Finally got a chance to use my pressure testing unit. I traded a feller some reloading equipment for a used 835 barrel. I’m using that as a stand-alone test barrel. I started off by cutting the first section of the vent rib off to epoxy my strain gage over the chamber area:
You have to measure the chamber ID (easy using cerrosafe) and the OD of the area of the barrel where you’re placing the strain gage. Those are values you have to add to the ballistic software system.
Next, you have to standardized your unit with a known pressure load. The developer recommends choosing a load from Lyman’s. I chose to use the pressure results I got back from Precision Reloading from Uncle D’s Fury slugs.
Theres a correction you can add to the software based on the reading you initially get with your previously tested load. In my case, the first three shots UNCORRECTED with Uncle D’s known pressure slugs where coming in around 6kpsi. They should of tested out 10.5kpsi.
Apply simple math, I added a correction of 3kpsi and tested 3 more of the same loads. Those read on the money and I was in business.
I started off testing a 3.5” 18 pellet buckshot load I’ve used in the past. I knew these where heavy loads. I’ve had slight signs of over pressure but never really had any absolute pressure values.
I shot three loads through my system and they came in around 17kpsi...... 3kpsi over SAAMI spec for 3.5” 12 ga.
I also tested a couple of factory 2.75” buckshot. Those avg around 11kpsi.
Factory slugs came in around the same.
All in all, I’m happy I purchased this unit. It’ll pay for itself after about 2-3 range outings.
Sent from my iPhone using Tapatalk