OAL Gauge and Bullet Seat depth for Accuracy International AT, Berger 140gr Hybrids

[Senor_Barney]

For anyone reloading Berger 140gr Hybrids in an AT/AT rifle, what are you getting on your OAL gauge for touching the lands?

Depending on the position of Pluto to Mars...I am getting anywhere from 2.175 to 2.250.

For a period I got 6-8 measurements at 2.244 range...

I already wasted a bunch of time and resources by guessing w/o this gauge, and now that I have it I thought it would be pretty straight forward to get 3-5 consistent readings

I am trying to do it consistently each time , but what's frustrating is that the case neck on my modified Hornady case feel "sticky" and I am not 100% sure how much force is required to just tap the bullet out a tad vs. getting the neck friction to break. As such, I am not sure if I am pushing too hard on the gauge and actually pushing the bullet INTO the lands.

Any feedback on measuring technique or what your readings were would be a great start.

 

[VSP968]

Regarding the Hornady “modified” case- no matter what the cartridge, it’s close but it’ll never be as good as a once fired case from your chamber.

If you’ve got a lathe, or access to a lathe, you can make your own “modified” case with a 9/32 drill bit and a 5/16-36 tap (I bought mine from MSC, I think) and a once fired piece of brass from your chamber. The case will fit perfectly when you use the OAL gauge.

As far a gauging technique goes, I generally give the case a half twist in the camber to make sure it’s fully seated and push the bullet thru the case and into the bore until it stops and I lock the thumb screw down and pull out the case.

The bullet will stick in the lands and I gently tilt the muzzle up a and use a brass “drop rod” to knock the projectile out of the bore. I stick the bullet back into the case and measure and record the cartridge base to ogive. I measure a couple of times using a couple different bullets and write down the results each time.

After you gauge your chamber a few times, you’ll develop a technique of your own. You’ll be able to judge how much pressure to apply to the projectile without engraving the shit out of it on the lands.

Don’t overthink this stuff- it’s supposed to be fun, right?

 

[TheOfficeT-Rex]

2,964" COAL
Factory 6,5 manbun barrel from my AT, 400rnds on it. It's sitting on my workbench, so I measured three times with a hornady tool and came within a thou each time, with a light jam (bullet stuck in rifling, but came out dropping the barrel from about an inch above the bench).

2,25 is the COAL I load my 223 to - I have a hard time believing that's even close - unless you mean CBTO, in which case, that's pretty close to what I have written down when the barrel was new.

 

[jakelly]

Push it in firmly, Barney. Envision touching the lands across the entire circumference of the bullet and then press firmly enough to ensure that is happening. This should help.

 

[Dthomas3523]

Use Wheeler method.