24hourcampfire.com
24hourcampfire.com
Previous Thread
Next Thread
Print Thread
Hop To
Joined: Aug 2002
Posts: 14,440
S
SU35 Offline OP
Campfire Outfitter
OP Offline
Campfire Outfitter
S
Joined: Aug 2002
Posts: 14,440
Is one more important than the other in terms of saftey?

BP-B2

Joined: Dec 2000
Posts: 29,348
Campfire Ranger
Offline
Campfire Ranger
Joined: Dec 2000
Posts: 29,348
no difference

Joined: Feb 2003
Posts: 647
Campfire Regular
Offline
Campfire Regular
Joined: Feb 2003
Posts: 647
When you mention breach pressure, were you thinking about bolt thrust? That thrust is caused by the pressure in the case
and as Ken says the pressure inside the case is the same against back as well as sides of case...But bolt thrust is a
factor of the pressure times the area of the base of the case,
against the bolt in simple terms.Ed.


Ed Hubel
Joined: Dec 2002
Posts: 15,836
A
Campfire Ranger
Offline
Campfire Ranger
A
Joined: Dec 2002
Posts: 15,836
Hubel, when calculating bolt thrust, do you use the surface area inside the case, or do you just use the diameter of the case base?



Al

Joined: Feb 2003
Posts: 647
Campfire Regular
Offline
Campfire Regular
Joined: Feb 2003
Posts: 647
AJ--I use a simple formula that is within 5% of complicated
ones.Base outside diameter times pressure times 2/3.
Example- 30-06 with .470 base has area of .1735 sq inches,
times a 60,000 psi load, times 2/3 = 6950 lbs of thrust.Ed.


Ed Hubel
IC B2

Joined: Dec 2000
Posts: 29,348
Campfire Ranger
Offline
Campfire Ranger
Joined: Dec 2000
Posts: 29,348
Since it's the powder gas that's exerting the force, the flat portion of the inside surface of the web (exclusive of wall thickness, etc) is the active piston surface. Using the diameter of the rim produces an area figure that is too large.



In lieu of direct measurement, I methodologically estimate the area of this net surface by using 90%-95% of the outside diameter. This allows for the fact that the case wall and the fillet (curved transition from web to wall) are not subject to the straight-back force.



Peak chamber pressure (lb/sq in.) times this net web area (sq in.) equals the force (lb) pressing the case rearward against the resistance of the locked lugs.



Obviously, actually measuring the diameter of the flat area of the web produces a figure that is more accurate than my hasty estimate.

Joined: Dec 2002
Posts: 15,836
A
Campfire Ranger
Offline
Campfire Ranger
A
Joined: Dec 2002
Posts: 15,836
Thanks guys. I figured it was the surface area inside the case, just wondering how you went about calculating it. I'm anxiously awaiting release of Ken's book so I can get edjumacated beyond my intelligence <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />



Another queston, which would have a higher force, say the inside measurement was .375" diameter, flat surface, or if the surface was shaped in a semi-hemispherical, .375" diameter, with the height of the crown being .050". My line of thinking is that you would have to concider the force vector on the curved surface, total force would be lower than on a flat surface. It's been too long since my math courses.



Al

Last edited by AJ300MAG; 02/21/04.

Moderated by  RickBin 

Link Copied to Clipboard
YB23

Who's Online Now
574 members (219 Wasp, 007FJ, 160user, 10gaugeman, 17CalFan, 1Longbow, 54 invisible), 2,377 guests, and 1,108 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums81
Topics1,187,597
Posts18,398,217
Members73,815
Most Online11,491
Jul 7th, 2023


 







Fish & Game Departments | Solunar Tables | Mission Statement | Privacy Policy | Contact Us | DMCA
Hunting | Fishing | Camping | Backpacking | Reloading | Campfire Forums | Gear Shop
Copyright © 2000-2024 24hourcampfire.com, Inc. All Rights Reserved.
Powered by UBB.threads™ PHP Forum Software 7.7.5
(Release build 20201027)
Responsive Width:

PHP: 7.3.33 Page Time: 0.121s Queries: 13 (0.003s) Memory: 0.8145 MB (Peak: 0.8702 MB) Data Comp: Zlib Server Time: 2024-03-28 12:48:11 UTC
Valid HTML 5 and Valid CSS