Seating Depth Consistency

truck driver

Ammo Smith
Mar 11, 2013
6,964
329
I just might spring for one of these, it looks like it would make cleaning primer pockets easier.
 

DrMike

Ballistician
Nov 8, 2006
35,467
2,247
You definitely need a primer pocket uniformer, Rodger. Should have had this years ago. For primer pockets that are drilled (e.g. Norma) it is needed less than for the more common method of creating brass by punching (which leaves slightly curved pockets).
 

Whitesheep

Beginner
Jan 6, 2015
167
1
Great conversation. I have always wondered why bullets wouldn't seat to exactly the same depth measured base to ogive. I think the answer is in the bullet, not the case.

Sierra's usually run about +-0.003" in the 7mm and .30 cal bullets base to ogive from my experience. Interestingly Berger has a much much larger extreme spread in length, but they have a large accuracy following anyway (they work for me too). If you are compressing loads than you already know the answer. Maybe a little tap on the press before seating the bullet will more tightly pack your powder. Works for me.

I don't understand how manipulating the ram would change seating depth for the exact same bullet shape. The distance from the shell holder to the seating stem should be fixed no matter how hard you do or don't slam the ram as long as it is a good quality press. If you don't tighten down the dies, maybe they could move under pressure, but other than that I would look to the bullet. Not being a machinist maybe I am missing something and would gladly be educated by those who know more than me.

A protruding primer also can not be the issue because of the primer hole in the shell holder. If there wasn't a hole big enough to extract a primer, how could it push the case up and result in a more deeply seated bullet? A shell holder with out a sufficiently large hole for the primer could be quite exciting. :shock:

I suggest anyone with this problem measure their bullets base to ogive and sort them into piles that differ by 0.001". Then seat them in groups from the longest to the shortest adjusting your seating stem down as you go. I used to do this but it has no impact on practical accuracy for me so don't bother anymore.

As for the concentricity gauge I highly recommend Hornady's as it allows you to actually fix problems, not just identify them. The loads I tune with this tool are quite accurate in several firearms. I aim for +-0.001" or run out which isn't hard to do with this tool.

Let us know what you find from your own research and stay safe.
 

SJB358

Ballistician
Dec 24, 2006
31,398
757
I use a Hornady comparator to measure. A few thousandths are for bench Resters in my book. Bullets are going to be different to some extent. Get a solid average. If it is a decent rifle, it'll shoot. If it's crooked you'll play heck trying to make it shoot.
 

bboswell

Beginner
Feb 20, 2016
79
0
Whitesheep":r1ycm1sf said:
Great conversation. I have always wondered why bullets wouldn't seat to exactly the same depth measured base to ogive. I think the answer is in the bullet, not the case.

Sierra's usually run about +-0.003" in the 7mm and .30 cal bullets base to ogive from my experience. Interestingly Berger has a much much larger extreme spread in length, but they have a large accuracy following anyway (they work for me too). If you are compressing loads than you already know the answer. Maybe a little tap on the press before seating the bullet will more tightly pack your powder. Works for me.

I don't understand how manipulating the ram would change seating depth for the exact same bullet shape. The distance from the shell holder to the seating stem should be fixed no matter how hard you do or don't slam the ram as long as it is a good quality press. If you don't tighten down the dies, maybe they could move under pressure, but other than that I would look to the bullet. Not being a machinist maybe I am missing something and would gladly be educated by those who know more than me.

A protruding primer also can not be the issue because of the primer hole in the shell holder. If there wasn't a hole big enough to extract a primer, how could it push the case up and result in a more deeply seated bullet? A shell holder with out a sufficiently large hole for the primer could be quite exciting. :shock:

I suggest anyone with this problem measure their bullets base to ogive and sort them into piles that differ by 0.001". Then seat them in groups from the longest to the shortest adjusting your seating stem down as you go. I used to do this but it has no impact on practical accuracy for me so don't bother anymore.

As for the concentricity gauge I highly recommend Hornady's as it allows you to actually fix problems, not just identify them. The loads I tune with this tool are quite accurate in several firearms. I aim for +-0.001" or run out which isn't hard to do with this tool.

Let us know what you find from your own research and stay safe.

On point!
 

muleman

Handloader
May 12, 2009
1,373
5
TD,
What powder are you loading? I've found stick powders a whole lot easier to compress - ball powders not so much.

Scott
 

rick smith

Handloader
Apr 6, 2005
1,249
0
bboswell, try it for yourself. I load most of my rifle rounds on a forster Co-Ax and can easily seat a bullet 0.002-0.003 deeper by raising the handle an inch or so off a seated round and bumping the handle hard to put more pressure into the system. Using competition seaters. the distance hasn't changed only the pressure put into the seating. I have done the same operation on several different presses and they all do the same thing. Rick.
 

Kodiak

Handloader
Oct 4, 2006
1,051
0
Got my attention; so I just measured 10 of my last handloads for the 270wsm.

Loaded with 140 NABs: 2.841, 2.841, 2.841 (yawn) 2.841, 2.841, .... and so on. Test-round used to adjust seating-die is set at 2.841.

Bullet-seating dies used are RCBS.
 

jimbires

Handloader
Aug 16, 2011
2,505
476
one thing I didn't see mentioned . is your seating stem pushing on the bullets ogive ? you need to be careful the seating stem is not pushing on the bullets tip .
 

Darkhorse

Handloader
Mar 14, 2014
757
33
Whitesheep":1uouqehs said:
Great conversation. I have always wondered why bullets wouldn't seat to exactly the same depth measured base to ogive. I think the answer is in the bullet, not the case.

Sierra's usually run about +-0.003" in the 7mm and .30 cal bullets base to ogive from my experience. Interestingly Berger has a much much larger extreme spread in length, but they have a large accuracy following anyway (they work for me too). If you are compressing loads than you already know the answer. Maybe a little tap on the press before seating the bullet will more tightly pack your powder. Works for me.

I don't understand how manipulating the ram would change seating depth for the exact same bullet shape. The distance from the shell holder to the seating stem should be fixed no matter how hard you do or don't slam the ram as long as it is a good quality press. If you don't tighten down the dies, maybe they could move under pressure, but other than that I would look to the bullet. Not being a machinist maybe I am missing something and would gladly be educated by those who know more than me.

A protruding primer also can not be the issue because of the primer hole in the shell holder. If there wasn't a hole big enough to extract a primer, how could it push the case up and result in a more deeply seated bullet? A shell holder with out a sufficiently large hole for the primer could be quite exciting. :shock:

I suggest anyone with this problem measure their bullets base to ogive and sort them into piles that differ by 0.001". Then seat them in groups from the longest to the shortest adjusting your seating stem down as you go. I used to do this but it has no impact on practical accuracy for me so don't bother anymore.

As for the concentricity gauge I highly recommend Hornady's as it allows you to actually fix problems, not just identify them. The loads I tune with this tool are quite accurate in several firearms. I aim for +-0.001" or run out which isn't hard to do with this tool.

Let us know what you find from your own research and stay safe.

Seems like you are missing the point on the primer issue. Forget the shell holder size and the idea that a protruding primer will push the case up and cause a bullet to be seated deeper. Though I agree that is a possiblility but that's not what I'm talking about.
After your cartridge is completely finished (reloaded), and the primer is protruding .005, then when you measure the round it will be .005" longer than it would be if the primer was flush or below flush.
Do your own test; Load a round without a primer or powder and measure the OAL.
Now load another one without powder but with a primer. Make sure the primer is protruding. Now measure the OAL and see what you get. Be sure you measure across the primer not to the side.
Many reloaders try to make their cases as uniform as possible and this includes the primer pocket is uniform from case to case and does not allow a primer to protrude.
Now I'm not saying a protruding primer is always the cause of varying OAL measurement but it is one.
Eliminate one possibility at a time in order to find the real reason/s.
 

truck driver

Ammo Smith
Mar 11, 2013
6,964
329
Sorry I haven't answered this post lately. I've been under the weather with a sinus infection that has had me down for two weeks. As soon as my head clears I'll get back to it.
 

Whitesheep

Beginner
Jan 6, 2015
167
1
Yes Darkhorse, the situation you explained in more detail has happened to me. Thank you for the clarification.

I misunderstood your post as saying the protruding primer would cause a bullet to be seated deeper. The situation you mentioned is a pain as you should take the cartridge apart seat the primer completely. Not a good idea to try to seat a primer deeper in a loaded round IMHO. For this reason I check each primer after it is seated.
 

truck driver

Ammo Smith
Mar 11, 2013
6,964
329
Thanks for all the replies and helpful ideas. I do check each primer by running my finger across the base of the case after seating a primer and it hasn't let me down yet. I also checked them with the blade of my caliper and there was clearance but not much.
I loaded some last night and used the press to seat the CCI BR2 primers I picked up and found a difference in seating depth when checked and had to tweak them on the Dillon 550 which lets you crush the primer, so there is some discrepancy in the primer pockets.
I did order a Redding tool to clean up the primer pockets though a little more expensive and a Redding Micro seater stem for the 35 Rem -375 H&H.
The seater stem is touching the Ogave on the Accu Bonds and not the tip.
90% of the Accu Bonds I have loaded are seconds and wonder if the Ogave length is off and this is one of the reasons for the inconsistency?
The powder I was using was stick when I discovered the seating difference. I did notice a velocity increase as I was seating the bullets deeper looking for the perfect OAL. As little as .005" would cause an increase in velocity so I'm guessing the pressure was going up as the bullet was seated deeper.
Again thanks for your help.
 
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