Falling block help

[6mm06guy]

I have a hopkins allen 932 In 32-20, I picked it up cheap and it doesn't need much work. After cleaning the bore you can see it's pitted badly. So now for the million dollar question. Do I install a liner and go back 32-20 or how big can I go with an 1880s action and a cartridge that has a better brass selection?

I'm a big fan of falling blocks but I know nothing about the H/A and I'd hate to go with a 22 ackly hornet and it blow up after all the work.

 

[Rosebud]

.357 mag will do well in it. My contender with16 inch barrel will hit 1800 fps with140 XTP.

 

[Bert01]

I think 38 special would be more inline with the 32-20 as far as respective pressures.

 

[Rosebud]

Action will be strong enough, needs a new barrel. Pressure from.357 isn't going to be any problems.

 

[6mm06guy]

I picked up a 300 blackout bolt action for my youngest son and a buddy swung by last night with his pew pew muffler, wow it was dead silent and just made me smile. So I did some digging and it seems several people are taking 357 brass and running it through a 300 blackout die to make a rimmed 300 bo, does anyone off hand know how much pressure a 300 bo sub sonic round has, the 32-20 if memory serves is supposed to be around 16000 psi.

 

[ntsqd]

Peak pressure will be important to an older action, but to an older design falling block so will "bolt thrust" as that may be even more critical to safety. Not familiar with the action in question, but I do know that some of the older designs will not survive a high bolt thrust chambering.

 

[6mm06guy]

Peak pressure will be important to an older action, but to an older design falling block so will "bolt thrust" as that may be even more critical to safety. Not familiar with the action in question, but I do know that some of the older designs will not survive a high bolt thrust chambering.

I 100% agree, I have a gunsmith I'm going to have look at it before I do the work. The rimmed 300 blackout, just for clarification, if I do it will be sub sonic only.

 

[Bert01]

Somewhere I have a xecel spread sheet with the bolt thrust calculations figured in and a lot of cartridges listed for comparison. I've used it for similar decisions on building double rifles and adding rifle barrels to shotgun sets.

 

[ntsqd]

Bolt Thrust is a fairly easy calc to do simply, and a very difficult calc to do exactly. Peak pressure times case head internal area is the simple version. First .300 BLKO entry is the SAAMI spec, second is the pressure that I backed down until the bolt thrust was roughly the same as that of the .32-20

CUP Est. PSI Case Head Ø Case Head Area Simple Bolt Thrust

.32-20 16000 6320 0.353 0.0979 619

.38 SPL 17000 7840 0.379 0.1128 884

.300 BLKO 52000 61040 0.376 0.1110 6778

.300 BLKO 15500 5560 0.376 0.1110 617

Formula for approximating PSI from CUP found here: https://en.wikipedia.org/wiki/Copper_units_of_pressure

EDIT: Sorry, the formatting is PERFECT in editing mode, posting it screws it up.

 

[Rosebud]

This is a falling block action. Same as a 1885 Winchester. This one is made by Browning, and is chambered in 25-06. They will handle pressure if its a well made gun. Have a Gun Smith check it out.

 

[dwcars]

Peak pressure will be important to an older action, but to an older design falling block so will "bolt thrust" as that may be even more critical to safety. Not familiar with the action in question, but I do know that some of the older designs will not survive a high bolt thrust chambering.

That kind of info in very available on the internet by very knowledgeable people.
If it's an older 1885 Winchester lo-wall the max pressure you can run will be 17,000-19,000 psi. Otherwise the receiver will begin to develop cracks which cannot be repaired.

 

[dwcars]

This is a falling block action. Same as a 1885 Winchester. This one is made by Browning, and is chambered in 25-06. They will handle pressure if its a well made gun. Have a Gun Smith check it out.

Yes, the current 1885s made by Miroku are made from modern metals and can take some very high pressure modern cartridges

 

[8x68s]

I picked up a 300 blackout bolt action for my youngest son and a buddy swung by last night with his pew pew muffler, wow it was dead silent and just made me smile. So I did some digging and it seems several people are taking 357 brass and running it through a 300 blackout die to make a rimmed 300 bo, does anyone off hand know how much pressure a 300 bo sub sonic round has, the 32-20 if memory serves is supposed to be around 16000 psi.

interesting concept for a wildcat. keep us posted!

 

[ntsqd]

That kind of info in very available on the internet by very knowledgeable people.
If it's an older 1885 Winchester lo-wall the max pressure you can run will be 17,000-19,000 psi. Otherwise the receiver will begin to develop cracks which cannot be repaired.

Not all falling block actions are the same design as an 1885. Some are decidedly only good for low to very low pressure chambers due to the nearly or completely unsupported breach block. This Hopkins Allen 932 appears to be one these designs although I've not done a huge deep dive on them. Yet. So far I'd say that a .300 BLKO, even when kept to sub-sonic loads, is likely to be too much for it.