Miroku 1886 with a .4555 bore.

[eodcoduto]

Gentlemen,
This is my first post on this site and I need some advice. I have a Miroku 1886 takedown in 45-70, with the 26" Octagonal barrel that intend to hunt elk with this fall. I slugged my barrel and it comes out at .4555, I repeated this three times and came up with .4555 each time. My question is, are .458" projectiles what I need for this bore or do I need to size them down to .457"? This is the first time I have loaded cast boolits so be gentle.

[2ndAmendmentNut]

Gentlemen,
This is my first post on this site and I need some advice. I have a Miroku 1886 takedown in 45-70, with the 26" Octagonal barrel that intend to hunt elk with this fall. I slugged my barrel and it comes out at .4555, I repeated this three times and came up with .4555 each time. My question is, are .458" projectiles what I need for this bore or do I need to size them down to .457"? This is the first time I have loaded cast boolits so be gentle.

Welcome to the forum!

If a cast .458" boolit will load and chamber fine I would not hesitate to shoot it. In fact I personally shoot a .459 hollow base boolit out of all my 45cal rifles. A bore of .4555 doesn't sound that tight to me, but then again I am a terrible person and only slug my bores if I have a problem. Just follow all standard loading procedure and stick with published data.

[Outpost75]

Groove, not bore.

Cast projectiles should be sized to fit the unrifled portion ahead of the case mouth before the origin of rifling starts.

Fit bullets to the THROAT, not the barrel groove diameter.

Do a pound cast. Read the sticky, if unfamiliar. Goodsteel wrote a great tutorial on this.

[Nueces]

Because of your invarying measurement, to tenths, coming out at the same half thousandth, I suspect you were using a dial caliper. Barrel slugs need to be measured with a micrometer, several times, as you have already done. Are you able to access anyone nearby with a decent mike? I wager you will get mike measurements more toward the nominal 0.458"

[Bad Ass Wallace]

Always confusing!

http://img.photobucket.com/albums/v152/BAWallace/bore_groove_zpsfslexacp.jpg (http://smg.photobucket.com/user/BAWallace/media/bore_groove_zpsfslexacp.jpg.html)

[AZ Pete]

I have had a Browning High Wall (Miroko) for about 14 years. It mic's the same as yours, I still have the slug, and mic'ed it again this afternoon. I size my bullets to .459. They feed and shoot just fine, as do .458 jacketed bullets. The Browning action is exceptionally strong, so I don't think that any published cast bullet data will be a problem.

[NSB]

Unless you have a set of mics that read to five decimal places, don't even bother trying to interpret the last decimal. If anything, round it up. You're not that low with your readings. Just use a .458 or .459 and you won't have a problem. Bullet choice will make more of a difference than the dia you're getting.

[eodcoduto]

I'll borrow a micrometer this week and see what the reading is. Thanks for the help on this, since my measurement seemed smaller than what I was expecting. I will give the results once I have them.