Help me I feel Stupid!!!!

[Qzilla]

Ok, I know I should not be in any sort of hurry with a new rifle but, I am sort of.

Its a long story but, the rifle got done late and I am leaving tomorrow once I get the barrel break in done. Worse case scenario I can shoot some factory rounds but, I would rather not do that.

Ok, here is the gun and the issue.

Rem 700 257 WBY. I had Shawn take the freebore out. Not sure exactly how much he cut it down but, he cut it down to what he felt was best. And yes I tried calling him, all day! I am sure he is hunting or something.

Anyhow I was trying to determine COL for this chamber. I was trying to take a short cut. I took a fired case from this chamber. Dented the mouth and shoved a 110gr Accubond in it. Used a marker to color the bullet and chambered the round then tapped the bullet out of the lands.

You can see how far the bullet went into the case by how much of the marker was scraped off.

The problem is that if this is truly my COL, then it is really SHORT!! The books say 3.250 max COL. This cartridge was 3.154". If I wanted to be .010 or .015 off the lands then it would be somehwere in the 3.139-3.144 range.

Factory loads are around 3.155.

What gives? How is this going to affect my loads? Do I really want to chamber the round this short?

I did up a dummy round at 3.250 and it chambers fine.

What am I missing???

HELP ME BEFORE I GO CRAZY!!!!!!!!

 

[Buffalobob]

There are a couple of things that might be happening.

First the scrape marks may not be the rifling unless you can clearly see that it is rifling by there being distinct lands marks. The free bore that is there may be really tight like mine is (240 Wby). Mine is so tight that it will hold a bullet that is the least bit off in runout. This will result in great accuracy but is difficult to get a good measure of COL. If this is true then your gun will be a joy and delight to shoot, except every once in a while it will eat one of your bullets and you will have to get a cleaning rod and tap the bullet out.

Second, is the same type of thing but it is very tapered lands. These have a very small angle for the bullet to start on and make measurements difficult.


When a gunsmith puts both a tight throat and tapered lands together it is very very difficult to find the lenght.

 

[Buffalobob]

P.S.

Email Richard Graves or Kirby and get yourself some Wildcat 130 gr HP RRBT or some 142s and give them a whirl.

 

[Steve Shelp]

Qzilla,
First of all forget about COL, IF the round feeds through your magazine at your given length. COL changes everytime you seat a different bullet in a case anyway. I've loaded for the better part of my whole life for everything from basic 100yd deer rifles to full blown competition BR rifles and never once looked at the COL of what "the book" said.

Your description of how you actually inserted the bullet in the case and measured it is a bit confusing to me. I will seat a bullet long in a partial sized case. Blacked the whole upper ogive portion of the bullet and carefully put the case into the chamber (no primer or powder at this point) and guide it into the chamber by hand. Then close the bolt to fully seat the bullet back into the case. Carefully extract the case from the rifle making sure to catch it so the ejector doesn't toss it onto the floor.
Take a measurement and repeat this process 3 times to make sure you gets 3 consistant measurements. If you don't, there isn't enough neck tension to hold the bullet upon extraction.
Once you get 3 consecutive consistant measurements (within a couple thousands) then this measurement is basically your maximum seating depth period. The bullet is actually hard into the lands at this point. But I use this "dummy" cartridge to setup my seating die. Then make adjustments to back the bullet down some so it's not so hard into the lands. Normally a .010" difference is all it takes.
This can easily be varified by using the same method and blacking the bullet again and reseating. Upon extraction you should get slight scratch marks from each of the lands in your barrel.

I have used the dented case mouth method in a pinch, but there normally isn't enough friction to keep the bullet in place once you go to extract the case and measure. And you end up with different measurements each time you try to measure it. This is what BuffaloBob was getting at with the taper pulling the bullet out of the case once in awhile.

If the base of the 110gr bullet is anywhere between 2/3 down your case neck and the neck/shoulder junction, forget the COL measurements. Even if it is a little deeper into the case body isn't the end of the world. Just means you have more throat to burn out before your rebarrel it. Make sure that this new length feeds through your magazine (if you plan on using it) and go shoot.

Just remember with a shorter throat your old loads will run higher pressures now. So work up your load accordingly.

Hope this helps.

Steve

 

[Boss Hoss]

Quad---is this you???? Don't know anyone else who uses that name.

David