New rifle - bullet questions?
 

I have a new rifle(to me) in my safe, got it as part of payment for a job I did.

It's a Mkontho in-line rifle based on the Pauley design(plunger), they are build in South Africa by a local gunsmith and proofed up to 150gr loads.
The rifle has a 1:24 twist, 21 1/2 inch barrel(measured from crown till touching breechplug), .451caliber and ignited with a standard no11 percussion cap. No open sights, fitted a old Bushnell 3-9x40 scope.

I have slugged the barrel, 0,457" and 0.452" measured. I have the Lee .457"mold that cast them at 405gr depending on the lead. I also have a .452" Lee re-sizer. I want accuracy and not so much speed as the rifle are supposedly very accurate at longer distances. From what I've read so far the ideal speed should be around 1250-1350fps with the Gibbs target rifles, I guess it should be the same with my rifle.

Edit: Let me rather re-phase my question. How do I determine the ideal size with the measurements above to be able to shoot the rifle accurately without having to think about paper-patching? Lee make a .452, .454 and a .457 re-sizer but my bullets already are .457".

I would love to see a picture of your new asset. I sounds like a nice addition to your collection.

I shoot a 465 grain conical out of a 45 with 75 Grains of 3F. It's very accurate. My guess is the higher charges may work but will not be necessary.

I have been told but never verified that rifles will often have two sweet spots, one down low at 65-75 and then another up high in the 90-100 range. This big bullets really kick at the higher charges.

Have fun and post a pic.

you should be about .010 thou under sized of the barrel and really shouldn't size more that about .003 thou difference from size cast to final size you probably should get a new mold in that case. are you shooting round ball i should have asked that question first. 3f is ok but i would try both they say 3f for .45 cal and smaller but not always the better choice you just have to experiment with load combinations if your planning on target shooting 50-80 gr max if hunting 80-max load depending on game,possible distances and of course accuracy.

I will post a pic later tonight of the rifle.
Roundball won't be practical in a 1:24 twist except with a light charge which means I wont be able to hunt or shoot longer ranges with the rifle.
The .457/405gr bullet is a flat based design, being that undersized(.010 thou) I'm scared of blow-by or am I wrong? I thought the bullet must match or closely match the barrel.
Reason for my post as I'm used to my sidelocks and inlines are bit new to me.

PM sent to you Wildboer.

IMO I would cast a few bullets and try them out with different loads. Start at 70 gr of FFFg and work your way up. You can also try putting a felt wad between powder and bullet. That sometimes improves accuracy but not always.

Thanks Bronco. I have tried 70-80gr of 3F in my rifle with a 500gr .451" bullet but no luck. Haven't thought about a felt wad though, do I need to lube the wad?

.452" pure lead or close to pure will be .001" over land bore. Each land will engrave .0005", and keep your bullet on the powder. A .030"-.060" thick by .462"ish diameter vegetable fiber gasket wad would be best in this application, between powder and bullet. I prefer the. 060" thick wad in my 3 different brand .451's with 1:20 twist. 70 to 90 volumetric grains of powder should do it for you. Start low and work up in 5 grain intervals, then fine tune from there.

If you want to shoot a squib load to foul your bore before hunting our target shooting, you could get away with a .451" diameter bullet.

I prefer pure lead at .001" over land diameter, with the veggie wad.

http://www.sagebrushproducts.com/catalog/item/7274306/7655238.htm

Looking forward to seeing the pic of your rifle!! I prefer my White S91 in .451 to all of my ML rifles.

Here is 2 quick pics taken after dark. The rifle has sort of a bull-barrel with a step in. Quite a shortish compact rifle. Wood is of course walnut as the rifle is a custom built with checkering, palm-swell etc...
Actually fits me perfect in the shoulder:rock::rock: