I'm toying with a long term project.....a double rifle for deer hunting.

I've chosen the .25-35 because I think it can have the power required and is a rimmed case for good extraction in a double rifle. The idea of creating a "Gibbs like" cartridge is interesting as it can be quite a bit larger case and can be fireformed using .30-30 cases. Feeding is never a problem in this type gun so almost straight walls are fine and pushing the shoulder ahead 3/16" still leaves plenty of neck for the round. A 25 degree shoulder seems adequate as well!

Anyone see flaws in this idea?

Anyone venture to guess how fast a 117 grain bullet will exit a 20" barrel at 50,000 PSI? Does 2,700 seem too optimistic?

The major flaw which comes to mind right away is that you aren't building it for me!!

If you were, then on close examination I wouldn't see anything at all wrong with the idea.

Let us know how it works out and what the ballistics & best loads turn out to be, okay?

Hair on ya'.....

Vapo, if it works out and doesn't cost an arm and a leg, would you make one for me too?

Good luck!

friar

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Vapo, if it works out and doesn't cost an arm and a leg,

I expect to have very little in it at the end.....but possibly several hundred hours of my "free" time.....

It'll likely be a "one-of-a-kind"

Using modern 30-30 brass at 50,000psi, your 25 degree shoulder .300" neck length, .410"dia. at body neck junction ,and a .400" throat depth, 2700 fps. using something close to 4831 may not be entirely unreasonable. Even if you don't quite get the 2700 fps. you'll have a neat rifle that is far from being marginal as a deer slayer.
You'll probably have this project DONE by the time you receive my barrel ( a little tongue in cheek). roger

if i find a 410, its going to become either a 30-40 or 30-30 .. just cuz its easy!!

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if i find a 410, its going to become either a 30-40 or 30-30 .. just cuz its easy!!

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Using modern 30-30 brass at 50,000psi, your 25 degree shoulder .300" neck length, .410"dia. at body neck junction ,and a .400" throat depth, 2700 fps. using something close to 4831 may not be entirely unreasonable.

A little more research shows the 7-30 Waters case to be close to what I was thinking....neck it to .257 or even .264....or what the heck...leave it as is!

Jeffeosso,
I looked at the .30-40 Krag....great round but I just wanted something smaller in caliber...

My previous (failed) attempt at this was to make a .30-30 using springfield and enfield barrels attached to a Brazillian .410. The end result was much too heavy....I wanted something I can carry and not hire a gun bearer for deer hunts! The milsurp barrels were too much!

I have an little Uplander double trigger 410 just taking a nap in the gun safe, waiting to be come a little double rifle!

Vapo,
I put a strain gauge on my marlin 336 while working up loads for the 25/35 imp it's chambered in. The rifle has a 24" barrel, but with 4320 reached 2700 fps within pressure levels of the 30-30 case design. If you use 375 win brass, and boost pressures to 444/450 marlin levels it's very surpriseing what you can get. The 30-30 brass is cheap/free from friends shooting, and does plenty well so I keep to the lower pressures. If you want a few imp cases to look at or measure ect I'll send you some.

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Originally posted by Rusty:
I have an little Uplander double trigger 410 just taking a nap in the gun safe, waiting to be come a little double rifle!

May I suggest the .218 Bee or the .25-20 either WCF or single shot round....?

The idea of a small caliber double just seems right!

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Originally posted by theback40:
Vapo,
I put a strain gauge on my marlin 336 while working up loads for the 25/35 imp it's chambered in. The rifle has a 24" barrel, but with 4320 reached 2700 fps within pressure levels of the 30-30 case design. If you use 375 win brass, and boost pressures to 444/450 marlin levels it's very surpriseing what you can get. The 30-30 brass is cheap/free from friends shooting, and does plenty well so I keep to the lower pressures. If you want a few imp cases to look at or measure ect I'll send you some.

IIRC the .30-30 operates at about 40,000 PSI....so are you saying that you was able to muster 2,700 FPS from a 117 grain .257 caliber bullet using a .25-35 Improved case at 40,000 PSI?

If so....the .25-35 Gibbs will certainly achieve my goals for velocity....and then some. I was concerned that I was overly optimistic!

yup, 40,000 and a little change, I dont have the numbers right handy. That was with a 24" barrel not a 20", but a gibbs type capacity should make up that differance easy enough.

OK, I had to go look. 40,000 is the cup pressure, the strain gauge is in psi and the 30-30 is rated at 42,000 psi. My loads were at 42,168 psi.
If you look in the accurate reloading book you will find the 7x30 waters loaded to 40,000 cup and a 120 bullet in a 24" barrel doing over 2700fps.That is compareable to what I get with a 24" barreled 7x30 I have on a martini cadet action. The 25/35 gibbs would have more capacity then the 7x30 even though a smaller bore.

I would try a .25 cal using .444 Marlin brass and .257 Roberts dies for absolutely nothing new.
Existing dies, reamer, and loading data.

Another route would be a 6.5 rimmed round using .303 or .444 brass.
The dies could be Mannlicher, Dutch Steyr or Carcano using .303 brass.
Take your pick using .444 brass.- 6.5X57 or something shorter.

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Originally posted by vapodog:
I expect to have very little in it at the end.....but possibly several hundred hours of my "free" time ...

I envy your "free" time!!!

Just let me shoot it once or twice and I'll be happy!

6.5x303 Epps? roger

Wildcat Cartridges Volume II on pages 277-279 has a good article by James Gates on ".25 Krag Improved."

2982 fps with 117gr bullet and 50.9 grains of H4831 in a 24 inch barrel

Built on a Ruger #1

Of course 30-40 Krag brass is getting very difficult to find now days.

Barstooler

Bartsche and Barstooler beat me to it: The .25 Krag was a very popular round among wildcatters back when. Improving it with a Gibbs-type treatment would certainly provide plenty of zip for a deer gun.

By the way, the great thing about a double rifle is that since it is absolutely impossible to get both barrels to shoot the same place, anyway, you can zero one for 75 yards and the other for 150 yards and thus be ready for any reasonable iron sight distance !

I would vote for a 25 Krag FL. I had one in a sporterized Krag back in high school. Neat cartridge, even neater in a DR.

Rich
DRSS

You could just go the 25/303 route and operate it at its design pressure (same as 303 Brit) and get the desired velocity. (Think of 257 Roberts starting loads).

Chances are you could get a pair of barrels from Ozz plus a reloading die set.

The 25/303 should also be obtainable from Canada.

You could also go the 25x57 Rimmed route (necked down 7x57 Rimmed). Use 257 Roberts barrels and sizing dies. That will produce the desired performance at even lower pressure. Cases are available in Europe.

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You could also go the 25x57 Rimmed route (necked down 7x57 Rimmed). Use 257 Roberts barrels and sizing dies. That will produce the desired performance at even lower pressure. Cases are available in Europe.

Cases are available at Midway too! This solves several other problems too....barrels and dies just got a lot cheaper with this idea! This just saved me a ton of cash!

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You could also go the 25x57 Rimmed route (necked down 7x57 Rimmed). Use 257 Roberts barrels and sizing dies. That will produce the desired performance at even lower pressure. Cases are available in Europe.

Great idea. roger

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You could also go the 25x57 Rimmed route (necked down 7x57 Rimmed). Use 257 Roberts barrels and sizing dies. That will produce the desired performance at even lower pressure.

I'm now thinking I'd go with the standard 7 X 57 Rimmed....

Does anyone know if the only difference (dimensionally) between the standard 7 X 57 and the 7 X 57 rimmed is the rim?

I can use the 7 X 57 F-14 contour A&B barrels from Midway for less than $100 each and fit them into a monoblock with no trouble!....I already have the chamber reamer and dies to reload.....assuming all is the same except for the rim!

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Originally posted by vapodog:
I'm now thinking I'd go with the standard 7 X 57 Rimmed....

Does anyone know if the only difference (dimensionally) between the standard 7 X 57 and the 7 X 57 rimmed is the rim?!

Cartridges of the Wrold shows the dimensons to be the same.
Just another option. You could do the same using .260 chambers and .307 brass. If you added a deep throat feature*** You know the drill***.Or you could use the .307 brass and use the 6.5x51.8 reamer. Looks like you got a few nice doable options. Life is sweet! roger

The 7x57 is a serious contender against the 303 Brit as being my favourite cartridge. The 6.5 Swede has an appeal of its own. Now, how about a 6.5x57 Rimmed? Best of all worlds. Good for break actions and doubles AND would be just fine on a No4 Lee Enfield. (My favourite). But a light weight double in something like that would be just the sweetest thing! The downside is I would have no more use for all my other guns! Mind you, picture this, a 6.5x57 Rimmed double with a set of scopes set for each bullet weight and type. Varmint rifle up to medium game in one rig! Open sight option remains. (Only one barrel would need to be sighted for varminting). What's not to like?

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Or you could use the .307 brass and use the 6.5x51.8 reamer.

That sounds interesting!

You know, a hundred cases would last a lifetime if they don't get lost!