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Shooting & Reloading - Mausers, Big Bores and others >> Lee Speed Forum & Archive

Old_rifle_nut
.275 member


Reged: 13/12/06
Posts: 82
Loc: Manitoba, Canada
Re: BSA Sporter for sale/sold
      02/05/17 02:31 AM

Well, I finally received it, after waiting what seemed, at least to me, an inordinate amount of time. Then again, this happens every single time I buy a rifle that has to travel through the post. In any event, after a suitable period of ogling it, throwing it to my shoulder, working the bolt & dry firing it, I disassembled it, cleaned it, installed a magazine cut-off that had been removed (at least the magazine cut-off screw was still there), added a brass oiler & pull-through underneath the trap door, as had been there originally, and set to work cleaning the bore. Six days and a half can of Wipe Out foaming bore cleaner later, three patches finally came out clean.

The bore is OUTSTANDING! Sharp lands, sharp grooves & NO cordite frosting. Quite likely it was ordered new for delivery in Canada and never had to put up with that EVIL cordite, but rather just good old Canadian-made nitrocellulose. (Why does everyone seem to forget that the Dupont plant is in Quebec, Canada & NOT in the U.S. of A., I wonder)

I measured the barrel's interior, after being advertised as having a bore of 0.318" and here is what I got (for those of you who forget that Lees, as most other British rifles, have an odd number of lands & grooves; in this case 5 of each):

lands 0.302"
grooves 0.314"

How did I get that you ask?

A lot harder than simply measuring the lands and then the grooves across opposite points of the barrel, like you do with non-European barrels! Well, not really, you just have to go about it a different way.

A: Outside diameter of barrel to front face of front sight base collar: 0.5570"
B: Thickness of barrel to land (thickest part) measured to the same point: 0.1275"
C: Thickness of barrel to groove (thinnest part) measured to the same point: 0.1215"

Now, there undoubtedly exists some fancy geometric / algebraic / calculus formula to figure this out, but I'm just a dumb retired nut, so I had to figure this out myself.

Knowing that the thickest part of the barrel between the lands equals the bore diameter, we get A - (B x 2) = land diameter

=0.5570-(0.1275 x 2)
=0.5570-0.255
=0.302"
Confirmation: (my bore gauge plug of 0.302" fits, but my bore gauge plug of 0.3025 does not). Further confirmation: one of my Accurate Moulds bullets that I designed (31-210H), with a bore ride diameter of 0.303" fits very snugly into the muzzle with a light coating of sewing machine oil, BUT there are very distinct grooves impressed into the bullet showing 5 fully developed land marks.

Now for the groove diameter:

Knowing that the thinnest part of the barrel opposite the lands equals the groove diameter,
we take the outside diameter of barrel minus twice the thickness of the thinnest portion of barrel, we get A - (C x 2) = groove (required bullet) diameter

=0.5570-(0.1215 x 2)
=0.5570-0.243
=0.314"

Notice the thickness of the rifling is 0.006" ((0.314" - 0.302") / 2). The British Minimum requirement is 0.005", while the rejection is 0.008", so still on the tight side.

You know why we don't have the right size jacketed bullets (well, you don't, I have 1,000 S.R.Custom 200 gr. SP bullets measuring 0.314" back from when he was still making them)?

It's because the American standard is typically 0.004" rifling thickness:

30 caliber 0.300" / 0.308"
338 caliber 0.330" / 0.338"
35 caliber 0.350" / 0.358"
6.5 caliber 0.256" / 0.264"
405 caliber 0.403" / 0.411" & 0.405" / 0.413"
45 caliber 0.450" / 0.458"

If they would have simply manufactured the correct size bullets in the first place using the ACTUAL groove diameter, like they do for the .22 (0.006"), .243 (0.007"), .257 (0.007"), .277 (0.007"), .284 (0.007") & .375 (0.009"), we would not have the problem of having to use cheap undersized .310", 0.311", or 0.312" diameter bullets or springing for expensive, correctly-sized bullets. Our 8mm shooting brothers go through the same thing with American-produced 8x57JS ammunition (0.320-0.321" bullet diameter), but at least they can easily obtain correctly-sized bullets so they can load their own. That, however, is because the American-made 8mm Remington Magnum, has barrel measurements of 0.315" & 0.323" (there's that 0.004" rifling thickness again)

<<<<END RANT!

Range test to follow in a month or so, after I get some ammunition loaded up and head to the cottage for the next 6 months or so.

Field test will hopefully follow come November & deer season opens here in the Great White North!

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Entire topic
Subject Posted by Posted on
* BSA Sporter for sale/sold Strathcona 21/04/17 02:26 AM
. * * Re: BSA Sporter for sale/sold Daryl_S   24/04/17 12:53 PM
. * * Re: BSA Sporter for sale/sold Old_rifle_nut   02/05/17 02:31 AM
. * * Re: BSA Sporter for sale/sold Daryl_S   02/05/17 03:10 AM
. * * Re: BSA Sporter for sale/sold yumastepside   02/05/17 05:42 PM
. * * Re: BSA Sporter for sale/sold Claydog   21/04/17 08:03 AM
. * * Re: BSA Sporter for sale/sold Old_rifle_nut   22/04/17 01:47 AM
. * * Re: BSA Sporter for sale/sold Strathcona   22/04/17 03:05 AM
. * * Re: BSA Sporter for sale/sold Sarg   22/04/17 03:43 AM
. * * Re: BSA Sporter for sale/sold Strathcona   22/04/17 06:50 AM
. * * Re: BSA Sporter for sale/sold Old_rifle_nut   22/04/17 07:45 AM
. * * Re: BSA Sporter for sale/sold buckbrush   23/04/17 05:08 AM
. * * Re: BSA Sporter for sale/sold Strathcona   23/04/17 07:10 AM
. * * Re: BSA Sporter for sale/sold Sarg   23/04/17 12:00 PM
. * * Re: BSA Sporter for sale/sold Old_rifle_nut   24/04/17 09:59 AM
. * * Re: BSA Sporter for sale/sold buckbrush   05/05/17 05:29 PM
. * * Re: BSA Sporter for sale/sold Old_rifle_nut   11/05/17 12:09 AM

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