Originally Posted by Tim in PA
Originally Posted by graybeardtmm3
Originally Posted by Tim in PA
The plan is card and fiber wads, I have PB and 7625, and the load data is in LUP. I'll just keep pressures for that down around 7,000 too, I would think that should be safe.

Tim
if you have supplies of both PB and 7625, this reference will offer you numerous loads - down to pressures that are amazingly low. my one comment regarding the gun is that there are older bore proofs 13/1 (right tube), and a faint 12 (?) on the left tube. that could be a tube originally as tight as .719", and last time through the process measured .736" - and that's the exact scenario that makes me keenly interested in knowing wall thickness. i have several guns in this same general condition - nicely cleaned up bores - but marginal wall thickness. i think it smart to take that in consideration with load pressures. http://pdf.textfiles.com/manuals/FIREARMS/imr_reloading.pdf

very handsome old gun, use it in good health.



So, I had the gun up to my gunsmiths to look at the barrels. He has a bore gauge but it's just an inside gauge, when he measured he came up with a measurement of .734, the proof house came up with .736. We measured the outside barrel diameter at.800, so subtracting 736 and dividing by 2 gives me about 30 thousandths wall thickness.

I was concerned a little about the wall thickness when I bought it, but it seems okay. You gentlemen know a lot more about this than me, I'm just guessing that since the gun was set up to weigh 6 and 3/4 lb instead of 6 and 1/2, and the barrels are only 28 inches instead of 30, they struck the barrels a little heavier to get the weight up.

Tim

others will show up here with more nuanced knowledge - but my general comment is that the difference between average outside diameter and average inside diameter is not a reliable means of determining minimum wall thickness. i have struggled with this exact situation, i bought a manson wall thickness gauge to compliment a couple of interior bore gauges, inside micrometers long enough to measure most chambers and chokes, and crummy choke gauges from earlier days. i discovered that the wall gauge is a great challenge for me to use. i was paralyzed briefly as a 5 y.o., and have some lifelong damage that manifests itself as a fine motor tremor or shake. i'll soon turn 77, and age has certainly not brought any improvements in that regard. in spite of many helpful tutorials here, regarding best practices to achieve consistent results - i simply cannot handle the leveraged micrometer smoothly enough to trust. most of my guns were measured with assistance from several "steadier" friends, and i abide with the generally stated opinions that below 25 thou, you should pay attention - and below 20 thou - a lot of attention.

"it's a poor sort of memory that only works backwards."
lewis carroll, Alice in Wonderland