2400 in a 22???

[uscra112]

One of my first projects with my then-new interior ballistic software was to try to figure out what powder .22LR High Speed ammo is loaded with. My conclusion, such as it was, was that it's close to Herco, based on pressure required and volume of powder extracted from cartridges I pulled down..

Would I ever try to reload .22LR hulls? Not on yer life.

[Traffer]

The fast pistol powders generally only need one grain of powder to get near maximum. Be warned!

[uscra112]

??? Get a grip, there! I didn't consider the visual appearance of the powder into account at all. Only the weight and volume, and pressure as inferred from the resultant velocity.

I then used Quickload to build a model of the .22 LR cartridge, in which I tried various powders from their database until I found one that fit the observed parameters. The closest was Herco. I didn't say it WAS Herco, only that Herco fit the parameters best.

I at least used a little scientific method..........

[rking22]

Out of curiosity, what chamber pressure did you use with the quick load query? I Think I remember reading that 40,000psi was correct for 22lr hi speed. Many moons ago, so ????

[uscra112]

There's been some wild claims about .22 LR pressures. I kinda "backed into" a pressure by letting QL calculate the pressure necessary to get the observed velocity. You can do this for any cartridge; it turns out that the size of the case matters only a little. Which makes sense, since Newton showed us that deltaVee=Impulse/Mass everywhere in the known universe. Or, using simple algebra, Impulse=mass x deltaVee. The actual value of Impulse in interior ballistics is integral calculus, since it is the area under the Pressure-Time curve.

My original pressure calculation used the model for the .22 Hornet that's already in their database.

In QL you can build your own dimensional model, length, diameter, volume, etc. of a cartridge, which I then did. Measuring the actual water volume of that tiny .22LR case is tedious. I had to use a medical syringe to get the cases exactly level full. A meniscus, positive or negative, throws the measurement off significantly. I did it ten times and took the average. Used a Pact digital scale to do the weighing.

You also have to build a dimensional model of the bullet, which a bit tricky, because the model doesn't allow for heeled bullets, only boattails, so I had to approximate a little there.

All done, using best judgements to fill in the parameters, the typical pressure for High Speed with 40 grain bullet is more like 14,000 psi, and nowhere near some of the claims that have been made.

Subsonics are more like 10,000.

I have not adjusted the model to cover the hypervelocity .22 rounds, (i.e. Stingers). They use a longer case and thicker brass, which means another fussy job of measuring actual volume. Fudging it, by just using the LR case volume, a 32 grain bullet, and assuming that the claimed 1640 fps is out of an 18" barrel, the pressures might be about 20,000, but that's got a higher error bar than my LR calculation.

All this was done in an attempt to get a value for bolt thrust of the .22 Standard Velocity, which I wanted to know so as to judge whether some of the old "boys' rifles" would be safe when converted to .32 Long Colt centerfire.

[rbuck351]

I would suspect that the longer, thicker case is necessary to safely get more velocity from the 22lr. As many different manufactures that have loaded 22lr over the last 100+ years, I think one of them would have found a solution for a faster 22lr in the standard case if it was possible. They obviously tried and found the Stingers longer thicker case to be necessary. Nothing wrong with trying, just be safe doing so.

[uscra112]

Of course. I've tried the dodge of making .25 Stevens rimfire by reforming .17 WMR, and found that the .17 WMR brass is made so thick and hard, so as to contain the pressure, that most of the lightweight boys' rifles that I wanted .25 ammo cannot fire it. Hammers and springs too light.

Going the other direction historically - blackpowder .22 cases were not even brass. They were copper. The WW2 enterprise of making varmint bullet jackets from .22 cases depended on this fact. Copper cased .22 ammo was still being made into the 1930s. "Acorn" blanks used by dog trainers are copper today.

BTW the longer case used for Stingers is I think meant to get the ogive of that tiny bullet closer normal sporting rifle chamber throats, to improve accuracy. Ironically that extra length precludes their safe use in tight "target" chambers, because the brass actually gets squeezed in their shorter throats, which can cause overpressure conditions to occur, possibly bursting rims. At least that's what the mavens at Rimfire Central say.

[M-Tecs]

Out of curiosity, what chamber pressure did you use with the quick load query? I Think I remember reading that 40,000psi was correct for 22lr hi speed. Many moons ago, so ????

SAAMI is 24,000 PSI

https://saami.org/wp-content/uploads...MI_Rimfire.pdf

[Chev. William]

SAAMI is 24,000 PSI

https://saami.org/wp-content/uploads...MI_Rimfire.pdf

That is the Pmax MAP SAAMI lists.
It is NOT the Impulse value as stated by uscra112.
There are Other Limit Numbers involved also to take into account production variations in cases, Propellants, Primers, etc. and the Actual Peak pressure can be higher than the Pmax MAP without incurring damage. the Integrated value of Pressure-Time curve(s) will be a result in a Pressure equivalent lower than the Peak or MAP Values.

Oh, by the way, the QuickLOAD (QL) water volume of the .25ACP case is LOW! I found it has to be increased to get QL calculations to match Hodgdon loading data for the powders specified by Hodgdon.

I expect the Same applies to any straight walled case, .22LR included.

Chev. William

[uscra112]

Quickload didn't have anything at all for the .22LR case in its' database. As stated, I had to construct a model of it myself. The volume I determined by the tedious water-weight method. I know of one other instance where we found the database volume not to coincide with direct measurement, and it was a straight-wall case, but I rather doubt that there's any systemic bias to the case volumes there. Still, proper scientific method requires that you verify all the input parameters yourself, insofar as you can. By actual measurement, not by tweaking inputs until you get an answer you are more satisfied with. That's how the global warming hoax has been operated for the last 30 years.

As for the 24,000 psi max pressure. You CAN get the QL model to calculate 24,000 peak pressure and still yield published velocities, but you have to choose the fastest powders on the list, and load very little of it. The powder charges that I was extracting from my factory High Speed rounds weighed more, which shows me that they weren't loading such fast powders. The weights coincided better with Herco, or Ramshot Silhouette, or Vihtavuori 3N37. According to the Vihtavuori site, 3N37 is specifically developed for .22 Rimfires. www.vihtavuori.com/powder/3n37-handgun-powder/

[Chev. William]

You are Correct uscra112 that Scientific Method indicates an experimenter should verify as much as possible of the basic data points used.
In My case I used Hodgdon's published data which included pressure test results and Velocity/energy numbers.
I do not own any Pressure Testing Equipment suitable for balistics use.

I do own a chronograph with about a 1% to 3% accuracy, not stated by the Manufacturer, but empirical from both my, and others reported, results.

I have begun acquisition of a 'Labradar' Doppler Chronograph but still need some other items, not yet obtained, before i can put it into use.

My "Matching" method of using Hodgdon data for a Specific Cartridge, Propellant, and Projectile to find the 'correction' needed to get QL output to match Hodgdon reported Measured Results, I believe, is reasonable under the Circumstances.

Chev. William

[rking22]

Thank you for the info, my interest was likewise in evaluating the strength of 22lr bolt actions for the 32SWL. Perhaps the 24,000 psi limit is allowing for Stingers??? The 14,000 psi seems more in line with the thin case construction. At any rate, wery good info all around!
M-Tecs, thank you for the link. No idea why I didn't just go look at the source, sometimes I get headed down a path and forget why!

[Chev. William]

In my opinion, Rimfire cartridges need to have their full case, including the Rim portion completely enclosed and supported for 'safe' firing at Pressures above 25,000psi Pmax MAP.

All Rimfire firearms I know of to date do NOT comply with that opinion. Most have only part of the rim area supported by design.

Examples:
= Stevens Favorites, Marksman and Model 44s all hav extractor tip clearance cuts in the breech face that leave part of the rim free of support.
= Marlin "Levermatic" Rifles hav ea 'inverted U' cut in the Bolt face to pocket the Rim, leaving the lower half of the rim unsupported.
= Winchester 1890, 1906, and 62 series Pump rifles in .22LR have a Vertical channel cut in the bolt face to clear the RF Rims, leaving almost all of the Rim unsupported.
= Ruger Standard Auto Pistol has an 'inverted U' cut to 'pocket the RF rim in the bolt face, leaving the Lower half of the rim unsupported.

I believe there are/were .22LR revolvers that are/were made with the rims unsupported by any metal pocket in the Cylinder.

From limited group of .22LR case measurements I believe most Cases have about a .015" wall in the area of the Rim. With rim overall thickness of about .049" and a .015" wall, that would leave about .019" internal space for the Primer Mixture; and a maximum 'crush' of about .019" is also implied.

Powder actuated Tool Loads (PTL) seem to have about the same range of measurements; so it would seem similar pressure withstanding limitations.
BUT: PTL also have a range of loadings that generate higher firing pressures! A Grade 2 or Grade 3 generate pressures that result in propelling a (Breech loaded) bullet out of a Rifle barrel at velocities comparable to actual rimfire ammunition.
PTL loads of grades 4 and above, up to Grade 12, would generate higher firing pressures.
Past Experience firing Grade 7 PTL in a Pistol with a 'Blank Firing Adapter' support this idea (about 200 PTL Fired).

Chev. William

[uscra112]

Thank you for the info, my interest was likewise in evaluating the strength of 22lr bolt actions for the 32SWL. Perhaps the 24,000 psi limit is allowing for Stingers??? The 14,000 psi seems more in line with the thin case construction. At any rate, wery good info all around!
M-Tecs, thank you for the link. No idea why I didn't just go look at the source, sometimes I get headed down a path and forget why!

I thought I'd already posted this, but I don't see it.

My bolt-thrust calculator tells me that the .32 Long Colt load which approximates the bolt thrust of .22 High Velocity ammo has to be pretty light. Won't quote the exact charge of Bullseye that I've used, but the muzzle velocity is about 950 fps, assuming the canonical 88 grain bullet and a 20 inch barrel. I have not yet run this thru the Chrony for validation.

Looking online, my load seems to be comparable to the .32 S&W Long HBWC target load shown in the Alliant database. But: It appears that SAAMI allows 15,000 psi in the .32 S&W Long, which is more than double what I calculated for safety in my Favorites. Many factory S&W Long loadings are probably not safe in a converted .22 "boys' rifle". We can speculate that the .32 S&W Short is commercially loaded to safer pressure, since there's thousands of old, weak revolvers still around, but I have no way to verify it. This is one big reason that I've kept to the .32 Long Colt. It's strictly a handloading proposition these days, and the Colt chamber won't accept the S&W cartridge.