OAL length guage errors

[comagutsa]

Hey Eric, I did what you said with a clean chamber and made sure the hornady case didn't back it self out when I pushed real hard on the stick and I got 1.843 4 times and 1.842 twice. That bullet went along ways in. So my original measurement was 1.673. Next with the 3 taps was 1.700 and now with lots of force im at 1.843. The shank of the bullet is well over half way up the case!! So is this method to find the lands where you yourself would start when working up a load for a new rifle?

So now you know why I tell people to do it that way... Because it's easy to get repeatable results!

I start working up loads .020" away from jam.

sweet now i know what you mean by your jam
cheers erik

 

['Freak]

Thanks, Erik, your development @ 100 yards thread is making better sense now that “jam” finally jammed its way through my thick skull. Seems I repeatedly overlooked where it was well defined at about page #13.

 

[comagutsa]

Thanks, Erik, your development @ 100 yards thread is making better sense now that “jam” finally jammed its way through my thick skull. Seems I repeatedly overlooked where it was well defined at about page #13.

haha you weren't the only one mate :

 

[Brians356]

Erik, Using your method, does it leave a rifling mark on the bullet? If it does, how long?

Yes. I don't know how long, I have never measured them.

FWIW Virgil King of "The Houston Warehouse" fame said he seated so as to leave a witness mark on the bullet which was 1/2 the width of the lands. Dunno what the magic significance was of that dimension, or if he used some kind of layout bluing on the bullet, but there it is.

 

[Erik Cortina]

Erik, Using your method, does it leave a rifling mark on the bullet? If it does, how long?

Yes. I don't know how long, I have never measured them.

FWIW Virgil King of "The Houston Warehouse" fame said he seated so as to leave a witness mark on the bullet which was 1/2 the width of the lands. Dunno what the magic significance was of that dimension, or if he used some kind of layout bluing on the bullet, but there it is.

How would you measure it consistently and accurately?

They were shooting 100 yards with FB bullets, probably different with long BT bullets like the ones we use for 1000 yards.

 

[Brians356]

Erik, Using your method, does it leave a rifling mark on the bullet? If it does, how long?

Yes. I don't know how long, I have never measured them.

FWIW Virgil King of "The Houston Warehouse" fame said he seated so as to leave a witness mark on the bullet which was 1/2 the width of the lands. Dunno what the magic significance was of that dimension, or if he used some kind of layout bluing on the bullet, but there it is.

How would you measure it consistently and accurately?

They were shooting 100 yards with FB bullets, probably different with long BT bullets like the ones we use for 1000 yards.

As I said "FWIW". The question arose of looking for marks on bullets to determine how "jammed" they were. Seems like any such marks could vary in length depending on how hard you jam the bullets into the bore, and apparently King thought so.

If you say something like "start with .020" bullet jump" or the like, for you is that .020" out from "tapping lightly on the depth gauge rod" jammed, or what?

 

[Brians356]

Erik,

Never mind, I found this:

"I have a certain way I hold the body with one hand, then I gently push the bullet forward with the other. At this point I tap the rod 3 times and hold fairly tight when tightening the lock screw."

 

[Erik Cortina]

Erik,

Never mind, I found this:

"I have a certain way I hold the body with one hand, then I gently push the bullet forward with the other. At this point I tap the rod 3 times and hold fairly tight when tightening the lock screw."

You do not find jam that way. You find jam by pushing the rod in really hard and locking set screw.

 

[Brians356]

Erik,

Never mind, I found this:

"I have a certain way I hold the body with one hand, then I gently push the bullet forward with the other. At this point I tap the rod 3 times and hold fairly tight when tightening the lock screw."

You do not find jam that way. You find jam by pushing the rod in really hard and locking set screw.

Ok, got it. As you say, it's all relative, you must have some repeatable reference to work back from, and jammed is probably the most repeatable, requiring the least "feel".

In addition to holding the rod against the bullet while tightening the thumbscrew, I also strive to keep the fired case firmly forward in the chamber. Actually, I stand the rifle between my knees, muzzle down on a pad on the floor, and enlist gravity as an assistant.

 

[Erik Cortina]

Erik,

Never mind, I found this:

"I have a certain way I hold the body with one hand, then I gently push the bullet forward with the other. At this point I tap the rod 3 times and hold fairly tight when tightening the lock screw."

You do not find jam that way. You find jam by pushing the rod in really hard and locking set screw.

Ok, got it. As you say, it's all relative, you must have some repeatable reference to work back from, and jammed is probably the most repeatable, requiring the least "feel".

In addition to holding the rod against the bullet while tightening the thumbscrew, I also strive to keep the fired case firmly forward in the chamber.

This is the correct thing to do.

 

[Brians356]

FYI Erik, I added this while you were typing:

Actually, I stand the rifle between my knees, muzzle down on a pad on the floor, and enlist gravity as an assistant.

 

[Erik Cortina]

FYI Erik, I added this while you were typing:

Actually, I stand the rifle between my knees, muzzle down on a pad on the floor, and enlist gravity as an assistant.

To enlist gravity as your assistant, you would aim muzzle at ceiling and balance the weight of the rifle on the OAL tool!

 

[Brians356]

FYI Erik, I added this while you were typing:

Actually, I stand the rifle between my knees, muzzle down on a pad on the floor, and enlist gravity as an assistant.

To enlist gravity as your assistant, you would aim muzzle at ceiling and balance the weight of the rifle on the OAL tool!

Could I get you to demonstrate that, please? 8)

 

[Erik Cortina]

FYI Erik, I added this while you were typing:

Actually, I stand the rifle between my knees, muzzle down on a pad on the floor, and enlist gravity as an assistant.

To enlist gravity as your assistant, you would aim muzzle at ceiling and balance the weight of the rifle on the OAL tool!

Could I get you to demonstrate that, please? 8)

I was hoping you would! ;D

 

[Brians356]

I was hoping you would! ;D

It was your idea! You assumed "gravity assist" meant providing the pressure on the bullet and case.

 

[Erik Cortina]

I was hoping you would! ;D

I was your idea! You assumed "gravity assist" meant providing the pressure on the bullet and case.

I didn't assume anything, it was a joke.

 

[Brians356]

I didn't assume anything, it was a joke.

Uh oh, I blinked first. Dang.

What's up with that new product you were about to unveil a few months ago?

 

[Erik Cortina]

I didn't assume anything, it was a joke.

Uh oh, I blinked first. Dang.

What's up with that new product you were about to unveil a few months ago?

Day job keeping me very busy right now.

 

['Freak]

Mine is the Sinclair tool but thinkin’ checking using it and working from an honest jam with muzzle straight down ought to work out just as well. Jam has to be easier to repeat consistently than trying to feel out and reference from an assumed first contact.

 

[Brians356]

FYI I just like the muzzle down, but you want the rifle horizontal when inserting the Stoney Point assembly w/ bullet. After that I stand it on the muzzle, seated in on a stool w/ rifle between knees, and that leaves the hands freer (for me) to operate the gauge. Probably an awkward and overly complex approach for most folks.