Shooters Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
174 Posts
Discussion Starter · #1 ·
Hi,

Question (a repeat from my intro in General):

How do you mount a chamber pressure strain gauge over the center of the chamber of a Contender? To try to stay away from the barrel cross section changes of the barrel locking lug, on top of the barrel seems to be the ideal. BUT, over the chamber, on top, is where the sights or sight base for a scope is mounted.

I want to test pressures in .357 Herrett (iron sights), .223 Rem (scope mount), .44 Rem Mag (ribbed barrel with the shot spreader removed) barrels (more IF I can afford them). It is a GEN 1 frame.

Open to ideas/suggestions/blueprints!!!!

2Tall
 

·
Registered
Joined
·
1,839 Posts
Hi,

Question (a repeat from my intro in General):

How do you mount a chamber pressure strain gauge over the center of the chamber of a Contender? To try to stay away from the barrel cross section changes of the barrel locking lug, on top of the barrel seems to be the ideal. BUT, over the chamber, on top, is where the sights or sight base for a scope is mounted.

I want to test pressures in .357 Herrett (iron sights), .223 Rem (scope mount), .44 Rem Mag (ribbed barrel with the shot spreader removed) barrels (more IF I can afford them). It is a GEN 1 frame.

Open to ideas/suggestions/blueprints!!!!

2Tall
Take the sights or scope base completely off if possible. If you're testing for pressure you shouldn't be trying to shoot groups anyway.
 
  • Like
Reactions: Darkker

·
The Shadow (Moderator)
Joined
·
8,981 Posts
Like Rifter suggested, take them off it move the guage to the side.

Cheers
 

·
Super Moderator
Joined
·
13,769 Posts
I put one on an Encore barrel I had made custom in .45 Auto for testing pressure. It is on top. It actually works well, giving me readings of just over 19,000 psi on military ball ammo rated at about that. It's back edge is just barely a quarter inch forward of the breech end of the barrel; maybe 0.3". I'll have to dig it out and look.

I don't think being over the exact middle of the case is necessary. I would take a case that has been fired and resized a few times and use a caliper to identify where the pressure ring is forming and would be sure the back edge is at least that far forward to be sure the chamber steel under it is exposed to maximum pressure.
 
  • Like
Reactions: MusgraveMan

·
Registered
Joined
·
1,839 Posts
I put one on an Encore barrel I had made custom in .45 Auto for testing pressure. It is on top. It actually works well, giving me readings of just over 19,000 psi on military ball ammo rated at about that. It's back edge is just barely a quarter inch forward of the breech end of the barrel; maybe 0.3". I'll have to dig it out and look.

I don't think being over the exact middle of the case is necessary. I would take a case that has been fired and resized a few times and use a caliper to identify where the pressure ring is forming and would be sure the back edge is at least that far forward to be sure the chamber steel under it is exposed to maximum pressure.
I read somewhere once that the area just below the neck of a bottleneck case is where case pressure is highest, since that is the thinnest part of the case body and the part that expands to seal the chamber first. Most of the guys I know who use the piezo type of transducer tend to mount it in that general area. Seems logical to me. What do you think, Nick?
 

·
Registered
Joined
·
6,828 Posts
Hi,

Question (a repeat from my intro in General):

How do you mount a chamber pressure strain gauge over the center of the chamber of a Contender? To try to stay away from the barrel cross section changes of the barrel locking lug, on top of the barrel seems to be the ideal. BUT, over the chamber, on top, is where the sights or sight base for a scope is mounted.

I want to test pressures in .357 Herrett (iron sights), .223 Rem (scope mount), .44 Rem Mag (ribbed barrel with the shot spreader removed) barrels (more IF I can afford them). It is a GEN 1 frame.

Open to ideas/suggestions/blueprints!!!!

2Tall
A great deal can be said about stretch gauge mounting but one does not want to state stuff that already are common knowledge for the potential user. Apart from the Contender's outside chamber profile which I have not studied up close I assume that the OP understands that using this mode of measurement is not a good way to build up a load to nominated pressure levels that had been published by the piezzo-electric way of measurement.

And furthermore, particularly to not use it to achieve maximum pressures measured by SAAMI or CIP. Please do not go towards maximum pressure levels indicated by Quickload - as for all its expense QL uses simplistic formulae that had been developed for particularly the 30-06 and .308W cases and have up to a 16% negative calculation error for any cartridge showing any amount of overbore. -16% means that you will get a 16% overpressure by building towards the QL figure given as maximum.

Building a user-defined database of own pressure traces and safe maximum values based on known velocities is the clever way to go. Can one ever overstate the following?: "There is not one iota of value in attempting to wring the last 50 ft/sec from a cartridge bullet combination". Why would one want his expensive, nice rifle to be working at maximum rpm every time he turns on the ignition?
 
1 - 6 of 6 Posts
Top