OAL Gauge Question

[9ptbuk]

I have a question and would like to hear what everyone else thinks about it . I've been using the Hornady OAL Gauge and a Hornady Modified Case on my 25-06 to obtain the seating depth for my loads , When I try to set the seating depth .010 off the rifling I'm getting faint marks on the ogive on some of the bullets, Not all but some . Am I seeing the difference in headspace between the Hornady Modified Case and my fire formed cases ? To obtain Exact measurements do I need to use a fire formed case on the OAL Gauge ? Thanks for any suggestions !

 

[B23]

I don't know for certain that using the generic modified case is your problem but the one and only time I tried using one of those store bought Hornady modified cases with my OAL tool, the measurements weren't even close. I always have my OAL case gauges made from a piece of brass that's been fired in that particular gun and it's worked out good so far.

Maybe in some chambers they fit better than others, but the one time I tried using one of those one size fits all modified cases, it didn't have a very good chamber fit and was hard to get usable accurate measurements.

 

[9ptbuk]

I don't know for certain that using the generic modified case is your problem but the one and only time I tried using one of those store bought Hornady modified cases with my OAL tool, the measurements weren't even close. I always have my OAL case gauges made from a piece of brass that's been fired in that particular gun and it's worked out good so far.

Maybe in some chambers they fit better than others, but the one time I tried using one of those one size fits all modified cases, it didn't have a very good chamber fit and was hard to get usable accurate measurements.

Thanks for confirming what I suspected, I'll buy the correct size tap and build my own .

 

[Greyfox]

Question; when you measure the case/bullet after taking a seating depth with the guage are you measuring to the tip of the bullet, or to the bullets ogive using a comparator? Bullets can have variation in OAL(as much as .010") but the base of the bullet to ogive is generally very consistent. This is particularly the case with match style hollow tip bullets from Berger, Sierra, and JLK. Also, the important measurement is from the bolt face(bottom of the case) to the bullets ogive. It's important that the test case be in contact with the bolt face when the action is closed and a measurement is taken. Too much headspace will also give erroneous readings. IMO.

 

[9ptbuk]

Question; when you measure the case/bullet after taking a seating depth with the guage are you measuring to the tip of the bullet, or to the bullets ogive using a comparator? Bullets can have variation in OAL(as much as .010") but the base of the bullet to ogive is generally very consistent. This is particularly the case with match style hollow tip bullets from Berger, Sierra, and JLK. Also, the important measurement is from the bolt face(bottom of the case) to the bullets ogive. It's important that the test case be in contact with the bolt face when the action is closed and a measurement is taken. Too much headspace will also give erroneous readings. IMO.

I'm using the comparator to measure with . Thanks

 

[tbrice23]

I have a question and would like to hear what everyone else thinks about it . I've been using the Hornady OAL Gauge and a Hornady Modified Case on my 25-06 to obtain the seating depth for my loads , When I try to set the seating depth .010 off the rifling I'm getting faint marks on the ogive on some of the bullets, Not all but some . Am I seeing the difference in headspace between the Hornady Modified Case and my fire formed cases ? To obtain Exact measurements do I need to use a fire formed case on the OAL Gauge ? Thanks for any suggestions !

Unless your chamber is headspaced very short , every Hornady HS modified case I've use is shorter than my actual chamber.

 

[Mikecr]

I've been using the Hornady OAL Gauge and a Hornady Modified Case on my 25-06 to obtain the seating depth for my loads

This isn't 'seating depth', it's ogive to land relationship. Your seating depth is whatever you choose.
Which brings a point about this; you should be testing different seating depths for best (tightest grouping performance), and when you find it, you measure and log your cartridge base to ogive(CBTO), and never change it for the life of that barrel.