.45/90 Win. cast loads with smokeless powder

[franklin!]

I have a .45/90 Win. custom rifle on a High Wall Action. I'm looking for load suggestions with smokeless powder and cast boolits of 385 grains and 500 grains. I have ordered a 500 grain mold but haven't cast any of them yet. Accuracy is more important than velocity. All shooting thus far is from a bench rest at 50 yards. Rifle has a ladder tang rear sight, Hadley eye cup and spirit level front sight. With Lyman #457124 385 gr. boolits, here are the loads I have tried with poor results: 55.0 gr. Varget; 49.1 gr. Rel 12; 45 gr. Rel 7. Of the 385 gr. loads which showed some promise, these first two,17.1 gr. Unique and 27.2 gr. SR 4759 gave 5 shot groups at 50 yards of 3" or slightly less. The other loads, 33.0 gr. SR 4759; 41.0 gr. IMR 4064; 49.1 gr. H 322 did not do as well, printing more than 3'' but less than 4". This is my first experiment with .45/90, and I'm not sure what to expect. Your experience might help me "rediscover the wheel!" Thanks for your replies.

[country gent]

I havent done alot with smokeless in the 45-90 but Lymans cast bullet manual does gives some loads. I would look for around 1200-1300 fps performance with the 500 grn bullets. Another plus here may be a bullet that seats deeper into the case taking up more of the air space. What twist rate is your barrel? 1-18 should do well will 500-550 grn bullets at the above velocities. My current BPCR shilouette loads 1250 fps and a 55o grn shilouette bullet from old west moulds. It rocks the gongs nicely, and shows great accuracy. Shorter bullets may not do as well in the faster twist.

[sharpsguy]

Check the barrel twist. If it is 1-18 or faster, you are doing about as well as you will ever do with 385 grain bullets. You will need 500 grain or better bullets for the rifle to shoot well if it has the fast twist. A twist of 1-20 will work with the lighter bullets, but the 1-18 is definitely a heavy bullet proposition.

[Ballistics in Scotland]

The early 1886 lever-action had a 32in. twist, limiting bullet weight to around 330gr. I don't know if Winchester themselves made the Single Shot with that twist, but in 1900 they went over to a 20in. twist, special orders probably excepted.

I don't believe overstabilisation of a jacketed bullet does much harm. I once had a .300H&H Magnum with a 10in. twist which was pretty consistent in giving its best groups, about 1⅛in. at 200 yards, with 125gr. spire-points. It becomes more significant with cast, and especially cast when you are straining for velocity. But keep the velocity moderate and I don't think 385gr. in a 20in. twist should be bad.

[franklin!]

I'm learning already, and I'll check the twist at first opportunity and report. Thanks for your time and expertise. Keep the suggestions flowing, and we'll see what develops.