By: M Wyman

M Wyman — Sat, 30 Sep 2017 15:11:08 +0000

I may be wrong, but he purpose of using this tool is to adjust the JUMP distance when seating bullets that is desired to be consistent to within .0005″, well under the + – tolerance allowed under SAAMI specs for chamber dimensions. I understand that the measurements are being taken from the bullet Ogive to the base of a foreign case that has not been fire formed to that chamber, yet the case is indexed against the chamber shoulder. The only accurate measurement you could obtain would be the distance from the shoulder to the lands,(a useless fact) but is still dependent on the compatibility of your comparator bushing and the seating stem in your die. Who needs that? The difference in headspace on that case will provide false OAL readings from the case base, or bolt face to the lands as compared to fire formed cases, and even then you have to guess how much the case relaxed after full expansion (estimated to be .001 – .002″) It makes sense to me to drill and tap a fire formed case to use with the tool instead of a case provided by a tool supplier. Additionally, the bushing of the comparator is providing a measurement based on the opening diameter of the bushing. If this diameter does not perfectly match the diameter of the contact point of your seating stem on the bullet, slight differences varying bullet shape of the same lot will cause inconsistencies with your OAL as the points of reference are not the same. Someone needs to design a tool that incorporates the seating stem in your die as a component of the comparative system, but you still have some inconsistency by not knowing the true dimension between the bolt face and the lands. Try using a fired formed unsized case and insert a bullet into the neck leaving it long. Then chamber it and allow the lands to seat the bullet further. Measure and repeat making sure there is no increased tension when closing the bolt and the bullet has not stuck into the lands. measure and adjust until you can get consistent OAL’s. try seating the bullet to this depth with dummy rounds and check the ease of chambering.
You might also try measuring from the muzzle to the bolt face when closed and locked, and compare that measurement to the bullet tip held against the lands. The difference gives you an OAL, but you also have to consider the difference in length on that specific bullet from the ogive to the tip and deduct that measurement for the maximum ogive length relative to your comparator bushing.

EDITOR: Yes there are differences between a Hornady Modified Case and your own fire-formed case. But in reality none of the concerns expressed above actually matter at all, so long as you get repeatable measurements. The reason is that you determine the best seating depth experimentally with your fire-formed cases. If you load .005 longer than your tool-determined base to ogive measurement or .020 shorter, for example, that’s all you need to know. The biggest problem with the tool is that some guys push too hard and actually jam the bullet into the lands. That can lead to inconsistent results. Practice with a gentle touch, then you’ll get a repeatable measurement. Then determine your load from there experimentally.

By: steve Alldis

steve Alldis — Tue, 24 May 2011 17:25:27 +0000

Do you carry a modified case for the Hornady AOL gage in 7.62 (not 308)? Thx Steve

By: LH Lester

LH Lester — Sat, 06 Feb 2010 16:12:49 +0000

Just purchased the last component of this gauge (comparator); waiting for it to arrive. Anxious to try it out. Your description of the technique to obtain consistency helps considerably. Thanks, LHL

Comments on: Hornady (aka Stoney Point) OAL Gauge on Sale at MidwayUSA

By: M Wyman

By: steve Alldis

By: LH Lester