seating depth

[stew]

Have a quick question for years have used a bullet in the case method for finding max seating depth. Lately have been checking these by using a dowel in the barrel to bolt then to a bullet dropped in barrel and have been finding quit a difference. For example
in the 280 with a 145 speer bullet using a split case I come up with 3.250 and have been loading at 3.230 for a few years and they shoot great I recently checked with
the dowel method and came up with 3.185 so checked some of my other loads and guns and with the dowels always come up shorter, so Im guessing I should be going with the dowel method. Any thoughts, I do not have access to a proper guage.

 

[lefty315]

Is the dowel thick enough where it could be stopping where the throat and shoulder area meet???

 

[stew]

Is the dowel thick enough where it could be stopping where the throat and shoulder area meet???

No it will go all the way through the barrel

 

[Darkhorse]

I don't understand the "Split Case" method.
Here's how I have done it for literally, decades. I take a unsized case that a bullet will slide through and push the case mouth against my bench until it has a slight flat spot on one side. This will provide enough tension to hold the bullet without getting it stuck against the lands.
Now with a bullet just started in the case (you want it sticking out there beyond the factory OAL) drop the case in the chamber and slowly close the bolt. Remove the case gently and measure with a bullet comparator. This measures where the bullet ogive actually touches the lands or rifling. This is the most important measurement. Write this number down.
Now do it all again and write that number down also.
Now do this 5 or 10 times writing down the measurement each time.
Look at your list of numbers, there should be several with the same measurement.
Keep those and toss the rest. This is your repeatable measurement of where the bullet touches the lands.
For each bullet I keep a standard list starting with where the bullet touches the lands, this is on top of the list.
Then I calculate the measurement for several seating depths, .005 off the lands, .010 off the lands etc. and add these to my list.
I can reference these measurements to my desired seating depth.
I retain this list both in a notebook at my bench and in a file on my computer.
Want to try a new bullet? Just start over and build a new list for each bullet.
It's not as complicated as it sounds, just be sure your top measurement is accurate.

 

[mjcmichigan]

First, do you get the same accuracy with the dowel method?
Every bullet manufacturer has differences in the secant, meaning
bullets engage at different surfaces. The reason for minimizing jump is about getting consistent pressure behind the bullet...leading to consistent velocity, leading to consistent point of impact.

If you haven't seen the Bullet comparators... google it. I have Hornady. I think Sinclair makes them too. I need a case gauge for a couple obsolete cartridges.. considering making my own case.

First things first...how's it perform on the range.


Sent from my iPad using Tapatalk

 

[stew]

Thanks guys sorry for the brain glitch but figured out what was wrong.

 

[lefty315]

Will you share what was wrong? I'm not always the sharpest tool in the shed and always appreciate learning from others mistakes

 

[ShadeTree]

Here's my method. It's quick and simple once you've done it a few times. I used to do the case method, but for me this is fail proof on its accuracy and much quicker. I've double and triple checked it numerous times on different guns and get right on consistent readings with a particular bullet I'm using. It's the same concept as stew's but I'll explain mine in full.

I take a cleaning rod with a plastic cleaning jag threaded on the end that I filed the tip down on so it's a simple flush and flat base. I feed the rod in from the muzzle against the closed bolt and mark it with tape flush against the end of the barrel.

I then remove the bolt and take a bullet I'm loading for and drop it in the chamber. Put the gun back in the vise and take a short section of cleaning rod (anything you can use to push against the back of the bullet from the breech end will work) I take the same original cleaning rod with the plastic jag on the end and run it up the muzzle against the front of the bullet.....I push the bullet back and forth a few times with both rods to make sure I'm feeling when it's just lightly but stopped against the lands. Mark the cleaning rod again with tape flush against the barrel. Pull the cleaning rod out, measure the 2 leading edges with a caliper. Done.

Both measurements are a hard flat surface against a hard flat surface. As long as you don't either gap or wrinkle the tape against the end of the barrel it's fool proof. You can take the tape off and start all over and when you're done you will get the same measurement as the last time down to a thousand'th.

 

[ShadeTree]

Will you share what was wrong? I'm not always the sharpest tool in the shed and always appreciate learning from others mistakes

I'm gonna guess that the dowel was too thick and the outside edge was catching the protruding extractor against the bolt giving him a shorter overall reading. Of course I've been known to be wrong 100's of times in my life, maybe even thousands. :mrgreen:

 

[waveslayer]

Just buy the Hornady modified case and OAL measuring tool, then you can take all the guys work out of it. Also, you can jam a bullet and push it in good.. then you will have a lot of variances

My wife thinks I only have 3 guns

 

[stew]

Will you share what was wrong? I'm not always the sharpest tool in the shed and always appreciate learning from others mistakes

I'm gonna guess that the dowel was too thick and the outside edge was catching the protruding extractor against the bolt giving him a shorter overall reading. Of course I've been known to be wrong 100's of times in my life, maybe even thousands. :mrgreen:

Ya pretty much what you say, I had broke my other dowel and when I picked up a new one bought the next size up, and breaking my number 1 rule with reloading when your not really into it and focused don't do it.

 

[ShadeTree]

Will you share what was wrong? I'm not always the sharpest tool in the shed and always appreciate learning from others mistakes

I'm gonna guess that the dowel was too thick and the outside edge was catching the protruding extractor against the bolt giving him a shorter overall reading. Of course I've been known to be wrong 100's of times in my life, maybe even thousands. :mrgreen:

Ya pretty much what you say, I had broke my other dowel and when I picked up a new one bought the next size up, and breaking my number 1 rule with reloading when your not really into it and focused don't do it.

Hey I got lucky and was right! :grin: The reason I thought maybe that was it, was when I first started using the method I described above, it all of a sudden occurred to me that could happen so I double checked it against the bolt and didn't have a lot of clearance but it did miss the extractor every time when pushed straight in from the muzzle. I used a 27 caliber jag because I don't need that size....works for my 6mm and obviously up through the 30 caliber's and beyond. Based on that any jag from 22-27 caliber should work, but a spare 22 caliber would probably be best to make sure you're always clearing any extractor on a bolt that might vary somewhat in design placement or size. Just thought I'd throw all that out there, might save someone else some frustration or a bad mistake from a false reading.

 

[ElmerThud]

With the Lee Collet Neck Sizing Die, you can adjust the tension on the sized case neck to 'just hold' a bullet. You can adjust tighter or looser so it's good for test OAL of cartridge head to the lans.
Just my thoughts.

 

[TackDriver284]

I recently checked with
the dowel method and came up with 3.185 so checked some of my other loads and guns and with the dowels always come up shorter,

If seating measurement have come up differently from prior years in your rifles, if that is what you meant, then its throat erosion which is normal. My 6.5 x 284 measurements were longer in seating depth from my last data a few years ago by as much as .025"
I noticed that it did not shoot as well as it did, which prompted me to check and readjust seating depth and it fixed the issue.