Printable View
http://i155.photobucket.com/albums/s...psrfqd4p5r.jpg
are the lands where the 2.8108 "throat" measurement ends? 140 berger or amax is about .7 something inches from ogive to the tip of the bullet, seeing what to throat for to still fit in magazine. Just using this print as reference
TIA
-Luke
Lands and grooves are features of a rifled barrel, not a cartridge.
http://www.hunter-ed.com/images/graphics/bores.gif
I think what he wants to know is how far into the chamber namely the throat do the lands and grooves begin. 2.108 looks about right. Even though there is a short taper the lands will start to engrave lightly at that point.
Fixed it for ya.Quote:
Originally Posted by jonbearman
ETA: I question the accuracy of that print. Points U and V, as drawn, cannot be the same measurement.
Thanks guys!Quote:
Originally Posted by Hotolds442
its a print from mcgowan
I've noticed most my rifles accuracy seating depth are from right at contact with the lands to about 40 thou off depending on rifle. Just want to make sure I could get there and still be a reapeater? 2.8" at the beginning of the lands just seems like a long throat! Even .1" off lands I'd still be longer than mag length of 3.4
My 6x55 BR needed a long action magazine length to shoot the Hornady 105's at .0000. The 140's in the 6.5 will be even longer using the same parent brass.
This is for a long action at length of 3.4! That's why it suprised me that they would throat it so long
From Mcgowans lead gunsmith who sent me the print.
"SAAMI is 0 freebore. with a 0 deg-42-51 throat. Our reamer matches that. The throat starts a gradual taper to the 2.81 dimension but full land will be slightly shorter than that. I am sorry I cannot give a more exact number"
so i guess the only way to find out is to test it?
the easiest way to get the lands where you want is to send in a few dummy rounds seated where you want them but make sure to use a lot of neck tension on the dummys so the bullets dont move in shipping or if dropped.
yep long range i agree! i was just trying to see if there was a way to set up the diagram to know what your COAL would be, like if you wanted to order a barrel before you had components to set up a dummy round.
example if you could measure your ogive to tip of your bullet, and have a known measurement on the reamer diagram where they would touch the lands you could set up your chamber to touch lands at mag length and have room to play without needing dummy round, but i guess that's impossible!
its not impossible but why guess...resize a couple pieces of brass seat a couple of bullets and send them in then you know what your going to get...id also suggest you seat the bullets .010 or so deeper then mag length so you can chase your lands as they erode.Quote:
Originally Posted by Luke45