Pressure of unknown loads?

Cherokee_Jon · Member Joined: Dec 16, 2008 Posts: 26 Location: PA

How do I determine the pressure of unpublished loads without a test lab? I'm wanting to develop loads for a modern made 44-40 guns, which has very little loading data published.

PaulS · Posted: Tue Dec 16, 2008 2:02 pm Post subject: Re: Pressure of unknown loads?

There is no way to determine anything more than approximate pressure levels without a ballistics lab.
Modern made gun - is it a Euger or Thompson? If so you can use the data developed for those firearms. No other firearm that I know of is built for higher than "normal" pressure loads. All of the normal pressure indicators are unreliable at best and at pistol pressures can be dangerous. I have extrapollated loads for smaller straight wall cases that have been usable but I always am very conservative when doing so and they are used in guns made for much more pressure. (ie: 38spl in 357 mag)

Cherokee_Jon · Member Joined: Dec 16, 2008 Posts: 26 Location: PA

Older made firearms chambered for the 44-40 were made with lesser metals. Also the barrel diameter is .427 for these firearms. Older made firearms = prior to 1950. 3rd generation Colts, Rugers, Marlin rifles, and Italian made reproductions are .429 (most of the time) and better metals. Speer, Hornaday, Lyman and others have data based upon the older made firearms. Also the data is about a limited number lead bullets, not jacketed bullets. There a large verity of 44 bullets sized .429. The published data also has a limited verity of powders to chose from. The 44-40 case is conservitively rated for 13000 CUP. I'm hoping there is burn rate charts and other data on powders that will give me therological pressures.

Pumpkinslinger · Posted: Tue Dec 16, 2008 4:39 pm Post subject: Re: Pressure of unknown loads?

"Modern Reloading, Second Edition" from Lee has cast and jacketed bullet loads for the .44-40. "Handloader" magazine might have some info too but you'd have to search it.

There is no way to calculate peak pressures, you've got to measure them. There are some ballistic programs that can estimate them but I haven't used one yet.

Personally I'd stick with published loads and not try to "magnumize" it. If you want a .44 Magnum type cartridge get a .44 Magnum! Years ago a buddy of mine tried to push the .45 Auto into magnum territory, thinking he was safe because the carbine he was shooting was a strong action. I still have some of the blown brass from that experiment and distinctly remember picking shards of brass out of another friend's arm. I can't remember if we ever found all of the magazine parts...

Cherokee_Jon · Member Joined: Dec 16, 2008 Posts: 26 Location: PA

Thanks everyone for the info. I've already done a load and test fired it without incident. There does not appear to be data for a 180g JHP and Tightgroup powder. Are there any visual signs on the cases that might indicate high pressure or possible case failure from high pressure?

gelandangan · Posted: Tue Dec 16, 2008 5:11 pm Post subject: Re: Pressure of unknown loads?

On bolt action, you can feel the bolt lever getting a bit harder to lift.

On the primer, you can maybe see how the pin crater overflows if pressure are too high..
Some primer cup are softer than the other (Federal primers are very soft)

You can also mike the case head for any minute expansion between two parallel filed edges.
Any expansion on the case head at all means that your pressure is too high.

Best of all is if you can get a strain gage installed on to your rifle.
Shoot a few known loads for calibration, then shoot your proposed load in ascending order.
There is coefficient of expansion (Youngs Modulus) you could use to determine the pressure in scientific way.

I shoot wildcats calibers where there are very little published loads.
I have to learn in a hurry to watch for the pressure signs.

Cherokee_Jon · Member Joined: Dec 16, 2008 Posts: 26 Location: PA

Thank you very much. That's exactly what I need to know. I do not have $800 for a personal pressure lab. The firearms I'm using can withstand about 60% pressures of a 44 Mag. (30,000 CUP), but the 44-40 case can only do 13,000 CUP. If I monitor the cases I should be able to develop an effective load within the capabilities of the case.

SingleShotLover · Posted: Wed Dec 17, 2008 7:48 am Post subject: Re: Pressure of unknown loads?

It looks like you realize that the weakest link here is the case itself. 44/40 cases are very thin compared to more modern rounds and can't take much more than standard pressures. Adjust your dies for as little sizing as possible for function...case heads are known to separate with very few loadings even with mild loads and minimal sizing.

Cherokee_Jon · Member Joined: Dec 16, 2008 Posts: 26 Location: PA

I've loaded (about 30,000) 165g LFN with 6g Unique or 7g Trailboss for CAS for the past 4 years. I've rarely had a split case with *-* brass. RP & Win. is another story. My wife only shoots CAS and knows her '73 very well. I'm trying to develop a hunting load for her. The 44-40 works very well in brushy areas and ranges less than 100 yards. I'm thinking a 200g JFN going about 1300 FPS out of a 24" barrel is about right. I currently have several powders, but most of them are for regular rifle (30-30, 308, 30-06 ect.).

PaulS · Posted: Wed Dec 17, 2008 3:00 pm Post subject: Re: Pressure of unknown loads?

If this was a modern bolt rifle you could do a lot of things but the pressure signs that affect cartridges and primers are well above your pressure limits. That case will not split until it gets brittle or the pressure is high enough to expand the chamber beyond the elasticity of the case. Basically if you can't get at least ten reloads from a case your pressures can be dangerous. The problem there is that it might blow the gun apart on the third load ot the 3000th load.
I wish you the best.

SwampFox · Posted: Wed Dec 17, 2008 4:11 pm Post subject: Re: Pressure of unknown loads?

Jon,
Once in a while I have occasion to check my old edition books, this is one of those occasions:
Lyman 1964 Edition #43
44-40 Rifle (do not use baloon head cases)
200gr JFN
start max
2400 25gr 1870 ---- 27.5gr 2100
4227 27gr 1850 ---- 29gr 1990
4759 14gr 1525 ---- 18gr 1625

205 Cast Plain Base FN
Unique 11.3gr 1525
2400 22gr 1530
4227 24gr 1600
4759 13.7gr 1300

I hope this gives you some ideas for hunting loads for your Mrs. In an old style lever gun, Marlin or Winchester, the pressure indications are a bit different than other guns. The first thing to watch for is the lever dropping, unlocking the bolt when fired. The lockup on these old guns or designs is weak and a high pressure load tends to spring the bolt open, thus causing the lever to drop. All other indicators apply but, whatch the lever it is usually the first sign.
Best,
Ed

Cherokee_Jon · Member Joined: Dec 16, 2008 Posts: 26 Location: PA

I'm going to plan a hunting trip to a good used book store for older reloading manuals. I'm out of Unique, but I have Titetgroup, so I chose 7g as an educated guess being equal to 8g of Unique (newer Lyman #48). Lyman #43 has a 205g lead bullet @ 11.3g of Unique, which brings up the question of how does lead compare to jacketed? Does the pressure depend on the weight of the bullet or does its shape make a sizable difference, or combination or both? I'm still on the learning curve with unpublished data. Following instructions are much easier.

ElyBoy · Posted: Wed Dec 17, 2008 9:59 pm Post subject: Re: Pressure of unknown loads?

Jon,

If I were you, I'd give a PM to Handloader.

He has helped me a lot in the past, and has many, many years of experience with the 44/40 and many other calibers.

Eric

1895ss · Posted: Thu Dec 18, 2008 1:23 am Post subject: Re: Pressure of unknown loads?

SwampFox wrote:

Jon,
Once in a while I have occasion to check my old edition books, this is one of those occasions:
Lyman 1964 Edition #43
44-40 Rifle (do not use baloon head cases)
200gr JFN
start max
2400 25gr 1870 ---- 27.5gr 2100
4227 27gr 1850 ---- 29gr 1990
4759 14gr 1525 ---- 18gr 1625

205 Cast Plain Base FN
Unique 11.3gr 1525
2400 22gr 1530
4227 24gr 1600
4759 13.7gr 1300

I hope this gives you some ideas for hunting loads for your Mrs. In an old style lever gun, Marlin or Winchester, the pressure indications are a bit different than other guns. The first thing to watch for is the lever dropping, unlocking the bolt when fired. The lockup on these old guns or designs is weak and a high pressure load tends to spring the bolt open, thus causing the lever to drop. All other indicators apply but, whatch the lever it is usually the first sign.
Best,
Ed

The thing to remember with lever guns is that LONG before you get to the most common indicators such as flattening of primers etc, you have crossed the safety margin. I agree with Swampfox, and another indication is that if you try to eject a spent cartridge right after firing and it is stuck in the chamber, you're loaded way too hot.

SwampFox · Posted: Thu Dec 18, 2008 7:11 am Post subject: Re: Pressure of unknown loads?

Jon,
With regard to handguns in general and your specific gun as subject. Considering lead VS jacketed bullets one should take three things into consideration, one, jacketed bullets tend to produce higher pressures to attain the same velocity as a cast bullet of the same weight. Lead is softer and is lubed thus has less resistance in the bore. Second, a jacketed bullet will attain a higher velocity than a factory made lead bullet, without leading. However, some hard cast, especially heat-treated cast, with a gas check, can attain similar top end velocities to a jacketed bullet. Third, a plain base cast bullet cannot be driven to the same velocity as a gas checked cast bullet given that the two are the same alloy and using the same lube.
Best,
Ed

PS: At a nominal velocity, such as you are looking to develop, you are close to 44mag handgun velocity. The 44 is notorious for not expanding but having excellent penetration, like 100% on a deer. Thus you could well use a hard cast GC bullet in the 44-40 and achieve the exact same result as the 200 JFP.