Bore Riders and "throatless" guns.

Old Ironsights
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Joined: Mon Jun 30, 2008 1:53 pm

Bore Riders and "throatless" guns.

Post by Old Ironsights » Sat Jul 05, 2008 2:40 pm

Apparantly my Miroku/Win 1886 has no throat - only a short .132 or so from the case mouth to direct land engagement.

Looky this:


All loaded on a Lee Loader (hammer time).

Boolit #1, Lyman 457122, 3ww/1pb alloy. Sized .457, Seated to crimp groove. COAL 2.555. This feeds slicker than snot and is my "go to" load. Dia in front of front driving band (length .060?) is .445.

Boolit #2, LBT .458 450 LFNGC, heat treated WW, sized .459. Seated to crimp groove. Pre chambering COAL 2.48 post chambering COAL 2.4695. Note the Land Engagement at 2.29. Dia here is .455. Point of land engagement is .13x (+/-) from case mouth.

Boolit #3, 600gr .459 LBT. Quenched WW, Sized to .457 (PITA). No crimp groove. Pre chambering COAL 2.555. Post chambering COAL 2.528, Again, land engagement dia .455.

Boolit #4 is the same boolit, but it actually almost pulled from the case on extraction.

When I load a 405gr Rainier TCFMJ out to 2.555 and chamber it, it seats itself to 2.423 on loading... tight to the lands.

Glad I only loaded up a couple of rounds to test-chamber...

SO, if I run the Program to make a BTAN of .445 and a nose of .445 with a band dia of .459 will I be able to seat to the crimp groove and get a COAL of 2.550" without engaging the lands? (Nominal case length 2.105 + .445 = 2.550, max OAL 2.555....)

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Re: Bore Riders and "throatless" guns.

Post by mtngun » Sat Jul 05, 2008 7:27 pm

You get bonus points for testing dummy loads in your lever gun, and more bonus points for sharing your results. :D

You are on the right track. My only suggestion is to make the bore riding diameter a snug fit, maybe 0.449". A typical 45/70 bore would be 0.448" - 0.450", but they do vary. However, since the bore riding section is so short, and since the bullet is pretty long, it is not a matter of life and death for the bore riding section to engage the lands, in this particular application.

Sounds like a typical 45/70 throat, by the way.

Old Ironsights
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Joined: Mon Jun 30, 2008 1:53 pm

Re: Bore Riders and "throatless" guns.

Post by Old Ironsights » Sat Jul 05, 2008 7:43 pm


Since a Gould is a BTAN, Step, .445 no GC Here's the latest thoughts:

..............Gould ..............................Gould 450 GC ..........................Gould 450 GC75%meplat


The biggest qusestion there would be whether or not the meplat would hang when lifted, because it looks like it would otherwise chamber the same way as the Gould.

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