Iron Jim Rackham Posted March 19, 2022 Share Posted March 19, 2022 Does anyone know the maximum pressure of the obsolete 25-20 Winchester Single Shot cartridge? I've got an 1891 Winchester Low Wall that I'd like to rechamber as a 30-30. The pressure of a 30-30 with 160 grain bullet is around 33,000 CPU. I could load it softer, but am curious what the type of pressure the 25-20 Single Shot generated Link to comment Share on other sites More sharing options...
Zeb Gray, #36839 Posted March 19, 2022 Share Posted March 19, 2022 25-20 SS & 25-20 WCF have similar characteristics though different cartridges. You can probably use 25-20 WCF pressure data. I too, have a Low Wall In 25-20 SS. 1892 mfg. with a single set trigger. Fun shooting. Link to comment Share on other sites More sharing options...
Cusz M. Dutch SASS Life 55326 Posted March 19, 2022 Share Posted March 19, 2022 I am sure a full case of Goex might work... Link to comment Share on other sites More sharing options...
John Boy Posted March 19, 2022 Share Posted March 19, 2022 28.000 CUP …. https://en.m.wikipedia.org/wiki/.25-20_Winchester Link to comment Share on other sites More sharing options...
High Spade Mikey Wilson Posted March 19, 2022 Share Posted March 19, 2022 The original black powder 25-20 WCF rounds were about 20,000 PSI. The later smokeless powder rounds averaged about 28,000 CUP. Link to comment Share on other sites More sharing options...
Tom Bullweed Posted March 19, 2022 Share Posted March 19, 2022 Opening a low wall barrel to a .30-30 would be mighty thin chamber walls. That old steel was likely surface hardened, so those new surfaces might not be as strong. If it was my gun, I would consider a .32/20 barrel. Link to comment Share on other sites More sharing options...
Iron Jim Rackham Posted March 19, 2022 Author Share Posted March 19, 2022 Thanks for the feedback. I knew the pressure of the shorter 25-20 WCF was north of 27,000 CPU but was curious if anyone knew the pressure generated by the longer and more powerful 25-20 pushing an 86 grain bullet. The barrel is very thick and the case diameter of the 25-20 SS measures .296 as compared to .401 for the 30-30 but there is plenty of steel remaining after re-boring. A 30-30 generates 23,000 CPU pushing a 160 grain lead bullet at 1,562 fps, and 33,000 CPU pushing a jacketed 160 grain bullet at 1,900 feet per second. Has anyone "updated" the obsolete 25-20 SS to another caliber? Link to comment Share on other sites More sharing options...
Michigan Slim Posted March 20, 2022 Share Posted March 20, 2022 Look up Reboring by JES. He does great work and could guide you where you need to go. Link to comment Share on other sites More sharing options...
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