I noticed that while seating cartridges into my 1885 High Wall in 45-90, the cartridges, with cast bullets, needed a thumb push to seat them the last .2 inches in the breech. Not having any factory ammunition with which to chamber and see the difference, I assumed the bullet diameter was the cause. Combined with no throat possibly, seating was always accomplished with a slight thumb push for the final .2 inch of travel. (that's 5mm for my Metric friends).
Black magic marker on the bullet and case mouth revealed no interference with the chamber or any area whatsoever causing the failure to "drop in" the chamber with gravity alone. I was stymied and figured the thumb push was going to prevail with my cast bullets. Know that I did not discover the thumb push right away and assumed my cast bullets were too large (length and/or diameter) to allow seating. In frustration one day, I pushed the cartridge into the chamber to get some rifling marks in the bullet to show me the distance I would need to deep seat the bullet and allow gravity to chamber the round.
To my amazement, no rifling marks of any kind were on the bullet. I then went a got a new cartridge case from the box, sized it in the sizing die, and inserted the empty cartridge case in to the breech. Lo an behold, the case needed to be pushed into the breech the final 5mm of travel. Magic marker on the same brass case at the mouth revealed no rubbing or interference on that end.
I light bulb went off in my feeble brain when I was chambering a bore riding, paper patched bullet into the breech, and a thumb push was needed to seat it. What the heck?
The rear of the CHAMBER at the breech end is just a tad tighter and necessitates the thumb push to seat the cartridge. Using 45-70 brass and factory 45-70 cartridges in the chamber was the same. Thumb push required. I can't believe how this misled me and had me working on the wrong end of the cartridge. The new .458 and .457 size dies were money misspent in trying to solve this mystery.
I know you are thinking a chamber cast would have revealed the issue but:
- I am bad at making chamber casts
- I would have been measuring the wrong end of the cast and seen that the throat went halfway to the muzzle.
- Getting the chamber cast all the way to the base (breech end) of the chamber is a real issue when the stupid metal flows out of the breech into the action area.
So now I once again say that I learn something each and every day. This rifle simply has a TIGHT breech end and a thumb push will be need to seat cartridges.
I will live with the thumb push to fully seat the cartridges and know I have a really good breech seal with this rifle!
With rifle in hand, I confidently go forth into the darkness.
