jacket vs cast (hard lead alloy) in 32-20

[bigdog454]

I have 2 32-20 rifles, one has a .3085 bore the other is .314. If I were to shoot 314 jacketed bullets in the 308 bore, how much would the pressure increase? Lets say that these were both max loads. would the pressure be dangerous?
I think that this is a good question for Larry Gibson, as he has the ability to measure pressure.

Doing the same, what about if it were a 32 H&R mag?

BD

[Outpost75]

What matters a lot is the type of rifle, strength of the action and how the chamber is throated. A .308 barrel with gradual throat will raise pressure less than SAAMI chamber with abrupt transition.

Slower powders like 4227 result in a more gradual pressure rise than faster pistol or shotgun powders. I shoot .313 cast 150-grain bullets in my .308 groove ten-inch twist H&R single-shot .32-20 all the time. Chamber has origin of rifling cut like a .30-'06 and I use a case full of 4198 with 150-grain bullet and 4227 with 115-grain bullets. John Taylor made the barrel from a US military 4 groove pull-off.

[Castaway]

Suggest you recheck your measurements. Nominal bore diameter is 0.305 and groove diameter is 0.311. I bet the groove diameter of your 0.3085 is closer the the measurement of 0.311-0.314 depending on the rifle

[megasupermagnum]

There's been a number of rifles for 32-20, 32 H&R, and 327 federal I've seen with .308" groove barrels. I've never heard of any issues.

[PositiveCaster]

Suggest you recheck your measurements. Nominal bore diameter is 0.305 and groove diameter is 0.311. I bet the groove diameter of your 0.3085 is closer the the measurement of 0.311-0.314 depending on the rifle

I bet the OP’s groove measurements are spot on. One of my .32-20s was chambered on a .308” barrel, it shoots just fine with .312” to .307” j-bullets. (BTW that barrel shoots 220-grain jacketed bullets very well). The only cast I’ve used measured .312”, no problems - but the action is a Contender so pressures are less critical than in an antique rifle.

I’m wondering where the OP got his .314” jacketed bullets…



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[Castaway]

I knew Ruger put 30/.308 barrels on their mini 30’s but always thought they did it bacause they were “Ruger Strong” and that’s what they were tooled up for. Now I’m curious as to what the rifles are the OP posted about

[Dom]

I have a Marlin 94 CL in 32-20.I shoot my own 115gr GC cast bullets sized .311. Bullets are made from scrap wheel weights & run 10.5 BRN. Driven at about 1200 FPS they are deadly accurate.