Proposing "6.35x26mmSR / .25 Magnum Auto. Colt Pistol" cartridge:

On April 16th, 2016 I took the "plunge" and proposed a third "Mildcat" cartridge for inclusion in the "Ammoguide Cartridge Master Data Base".

On June 1st, 2016 this Design was PUBLISHED in the "Master Cartridge Data Base" of "Ammoiguide Interactive" website as Case Number 971

This one is intended as a Larger diameter and harder hitting Center Fire Alternative for the .22WMR for use in Firearms converted to Center fire that were previously chambered for the .22WMR. it is shorter than the ".25 Stevens (Long) Rim Fire" of similar diameters.

It WILL require Barrel revisions / replacement as the proposed cartridge uses .250"-.251" diameter bullets.

Case length is trimmed to 1.024" Nominal with 1.056" maximum case length and they are Resized down to .276" diameter. Rims are specified as .050"-.045" thick and .314" diameter maximum, with the Extractor Clearance Cut similar to the 5.7x28MM Cartridge.

Overall Length is specified as 1.260" to match .22WMR overall length. This should simplify firearm conversions.

A 65 grain Round flat Nose bullet is intended but lighter and heavier Bullets are possible within the Maximum Cartridge length. Twist rate is stated as 1 turn in 9.8 inches to match the Available "Lothar Walther" (LW) .25ACP/6.35 Browning Barrel Blank specifications.

The LW Blank is specified as .243" Bore with .250" Grooves (tolerance is .001" on inner diameters), 1.024" outside diameter and about 23.82" Long so a rifle could be made from them. These Blanks are Made with 6 grooves and a one turn in 9.8 inches Twist to the rifling LW uses Button rifling in both Cr-Mo Alloy Steel and Stainless Steel Blanks.
LW says their blanks can be made into barrels with only about .050" trimmed from the ends compared to others barrels that need 3/4" to 1" trimmed off.

For converted Revolvers and 'blow-back' semi-auto Pistols the loaded MAP probably should be limited to around the same as the .22WMR, or about 24,000psi or slightly higher, perhaps 25,000psi.

for "Locked Breech" actions perhaps the limit may be the 40,000psi of parent .22 hornet, or the 50,000psi of the parent 5.7x28mm Cartridges. Careful Development is Indicated.

I already have a Converted Ruger "Convertible Single Six" in the works that is set up for Center Fire and use of Reproduction 8 shot Replacement cylinders. I have three, now four, cylinders being reworked for it at the moment, one is in ".25ACP", a second is being chambered for ".250ALRM" (a 1.250" case length 'Mildcat' development project) which will also accommodate my "6.35x32mmSR when loaded to a Overall Length of 1.400" or slightly less, and a third that will be chambered for my "6.35x28.6mmSR" 'Mildcat' of 1.125" Case length which will accommodate this new length cartridge also.

My reamers are all products of "Pacific Tool and Gauge" (PTG) and have the drawing on file with them. PT&G Reamers have Taper to the Chamber Bore for ease of ejection. A separate Series of reamers By JGS Precision (JGS) Have Tight Straight parallel wall chamber Bodies of about .2795" diameter.Talk to Dave Kitt at PTG if you are interested in getting one of the Chamber reamers made.

Best Regards,
Chev. William

I have used "QuickDESIGN" software to generate a Cartridge design for the proposed .25MACP and will attempt to attach a '.pdf' file of the Generated Data Sheet.

Attachment 167198

Best Regards,
Chev. William

I was informed that "Handloader" Magazine number 302 has an article about a '.25 Caliber Magnum pistol round' that they feel would be a good fit between .22 and .32 calibers in a revolver.

Interesting how similar ideas occur to many people about the same time.

Best Regards,
Chev. William

There is not a lot of web in the base of a .25 ACP to hold that primer in. I would think the shells would lose their primers quickly if run at "magnum" pistol or rifle pressures.

Personally, I think the .25ACP "Web" thickness (from Powder chamber to Primer Pocket) is adequate to handle higher Pressures.
I believe the Chamber of a Semi-Auto Pistol is too Loose to support the case and allows it to expand more than enough to exceed the Elastic limit of the work hardened Brass case at higher pressures. The 5.7x28mm and .22Hornet case webs are not any greater in thickness from what I have seen. but their chambers are a better fit at the Base than typical .25ACP chambers.

I find my .25ACP Lee Sizing die in normal use does not size the base, which is typical of all normal sizing dies. When I use it to Swage cases down to the Rim, by forcing the case up without a Shell Holder to "two block" the Rim/Base against the Bottom of the die , I find the Base near the rim is about .280" diameter and about .30" up from the flat base measures .276" diameter. This is a taper built into the Lee Carbide Ring die.

I do have one 'HSS' sizing die that will size to .276" right after the mouth fillet radius but I do not normally use it to form a case down from larger diameters as it will not handle much more than half of its mouth radius over nominal case final size.

Compare the relative base end case maximum to chamber mouth Diameters on SAAMI Drawings for the .25ACP against the same dimensions of something like a .44 Magnum Cartridge and note the relative percentage of case base diameter the "clearance" is.

I believe many High power Rifle shooters and reloaders consider a Base growth of over .001" between unfired and fired case to be an indication of excessive pressure in firing.
and that is on case bases in the 3/8" to 7/16" diameter range. not one in the 1/4" range.

I also believe that since .22 Hornet is rated at about 40,000psi MAP (now 49,000psi MAP per SAAMI), a case swaged down to .25ACP diameters and fired in a Close fitting (Match Grade?) Chamber would handle the same MAP in a LOCKED BREECH action; NOT a 'Blow-Back one!

Similarly, a 5.7x28mm case swaged down to .25ACP diameters should withstand the same 50,000psiMAP of the Parent case in a close fitting Locked Breech chamber.

Perhaps I am mistaken, so I am open to further research on this.

Best Regards,
Chev. William

Here is Alliant's answer to my inquiry:
"RE: Alliant Powder - Ask the Expert Form
Date: May 11, 2016 10:19 AM

William,
Alliant has no tested load data for the 25 Auto using the BE-86 propellant.
Thanks,
Shoot Straight
DuaneVB
CCI/Speer/Alliant
2299 Snake River Ave.
Lewiston, ID"

So it seems I, and other Experimenters, are in "Uncharted Territory" to use of BE-86 propellant.

Best Regards,
Chev. William

While waiting for my Ruger revolver to be Reworked by my gunsmith after Test firing it, I formed up and trimmed twenty 5.7x28mm parent cases to dimensions of the .25MACP/6.35x26mmSR case; in that they are .276" body diameter and ~1.055" case length.
They seem to end up with wall thickness of .010" to .011" at the Mouth of the case.

I now have cases of .276" body diameter in nominal lengths of .615", 1.055", 1.125", and 1.250" all made from 5.7x28mm parent Brass.

I also have some "Hunter's Supply" Cast Lead RFN Flat base Bullets of 63 grain nominal weight to load into them after Lubing and sizing them down to .251" diameter.
Another poster on another thread has tested some loads in the 6.35x28.6mmSR cases, trimmed to 28mm case length, of Unique and using 50 grain bullets that indicate 2.1 grain charge yields about 1100fps out of a 24" 1:18 twist barrel.
I may try this Unique charge weight behind a few of the 63 grain bullets to fire in my revolver later.

Best Regards,
Chev. William

Another day of "Puttering" and I now have 20 pieces of Reformed 'PPU' Hornet Brass cut to 1.055" case length. but the rims are still at Hornet diameter so I will need a session on a Lathe.

This gives me 20 samples from each parent case to work with for the .25MACP and 6.35x26mmSR Cartridge Development. I think I will load part with 50 Grain FMJ-RN and part with 63 grain Lead RN initially with charges of Either Bullseye, BE-86, or Unique propellant.
I have WSP primers and also CCI SP primers I can use. Decisions, Decisions.

Best Regards,
Chev. William

"Ammoguide Interactive" as of June 1st has added this cartridge to their 'Cartridge Master Data Base as entry number 971 under the Name '6.35x26mmSR STEWART/.25Magnum Auto' with a listed case length of 1.024" and a simplified case drawing.

I will be proposing revisions to both in the next few Days.

I am primarily using cases reformed from 5.7x28mm FNB Brass for my Testing as they have the same Rim and Extractor Clearance Groove of the original 5.7x28mm Brass cases, except the Body diameter just above the Extractor cut is about .280" as a result of the .25ACP Sizing Die Taper. Further my testing is being done with cases trimmed to 1.055" nominal Case length.

Best Regards,
Chev. William

As of August 7th, I have not been Able to do much further work on developing this Cartridge due to loss of one of my Sizing Stage dies and Lee Saying a replacement will not be made until after November of this year or longer.

This Loss has also Curtailed my other 5.7x28 Resizing efforts as the process Requires at least Three roughly equal steps in the Swaging Process for Good Yield results. So my Experiments with all of my 6.35 . . . Case designs is Impacted by the delay in getting a Replacement die made.

Additionally the Last two Utility Billings Have Been Very High due to Adverse Weather here (Hot And Drought) curtailing my "Discretionary Spending Funds" for the time being.

Please accept my apologies for the delay in further News of Progress.

Best Regards,
Chev. William

Pacific tool and Gauge has a Chamber Reamer Print on file for this ".25 Magnum auto" cartridge:
25 Mag Auto fin REV B William Stewart 44691

I am still waiting for my 6.35x26mmSR reamer from PT&G to be finished and shipped.
Sigh.
Also, my Swaging of cases from 5.7x28mm Brass is still halted due to the Broken "middle Swaging die", actually a Lee 'Opened' .25ACP Carbide Ring Sizing Die, and it looks like Lee won't be doing any until at least November.

Some discussion on case lengths:
The .22LR has a case length of .613" while the .25ACP has a case length of .615".
The .22 Rem. Auto case length is .663".
The .22 Win. Auto. case length is .665".
The .22 Stinger case length is .710".
The .22 Win. Rim Fire case length is .960".
The 6.35x24mmSR/.25 ALR has a nominal case length of .960", similar to the .22WRF.
The .22 Win. Mag. RF case length is 1.055".
The 6.35x26mmSR/.25 Magnum Auto has allowed case lengths from about 1.010" to about 1.055" .
The .25 Stevens has a case length of 1.124".
The 6.35x28.6mmSR and .250ALS have case lengths of nominal 1.125".
The 6.35x32mmSR has allowable case lengths of 1.220" to 1.260" and the .250ALRM has a case length of 1.250".
The .250ALC has a case length of 1.290".
There are other cases based upon the Swaged .22 Hornet up to about 1.380" case length.
Lengths of the Swaged 5.7x28 are limited to about 1.260" maximum by the swaging Process to date.

A review of the above data seems to indicate Case lengths of Viable Commercial Cases seem to fall at about .615", .960", 1.055", 1.125" Lengths and possibly extend to 1.200", 1.250", 1.290"/1.300", or 1.350".

Obviously lengths between these numbers are Possible but history seems to favor these particular ones somewhat.

For Semi-Auto Pistols it seems case lengths above 1.1" or so get less preference than those below 1.1".
For revolvers case lengths can be longer with out as much constraint on function; witness the "Judge" revolvers that accept .410 Shot Shells as acceptable.
For Rifles and Carbines, case length seems to depend on the Action design more than any other factor.

What Would be the "optimum" case length also is highly subjective and would depend upon the end use intended and as used in fact.

Example: the number of Men having hand grip size to allow comfortable hold and fire of a Double Stack .45 Win. Mag. Semi-Auto. Pistol with the Magazine within the Grip is Very Small.
On the other hand, Pistols in .32 Auto, .38 Auto, .40 Auto/.41 Auto and .45 Auto are Popular.

Revolvers seem to have similar Grip sizes regardless of cartridge used.

Things to ponder and hopefully comment upon.
Best Regards,
Chev. William

Today, just before the first Presidential Candidate Debate, My PTG ".25 Magnum Auto" Finish Chamber Reamer arrived. It is a "Premium one with a replaceable Pilot bushing on a HSS Reamer.
Now I need to Verify its dimensions before I use it.

Best Regards,
Chev. William

The New PTG ".25 Magnum Auto. FIN Reamer does cut a usable Chamber, i made a "dummy chamber in a Blank die body i had on hand.
The Reamer, along with a Rim counterbore Tool to fit the .22 Hornet Parent Rim diameter, my Dummy chamber, and a Replacement 8-Shot Ruger .22-MAG Cylinder for Rework went ot My gunsmith and are in his line to get done.

In the same Batch, I took a .32 LC Finish chamber reamer and a Used .22LR Ruger 6-Shot to be re-cut in .32 LC I am talking the OLD Colt Cartridge of .318" body diameter. this will be reviewed to see if I like the Chambers then if Acceptable be Reworked to fit a .32 H&R Magnum Ruger Single Six I recently Acquired as A Used Revolver Purchase.

Today I placed Orders with PT&G to get a "6.35x28.6mmSR Stewart" Replaceable Pilot Finish Chamber Reamer, Two .25 Cal. Pilot Drilled Blank Die Bodies, Two .30 Cal. Pilot Drilled Blank die bodies. and sets of Bushings for .25 Ca. and .30 Cal to use in reaming the Die Bodies.

Now I Wait. Patiently I Hope.

Best Results,
Chev. William

Quote:

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Originally Posted by Chev. William

Now I Wait. Patiently I Hope.

Best Results,
Chev. William

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I am very interested in this project. Have you made up dummy rounds you can post of pic of?

R.

Photo(s) of the .250ALRM, The .250ALS, and 6.35x32mmSR, 6.35x28.6mmSR do exist but I have yet to make photos of the .250ALR, .25 Magnum Auto, or 6.35x26mmSR Cartridges or cases.

If you are interested in them post a request again.

Best Regards,
Chev. William

I took this Photo This Afternoon:

http://i839.photobucket.com/albums/z...psu1m4fhq2.jpg

Left to right is shows a .25 Magnum Auto pair of cases (1.055" long); a .250ALS Pair of cases (1.125" long); a pair of cases and a Loaded 6.35x28.6mmSR round (1.125 case length and 1.395" OAL); a Pair of .250ALRM cases (1.250" long); and a 6.35x32mmSR round loaded to 1.400" OAL; A Pair of .250ALRx Formed Parent cases about 1.380" long. These '.250' cases are formed from .22 Hornet PPU brass; the '6.35' cases are formed from 5.7x28mm FN Brass.

The rightmost Two cases are as Formed From .22 Hornet Brass before the Turning operations on the rim.

The Loaded rounds use a 63 grain Lead bullet and WSP primers. the Propellant used is NOT Listed deliberately at this time. these are experimental loads that I have not Chrono'd Yet.
Best Regards,
Chev. William

Further comments on the Photo and Cartridges:
The Loaded "6.35x28.6mmSR" Cartridge is at 1.395" OAL and is 'roll crimped' on the 63 grain FN Hunters Supply bullet just ahead of the first Driving Band. It is intended for my Ruger Single Eight and the ".250ALRM" chambered Cylinder.
This is a Strong Crimp to insure Pressure Builds Before the bullet moves. as I am experimenting with Propellant charges in this case which has NO Book Published Loading data, only Web posted Loads.

The Other Loaded cartridge is a "6.35x32mmSR" loaded to 1.400" OAL and VERY Heavily 'roll crimped' using a .25ACP crimp die. Look closely and you can see the case mouth is swaged down against the Bullet Nose until it encounters the first driving band on the Same 63 grain FN Hunters Supply Lead Bullet. Again this is an experimental load and i want the Pressure to build before the bullet moves. Again it is intended for my Ruger Single Eight and its ".250ALRM" chambered Cylinder.

Another experiment I did before I obtained a Chronograph was three Rounds of ".25ACP Ruger" using the 63 grain FN Hunters Supply Bullet in front of 3.0 grains of BE-86 Propellant and CCI SP primers in Fiocchi Nickel Plated cases loaded to .905" OAL and fired in my Ruger Single Eight and the ".25ACP" Chambered Cylinder. Compared to PPU factory "5,35 browning Loads, they are Definitely +P loads and did rock the revolver back in my grip more than the Factory loads (about double the Muzzle rise). No Pressure signs on the Primer, both firing pin pit and edge radius were the Same as Factory Loads. extraction was similar and fired Case looked the same as the factory Loads, perhaps a little less soot around the mouth.
I would NOT RECOMMEND firing this in a Semi-Auto Pistol that is not of STRONG Design and construction. Perhaps a Delayed Recoil Action might be Suitable; but NOT a Weak, or Older, straight Blow-Back pistol Action.

Best Regards,
Chev. William

My gunsmith Has My "6.35x26mmSR/.25 Magnum Auto Finish Chamber Reamer" and a 8-shot donor cylinder for Re-cut of the Chambers to this Cartridge.

Now to wait Patiently.
Chev. William

It is now July, the 15th to be exact.
My Gunsmith is out for his second Knee replacement surgery and will probably be out until Mid august to recover.


I am back to forming Parent "6.35" cases from 5.7x28mm 'Once Fired' Brass as I bought a Lot of them at the June Costa Mesa Gun show. Finally got them De-capped, placed in boxes and the final count is: 1852 ea 5.7x28mm Cases; 6 ea 4.6x30mm Cases; 2 ea .30 Carbine Cases; 5 ea .22LR cases; 1 ea .17WRM case; and 1 ea .17HMR case.

This added to my other Purchases Gives me about 3000 Cases for forming.

I have purchased 300 ea Hornady #2510 .257" 60 grain Soft Flat point Half Jacket Bullets to Test with. I have sized 1/3 to .250" diameter and another 1/3 to .253" diameter so far.

Trying to seat one in a .25 Magnmum Auto Case resulted in the Seating Stem reforming the Flat Tip to a Bulged Rounded Tip with a Noticeable bulge in the Nose part of the Jacket. I feel this is NOT acceptable for accuracy but will use such deformed ones in Chronograph testing of Loads until I can get a custom Seating Stem made to preserve the Hornady Nose contour.

Best Regards,
Chev. William