The Firing Line Forums

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

Reply
 
Thread Tools
Old March 30, 2007, 11:04 PM   #1
dirty habit
Member
 
Join Date: December 18, 2006
Location: New Zealand
Posts: 57
Bullet Seating Question

My question: Ive set up my Stony Point Guage and found the cartridge length i need for the bullet to be sitting just off the rifling. In theory this measure is from the base of the cartridge to the ogive of the bullet? So this measurement will be the same for any style or different type of bullet i load because im measuring off the ogive each time correct? So once ive set my seating die up i shouldnt have to change it?
Ive been thinking about this all morning and while it makes sense to me now i thought id better check first...
__________________
Happiness.......is a warm gun
dirty habit is offline  
Old March 30, 2007, 11:40 PM   #2
Bullet94
Senior Member
 
Join Date: September 8, 2004
Location: Kansas
Posts: 723
If you change bullet weight or brand you will have to start over. Different bullets (weight or brand) will be shaped differently and this will change the measurement. Here’s another one to think about a bullet comparator, the seating die and the lands all contact the bullet in different places.
__________________
PRO-SECOND AMENDMENT - Live Free or Die
Bullet94 is offline  
Old March 31, 2007, 06:14 AM   #3
dirty habit
Member
 
Join Date: December 18, 2006
Location: New Zealand
Posts: 57
Aaaaahhhh more perplexing still...The seating die is the part i didnt take into account. I assumed the seater would contact the bullet at the ogive but realise now that thats not the case soooo...i will have to keep doing what im doing, working to an overall to ogive measurement and adjusting the seater die with each different bullet i load.
A little bit clearer, cheers!!
__________________
Happiness.......is a warm gun
dirty habit is offline  
Old March 31, 2007, 11:13 AM   #4
kingudaroad
Senior Member
 
Join Date: March 11, 2005
Location: austin
Posts: 735
Quote:
So this measurement will be the same for any style or different type of bullet
Absolutely not. The ogive is not the same for different bullets. You will have to remeasure and adjust your seating die for each type of bullet.
kingudaroad is offline  
Old March 31, 2007, 09:50 PM   #5
williamd
Senior Member
 
Join Date: March 13, 2007
Location: SoCal
Posts: 801
Concur with all above. I have found over too many years of blasting .. but my eyes are still good ... that seating a bullet long in an empty case, closing the rifle action gently and gently extracting, then turning the seating die down one turn (gives you about 1/14" to lands works well in most calibres (all I have tried). B ut, yep, every bullet is different. That's ok because when you find the right load for THAT rifle you keep it!
__________________
"Outlaw guns and only outlaws will have guns!" Unfortunately, we may be moving in that direction.
NRA Benefactor, Conservative!, VN '64-'65.
Never sell a gun or a car ... and retire rich!
williamd is offline  
Old March 31, 2007, 11:21 PM   #6
mrawesome22
Senior Member
 
Join Date: November 9, 2005
Location: Ohio, Appalachia's foothills.
Posts: 3,779
Every bullet's ogive is in a different place. Your reasoning is way off. With every ogive change, your measurement from head to ogive will change.
mrawesome22 is offline  
Old April 1, 2007, 02:38 AM   #7
Bullet94
Senior Member
 
Join Date: September 8, 2004
Location: Kansas
Posts: 723
Just to make terms clear –

From SAAMI –

http://www.saami.org/Glossary/display.cfm?letter=O

OGIVE
The curved portion of a bullet forward of the bearing surface.
__________________
PRO-SECOND AMENDMENT - Live Free or Die
Bullet94 is offline  
Old April 1, 2007, 10:16 AM   #8
cheygriz
Senior Member
 
Join Date: May 11, 2002
Location: high up in the rockies
Posts: 2,232
If you use a bullet comparator, such as those from Sinclair International, you only need to measure it ONCE. Then you set your seating according to the measurement from the comparator.

Yes, you must reset the seating stem when you change bullets, but that's no problem when using the comparator.

The easiest way that I've found is to take an unprimed, resized case, and make a "dummy round" for each load, and use the dummy for die adjustments.
__________________
If you think a mighty military force is expensive, wait 'til you see what a weak one costs.
cheygriz is offline  
Old April 1, 2007, 05:42 PM   #9
James A. Mullins
Senior Member
 
Join Date: October 10, 2006
Location: Vancouver Washington
Posts: 124
cheygriz Has it nailed. The settings are manuf. sensitive, you will notice a differance.
James
James A. Mullins is offline  
Old April 1, 2007, 06:55 PM   #10
cdoc42
Senior Member
 
Join Date: March 13, 2005
Location: Pennsylvania
Posts: 408
Even using a dummy round for each bullet style I load, I've found when I buy another new lot number it makes sense to recheck those loaded rounds.

I had an experience with Hornady 7mm 175gr bullets where they completely changed the bullet design, and the cannelure was in a different spot. That obvious difference caused me to recheck the over-all length to the ogive (I call it OAL-OG) and the new design clearly seated differently. Since then I double-check by measuring the first round out of a new lot. It seems Nosler rarely gives me this problem. Barnes was frequent, even in the same box of the same lot!! Hornady SST vary little, if at all.
cdoc42 is offline  
Old April 1, 2007, 09:59 PM   #11
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,332
Agree with the last post. I have seen the very same design differ a little from lot-to-lot. New tooling, I presume. Sierra doesn't even mix bullets off the same tooling if a different operator was running the machinery. Everyone's touch is a little different.

Note that most chamber throats have a very gradual angle onto the rifling. It is an OK match to some of the older tangent ogive bullet designs, but the newer high BC secant ogive designs depart the cylinder of the bearing surface more abruptly. Your comparator, won't necessarily intercept these the same distance ahead of the bearing area as the actual throat does.

Just to complicate your life further, if you are loading for a rimless, non-belted bottleneck rifle cartridge, it headspaces off the middle of the case shoulder. Remember that the firing pin will shove the cartridge foward into your chamber until the shoulder stops it. This is an amount equal to the difference in the headspace measurements of your sized cases and a case fireformed in your chamber. In other words, if you try to seat the bullets 0.020" off the lands, but your loaded case is 0.005" shorter in headspace than a fireformed case from your chamber, the cartridge will shove forward 0.005" on firing. Thus, your bullet will actually be 0.015" off the lands when it goes off. It is actually the difference between the bullet ogive distance from the casehead and the case headspace that needs to be consistent to control the bullet's distance from the lands on firing. Read both the ogive and the headspace of your Stoney Point adapter case and use the difference to setup your seating die for land touching, then reduce the seating stem by your desired amount of bullet distance off the lands from there.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member
Unclenick is offline  
Old April 1, 2007, 10:50 PM   #12
jamaica
Senior Member
 
Join Date: March 24, 2006
Location: Northern Utah
Posts: 520
Yep, and when you get the first one off, check and make sure it is not too long to work in your magazine.
jamaica is offline  
Old April 2, 2007, 12:12 PM   #13
cdoc42
Senior Member
 
Join Date: March 13, 2005
Location: Pennsylvania
Posts: 408
Unclenick, the headspace phenomenon you describe is something that never occurred to me, nor have I ever read about it. That may well explain the occasional flyer no matter how precisely I reload my cartridges. I have tried to resize my cases such that the shoulder is bumped back 0.002" but with the arrival of the RCBS "X" die, that plan is destroyed. RCBS stated I can't have it both ways with the "X" die.
cdoc42 is offline  
Old April 2, 2007, 11:39 PM   #14
tommys
Junior Member
 
Join Date: April 28, 2006
Location: People's Socialist Republic of Illinois
Posts: 7
cdoc42
Hi, I don't understand your post that stated "RCBS stated I can't have it both ways with the "X" die" . Am I missing something ? I thought that the X Die resolved the cartridge growing problem. What does both ways mean?
__________________
"An appeaser is one who feeds a crocodile, hoping it will eat him last."

"Any man who is under 30, and is not a liberal, has no heart; and any man who is over 30, and is not a conservative, has no brains."

-- Winston Churchill
tommys is offline  
Old April 3, 2007, 12:27 AM   #15
cdoc42
Senior Member
 
Join Date: March 13, 2005
Location: Pennsylvania
Posts: 408
The "X" die when set up as directed prevents case growth. If you set up a conventional resizing die using a Stoney Point tool on your micrometer you can set the shoulder of the case back only 0.001-0.002" so it will just fit in your rifle. That prevents a case fired in a large chamber from being resized to a minimum, which, upon firing, "over expands" the case and shortens case life. This is also the preferred way of resizing belted cases so they headspace on the shoulder like unbelted cartridges. My discussions with RCBS on this subject resulted in my being told the "X" die could not be set up as I described because "I couldn't have it both ways."
cdoc42 is offline  
Old April 3, 2007, 01:37 AM   #16
Bullet94
Senior Member
 
Join Date: September 8, 2004
Location: Kansas
Posts: 723
Quote:
Unclenick
Note that most chamber throats have a very gradual angle onto the rifling. It is an OK match to some of the older tangent ogive bullet designs, but the newer high BC secant ogive designs depart the cylinder of the bearing surface more abruptly. Your comparator, won't necessarily intercept these the same distance ahead of the bearing area as the actual throat does.
Are you saying that the comparator and lands touch the bullet in different places?

Quote:
Unclenick
Just to complicate your life further, if you are loading for a rimless, non-belted bottleneck rifle cartridge, it headspaces off the middle of the case shoulder. Remember that the firing pin will shove the cartridge foward into your chamber until the shoulder stops it.
Couldn’t the OAL be determined by making a dummy round (using one of your sized cases) with the bullet seated long and then pushing it in the chamber until it headspaces off the shoulder? Then remove the dummy round and look to see the marks on the bullet from the lands. Measure the dummy round with a comparator and then reduce the OAL until no marks from the lands are seen. Once the distance to the start of the lands is determined then any amount off the lands could be measured.

What if you’re loading into the lands? Then does the cartridge headspace off the bullet?
__________________
PRO-SECOND AMENDMENT - Live Free or Die

Last edited by Bullet94; April 3, 2007 at 02:19 AM.
Bullet94 is offline  
Old April 3, 2007, 12:20 PM   #17
kingudaroad
Senior Member
 
Join Date: March 11, 2005
Location: austin
Posts: 735
Quote:
What if you’re loading into the lands? Then does the cartridge headspace off the bullet?
If your shoving the bullet into the lands until the point that the shoulder stops the cartridge from moving forward anymore, you are still headspacing on the shoulder.

If I'm interpreting Nicks post correctly, the force of the firing pin hammering against the back of the case will make a fireformed case move forward another .005.
kingudaroad is offline  
Old April 3, 2007, 08:35 PM   #18
Bullet94
Senior Member
 
Join Date: September 8, 2004
Location: Kansas
Posts: 723
Quote:
kingudaroad
If your shoving the bullet into the lands until the point that the shoulder stops the cartridge from moving forward anymore, you are still headspacing on the shoulder.
I uderstand,but I’m asking if you use a full length resized case and then load it so the OAL is long enough to be in the lands. The base of the case will be pushed back to the bolt face when the bullet engages the lands. So I assume the cartridge will be headspaceing on the bullet?
__________________
PRO-SECOND AMENDMENT - Live Free or Die
Bullet94 is offline  
Old April 3, 2007, 09:53 PM   #19
mrawesome22
Senior Member
 
Join Date: November 9, 2005
Location: Ohio, Appalachia's foothills.
Posts: 3,779
Take a empty case. Cut a vertical slit in the neck, barely into the shoulder, with a hacksaw. Barely seat the bullet you want to use in this case with your hands. Chamber this round in your rifle. Eject it with your hand covering the ejection port. Take it out and measure it from base to tip with your calipers. This will give you MAX OAL (over all length) for that bullet. In other words, this bullet is touching the rifling. Now you can experiment with different seating depths. I've found that my rifle usually gives best accuracy .030" away from the rifling. But you'll just have to experiment as to what shoots the best out of your gun. This method works very well and you don't have to waste money on a Stoney Point guage.
mrawesome22 is offline  
Old April 3, 2007, 11:49 PM   #20
cdoc42
Senior Member
 
Join Date: March 13, 2005
Location: Pennsylvania
Posts: 408
Bullet94, I understand what you are saying but I think "headspace" refers to the relationship between the brass case and the chamber, not the overall length of the cartridge which includes the bullet. If the bullet totally engages the rifling as you describe it, the headspace would be zero. But if we agree that headspace only involves the case, even with the bullet fully engaged against the rifling, the case would still have space to move and that "headspace" would need to be addressed. If anyone can correct me, I'm anxious to learn.
cdoc42 is offline  
Old April 4, 2007, 12:35 AM   #21
mrawesome22
Senior Member
 
Join Date: November 9, 2005
Location: Ohio, Appalachia's foothills.
Posts: 3,779
Dirty habit, your seater plug will land nowhere near the ogive. Every bullet's ogive is in a different place. For instance, a Hornady VMAX .224" 50gr looks identical to a Sierra Blitzking .224" 50gr. Max OAL with the VMAX in my rifle is 2.503". Max OAL with the Blitzking is 2.515". That means that the VMAX has a .012" longer bearing surface. In other words, the ogive's are in different places. The ogive is where the .224" diameter starts becoming smaller. In the case of the Sierra, it's farther back. In the case of a Nosler BT, they are usually way farther back, they have a smaller bearing surface.
mrawesome22 is offline  
Old April 4, 2007, 01:15 AM   #22
Bullet94
Senior Member
 
Join Date: September 8, 2004
Location: Kansas
Posts: 723
From SAAMI -

Quote:
HEADSPACE
The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats.
cdoc42 Looks like you’re right about headspace. But if the bullet is into the lands and forces the case back on the bolt face, when fired the firing pin couldn’t drive the case forward, could it?
__________________
PRO-SECOND AMENDMENT - Live Free or Die
Bullet94 is offline  
Old April 4, 2007, 03:20 AM   #23
dirty habit
Member
 
Join Date: December 18, 2006
Location: New Zealand
Posts: 57
Mrawesome22, yeah thats right, i think i may not have explained myself too well earlier. The measurement i was on about was from the base of the cartridge to the ogive, from what i can figure, this overall measurement should be the same with any bullet i use, although granted, ill have to change the seating die each time.
I think i got confused with the seating die and thought that it worked off the ogive of the bullet which it obviously doesnt.
Im pretty sure what im thinking is on track but dont think im explaining myself too well!!
__________________
Happiness.......is a warm gun
dirty habit is offline  
Old April 4, 2007, 08:19 AM   #24
rwilson452
Senior Member
 
Join Date: June 10, 2004
Location: Tioga co. PA
Posts: 2,361
Coal

Not exactly, the seating depth will be very similar even when you change bullets but bullets have different shape that means it will contact the lands differently. With pistol ammo this difference shouldn't matter much unless you seating them very close to the lands. A different shape could put you into the lands and not allow the cartridge to fully chamber or push the bullet back into the case. With semiauto pistols I always use the barrel as a case gauge to insure proper fit. holding the barrel upright the cartridge should drop in without force and be chambered correctly.


Mrawesome22, yeah thats right, i think i may not have explained myself too well earlier. The measurement i was on about was from the base of the cartridge to the ogive, from what i can figure, this overall measurement should be the same with any bullet i use, although granted, ill have to change the seating die each time.
I think i got confused with the seating die and thought that it worked off the ogive of the bullet which it obviously doesnt.
Im pretty sure what im thinking is on track but dont think im explaining myself too well!!
rwilson452 is offline  
Old April 4, 2007, 11:38 AM   #25
cdoc42
Senior Member
 
Join Date: March 13, 2005
Location: Pennsylvania
Posts: 408
"cdoc42 Looks like you’re right about headspace. But if the bullet is into the lands and forces the case back on the bolt face, when fired the firing pin couldn’t drive the case forward, could it?"

Good thought - probably not. But then we'd have to consider how many milliseconds transpire between the firing pin being struck, the primer and powder igniting, and the mouth of the case expanding, at which point the case would move forward since it no longer holds the bullet secure.
cdoc42 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 08:35 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 0.14860 seconds with 7 queries