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First chamber cast - Randy Bohannon - 02-27-2020
So after playing’guess what bullet will fit and work well’ and eventually stumbling on I have no leade in my chamber.
Always had to seat fat .410” 400 gr. bullets so deep I could never get 70 grs of any powder (B/P)
So I finally did a chamber cast and here’s what I have , I have not measured anything yet as I was interested in the chamber / rifling transition. I see no 45 degree transition , am I missing something ?
Rifle is a Shiloh 1874 Sporter # 3 40-70 SS , the only bullet that has showed any promise is a dual diameter Steve Brooks ‘Money Bullet’ cast 16:1 .
Now I want a paper patch bullet dual diameter mould . I am thinking .402” base for .375” then .394” to ogive 415 gr. Money bullet nose design .
Am I all wet here ? Just trying to learn to solve these kind of things.
RE: First chamber cast - Distant Thunder - 02-27-2020
Looks like you have some sort of an end stop, which is pretty steep if not 45 degrees. You have NO freebore, as in zero.
What is your twist rate, 1 in 16?
What is the inside diameter of a fired and unsized case mouth?
What is your bore diameter?
What are the diameters of your current bullet before and after wrapping?
What paper are you using?
What kind of shooting are you using this rifle for?
Answer those questions and I'll give you something to consider bullet design wise. If you want me to.
RE: First chamber cast - Randy Bohannon - 02-27-2020
Yes Sir.
Fired case mouth is .410”, .408X.400 barrel , two wet wraps to my .444” PP bullet brings it to exactly .450”. with my paper I don’t have a PP mould for this rifle except an adjustable Steve Brooks .395” PP mould which is dismal in this rifle. Yes 1:16 twist. Paper adds .06” two wraps. Current greaser bullet is the Dan T designed Money Bullet @ 410 grs. .410” dia. 1.42” long. I have a Paul Jones Creedmoor @410” and a Lyman Snover .410” dia. both require deep seating to chamber.
Thank you for your time
Randy
RE: First chamber cast - Don McDowell - 02-27-2020
Two bullets that work the best in the CSA Hepburn with a chamber almost indentical to that , are the BACO .400360 and the Brooks sharps style dual diameter bullet with his original postel nose. .400 on the base, and 395 at the base of the nose. Cast both from either 20-1 or 16-1, and wet wrapped in Seth Cole 55y. 55w works, but 55y shoots smaller groups at 600 yards.
[attachment=1635]
RE: First chamber cast - Randy Bohannon - 02-27-2020
I will be using Steve Brooks to cut the mould. I will go with your suggestions with the Brooks mould. Are Shiloh 40-70 SS chambers usually cut like this with no free bore ?
RE: First chamber cast - Don McDowell - 02-27-2020
Most of them are since Kirk and co took over. They used to have in the Wolf days quite a bit of freebore.
If you're not in a hurry, I could send you up some of these bullets you could try before biting off a new mould. I have some cast and wrapped, but don't know if I could get them in the mail to you before I get back from Phoenix.
Don't know how good of records Steve keeps on his customers moulds but he should have that bullet in his ledger I think.
RE: First chamber cast - Distant Thunder - 02-27-2020
Randy,
I'd still like to know what type of shooting you're doing with this rifle?
The first thing I'll say is what follows are just my thoughts and suggestions. You'll need to weight these against other opinions and decide where you want to go. YMMV
In a grease groove bullet you would need a bullet with the first two, maybe three, bands reduced to fit your bore. Anything else will have to be seated very deep in the case as you know.
I am assuming a muzzle velocity of about 1300 fps. Which shouldn't be a problem with a bullet that you can seat out a properly.
Whether you are shooting GG or PP that 1.420" length is too long for your 16-twist. It can shoot well in constant and stable conditions, but will get beat up pretty badly if there are any winds blowing and especially any head and/or tails winds gusting. You're not going to like this, but you would be much better served with a bullet at 1.325" long. The Snover would do well out to 600 or so unless you're up against some real nasty headwinds. You would need a 14.5-twist with that length. The length to twist thing is where many shooters go wrong.
A 2-diameter paper patch bullet could work pretty well for you if it fits your rifle correctly. I worked with a friend on his .45-90 that had a similar chamber, but I believe he had a little bit of freebore and you do not.
The hard part here is deciding how deep you can or want to seat a 2-D PPB. People seem to get a bit squeamish about seating PPB very shallow, but it works very well for me. Assuming that these are target loads your looking for, seating shallow should not be a problem. If they are hunting loads the design would be best if it allowed for deeper seating, .300-.400". That two depends some on bullet design.
If you use a 2-D PPB your brass needs to be just short enough to chamber, too short will cause problems that you don't need.
For target work your 2-D PPB should be no more than .125" in the case. I seat my 2-D PPB only .075" deep in my .40-65 and it is a 1 MOA rifle at 200 yards and shoots very well to 600 yards. Bullet fit is the main reason for it shooting as well as it does, but I believe shallow seating also helps.
You're not going to get much of the groove diameter portion out of the case, but let's assume .030" and maybe another .030" that you can cam into the rifling just closing the block. That portion should patch to .409-.410". It should be a snug fit in your unfired case.
Figuring .060" of the groove diameter portion out of the case and .125" in the case you would want it to be .185" long at .403-.404" diameter as cast, plus the transition length that should match the lead angle of your rifling. In my .40-65 2-D PPB I have just a step here and that works a bit better with rifles that don't have a lot of camming ability like my C. Sharp 1875.
Then the bore diameter portion should go from the transition to the start of the ogive and be .400" patched diameter. That means .3935 to .394" diameter as cast. This is the most critical diameter as cast because it gets complicated to size. The groove diameter is easy to size after patching if necessary. I size all my paper patch bullet including my 2-D PPB.
The nose style is totally up to you. I will say that the longer more slender nose shapes like the money require more spin than a more blunt design for the same length. I have found the more blunt designs to be easier to get excellent accuracy with and you can push the length somewhat more with them.
I could draw up 3 designs that you could look at, but it wouldn't before next week. Then we could discuss the merits of each design and you can go with whatever you believe would be best for you.
[attachment=1636]
This my .40-65 2-D bullet.
[attachment=1637]
This is a recent group I shot with that bullet in my scoped 1875.
These will repeat almost every time.
RE: First chamber cast - Randy Bohannon - 02-27-2020
Thank you for the information, So the original Postell nose using the Brooks Sharps PP mould .403” base for .250” then .394” to ogive would be a good way to go ?
I would like to get the best accuracy out to 500m for silhouette, gong matches.
RE: First chamber cast - Distant Thunder - 02-27-2020
I like that Brooks nose shape.
I think you will be best by a bullet not over 1.375" OAL and I would go with 1.325" for myself. My .40-65 bullet is only 1.250" long due to my 18-twist barrel. It weighs 382 grains and it works very well in silhouette, even on rams, and at gong matches out to 500 yards. Extra weight and length do you no good if your bullet is marginally stable. I went with an original round nose design to get as much weight as possible in my 1.250 lengths. I designed my bullet to fit my chamber, to fill all space completely. That I believe is most important.
With your paper adding .006" and an as cast base diameter of .403" you should end up at .409". With a very light taper crimp that would work. At .250" long you would end up in the case somewhere about .210 to .190" which I see as a bit deep, but would work without any problems if your brass is not to short. Brass length is important.
I'd hate to say .393" but you do not want over .394", .394+.006=.400". Brooks is very good at hitting these diameters pretty darn close. Probably say, .393-.394" to give him some room and then hope for the best.
RE: First chamber cast - beltfed - 02-28-2020
https://buffaloarms-ecomitizellc.netdna-ssl.com/media/catalog/product/cache/1/small_image/220,%20130x/0dc2d03fe217f8c83829496872af24a0/jim405390e.jpg
HOw about this bullet from Buffalo Arms. JIM#405390E
they can adjust the diameters easlily.