Measuring Lands & OAL

02 January 2010, 07:01

ah141nj

Hi Guys & Happy New Year to all.

Just bought a Hornady OAL guage & comparator.
Used it in my Colt Match HBAR II.
Lands/OAL measurement was 2.010 while using the comparator.
That gives me a conventional OAL (w/o comparator) of 2.39.
Do these measurements seem accurate?
How much of bullet jump to start out with?
Should I just seat to published OAL & not use these tools?

The bullet is a Hornandy 50 gr V max. Its length is 0.768 if that helps.

There's no such thing as a good gun. There's no such thing as a bad gun. A gun in the hands of a bad man is a very dangerous thing. A gun in the hands of a good person is no danger to anyone except the bad guys."
-- Charlton Heston, 15 Sep 1997

02 January 2010, 21:32

Ol` Joe

There`s no set length for the leade and that`s the reason for the tool. That, and it allows you to load bullets of various shapes to the same distance from the leade.
How far off you go is totally up to you as long as the bullet isn`t jammed in the rifleing or falling out of the case. I normally start about 0.005" off, do my load work up and then adjust the jump in 0.005" increments to tune it. The rifle will tell you the jump it prefers.

A semi-auto though may need a given COL for proper feeding/function, and if so you should stay close to the books recommended COL.

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03 January 2010, 11:58

ah141nj

quote:
Originally posted by Ol` Joe:
There`s no set length for the leade and that`s the reason for the tool. That, and it allows you to load bullets of various shapes to the same distance from the leade.

I am aware of that.

How far off you go is totally up to you as long as the bullet isn`t jammed in the rifleing or falling out of the case. I normally start about 0.005" off, do my load work up and then adjust the jump in 0.005" increments to tune it. The rifle will tell you the jump it prefers.

I was kind of looking for specific suggestions for my bullet & rifle's application.
Anyone use that bullet & what is the jump that they were happy with? What was the OAl they ended up with

A semi-auto though may need a given COL for proper feeding/function, and if so you should stay close to the books recommended COL.

The problem with that is Hornady doesnt list a OAL for that particular bullet in an AR

I was also inquiring about the measurements themselves. Do they seem reasonable?

03 January 2010, 19:27

Ol` Joe

As I said there is no set lenght and anything is possible. My M70 HV 223 measures 1.92" using a comparator or ~.25" of throat.
My Win 1885 High Wall in 223 barely lets a 55gr Hornady V max touch the leade with the bullet still in the case. Your 2.010" measurment falls right in between my two rifles.
The long throated 1885 shoots within a 0.10" or so as well as the M70 for 5 rd even with 5Xs the jump.

03 January 2010, 22:15

Zoboomafoo_dude

When using the OAL gauge make sure you have a wooden dowel to apply pressure in the opposite direction. That way you get a positive feel for when you actually engage the lands. I take the average of five measurements. With a little practice you shouldn't get much more than about 0.003 difference at most between measurements.

08 January 2010, 05:16

ah141nj

quote:
Originally posted by Zoboomafoo_dude:
When using the OAL gauge make sure you have a wooden dowel to apply pressure in the opposite direction. That way you get a positive feel for when you actually engage the lands. I take the average of five measurements. With a little practice you shouldn't get much more than about 0.003 difference at most between measurements.

Good tip, Thanks.