Did it jam or not??

[Webster]

This is a picture of my attempt to "find the lands" in my Savage 6mmBR. The bullet is a Berger 105gr Hybrid. I tried to use the Wheeler method to do this but as you with more experience than me found out it didn't work anything like what Mr. Wheeler demonstrates in his fine video and I'm sure the Savage floating bolt head is why. I have successfully found a "touch point" by marking the bullet with a magic marker and then seating it in a modified case that allows me to incrementally extend the bullet until it makes contact. The picture below shows what I see when the bullet makes contact. I get a perfect ring mark all the way around the bullet. I don't get this with my Brux barrel on my .308, I get marks from the lands. Is this ring mark a normal thing? I don't know. Any comments are most welcome.

Mike

View attachment 1098388

Looks like a very bad machining problem. Rifle doesn't go all the way around. Is it a metal ridge at the transition of the forcing cone to rifling?

 

[magic mike]

Looks like a very bad machining problem. Rifle doesn't go all the way around. Is it a metal ridge at the transition of the forcing cone to rifling?

As best I can tell, there is a shiny ring all the way around the cone just before the lands begin. This is where the bullet appears to contact the major diameter of the barrel and I don't believe it is correctly machined. At this point it doesn't make any difference anymore as I have installed a new Criterion barrel ( which is a thing of beauty by-the-way) on the gun and I am headed to a private range tomorrow to dial it in. I was very pleased to see that the forum boss placed an article in the Bulletin a couple days ago which reflects my situation exactly. The factory barrel on this gun is very disappointing and I am not going to waste any more time or resources on it. Someone may want it so they can re-chamber it but it's not going to be me. It may shoot great if it gets re-chambered to 6mm Rem by someone but I'm done with it.

Mike

 

[Webster]

As best I can tell, there is a shiny ring all the way around the cone just before the lands begin. This is where the bullet appears to contact the major diameter of the barrel and I don't believe it is correctly machined. At this point it doesn't make any difference anymore as I have installed a new Criterion barrel ( which is a thing of beauty by-the-way) on the gun and I am headed to a private range tomorrow to dial it in. I was very pleased to see that the forum boss placed an article in the Bulletin a couple days ago which reflects my situation exactly. The factory barrel on this gun is very disappointing and I am not going to waste any more time or resources on it. Someone may want it so they can re-chamber it but it's not going to be me. It may shoot great if it gets re-chambered to 6mm Rem by someone but I'm done with it.

Mike

I did a similar thing. I wanted a rifle with the correct bolt head diameter to build a 6BRX. I bought a Rem 22-250. Took the factory barrel off without a shot down the barrel. Next bought a 6BRX Kreiger barrel. A lot of bucks to put the barrel on.

 

[Texas10]

I see that frequently while exploring seating depth. This is the ogive making contact with the throat, just as it should. Repeated thrusts into the throat/lands, and then gradually backing the bullet out until no touch or jam is felt. Exactly how I do it and can get repeatability down to .001 or .002.

To confirm, install a new bullet and retest at that CBTO. Should be same or within .002 if you've got good quality bullets (you do).

 

[Martin52]

I loaded some new Palma cases yesterday with the projectiles seated long for jam with 0.002 NT.

At 2.147 (base to ogive measurement on my comparator) the bolt would not close.

Then stepped down in small increments and found at 2.142 the bolt would close and would consistently push back each projectile to 2.139 - to touch.

I can jam or jump from there.

However, this might not assist until the freebore is fixed, if that is the problem.

Martin