7 Mag seating question

3030tank · February 22, 2010, 11:43 AM

Hey guys, still pretty new to reloading, have been doin 30-30 for a little while and have started working up some 7mm rem mag loads.

My question is, when seating my 139 grain btsp bullets, it seems that if I seat the round on the cannelure, there doesnt appear to be enough neck tension on the bullet to keep it seated, I can turn it, or knock it down into the case. I am using a Lee Collet die, and I didnt plan on crimping these rounds as I was told it was not necessary. What am I doin wrong?

Also, for now I am seating the bullet just before the cannelure, is there anything wrong with this as long as I am not exceeding OAL? Will this hurt velocity any with a 139 grain bullet? Thanks alot for any help!

uncyboo · February 22, 2010, 12:16 PM

There should be more neck tension than that. First, make sure your bullets measure .284. Then make sure your die's expander ball measures .2825 - .283.

GeauxTide · February 22, 2010, 12:33 PM

Yep, I use 139s in 280 and 7mmRM. You're not getting the proper neck tension because the cannelure on those bullets is at full diameter.

Osageshooter · February 22, 2010, 12:37 PM

What do you mean by not staying seated? Do you have so much powder in the case that it is pushing the bullet back out? If so, check your powder charge. Either way, agree with uncyboo that this should not be happening.

uncyboo · February 22, 2010, 12:45 PM

Quote:

You're not getting the proper neck tension because the cannelure on those bullets is at full diameter.

Could you expand on this a little? I'm not sure I understand what you are saying. If the cannelure is at full diameter, then the problem would be the necks are not sized to .283.

Unless you meant the cannelure isn't at full diameter, as in where the bullet begins to taper forward. I've never used these bullets.

mrawesome22 · February 22, 2010, 09:28 PM

You're either not putting enough pressure on the handle to fully squeeze the neck down, or you need an undersized mandrel. Measure the mandrel diameter and report back please.

February 22, 2010, 11:43 AM	#1
3030tank Junior Member Join Date: January 18, 2010 Posts: 9	7 Mag seating question Hey guys, still pretty new to reloading, have been doin 30-30 for a little while and have started working up some 7mm rem mag loads. My question is, when seating my 139 grain btsp bullets, it seems that if I seat the round on the cannelure, there doesnt appear to be enough neck tension on the bullet to keep it seated, I can turn it, or knock it down into the case. I am using a Lee Collet die, and I didnt plan on crimping these rounds as I was told it was not necessary. What am I doin wrong? Also, for now I am seating the bullet just before the cannelure, is there anything wrong with this as long as I am not exceeding OAL? Will this hurt velocity any with a 139 grain bullet? Thanks alot for any help!

February 22, 2010, 12:16 PM	#2
uncyboo Senior Member Join Date: November 7, 2008 Location: Shelby, MT Posts: 1,013	There should be more neck tension than that. First, make sure your bullets measure .284. Then make sure your die's expander ball measures .2825 - .283.

February 22, 2010, 12:33 PM	#3
GeauxTide Senior Member Join Date: April 20, 2009 Location: Helena, AL Posts: 4,424	Yep, I use 139s in 280 and 7mmRM. You're not getting the proper neck tension because the cannelure on those bullets is at full diameter.

February 22, 2010, 12:37 PM	#4
Osageshooter Senior Member Join Date: August 27, 2009 Location: Overland Park, Kansas Posts: 179	What do you mean by not staying seated? Do you have so much powder in the case that it is pushing the bullet back out? If so, check your powder charge. Either way, agree with uncyboo that this should not be happening.

February 22, 2010, 09:28 PM	#6
mrawesome22 Senior Member Join Date: November 9, 2005 Location: Ohio, Appalachia's foothills. Posts: 3,779	You're either not putting enough pressure on the handle to fully squeeze the neck down, or you need an undersized mandrel. Measure the mandrel diameter and report back please.