converting an hopkins allen falling block to bp cartridge?

I would suggest that you read the section on them in Single Shot Rifle Actins by Frank deHaas. They are not a particularly strong action and the medium frame one that I rebarreled, was a nuisance because they do not extract the cartridge very far compared to other single shots.

cheers mooncoon
 
thanks ........dont got that dehaas book, but am in the looking into it stage of the project........figure to use a calibre like 38-55 minimum or a little bigger size ......again info ideas, or such most welcomed
it will be mostly used on targets , and the odd time fer close in brush deer /moose hunting
 
In a conversion I would suggest multiplying the working pressure of the shell originally chambered times the square of the base diameter and comparing that with the same for what you are going to. It gives you an approximation of whether or not you are putting a lot more load on the breach. As an example, if the Hopkins was made for black powder loads, they would run probably around 4-5000 psi and just to be generous I will allow 7000 psi. The base diameter of a 12 guage shell off the top of my head is around .8" so we get a number of 4480 that the gun was designed for. The 38-55 has a base diameter of .42 and I am guessing even in blackpowder with 3 F you could hit 25 - 30,000 psi so that works out to 5292 or a little over the thrust of the shotgun shell. Jumping to a 45-70 base, we have a diameter of .50 (shell not rim) and using the same pressure you get 7500 or approaching double the thrust of the 12 guage. This base diameter would also apply to lighter calibers such as 38-56 which is base on the 45-70 shell.
While the gun might stand up to the cartridge, you are also pushing the envelope of what it is capable of.

cheers mooncoon
 
currently using modern shotshells in it no problem but am i going a bad thing.....gun takes the normal 12 guages rounds a--1 no problem....was made about 1905 ish from info i got with the gun..........thanks
 
A new barrel is going to be expensive. Add fitting and chambering, and the price is going to be significant - at least $5-600. Personally, I don't think that this action would be a good base for the conversion. Easier to sell it, and get one of the H&R/NEF .45-70 rifles. Incidentally, what is the firing pin diameter? Many shotguns have pins WAY too big for a rifle cartridge. Even for black powder .38-55 there could be problems. The pin would have to be reduced, and the block bushed. How tight is the action?
 
GOOD Question, ..........NOT SURE about fire pin.its a 12 guage gun, using modern 2 3/4 rounds, ........guns still in use works a--ok seems action is tite, i aint a gunsmith.
the h$R and nef..........nice but my idea is to create a gun to use at my black powder /rendevous shoots , prefer the old look, black powder only, .any idea if barrel liners exist fer this idea /project? ( 38--55 or maybe 32-40 ?)
all replys most welcomed.
 
I doubt that there are any barrel liners available the would fit a 12 ga. bore. One could be turned from a blank, of course. Rebarreling would likely be easier and cheaper. Check the firing pin diameter. I bet its rather large. Is the firing pin fit loose in the block? A black powder rifle cartridge could easily generate three times the pressure of a shotgun cartridge, and a blown primer can be dangerous in these older guns with firing pins that pass straight through the block.
 
Cheap way to re-line.

Hello All, I Am A Newbie, Hope I Am Not Being Ignorant By Cutting In Here. Nagantsniper, If I Were To Make A Usfull Rifle Out Of That Shotty I Would Be Looking Around Gun Shows Ect. For A Good .38-55 Barrel That I Could Machine Down To Fit Inside Your 12g. barrel And Then You Are Almost There, Good Luck. .45-90:)
 
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Reply to claven2.

What i posted was intended only if the old H&A was up to it. I have built double rifles for a few of my customers from (strong) SxS shotguns over the years using this method with good results. Regards .45-90
 
I converted one of these H & A falling block actions to the 38-50 Remington Hepburn cartridge. It's the 303 British opened up to take a .375 bullet. Barrel blank was from Ron Smith, Wimborne, AB. Added new wood, tang sight and hooded front sight.
For black powder only. A lot of work for such an old, weak action. I will have it at the Lumby, BC gun show June 9 & 10 if anyone wants to see it.
jclayton
 
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