Colt 19117 New Service load data and sight picture question

[fiatdad]

I have an 1917 Colt New Service in .455 Eley. I am using Stareline .45 cowboy brass. I was using .45 auto with half moon clips until I found 45 Long Colt brass would work if I cut down the case to auto length. The bullet I an using is a 230 gr. flat nose with 5 grains of Unique. The gun shoots about 4 inches low at 30 feet even with 6 grains of powder. Does anyone have a load that will shoot to the point of aim? I do not want to file the sights if possible.
Thanks
Nick

[Texas by God]

Use a heavier bullet to raise point of impact. Try a 250 gr with 5 grs of Unique. Enjoy that great gun.

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[5.7 MAN]

Probably need a heavier bullet 260 grains or so.

[Der Gebirgsjager]

Usually a lighter load will shoot higher, so you could experiment and drop your 5 gr. down to 4.8 gr. and see what you get. How was it shooting with the .45 ACP loads? Bullseye is another good powder to try.

[Outpost75]

Use Accurate 45-262H with 3.5 grains of Bullseye for 600 fps, bullets sized to fit cylinder throats, probably .456-.457 for your Colt. Soft alloy like 1:30 or 1:40 tin-lead is best.

220345

[fiatdad]

Thats what I thought but 230 gr was the heaviest bullet I could find. How about a 405 hollow base?:-)

[fiatdad]

The cylinders mic at .454.

[Outpost75]

The cylinders mic at .454.

How measured? With gage pins, chamber cast or calipers? Calipers don't give an accurate measurement because the tiny flats on their knife edges will bridge against the curvature of the chamber throats. If your cylinder throats really pin out at .454", they are leaded or dirty, I've never seen a pre-1930 Colt NS .45Colt or .455 cylinder that tight. Minimum per the drawings was .4555 with +0.0015 tolerance being normal for a .455 Eley cylinder. If was refurbed with a US M1917 .45 ACP cylinder should be .4525 + 0.0015" and your .454 would be correct at max tolerance, but I have seen WW1-era cylinders as large as .457 due to cleaning wear and rust removal from wartime primers.

[fiatdad]

I used calipers and a lead slug.

[Outpost75]

Thats what I thought but 230 gr was the heaviest bullet I could find. How about a 405 hollow base?:-)

No, these are more nearly correct: https://www.mattsbullets.com/index.php?main_page=product_info&cPath=71&products_id=261&zenid=626iqj5akl95ask0vo1du8tkg1