40-65: Learning what I can

[Kurt]

Sometimes I think folks can think these things to death.
The Browning chamber is a proven winner. So is the Shiloh. 40-65 Rl is another good chamber, but the difference between it and the Browning are very slight.
Starline cases work fine, in all 3 of those chambers, sizing down 45-70 cases is how Ron Long came up with his 40-65 RL case, it's actually a tad longer than a typical 40-65 chamber.
16 twist will handle anything needing done with the 40-65 case and blackpowder. 14 twist best left to longer cases, and smokeless.
So long as those RCBS dies will expand the case mouth back to the proper diameter as to not put to much neck tension on the bullets they'll work just fine.

But man Don that Browning chamber has a .100" cylinder freebore. I'm not sure I Would want that much unless I shot greasers or a patched tight long ogive bullet.

Kurt

[Don McDowell]

Well that chamber is a good one , with a proven track record.

[Semtav]

Kurt
Have you tried patched to groove bullets in that Browning 40-65 that you had modified? I really like the little bit of freebore in my 45-90 with Groove dia PP bullets and need to get my keester in gear and try some PP bullets in my Browning 40-65

[SgtDog0311]

Kurt, help me decipher here. On the PRG Browning that is posted above what do the "two" numbers indicate where the transition is identified (12*-45-0)? Looks like it would be a 12* or a 45* but not both. The Win just shows a 45* and that's all. This is my first exposure to reamer diagrams. Gonna go shoot some but I'll check back in when I return. Thanks, John

[Kurt]

John.
The .435 is the case neck chamber wall diameter that is a 1/2" long in front of the body taper. That .435 is pretty generous. That leaves about .005" extra room for a .010" case wall thickness using a .410" diameter bullet. in other words that un sized case will hold a .415" diameter bullet. My feeling that is pretty loose for a .408-.410" diameter GG bullet. That leaves a bunch of room for the base of that bullet to expand and then gets swaged back down again to fit the throat.
That is a 12 degree 45 minute zero second. That is just slightly over 12-1/2 degree transition.
Then the next measurement- 2.045 to 2.1002 is how long the 12-1/2 degree is.
The 410 is the free bore diameter. The 2.1002 to 2.2002 is the length of the free bore.
The 1*-30-0 is the pitch of the lead angle on the lands.

[Kurt]

Kurt
Have you tried patched to groove bullets in that Browning 40-65 that you had modified? I really like the little bit of freebore in my 45-90 with Groove dia PP bullets and need to get my keester in gear and try some PP bullets in my Browning 40-65

Brian.

No I haven't. I don't have a mould for a PP that large for a .40.

Kurt

[SgtDog0311]

Kurt… Perfect! Thanks. Shooting with a friend today who clued me in about the 12-45-0. I was used to reading that angle the way SAAMI expresses it. Should have caught that one and now I recall TexasMac’s chamber cast in the “Lead” thread where he identifies a 12.75 for the Browning casts he posts.

So, .130 in front of the rim is where the case runs parallel (also as Texas Mac mentioned elsewhere) although the 40-65 cast he posts on page 3 does not appear parallel – looks to the eye more like the taper goes straight from the case all the way to where the base of bullet would be. Maybe that is just optical

And judging from dimensions the Datum line is the business side of the rim. And I see the .070 on the other side as well.

So reamer drawings are just boiler plate straight line representations so reamer manufacturers can plug the numbers in to a standard drawing.

[SgtDog0311]

Regarding the generous diameter of the Browning case mouth and free bore I notice the Winchester reamer diagram eliminates .003 at the case mouth and is .0015 smaller in the freebore at .4085. So if you had a .408 groove size, then the free bore diameter would not allow much over groove at all. That makes me think if you flattened the transition to take up nearly all the free bore or just did the same thing with a throat reamer you’d be fine.

Question for you Kurt that I’ve thought to ask more than once. At one time you made note of the original cast of an 1877 #1 Sharps having a 3.5 degree chamber end, and that you changed it to a 5 degree - but wished you’d have left it original. Is that wish due to performance or just staying true to the original? Just curious! I recall seeing some of the so called “match chambers” of ‘old dead guys’ that had 3.5 degree, so got me to wondering.

Also see that a modern SAAMI specs call for the 38-55 chambers to have a 6 degree. I’m wondering if there would be any harm having a 40-65 Winchester reamed so as to take up all the freebore with whatever angle transition that would work out to? That would look a little like your cast you corrected the oval with… was not much free bore left there after you applied that “fix”.

[Kurt]

John.

As far as the 3-1/2 degree funnel transition into the throat. I have 45 degree chamber ends, 12-1/2, 7, 5, and 4 degree, they all shoot great when the barrel is still free of lead smears when you shoot a GG bullet or PP. But I found that the flatter the transition is the longer I can shoot with consistent accuracy as well shooting "dirty" no fouling control. just load and shoot.
The funnel chamber ends alone will not give you top accuracy. They help but it's a combined effort between chamber dimensions all the way into the throat and lead. The less you deform the bullet when the charge goes off the better the rifle will shoot. This also means that you must match the bullet with the ROT. The bullet profile has a big bearing how well it stays stable in winds and at long range as the rotation decays. For an example, take a long slender top and wrap the string around the top, I had the string tied to a stick like a whip to give the top a faster spin and take a short stubby top about the same weight and see which top spins the longest, well bullets do the same thing. The stubby bullet might decay in elevation a little faster but it will stay stable.
The ODG's I'm sure also had tooling to make the .45 degree chamber end and that 45 degree chamber end started to show up about the time of the .30-40 Krag using the hard gilding metal for jackets and cordite powder as far as I have found when the sharper chamber end came around. The Sharps Borchardt started with a transition like what Browning is using. The cordite did not bump up the hard gilding metal jackets and that powder needs back pressure to burn efficient. I have done a lot of searching since I got the computer but I have not found much on this subject so I cant say if I'm right with this. The .22 rimfire still has a very flat slope into the throat, as flat as 1-1/2 degree some match chambers have.

But to answer your question if I use this type of chamber because it is what the ODG's used I will say; No. I use them because I know they work. I don't lock myself into doing it because that is what the ODG's did. I will go any direction I have too to get the best from my rifle.

Kurt

[Kurt]

John.

Here you go. Read through this and then wonder why they used these old flat nosed wash board bullets in the past when they also had the sharp pointed streamlined bullets also
http://www.castpics.net/subsite/HistMolds/Ideal1897.pdf
there is some good stuff in these links. http://www.castpics.net/subsite/HistMolds/default.html