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Discussion Starter #1 (Edited)
I am in the middle of an Experimental Investigation of possible lengthened .25 ACP or 6.35 Browning into a light rifle cartridge. So far it looks like reforming .22 Hornet cases will yield brass that will work (after resize, base machining, and trimming to suitable length(s)).
Also I have found 5.7x28mm Brass is suitable for reforming down to .25ACP diameters using a Multiple step Swaging process.
Barrel source is Lothar Walther as they make a 'Pistol Barrel Blank' in Crhrome-Moly Steel that is 23.4 inches long, 1.024 inch Diameter, .243 bore, .250 Groove, with twist rate of 1 in 9.8 that will work to re-barrel an action.
TJ Liners (sold also through Track of the Wolfe) makes a .25ACP liner with 1 turn in 14" Twist.
presently being investigated case lengths and temporary names are:
0.605 to 0.615 = .25 ACP Custom Reamer on hand
0.910 to 0.920 = .250AL
0.955 to 0.965 = .25ALR Custom reamer on hand
1.024 to 1.056 = .25MACP Custom reamer on Order 12/20/2017
1.124 to 1.128 = .250ALS
1.250 to 1.258 = .250ALRM Custom reamer on hand with taper in body.
1.350 to 1.358 = .250ALRE
1.358 to 1.400 = .250ALRx
The plan so far is to use the .25 ACP rim and extractor groove dimensions, or the rim and extractor clearance groove dimensions of the 5.7x28mm, on a straight body of about .276 to .278 diameter depending on whose Dies are used for resizing. The bottom about .180 of the resized Hornet brass needs to be machined to match the rest of the body, due to lead taper I found in the Lee Carbide .25ACP Resizing Die.
RCBS .25ACP Steel resizing die has a bore reduction at about .75 from the mouth so are not suitable for the Brass Conversion nor for future reloading of the Longer formed cases.
If the neck and shoulder of the hornet case is expanded before running them through the resizing die, almost all evidence of the original shoulder and neck will be 'ironed' smooth. The same observation applies to the reforming of 5.7x28mm cases.
I have found that I can use a RCBS Primer Pocket Swage Tool to allow re-sizing Both the Hornet brass and the 5.7x28mm brass all the way to it's original rim.
Since the .22 Hornet brass and the 5.7x28mm brass is designed for a higher chamber pressure than the .25ACP, I believe the resulting cases will also be capable of 'Hornet' or '5.7x28mm' chamber pressure limits.
Since I plan to head space the cartridges on the rim, not the case mouth, I will be able to use .25ACP head space gauges.

The plan is to use a 'locked breech' type of action, either 'lever' or 'Falling Block' at the moment. either will need re-barrel and chambering to fit the cartridge.

My Questions are do any readers see any problems with this project that I have not addressed?

There are FIVE Cartridges in this 'family' listed in "Ammoguide Interactive" Master Cartridge Data Base:
1. .25ACP with a nominal case length of 0.615".
2. .25ALR with a nominal case length of 0.960".
3. 6.35x26mmSR with a nominal case length of 1.024" to 1.056".
4. 6.25x28.6mmSR with a nominal case length of 1.125".
5. 6.35x32mmSR with a nominal case length of 1.250".
20130813 ADDED via EDIT: update to the list of possible cartridges including the tentative designations.
20171221 ADDED via EDIT: update to the listings of cartridges and their Designations.
 

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I see a problem: The case diameter of the 25 ACP round makes it one of the most anemic pistol cartridges still in use. Why would someone want to make a really long 25 ACP? Is there a good reason to make a lengthened 25 caliber straight-walled case? I can't help but point out that this design will be inferior to essentially every other 25 caliber rifle cartridge contrived in the last 100 years, perhaps worse than any centerfire design ever?

I like wildcat cartridges and I am all for experimentation, but this seems like a lot of work for what you already know will be a patently useless design. What are you hoping to accomplish with this idea?
 

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The 25 Hornet is a wildcat cartridge that goes, way, way back.
Every time a new basic case design is introduced, wildcatters neck it up down and sideways. That happened when the Army went from the 30 US (30 Krag) to the 30-06. The 30-06 case has been necked up and down every way possible. The same happened more recently when the 30 WSM cartridge came out, and many years ago, it happened when the 22 Hornet came out.
You might save yourself some work and expense by using what's already been done.
I'm sure P.O.Ackley's Handbook For Shooters and Reloaders will have some info on the 25 Hornet.
Anyone have experience with the .25 Hornet? [Archive] - Cast Boolits
 

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Discussion Starter #4 (Edited)
I see a problem: The case diameter of the 25 ACP round makes it one of the most anemic pistol cartridges still in use. Why would someone want to make a really long 25 ACP? Is there a good reason to make a lengthened 25 caliber straight-walled case? I can't help but point out that this design will be inferior to essentially every other 25 caliber rifle cartridge contrived in the last 100 years, perhaps worse than any centerfire design ever?

I like wildcat cartridges and I am all for experimentation, but this seems like a lot of work for what you already know will be a patently useless design. What are you hoping to accomplish with this idea?
I hope to explore the potential of this Caliber with more modern components, powders, and pressures. The idea comes from reading of older target shooting and early BP rim fire cartridges such as the 25 Stevens, and early center fire calibers like the 25-21. I feel the 25ACP is similar to a 22 Short and could be expanded favorably to follow the same progression as the 22 rim fire family, e.g.: 22 CB, 22 Short, 22 Long, 22 Long rifle, 22 WRF, 22 WMR.

If successful, this would also provide a possible center fire cartridge range that might tempt owners of old and well used Stevens Single Shot Rifles that have 'less than Collectable' condition to rework the firing pin/breech block to allow use of center fire instead of unobtainable rim fire cartridges of useful power without initial need to re-barrel them.
 

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Bullet egress?

Maybe I'm wrong entirely, but my question is if the bullet would even make it out of the barrel. You envision a barrel around 24 " long and a very small powder charge pushing the bullet past a great deal of friction in the lands. If the bullet does make it to Freedom, any estimates as to muzzle velocity and by extension, its range?
 

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Discussion Starter #6 (Edited)
Maybe I'm wrong entirely, but my question is if the bullet would even make it out of the barrel. You envision a barrel around 24 " long and a very small powder charge pushing the bullet past a great deal of friction in the lands. If the bullet does make it to Freedom, any estimates as to muzzle velocity and by extension, its range?
If you mean the basic 25ACP factory cartridge, there is a web site, "Ballistics By The Inch" that did test several Pistol Calibers, including 25ACP, in barrel lengths from 2 inch to 18 inch and found that the 25ACP gained velocity as barrel length increased to about 16 or 17 inches, then leveled off. These tests were done mostly with single shot locking breech firearm with easily changed barrels and are well documented on that web site.

From extrapolation, I believe 25ACP factory ammo is sufficiently powerful to allow bullet exiting the 23 to 24 inch barrel with velocity above the values measured in 2 inch specification Test barrels.
Changing powder or charge would allow increased exit, muzzle velocity, especially in the higher pressure design Hornet or 5.7x28mm derived case.

As an example in thought experiments: lets say we work up a load for the 25ACP that employs a slower than typical burn rate powder such as 2400. In a Rifle length barrel it would still all burn before the bullet left the muzzle, but would sustain a larger area under the pressure-travel curve, thereby probably imparting greater muzzle velocity to the bullet.
With the longer 'AL', or 'ALR' or longer, case; more powder volume would also be available to add additional power at a higher starting peak pressure limit. 25ACP are rated around (27000 PSI) a new SAMMI limit is 25,000psi raised from 17,400psi, Hornet cases are rated around 40000 psi and 5.7x28mm are rated around 50,000psi, or about double the peak pressure.
 

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So far it looks like reforming .22 Hornet cases will yeald brass that will work (after resize, base machining, and trimming to suitable length(s)).

Since I plan to head space the cartridges on the rim, not the case mouth, I will be able to use .25 ACP head space gauges.
Is there enough meat on the Hornet case to even attempt to machine the base.

I don't understand the use of .25 ACP gauges, rather than the Hornet gauge.
 

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Discussion Starter #8 (Edited)
Is there enough meat on the Hornet case to even attempt to machine the base.

I don't understand the use of .25ACP gauges, rather than the Hornet gauge.
AFTER Full Length sizing to 25ACP Body diameter all the way to the top of the rim, the Hornet case has about .180 from the powder chamber bottom to the breech face that measures about .280" Diameter, or larger for the rim. This area is what is machined slightly to get the full straight wall body and to reduce the rim to match 25ACP dimensions including the extractor relief.

As the 25ACP design is semi-rimless there is a small rim left that allows head-spacing on.

The 25ACP head space gauges have this rim precision ground to correct thicknesses in addition to having the body length ground to match the SAMMI chamber requirements for the 25ACP round to head-space on the case mouth in a pistol barrel.

These longer case lengths that are proposed will need to head-space on their rims as there is way too much change in length to use the mouth for head space reference. All the lengths from original 25ACP through 250ALRM will be accommodated in the one .250ALRM reamed chamber dimensions, just the distance the bullet moves before contacting the rifling varies, the same as .22 rim-fire rounds from 22 BB Cap through 22 long Rifle can be fired in the same .22Long Rifle chamber.

A side note: The .250ALS is the same length as the "25 Stevens Rim-fire" cartridge case.
 

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Discussion Starter #9
Maybe I'm wrong entirely, but my question is if the bullet would even make it out of the barrel. You envision a barrel around 24 " long and a very small powder charge pushing the bullet past a great deal of friction in the lands. If the bullet does make it to Freedom, any estimates as to muzzle velocity and by extension, its range?
Another writer found in his testing and experiments that bullets in the range of diameters we are considering take about 25 pounds per square inch of pressure to maintain constant speed inside the barrel. and there is, by calculating using gas expansion laws, more than sufficient pressure remaining from Factory 25 ACP powder charges to push the bullet out of a barrel longer than the proposed 23 to 24 inches.
 

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AFTER Full Length sizing to 25 ACP Body diameter the Hornet case has about .180 from the powder chamber bottom to the breech face. This area is what is machined slightly to get the full straight wall body and to reduce thge rim to match 25 ACP dimensions including the extractor relief.
OK, so you're reducing the rim, and not the base. I got ya.


As the 25 ACP design is semi-rimless there is a small rim left that allows head-spacing on.

The 25 ACP head space gauges have this rim precision ground to correct thicknesses in addition to having the body length ground to match the SAMMI chamber requirements for the 25 ACP round to head-space on the case mouth in a pistol barrel.
SAAMI only shows a headspace measurement on the rim thickness, .043-.053, none for the case mouth.

Looking at the two cases, the base of the ACP is about .2828, compared to the Hornet's .2963. I'm not sure full length sizing will correct this.

~~~

The .257 Magnum Revolver cartridge is a slightly tapered .22 Hornet case.
 

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Testing and experiments are fascinating, but the 270 REN is a known wildcat that makes a straight-walled case out of a 22 Hornet. It was quite anemic and enjoyed little success. Its use was restricted mostly to T/C Contender barrels or 14" or less.

A straight-walled 25 caliber, based on the 22 Hornet, will, by default, be of limited case capacity. The velocity attained, regardless of barrel length, will also be limited. There's a very good reason virtually all current 25 caliber rifle cartridges are of a bottle-necked nature.

Just as nature abhors a vacuum, the shooting world fills in every conceivable niche with a suitable cartridge. The reason there is no straight-walled 25 caliber, or a lengthened 25 ACP, is because there is no demand for such, let alone interest. If it appeals to you, I wish you nothing but success in your endeavor. Just don't be too disappointed if you find yourself unaccompanied at the end of a long and expensive journey. There's nothing wrong with that, as long as you know it's coming. :)
 

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I don't know if this will work for your wildcat, but Bertram makes cases for both the .25-21 Stevens and the .25-25 Stevens. Buffalo Arms is out-of-stock on the .25-25, but seem to have a good quantity of .25-21 in stock.
 

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Discussion Starter #13
The Buffalo Arms 25-21 Stevens Bertram Cases at $75.00 for twenty empty cases, with similar pricing for the 25-25, compare unfavorably with PPU .22 Hornet Bag of 100 empty cases at about $20.00 the time I bought two bags to experiment with from my local Reloading Supply Store here in Southern California.

Buffalo Arms also lists Winchester or Remington .22 hornet for back order at $27.00 per hundred empty cases.

I have purchased other reloading supplies mail order from Buffalo arms and will do so again in the future, just not this particular item(s) at this time.
 

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Discussion Starter #14 (Edited)
Today I visited "Hollywood Engineering", a manufacturer of Reloading Die sets, located in Sun Valley, California. I inquired about getting a form tool made to ease machining the rim and base of the reformed .22 Hornet cases and after the discussion of what I was trying to do, he said to come back Saturday and he would make one while I waited.
I think that is Very Good Customer Service indeed.
 

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25-20 ss

BBertram in Australia makes the old 25-20 single shot brass cases. What I believe you are missing is that there was a 22WCF. This was a black powder cartridge. When the 22 Hornet was developed, they mazimized the rim thickness so the new nitro load couldn't be chambered in the old Black Powder guns.

Trying to turn down this rim, and putting some kind of rimless ( semi rim) extracting rim on it, seems a strange way to go about what you want. FWIW, the 25-20 SS case has the exact same rim as the old S&W 32 Rim Fire, which dates from the American Civil War. Blown out to a straight 32 cal. it makes the Stevens 32 Extra Long RF, and contains 20 grains of black powder.

It is a little bit larger than the diameter of the 25 ACP case. But it's still smaller than the 25-20 R WCF, except its longer. The new solid head cases must also lose a bit of the historical 20 grains of capacity. When I was a kid, too long ago, I remember a Marbles insert chamber which grasped a 25 ACP in spring steel fingers ahead of the insert. It was made for a 25-35 WCF chamber.

So a factory 25 ACP round will certainly shoot out of a rifle length barrel.
 

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Discussion Starter #16 (Edited)
OK, so you're reducing the rim, and not the base. I got ya.

SAAMI only shows a headspace measurement on the rim thickness, .043-.053, none for the case mouth.

Looking at the two cases, the base of the ACP is about .2828, compared to the Hornet's .2963. I'm not sure full length sizing will correct this.

~~~

The .257 Magnum Revolver cartridge is a slightly tapered .22 Hornet case.
Converting the .22 hornet to straight walled .25 ACP diameters takes several operations.
1. Use a .250" diameter expander punch to expand the neck and shoulder out to about .25ACP diameters.
2.. Using Lee Carbide .25ACP resizing die with the decapping stem and collett removed and a .22 Hornet Shell holder the Hornet case is run into the die to the depth it will go, usually until about .200" from the case breech face to bottom of die.
3. Using again the Lee Carbide 25ACP sizing die but replacing the shell holder with RCBS Small Primer Pocket Swager Tool and the stripper cup with a nominal 3/16 inch ID fender washer between stripper cup and base of case, run the case into the die until the rim contacts the bottom of the die.
4 use a punch and light hammer blows to remove the case from the die. The Swager and Stripper Cup/Washer leave the case rim flush to the bottom of the die, hence the punch and hammer to start he case out of the die.
Alternatively, with a stronger Press (such as an RCBS Rock Chucker), the pocket punch assembly can be used to run the case in all the way to the top of rim in one smooth but quick Movement.

At this point the majority of the case is formed to about .276" diameter with the bottom about .180"-.200" length tapering to about .282"-.284" due to the taper built into the Lee Carbide Die Ring.
Also there is a roll of displaced Brass that forms a radius matching the mouth radius of the die next to the rim.
This 'tapered section' and The 'roll' is what need to be machined to match the rest of the case diameter.

5. machine the 'tapered' part of the body to match the rest of the case diameter, .276", and square up the top face of the rim to remove the displaced Brass 'roll', then cut the extractor clearance taper and groove.
Remount the partially finished case and machine the rim to diameter and skim the breech face to reduce it to 25ACP thickness of rim.
Alternatively, turn the TOP of the Rim to reduce its thickness.
6. De-burr the machined case then trim to final case length desired, remove burrs and lightly chanpfer the inside and outside edges of case mouth.
NOTE: the cases trimmed to 1.055 range will probably require inside reaming to seat the bullet deep enough due to inside wall taper of the original 22 Hornet casing. Longer versions should not need the reaming.
It seems the swaged down 5.7x28mm derived case when trimmed to 1.055" case length does not need inside turning of case mouth.

These machining steps do not remove sidewall thickness at the web as the web powder chamber face is above the taper section after sizing.

My expander punch is Drill Rod that measures .249" diameter so there will be sufficient tension to grip the planned .250" to .251" diameter Metal Jacketed bullets. Cast Bullets may need a slightly larger expander but mouth Outside Diameter should not be allowed to grow too much or the cartridges will not seat in the chamber.
I have modified a Lee Universal Expander die small punch to make a reloading Press mounted Expander Punch/Die for ease of operating use.

These cases will end up taking Small Boxer Primers, the same as both .22 Hornet and .25ACP cases. Whether Pistol, Rifle, or Magnum will be determined later. I doubt the use of CCI type 41 primers will be needed as the intended actions do not have movements that would impart inertia forces to the firing pin during loading of the cartridges, they are all manual function actions.

Actions contemplated for the Test Rifles are:
= Re-barreled Marlin Model 56 'Levermatic' action with modified ".256 magnum" bolt assembly. The conversion is fully reversible on this action but may be limited to length of cartridge that can be accommodated in the magazine well/fabricated clips.
= Re-barreled and reworked salvaged Stevens 'Favorite" Pivoting Block converted to Center fire. this salvaged action was originally set up for .32 Long Stevens Rim-fire cartridge, and was purchased for $65.00 in disassembled and with the original firing pin frozen in the breech block, missing extractor trigger and several other small parts. Both the original wood and metal parts show long use and possible abuse/weathering/refinishing attempts as there is Varnish flaking off both the wood and the receiver.
I am currently waiting out the ten day California hold to take possession of the rifle 'kit'.

As to the ".257 Magnum Revolver" cartridge, I have not reviewed it's dimensions, I will look at it in the future.
 

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Discussion Starter #17 (Edited)
SAAMI only shows a headspace measurement on the rim thickness said:
.257 Magnum Revolver[/I] cartridge is a slightly tapered .22 Hornet case.
Re: SAMMI Case and Cartridge Drawings; you are correct and I was mistaken on the comment about it head spacing on the mouth. Thank you for the correction and the incentive to go back and review basic data.
SAAMI Cartridge is shown as .278 +0.0/-.006 and cylindrical with a .302 +0.0/-.012 diameter rim. I believe the .29828 diameter is a Chamber Taper diameter dimension.
 

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Discussion Starter #18 (Edited)
Today I was able to purchase 1000 Winchester Small Pistol Primers, now with the pound of H-110 I have on hand I can load some experimental .25ACP rounds for the future rifle.
Due to the 'problem' with less than case filling charges, These are NOT for Blow-back action Pistols.
It looks like I will be doing a bunch of research figuring out what is the Case 'Loaded Capacity' for this powder and cartridge, using a 50 Grain FMJ RN bullet (I have a stock of Magtec bullets) to work with.

To save me some time if possible, has anyone used H-110 with a 50 gr FMJ RN bullet in the .25 Auto?
 

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H110 and "less than case filling charges" sounds like a train wreck waiting to happen.

If you aren't sure what your case capacity is, how can you know what powder to use? H110/W296 is a temperamental powder best left to KNOWN charge weights, as tested by professional ballisticians. If you determine that such a slow-burning pistol powder is, in fact, suitable for your lengthened 25 ACP endeavor, do yourself a favor and choose something like 2400 that isn't nearly so sensitive to fill percentage.
 

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Broom jm, looking at the Hodgdon's Powder data page, it looks like he needs to use Tite Group. This is the old non canister Bullseye 23, properly housebroken. From the dim recesses of my mind, I do remember that the idea of the 25 ACP was predicated on the ability of a very quick smokeless powder, to burn efficiently inside of a two inch long barrel.

This parameter is probably why we never see much longer barreled 25 ACP's. Plus the little popper is more reliable feeding, than any 22 RF cartridge. The funny thing to me is that the 22 LR is probably more lethal, even in a pocket gun, because of its soft nosed lead bullets. I still do not understand this Gentleman's concept, so I will drop off, and leave him to you.
 
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