Sinclair chamber length tool ?

J

janderson0

Guest
I just bought the chamber length tool for 6mm, tight neck. I'm not really sure what the measurement means now that I have it.

The reason I'm confused is the tool only measures .258 in dia, and the chamber is a .262 or about .004 slop. Then as I understand it the chamber is cut at about a 45 degree from case end into the throat.

I measured about 1.580 with the tool, but I do not for a second beleive that the chamber starts into the throat at that point.

Instructions with the tool state not to allow cases to become within .024 of the measurement.

What did I learn?

Thanks,
Jim
 
What are you wanting to measure? The tool you have is for measuring trim length for cases...not seating depth. The reason for the .024 is so the tool does not crush back into the case. You should trim about half the neck length off and then insert it in the chamber. Then you will know exactly where you need to trim your cases to or if your cases are getting to long.

Hovis
 
I want to check the trim to length. But as I see it the tool is a .258 rod inserted into a cone that starts at .262 and ends at about .244 or what ever the throat is. The measurement is just a point somewhere between the end of the case and the throat (I assume this is a taper from end of case to the throat)

The case used with the tool needed over .100 removed to work. The .024 number is in the instructions. They claim that if the user determines to trim longer than spec, not to trim longer than measurement from tool -.024.

Make any sense?
Jim
 
Interesting. You think the gauge goes past the end of the neck? Could be. Why not just buy a gauge for the standard neck and turn it down to say .261 and see.

I've used a couple of these gauges and it's surprizing how much longer one can let the brass grow before trimming and not having to trim them back so far.

Tom
 
reasoning

some individuals want the brass to fit the chamber perfectly.
i used one of these on my 300 win mag.
almost, everyone knows the 300 was made longer in the body so it would not fit rifles like the 264 mag for safety reasons. that made the neck shorter. so some zelous gun writer set out with the theory the shorter neck cartridges burn out barrels faster. then everyone shooting a short neck cartridge in competition wants the sinclair gauge to curb the bet so to speak. the reason for the warning is some unknowing individuals will try to leave too much and end up crimping the brass into the bullet with a full house load. the results disasterous if not fatal.
alot of things like this have diminishing returns. from talking to individuals that shoot magnum rounds in competition and won or set records i have never been told this is their winning trick. not even close. most will say anealing brass, consistent neck tension, and getting a lucky draw for a bench when the wind subsided won the matches.
Fred
 
Sinclair chamber length gauge??

What that little plug does is show you the "actual" length of the chamber to the end of the neck. Probably about .025 longer than the "maximum" trim length of your brass. That way you don't have to think about your brass being too long and taking a chance that you'll "crimp" the neck on a bullet when you close the bolt.
I've got them in 22, 6mm and 30 caliber. Havn't had to trim brass in a long time. ;)
 
I just made a couple of those gauges in the last month. I was surprised to find out that my 25-06 was over 20 thousands longer than the max length and my 35 Whelen was more in the neighborhood of 40. I understand that 20-25 thousandths over is common. Those are hunting rifles and I'll not be using longer brass than max but it's comforting to know I've got a little leeway in case I forget to check my brass length one time.
 
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