Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Do you have access to pin gauges? They are 1" long rods ground to a specific diameter?
When bores erode, definitely the throat (start of the lands) move but the rifling also wears thinner. That caught me one time cause it looked like there was rifling near the throat but it had thinned enough to allow the bullets to skip.
By using pin gauges, you can drop them into the throat and they will stop when they get to the bore diameter. Measure from the root of the chamber, agree with where you think the lands should be.. all good. Not so good when they fall into the barrel and go beyond where you expect the rifling to be. Cheap and simple way to diagnose bore wear.
The US army had a cartridge/throat gauge that worked on the same principle.. I saw them as armourers tools for Garands and such.
Bore scopes work great for this too but they can be pricey and a pin gauge is a 2 sec check.
Good luck with your testing... hope you find a new load.
Jerry
When bores erode, definitely the throat (start of the lands) move but the rifling also wears thinner. That caught me one time cause it looked like there was rifling near the throat but it had thinned enough to allow the bullets to skip.
By using pin gauges, you can drop them into the throat and they will stop when they get to the bore diameter. Measure from the root of the chamber, agree with where you think the lands should be.. all good. Not so good when they fall into the barrel and go beyond where you expect the rifling to be. Cheap and simple way to diagnose bore wear.
The US army had a cartridge/throat gauge that worked on the same principle.. I saw them as armourers tools for Garands and such.
Bore scopes work great for this too but they can be pricey and a pin gauge is a 2 sec check.
Good luck with your testing... hope you find a new load.
Jerry
