The Firing Line Forums

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

Reply
 
Thread Tools Search this Thread
Old December 27, 2012, 09:03 AM   #1
Jevyod
Senior Member
 
Join Date: May 5, 2012
Location: Pennsylvania
Posts: 172
Pressure question

Forgive me if this is a stupid question but here goes! Is there a good way to check chamber pressure? I have an old K98 8mm Mauser made in 1918 that I would like to work up some loads for. I had it checked out by a gunsmith that knows Mausers like the back of his hand. He told me that although those actions were tested to 75,000lbs pressure, he recommended I keep it somewhere in the neighborhood of 50-55,000. That still enables me to work up some pretty good loads.(much better than the American made factory ammo!) Anyway, how do I know how much pressure my loads are generating? Sorry if this is an amateur question but I still am one! Along with that question, what kind of velocity can I expect to get with a 200 Grn bullet at a 50,000 lb pressure level? Any advice is greatly appreciated!
Jevyod is offline  
Old December 27, 2012, 09:49 AM   #2
243winxb
Senior Member
 
Join Date: July 26, 2011
Location: USA
Posts: 1,730
QuickLoad -Pressure = estimated

Most reloaders have no pressure testing equipment, so we go by the looks of the brass, primer, web expanding measurement, bolt lift, hard extraction. Some use a chronograph to help get an idea. Compare loading data in manuals & online. http://data.hodgdon.com/main_menu.asp A computer program called QuickLoad,http://www.thehighroad.org/showthread.php?t=685303 may also be helpful to get a reading on pressure. http://www.sniperforums.com/forum/of...-software.html

Last edited by 243winxb; December 27, 2012 at 10:05 AM. Reason: add quickload
243winxb is offline  
Old December 27, 2012, 01:43 PM   #3
10 Spot Terminator
Senior Member
 
Join Date: January 3, 2008
Location: Central Oregon
Posts: 348
All of your top reloading manuals list pressures for starting loads as well as the recommended max loads for a given bullet weight and a specific powder in the calibre you shoot. There are 2 forms of measurement used in the industry , one is PSI and the other CUP depending on the test equipment used during the load testing by the provider of the manuals. There is no formula that I am aware of the convert CUP to PSI at this time but as with PSI if the listings are IN the CUP format, staying with the lower numbers will keep you and your firearm safe.
10 Spot Terminator is offline  
Old December 27, 2012, 02:07 PM   #4
Jimro
Senior Member
 
Join Date: October 18, 2006
Posts: 7,097
You have an M98 action. I wouldn't worry about pressure, just load up for accuracy with an appropriate powder for the bullet you are using and as long as you don't get any of the normal over pressure signs you'll be just fine.

Jimro
__________________
Machine guns are awesome until you have to carry one.
Jimro is offline  
Old December 27, 2012, 02:24 PM   #5
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 8,927
Having shot many 7.62 NATO proof loads in Garands that produce 65,000 cup or about 80,000 psi and none showed any signs of pressure on the case or primer, folks claiming one can look for signs of pressure may be leading others astray and into dangerous territory. MIL-SPEC normal max pressure's 50,000 cup or about 60,000 psi. Any data you see will be effected by how hard or soft the brass is in both the primer cup and cartridge case.

My advice is to load 8.57 Mauser no hotter than what decent data suggests. Not all M98 actions have the same strength, so why push the envelope when you don't know how strong it really is? Which is why SAAMI specs for 8x75 ammo's no higher than 37,000 cup or 35,000 psi.
Bart B. is offline  
Old December 27, 2012, 02:49 PM   #6
243winxb
Senior Member
 
Join Date: July 26, 2011
Location: USA
Posts: 1,730
33 Pressure signs by Unclenick-Link

http://www.shootersforum.com/handloa...ure-signs.html
Quote:
folks claiming one can look for signs of pressure may be leading others astray and into dangerous territory.
Cartridge Brass-
Material is 70 copper/30 zinc with trace amounts of lead & iron , called C26000. Material starts to yield at 15,000 PSI when soft (annealed), and 63,000 PSI when hard.
Material yields, but continues to get stronger up to 47,000 PSI when soft, and 76,000 PSI
when work hardened.

Last edited by 243winxb; December 27, 2012 at 02:57 PM.
243winxb is offline  
Old December 27, 2012, 03:47 PM   #7
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 21,024
If you want to measure pressure, the only system currently in production for handloaders that I am aware of is the RSI Pressure Trace. You can use it in conjunction with QuickLOAD and a chronograph to tweak the QL powder model to match your particular lot of powder better. I use one for three things. One is duplicating load performance. Another is to alert me to the echo of muzzle pressure spikes from using too slow a powder for the bullet weight (see a couple of examples lower down on that page I linked to). A third is that I generally try to stay under 58,000 psi unless I absolutely have to go higher, based on Geoffry Kolbe's observation that barrel erosion tends to grow exponentially with pressure above around that number.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member and Golden Eagle
Unclenick is offline  
Old December 27, 2012, 09:55 PM   #8
Jimro
Senior Member
 
Join Date: October 18, 2006
Posts: 7,097
Bart B.

The 8x57 CIIP pressure standards are a bit higher than SAAMI. The American standards are lower in case some knucklhead get a hold of an old .318 bore 8x57 instead of the .323 bore of the 8x57 JS.

An M98 manufactured in 1918 will have the .323 bore, and if any of the problems of a "weak" action are present, will make itself manifest through lug setback, which is easy enough to check by measuring headspace over time. Loading ammo to a lower pressure won't stop lug setback, just make it slightly slower.

Jimro
__________________
Machine guns are awesome until you have to carry one.
Jimro is offline  
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 04:54 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2021 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Page generated in 0.05322 seconds with 10 queries