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Lead, lead, led & leade (Read 9600 times)

rr2241tx Full Member Offline Posts: 138 Location: San Marcos Joined: Mar 27^th, 2012	Re: Lead, lead, led & leade Reply #15 - May 6^th, 2015 at 10:36am	Print Post
	Auto-Corrupt is one of my favorite features of my wife's smartypants phone.


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Aonghas Ex Member	Re: Lead, lead, led & leade Reply #16 - May 6^th, 2015 at 10:48am	Print Post
	marlinguy wrote on May 5^th, 2015 at 10:15pm: JS47 wrote on May 3^rd, 2015 at 11:57pm: My spell checker says that we're both wrong about the spelling of leade and freebore. I wish my spell checker would stop trying to change "buttplate" to butt plate! If you insist that it shows every change it wants to make, it will give you a range of options, ranging from 'surrender to the will of the speilchucker' to 'add to dictionary' Choose 'Add', and it will submit to your will ever afterwards. -- Aonghas


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texasmac Frequent Elocutionist Offline Posts: 2151 Location: Central Texas Joined: Aug 16^th, 2004	Re: Lead, lead, led & leade Reply #17 - May 6^th, 2015 at 11:18am	Print Post
	rr2241tx wrote on May 6^th, 2015 at 10:35am: I don't know whether the freebore in our BPCR rifles actually is tight enough to aid in alignment or not. It definitely helps with added powder capacity. Tom, From many discussions with Browning, the understanding at the time (April 1994) the chambers were designed was to design-in freebore with a slightly larger diameter than the groove diameter. The theory was that, when fired, the bullet will obturate to completely fill the throat; resulting in a bullet aligned with the bore and slightly larger than the groove diameter. Hence, the freebore in the Browning .40-65 and .45-90 chambers is approximately 0.002" larger than the groove diameter. The process is believed to reduce the negative effects of cartridge and bullet misalignment. I question the merits of this approach, believing that a bullet out of alignment with the bore will not be symmetrical after it obturates. But keep in mind that the Browning chamber designs were released over 21 years ago. I'm betting a more modern design would result in the same freebore and groove diameters. Wayne

	NRA Life (Benefactor & President's Council) Member, TSRA Life Member, NSSF Member, Author & Publisher of the Browning BPCR book
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rr2241tx Full Member Offline Posts: 138 Location: San Marcos Joined: Mar 27^th, 2012	Re: Lead, lead, led & leade Reply #18 - May 7^th, 2015 at 10:17am	Print Post
	Browning at least had a plan on the 40-65 and 45-90s. Like you, I suspect that if the bullet is not aligned with the bore when obturation begins it will not be aligned afterward either but I'm not an engineer so who knows. I understand their use of a SAAMI chamber on most of the 45-70s since they probably correctly surmised that their customers would shoot SAAMI-spec jacketed bullets and mostly factory loaded ammo in them. What I don't get is why they used that same chamber in the 45-70 BPCR rifle where it would be reasonable to assume that purchasers would be using full case blackpowder loads and long, heavy soft lead bullets. It looks like they would have followed the same logic used on the 40-65 and 45-90 BPCR models and used a chamber with a leade.


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texasmac Frequent Elocutionist Offline Posts: 2151 Location: Central Texas Joined: Aug 16^th, 2004	Re: Lead, lead, led & leade Reply #19 - May 7^th, 2015 at 7:02pm	Print Post
	rr2241tx wrote on May 7^th, 2015 at 10:17am: Browning at least had a plan on the 40-65 and 45-90s. Like you, I suspect that if the bullet is not aligned with the bore when obturation begins it will not be aligned afterward either but I'm not an engineer so who knows. I understand their use of a SAAMI chamber on most of the 45-70s since they probably correctly surmised that their customers would shoot SAAMI-spec jacketed bullets and mostly factory loaded ammo in them. What I don't get is why they used that same chamber in the 45-70 BPCR rifle where it would be reasonable to assume that purchasers would be using full case blackpowder loads and long, heavy soft lead bullets. It looks like they would have followed the same logic used on the 40-65 and 45-90 BPCR models and used a chamber with a leade. Tom, I assume you meant to say "... and used a chamber with freebore" because all the Browning .45-70's have a leade. It's an extension of the 12.75 degree transition step, therefore, due to the sharp leade angle the leade is very short. But to answer your question: Since both the .40-65 and .45-90 cartridges are considered obsolete by SAAMI, Browning had somewhat of a “free hand” in defining the chamber and throat dimensions. But, as a SAAMI member, they are compelled to comply with SAAMI’s chamber and throat specifications for the commercially available .45-70 Government cartridge which does not have a neck or freebore and has a leade angle of 12.75 degrees. This applies to all their .45-70 chambered rifles. BTW, I have not checked lately; SAAMI may have since added the .40-65 and .45-90 to their specifications. For the reasons you mentioned, if I ever get around to routinely using my Browning .45-70 rather than the .40-65 for silhouette matches I plan on having it "throated" (add freebore) and significantly reduce the leade angle at the same time. Wayne
	« Last Edit: May 7^th, 2015 at 7:07pm by texasmac »
	NRA Life (Benefactor & President's Council) Member, TSRA Life Member, NSSF Member, Author & Publisher of the Browning BPCR book
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