Hornady OAL Guage accuracy

[wake.joe]

I understand the method of using a cleaning rod to measure (Down the barrel) from the bolt face to lands. Makes perfect sense to me.

So how does the Hornady tool measure from "headstamp" to lands?
I understand how it can measure from the shoulder to the lands. But how do you know if that's where the shoulder will end up on a closed bolt, with your own sized brass?

 

[ChrisGarrett]

Re: Hornady OAL Guage accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JoeW</div><div class="ubbcode-body">I understand the method of using a cleaning rod to measure (Down the barrel) from the bolt face to lands. Makes perfect sense to me.

So how does the Hornady tool measure from "headstamp" to lands?
I understand how it can measure from the shoulder to the lands. But how do you know if that's where the shoulder will end up on a closed bolt, with your own sized brass? </div></div>

Headspacing does matter with the Stoney Point modified case gages, no doubt. The best way to do it is to send a couple of fired cases from a particular chamber, to Hornady and let them drill them out for you. This way, you'll have a snug fitting case sitting in the chamber.

I think my 7RM modified case is a something like ~.005" short when measured against a fired case using the SP/Hornady headspace bushings, but knowing that number, I can correct things somewhat.

Honestly, bullets, rifling, chambers, they're all imperfect. When somebody tells you his 3 boxes of ammo are all loaded precisely 7/1000ths of an inch into the lands, he's smoking crack.

We can minimize most of these variances, but we can't eliminate them all, entirely.

Chris

 

[bowdoctr]

Re: Hornady OAL Guage accuracy

Not to get up on a soapbox but could have not made that statement any better,between the brass,bullets,powder,its a thousand wonders we ever get ammo to shoot in the same hole period,you are spot on on the oal guage,if one is to have any luck you use a once fired case from the chamber of the gun,that tap i think is 5/16x38 yes its 38 a special order

 

[vinconco]

Re: Hornady OAL Guage accuracy

When you press the bullet forward and it touches the rifling there is about a +- .010 depending on how much pressure you put on the bullet. I usually press firmly and subtract .010" to put the bullet somewhat "on" the lands.

 

[X-fan]

Re: Hornady OAL Guage accuracy

I have followed this rabbit hole and the best accuracy I have attained was with a fired and re-sized case (to my spec) tapped with a fine machine screw. While you can be fairly precise it really doesn't matter.

Make your best measurements and seat 20 thou off the rifling then fine tune from there.
Or start well into the lands if you intend to try that.
Never just touching.

The rifle shoots where it wants and no measuring will change that.