[oley55]

Base question, when working up a load for 44mag revolvers, what are the over pressure signs?

A little background. I have a Rossi R92 SS 24" 44mag rifle with a very generous bore. I found some .431" 240 gr JSP bullets for it and have developed a fairly accurate load for it (consistent 3" at 100 yds with Marble tang sight).

I would like to be able to carry the same ammo (.431") for the Rossi R92 and my Ruger Red Hawk and/or Dan Wesson 44mags.

I'm fairly confident with identifying over pressure signs for a rifle cartridge, but am in doubt in regards to revolvers. With ,429" being the standard, I am concerned the .431" bullets will increase pressure. What are the signs of excessive pressure in a revolver?

[USSR]

oley55,

Unlike rifle cartridges, there are no reliable tell tale signs of over-pressure that can be read on handgun brass. The best you can do is follow published load data and run your ammo over a chronograph to establish that velocities are as expected.

Don

[dahermit]

Cases sticking in the cylinder...difficult to extract.

[FITASC]

Flattened primers, and of course - a blown cylinder or topstrap.

[oley55]

a blown cylinder or topstrap.

well yea, that would be a definite sign, or so me thinks.

[HiBC]

Have you verified the handgun groove diameter is 429?

And,there are the cylinder throats. You have to be able to load your ammo into the cylinder. If the cylinder throats are anything less than a clearance fit on your 431 bullets,how will you load them?

See if the 431 bullets will pass easily through your cylinders.

Agreed sticky extraction is a "back off" sign.

Slug the bore of your handgun. That's the start point.

From there....I'm not really qualified to tell you what to do. Maybe Unclenick can help you.

Your seat of the pants opinion is probably as good as mine,without data.


The "blown cylinder/top strap" might be a bit dramatic for your situation.

Though it might be the first "pressure sign" to show up in some revolvers.

Generally speaking,the dubious practice of "reading pressure signs"is best confined to modern bolt action rifles or equivalent. "Pressure signs" as most folks understand them come on at pressures exceeding the normal 60,000 psi + for modern bolt rifle cartridges.

[mehavey]

About the only sign is the pressure being sufficiently great to elastically expand/stretch the cylinder radially, which when it recovers, traps the similarly-expanded case and makes it more difficult to push out with the ejector.

Not only a pressure sign (which is different for each different make/model revolvers), but a practical limit as well as it affects your ability to reload quickly.

[USSR]

The trouble with "sticky extraction" from a revolver cylinder is, when it happens you are WAY beyond pressure limits.

Don

[mehavey]

It will come on gradually -- and in one or two specific/weaker cylinders at first -- as you increase charges.
There should be no sudden-cliff surprises.

[dahermit]

I remember one (or possibly more) of the handloading manuals stating: "Use factory cartridges for maximum or near maximum loads." It is advice than many seem to forget.

[oley55]

HiBC, good points on cylinder and barrels sizes. I knew all that but I was having a brain cramp or something. I've previously slugged my barrels and reamed cylinder throats for the purpose of firing bare lead.

My Dan Wesson is fairly tight (all cylinders .4299", barrel .4278" and accommodates most off the shelf lead bullets with minimal or no leading, but it will never accept these .431" JSPs.

The Red Hawk is considerably more generous, (throats .4326-.4327", barrel .4303"). Never bothered trying to shoot lead through it because I didn't have the appropriately sized lead bullets. That said, the Red Hawk ought to easily handle these .431" JSPs, and will hopefully match up with the Rossi R92 lever gun.

Guess I need to get my hands on a chronograph.

[BBarn]

Originally Posted by dahermit

I remember one (or possibly more) of the handloading manuals stating: "Use factory cartridges for maximum or near maximum loads."

I don't recall reading that in any of my manuals, but I can certainly understand the potential benefits of following that advice. Makes me wonder how often the factories pressure test their ammo.

[dahermit]

Originally Posted by BBarn

I don't recall reading that in any of my manuals, but I can certainly understand the potential benefits of following that advice. Makes me wonder how often the factories pressure test their ammo.

That is because it is likely that you do not go as far back as I do. Elmer Keith was still alive, shot sells were paper with cardboard wads, and I was using P5066 powder in a $40 War time P38...so I have read a lot of loading manuals.

[HiBC]

The Red Hawk is considerably more generous, (throats .4326-.4327", barrel .4303"). Never bothered trying to shoot lead through it because I didn't have the appropriately sized lead bullets. That said, the Red Hawk ought to easily handle these .431" JSPs, and will hopefully match up with the Rossi R92 lever gun.

Seems to me you found your answer. The 431's won't load in the Dan Wesson cylinder.The Redhawk groove diameter at .4303 is,IMO,not an issue for 431 bullets.But you have to make that choice.


I do not have a source to prove it,but I think your Redhawk is at least as strong as your Rossi 92.

[jetinteriorguy]

Another sign is if the primers are popped out and dragging on the frame so the cylinder doesn't rotate smoothly or won't rotate at all. I may be wrong but I believe what happens is the case will stick to the cylinder just enough to prevent it from moving back over the primer and reseating it. Now this is just my theory based on an experience I had where I ignored this situation and wound up blowing up my favorite gun. I attributed this to loose primer pockets and lacking the proper tool for checking my primer pockets I just tossed the previous cases that were doing this in my recycling bin. Upon blowing up my pistol, I dug them out and purchased a tool for checking primer pockets and discovered they were plenty tight. Now, I may be wrong in my thinking and if anyone has a better idea I'd sure like to hear it.

[buck460XVR]

Originally Posted by FITASC

Flattened primers, and of course - a blown cylinder or topstrap.

Flattened primers in a revolver do not tell you anything other than the round went off. While primers that are extremely flattened are a sign of a high pressure round, it does not indicate excessive pressure. Sticky extraction is a better sign and if my cylinders are clean and polished, I will always back off until extraction is better.

With jacketed bullets, diameter is not that critical. I'd be curious as to which jacketed bullets you have that are that oversized. If their diameter was to make that much difference in pressure, I'd be curious as to why the manufacturer would do it.

Rifle bores in .44 are generally larger than in revolvers, especially with levers because manufacturers are concerned about hot revolver loads creating excessive pressure in the longer barrels and without a cylinder gap to vent gas. Still, with jacketed bullets of standard size, they still shoot accurately.

[oley55]

Buck. yea the bore on this Rossi is very generous (.4328"). So much so that an appropriately sized and loaded lead bullet would not even pass between the guides. No doubt .429" would run in it, but the twist is so slow (1/33) that I felt a tighter bullet would give me higher FPS allowing me to confidently reach out to 100+yds without keyhole concerns and acceptable accuracy. Which they do.

I also have a 24" Rossi in .357" with a normal barrel and am able to push 185gr GC lead bullets with some pretty stout H110 loads and superb accuracy. Although attempts to use IMR4227 resulted in significant key holing, regardless of load. Who knows why.

I buy these .431" 240gr JSPs from Everglades Ammo in Naples Florida. No clue who/why they are manufactured, but I love them in my 24" Rossi R92, and am hoping to used the same load in my Red Hawk.

[mikld]

Flattened primers in a revolver do not tell you anything other than the round went off. While primers that are extremely flattened are a sign of a high pressure round, it does not indicate excessive pressure. Sticky extraction is a better sign and if my cylinders are clean and polished, I will always back off until extraction is better.

buck460XVR

I agree. IIRC from my "revolver 'smithing" research a round fired in a revolver, the case slides back against the recoil shield and often "flattens" primers. Quite often when any "signs" appear, the load is over safe max. anyway. Harder extraction is one method for recognizing loads nearing max. levels. When I was really involved with looking for high pressures I measured the case heads before and after shooting. More than .001" expansion indicated my loads were getting too hot (when I first started reloading for my 44 Magnums I had a full blown case of "Magnumitis", and nearly every load was approaching, and some reaching max.).

FWIW; when I got my Puma I slugged the barrel and got .432" slugged diameter. I almost sent the rifle back, but found the SAAMI spec. for 44 Magnum rifle is different than handgun (.431" vs .429")...

[TX Nimrod]

Judging handgun pressures by looking at the primer shape is a fool’s errand. Hornady pointed that out decades ago in their manuals, showing photos of primers fired at low, factory and excess measured pressures; they all looked the same.

Protruding primers are a sign of low pressure, not high pressure. Flattened primers can be an indication of excess headspace, not pressure. Sticky extraction can happen at factory pressures in rough chambers. The safest method is to forget trying to guess and use pressure-tested data from reliable sources. Yes they may vary, but they are a guide. An extra 100 fps is meaningless in most cartridges.


.

[Unclenick]

It is correct that primers are simply not a reliable indicator in a revolver. I've seen loads that were getting sticky in a cylinder (immediately stop shooting loads that do this and back your load data down at least 5%) that showed no problem on the primer. I've also seen primers that flattened and I think the gap between the recoil shield and a loaded round pressed forward into the chamber by the firing pin is probably a contributor. The primers all back out during firing and subsequent pressure forces the case back and reseats them, as we know from low pressure rounds leaving the primers sticking out. If they have to back out very far, the chamber pressure coming back through the vent can mushroom the primer cup and the head of the mushroom then is flattened when the case backs up.

Jetinteriorguy,

Yours is the first case I've heard of where backed-out primers were a revolver high pressure sign, but I think your explanation is plausible if the balance of the timing is right. But another explanation would be the whole frame stretching forward and taking the case with it. Pressures would probably have to be in the 40,000 psi + range. Thinner cylinder wall revolvers would never get there, but probably could not show your symptom anyway.

[FrankenMauser]

If you're using pistol primers, flattening can be an indicator.
But if you're using rifle primers (not advisable, but some people do it), you won't see pressure signs until you're well beyond max pressure.

[T. O'Heir]

Pressures for rifle .44 Mag jacketed bullet loads and revolver are not different. SAAMI spec is the same. Hodgdon shows 20" rifle loads running 36,100 to 38,500 CUP with exactly the same powders with exactly the same loads for an 8.275" revolver. Nowhere near the number of rifle loads tested.
Neither are the primers any different. Same primers used by Hodgdon.
"...would like to be able to carry the same ammo..." The issue is accuracy and the barrel diameter. It's unlikely you'll find a load that gives adequate accuracy out of a 24" barrel and your revolvers. I think I'd load for the revolvers and try the load in the rifle. Mind you, revolvers rarely if ever use a .431" bullet. And a .429" is too small for your rifle. Probably be ok with a cast bullet though.

[HiBC]

Mr Oheir: The groove dia for his Redhawk is .4303. Cyl throats are .4326 to .4327.
Which means the there is very little difference with the Rossi 92's bore.

I would not be able to find it today,but I used to have a Lasercast loading manual.

They listed handgun .44 Magnum loads,and they listed Win 92 level rifle loads.

They actually cautioned against assuming the 92 rifle could take more pressure than pistols made for the 44 Magnum.

Due to the spacing of the mag tube and barrel,the walls of the barrel shank will not be overly thick as the barrel shank thread diameter is limited in size.

Along with that,the actual barrel OD is limited. Now remember,there is usually a rear sight dovetail cut across the barrel.

I'm not saying the 92 Win design is not up to the 44 mag,its just a mistake to assume the Redhawk is less strong. If anything,its the rifle that needs you to "go easy".

Lets not forget the Redhawk handles 454 Casull and ,475 Linebaugh.Pressures get up to modern bolt rifle levels.

I know the Rossi is made in 454,and I can't prove it,but I suspect the Rossi would fail first.

One other FWIW,Hogdon;s 8 in bbl handgun data is usually taken from a test barrel with no cylinder gap. I figured out long ago the velocities shown were a bit optimistic for my SBH. Cyl gap has some effect on pressure and velocity.

I just shot the same load in both guns. The fun load was a 300 gr Lasercast TC. Flying hammer! IIRC,i got 1300 + fps out of my SBH with H-110.

5 in bbl at that!

[SHR970]

A friend of mine has a S&W Model 27 that bulges the head area of brass even with 38 Special loads. It does it in all chambers. If you were to "read" standard accepted pressure signs you would think that just about anything fed to it was grossly over pressure.

Back in the Day Fed. 200 primers were known as "Small Magnum Pistol / Small Rifle Primers". Don't believe me... check out Hornady #4 Vol. 1 pg 26.....it was no typo as the Fed. boxes said the same at that time. They showed overpressure signs well before CCI, Rem, or Win Small Rifle primers did.

Is your brass sticky or not? If it is you hit your limits and then some in handguns.

[USSR]

I'm not saying the 92 Win design is not up to the 44 mag,its just a mistake to assume the Redhawk is less strong. If anything,its the rifle that needs you to "go easy".

Actually, the Winchester Model 92 of current manufacture is an exceedingly strong action. Any .44 Magnum you can safely put in a cylinder it will easily digest.

Don