Vintage Marlin 1895 (40-65) chamber question

[SgtDog0311]

In looking at my chamber cast the transition from neck to groove size appears fairly gradual. I’m wondering two things and hoping there someone here has the answer since exact angles are hard to extrapolate from a chamber cast.

1). Does anyone know the exact transition angle Marlin used in these chambers. (mine was made in 1898)?
2). If it were something like an 18* (or whatever really) would that have been the same angle, continuing through the leade ramp?

[pietro]

.

While I certainly don't know the answers to your questions, if I wanted to know, I would speak to a Customer Service rep from Clymer Reamers.

(google Clymer, then click on "contact us")


.

[SgtDog0311]

Thanks for the response Pietro... I've seen a Clymer 40-65 and maybe they have one different than what I saw. This one from them does not replicate an original chamber, at least not mine. Maybe like PTG they have more than one on record. So far I've never seen a chamber drawing that claims to replicate the original in a Marlin 40-65. Come to think of it I don't think I've seen an original for any 40-65. An Winchester 1886 would be another and it would be interesting to see if they were the same.
155026

[Nueces]

I think the best way to get your answer is a chamber and throat cast.

[SgtDog0311]

Nueces, As I started out saying "in looking at my chamber cast" I've been there. It is not the best cast in the world and while it's the only way at the moment it is less than exact.

For the .022 or so that angle travels in length it is hard to arrive at an exact angle. And I can't really tell if it continues through the lead ramp without changing.

Also, where the leade ramp reaches it's full height it is not the easiest to tell on a 116 year old chamber. Maybe if I did a better cast I could get reasonably close but I was hoping there was some literature I've not uncovered yet that gave some exact numbers of find someone who has searched for the same info with some success.
155050

[Nueces]

Sorry, I generally do much better at reading comprehension. Slow down, dummy!

[SgtDog0311]

That's funny Nueces, appreciate your feedback just the same. Now if I could just rouse someone who has beat this bush before. I've found it pretty hard to get good data on vintage chambers.

[SgtDog0311]

just an addendum... Best I can tell from this cast - and it's not the best cast, it is about .054 from the chamber diameter to the top of the lands. And it DOES look like it's evenly divided if you estimate the groove diameter location. The cast is not the best and the chamber has been through a few rodeos but that does indicate the same angle - I don't even know if they did compound angles back in the day. Just thought if, as I've read in the past that an 18* was common, that was pretty steep for a leade ramp.

Was hoping to get this in the effort to design a heavier bullet than the original that has a good chamber fit.

I need to apply some geometry and maybe I can get close if I don't flush out someone who has done some of their own reverse engineering and discovered the chamber profile.