.25 ACP

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Kabic

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So as most know .25 ACP was created by John Browning to match .22 LR out of a 2 inch barrel.

Both have case length of 15.6 mm.

22LR overall length is 25.4 mm.
25ACP overall length is 23 mm.

Yes the 25 is shorter! Guess I never realized that until I went to buy ammo for new to me pocket pistol.

Anybody know why it was design that way?
 
Unlike the rimfire .22 the .25 APC is a center fire cartridge. The original .22 (Short) is similar in size to the .25 and was developed in the mid 1800's. The .22 Long (L) soon followed and then the .22 Long Rifle (LR) came along a few years latter. The .22 LR is by far the most popular of the three used today.
 
Browning's goal was to replicate the performance of a .22 long rifle cartridge with 40 grain bullet in a centerfire cartridge in a small defensive pistol.

Centerfire cartridges loaded with smokeless power with jacketed bullets were considered more reliable and durable than rimfire cartridges with plain lead bullets. In 1905 a lot of .22 ammo was still black powder, which why Remington and Winchester developed proprietary cartridges for their first. 22 semiauto rifles.


The design goal of matching standard velocity .22 long rifle cartridge with 40grain bullet from a 2 inch pocket pistol barrel dictated the spex of the cartridge.

Case size was dictated by the standard small pistol primer size, so the minimum caliber to fit a cylindrical case ended up being .25 inch. Making the .25 bullet proportional to the .22lr gave a bullet weight of 50 grains. The 25% heavier .25 bullet meant the muzzle velocity to attain equivalent muzzle energy was lower.
 
Yes the case is as small as it can be and still fit the center fire primer. I just shocked case height is the same, but overall length is shorter.
 
Kabic said:
Yes the case is as small as it can be and still fit the center fire primer. I just shocked case height is the same, but overall length is shorter.
Click to expand...

Off the top of my head, I would say that if the gun had been designed around 22 LR, then redesigned for 25 centerfire, with its longer bullet, shortening the case length might have been desirable in order to keep overall cartridge length the same. That would minimize the amount of redesign needed. With the rimmed, heeled-bullet 22 LR, overall case length had been the ruling factor; and since new 25 ACP headspaced on the semi-rim, changing the location of the case mouth was no big deal.

And seating the 25 ACP bullet more deeply in a 22 LR length case may have been undesirable. Manufacturing difficulty? Greater pressure needed to get the bullet moving? I bet the cartridge designer just seated it at whatever depth was then conventional for a bullet of its proportions, and then adjusted the case length to match 22 LR. Like I said, it does not seem like case length mattered much here, just overall cartridge length.

Of course, that's just me, a non-engineer and non-reloader, saying the first things that comes to my mind. Take it for what it's worth.
 
Kabic said:
Yes the 25 is shorter! Guess I never realized that until I went to buy ammo for new to me pocket pistol.

Anybody know why it was design that way?
Click to expand...

I think Monac beat me to it. It was to keep the overall length the same or very close so it would fit in the mag well.
 
It's not like an extra 2+ millimeters would have made much of a difference and had the .25 been made the same OAL as the .22 LR there could have been the potential for chambering the .22 LR in a lot of those vest pocket guns, not too mention given the .25 some extra space for another .1 grains of powder or a slightly heavier bullet. Instead what we get is the .25 being the equivalent of the .22 Short in terms of length and pistols it can fit into.

I guess JMB wanted to make the gun as small as possible and cutting that 2mm off the length was what pleased him, but hindsight being 20/20 he should have made the .25 a tad longer.
 
TTv2 said:
It's not like an extra 2+ millimeters would have made much of a difference and had the .25 been made the same OAL as the .22 LR there could have been the potential for chambering the .22 LR in a lot of those vest pocket guns, not too mention given the .25 some extra space for another .1 grains of powder or a slightly heavier bullet. Instead what we get is the .25 being the equivalent of the .22 Short in terms of length and pistols it can fit into.

I guess JMB wanted to make the gun as small as possible and cutting that 2mm off the length was what pleased him, but hindsight being 20/20 he should have made the .25 a tad longer.
Click to expand...

Wait, I am confused now. Is 25 ACP the same overall length as 40 grain RNL 22 Long Rifle? I'm off to Google!

Wikipedia states that 25 ACP has an overall length of 23 mm or .91 inch. It gives 1.000 inch, or 25.4 mm for 22 Long Rifle. That is a difference of 2.4 mm, or just under .1 inch. I am not going to theorize about that, because I don't know anything that would give me a basis for saying anything. Still, I learned something today!

Also, does anybody know if Browning originally designed the gun around 22 LR or 22 Short? I had the vague idea it was the latter, but that's probably based on something I misread 40 years ago.
 
Monac said:
Wait, I am confused now. Is 25 ACP the same overall length as 40 grain RNL 22 Long Rifle? I'm off to Google!
Click to expand...
No. Whatever gave you the idea that it was?

Also, does anybody know if Browning originally designed the gun around 22 LR or 22 Short? I had the vague idea it was the latter, but that's probably based on something I misread 40 years ago.
Click to expand...
I don't think JMB designed the .25 or the guns chambered for it around any rimfires, the only thing they have in common is that JMB wanted a centerfire with the same-ish size as the .22 LR, but be more reliable.
 
Well I thought someone had already
posted that JMB wanted a rimless round
for his small semi auto peestolla in the
same way he used a rimless 45ACP
in the 1911, but I don't see it here
 
bassjam said:
It's probably a good thing that a small primer couldn't fit in a .22 rimless case or forums would be flooded daily with the question "Can I shoot .22lr out of my .22 ACP?"
Click to expand...
It's then likely the firing pin is a firing bar that is wide enough to strike both rim and primer.

JMB thought ahead.
 
Sarge7402 said:
actually not the smallest. the velo dog was the smallest https://en.wikipedia.org/wiki/Velo-dog

Charlie Askins got in trouble using it in a modified woodsman pistol in the 1930 when it was any centerfire not as it is today any centerfire .32 or greater
Click to expand...
Thanks for that. It was an interesting little read. Never knew the critter existed. :)

At $179 (starting bid) I thought .25 ACP was expensive but Velodog has it beat. Wonder when the last of it was made? :)

Ron
 
I thought JMB was seeking more reliability in both ignition and in feeding. The LR round is very difficult to get to feed reliably in guns as small as the little .25 caliber ones. In addition to the rim design, wouldn't reducing the OAL have helped improve feeding in such small pistols?
 
So as most know .25 ACP was created by John Browning to match .22 LR out of a 2 inch barrel.
Both have case length of 15.6 mm.
22LR overall length is 25.4 mm.
25ACP overall length is 23 mm.
Yes the 25 is shorter! Guess I never realized that until I went to buy ammo for new to me pocket pistol.
Anybody know why it was design that way?


Don't know, but since it is the internet, I'll surmise:
After replicating the sectional density of a .22 bullet in .25 diameter,
and designing a centerfire .25 casing holding enough powder to match .22 LR power,
and seating the bullet deep enough to withstand stresses of being fed in a semi-auto action,
the cartridge overall length (COAL) just happened to end up that way.
 
I’m guessing the little .25 is close, as a scaled down .45. For more reliable feeding in a semi auto.

Every mouse gun I’ve ever owned, on .25 ACP, was worlds more reliable than a mouse gun .22 LR.

But, as I recall, I had a Beretta.22 short Minx that was pretty reliable.
 
Reloadron said:
Thanks for that. It was an interesting little read. Never knew the critter existed. :)

At $179 (starting bid) I thought .25 ACP was expensive but Velodog has it beat. Wonder when the last of it was made? :)

Ron
Click to expand...
my understanding is that it is still made in europe
 
Last source I saw for 5.75 Velodog was Fiocchi of Italy, but their website page for 5.75 Velodog is labeled Heritage and lists spex and ballistics only.
Not currently in production.
 
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