The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools
Old September 27, 2012, 10:15 PM   #1
funkmasterjs
Junior Member
 
Join Date: September 27, 2012
Posts: 3
Pistol Bullet Seating Depth

I'm sure that for you vetran pistol reloaders, this subject may be boring and repetitive, but here goes. I'm ready to make my first hand gun loads for a GP100 (.38/.357) 4" bbl. I'm a bit confused on how deep to seat the bullet? My Lyman 49 manual has the overall length for select bullets, and I know the seating depth must be short enough to not extend beyond the cylinder length. I also know that the bullet can't be seated too deep, for excessive pressure reasons. So,
1. Do I seat the bullet a couple of thousands less than the maximum overall length, and call it good?

2. How do I determine the overall length if I buy a brand of bullet that is not listed in my Lyman 49 specs? Do I find specs on a bullet of the same weight and build it using this data?

3. Am I making too much out of this? Each manual I'v seen basically says..."seat the bullet to the appropriate depth"....... but what is the appropriate depth?

HELP!

Jim
funkmasterjs is offline  
Old September 27, 2012, 10:28 PM   #2
SL1
Senior Member
 
Join Date: November 8, 2007
Posts: 1,999
For revolver cartridges, the bullets typically have a cannelure (crimping groove) that determines the seating depth. Seat the bullet so that the case mouth is about the center of that groove, and apply a roll crimp.

Some bullets (e.g., plated bullets) may not have a crimp groove. In that situation, simply seat the bullet so that the overall cartridge length is nominal, and apply either a taper crimp or a very light roll crimp.

Seating depth can affect pressure. If you are not using the same bullet that was used to make the pressure-tested data in your manual, then there may be a need to adjust the powder charge weight if the bullets have substantially different seating depths when seated to crimp in the cannelure.

SL1
SL1 is offline  
Old September 27, 2012, 10:32 PM   #3
SVO
Senior Member
 
Join Date: December 20, 2009
Location: Texas Gulf Coast
Posts: 674
You are reloading for a revolver and most jacketed bullets for a revolver has a cannelure for crimping the case mouth into. As long as the case is crimped in the cannelure and the overall length of your round isn't too long to function in your revolver, everything will be fine.
SVO is offline  
Old September 27, 2012, 10:42 PM   #4
Misssissippi Dave
Senior Member
 
Join Date: December 5, 2009
Posts: 1,407
There should be a groove around the bullet if you use jacketed bullets. I crimp at that ring since that is what it is for. For wad cutters I load with just enough of the bullet outside the case to allow a crimp. It has been too long since I loaded semi wad cutter bullets to remember just where to crimp them. probably the same as wad cutters. No matter where you are crimping you still need to work up the load to get something that works for you. A difference of .020" shouldn't make a lot of change in pressures. If you are within .020" compared to the listed OAL you probably will be fine. Just work up the load as you would any other new combination. At least with .38 specials and .357 Mag loads you don't have to worry about if it is going to cycle correctly. You just don't want the bullet to walk out jamming the cylinder or too light a load that leaves the bullet stuck in the barrel. It is much more forgiving to load for revolvers than any semi-auto pistol.
Misssissippi Dave is offline  
Old September 27, 2012, 10:54 PM   #5
funkmasterjs
Junior Member
 
Join Date: September 27, 2012
Posts: 3
Thanks for the info!!

So when I start reloading my .45 ACP, I just need to stick to the OAL with a light crimp, or no crimp at all?
funkmasterjs is offline  
Old September 27, 2012, 11:03 PM   #6
Adamantium
Senior Member
 
Join Date: June 6, 1999
Location: El Paso, TX
Posts: 992
A light taper crimp is all that is needed for 45acp. You certainly don't want to give it a roll crimp if your seating die is even capable of such. OAL will vary by bullet design but usually you are going to be fine by going off a round of factory ammunition of the same bullet type. Truthfully the two most important things with OAL is it needs to work in your gun and you need to stick with the same OAL that you worked up the load with.
__________________
New gun, same ol' shot.
Adamantium is offline  
Old September 28, 2012, 06:39 AM   #7
SL1
Senior Member
 
Join Date: November 8, 2007
Posts: 1,999
Now that the OP has brought auto-loaders into the discussion along with revolvers, it is important to tell him that pressure is more sensitive to cartridge overall length (COL) in autoloader cartridges than in most revolver cartridges. The reason is that they are usually shorter, so there is usually less space for the powder remaining under the bullet.

So, while a reduction of 0.03" in COL for a .38 Special is not likely to cause a pressure problem, the same amount of change in a 9mm Luger most definitely CAN make pressure MUCH higher in some loads.

SL1
SL1 is offline  
Old September 28, 2012, 10:18 PM   #8
shoot1forme
Junior Member
 
Join Date: July 4, 2011
Location: Northern Left Coast
Posts: 10
Auto reloads

Yes, watch carefully you don't ever have a bullet "set back" situation occur. Most reloading manuals will indicate how much taper crimp is required to prevent this from happening. Set back has happened to me twice while shooting the .45 acp round and it was very surprising to say the least. As cases are loaded many times the walls become thinner so the "bullet tension" can change thus allowing what was a normal "good" tension to become a "too little tension" situation. This wall thickness variation is apparant in different brands of cases also. The expander plug that works perfect for some cases may be too large for others. Anyhow, if you ever fire a round which has set back you will never forget it!
shoot1forme is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 09:32 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.07532 seconds with 9 queries