375 caliber Boolit size?

[ronniet]

What should a 375 caliber gas checked lead Boolit mic after lube sizing? checked and unchecked.
Just curious what you find in measurements O.D.

[Tonto]

It seems folks usually size this caliber to .378 - .379 and you would get to choose based on your needs. The as cast diameter depends on your mold and alloy used. There is a chance that you don’t need to size at all if the variables add up to the right diameter out of the mound.

[dh2]

my 375 H&H does the best with then sized to .377

[Stephen Cohen]

My 375 Whelen does well at .377. Regards Stephen

[Walks]

My .38-55 likes them at .380dia

My old .375H&H preferred .377

[rockrat]

My H&H shoots very well with boolits sized .379"

[ronniet]

I have some cast Boolits that were given to me to set up some dummy rounds for a 375 Nitro Express I was making. after threading and chambering, checking the headspace was set on GO, I found that I could not get only 2/3rds of the round in the chamber. Thought I had the wrong gauge or reamer, but after checking my rounds, I had formed the brass right but the Boolits were all @ .390 was a no go from there.
I don't have a lube sizer, just got along without one, thought I would have Lee make me one of their sizer kits in the needed size but they are not doing anything custom right now.
Was going to shoot cast in the rifle, so was sent some 270, 255 and 245 grain to check how it shoots with them but all are .390
New Shaw barrel but I have had it so long that I need to slug it and check the twist again.
Ron

[richhodg66]

My .38-55 likes them at .380dia

My old .375H&H preferred .377

Mine too, though it does pretty well with the .379 commercial cast ones I've been shooting lately. The ones I cast from the Lee mold dropped a hair over .380 and they shot well unsized.

[DonHowe]

Depends on uour barrel. My Gree Mountain .38-55 barrel is .375" groove and likes .377" bullets.

[DonHowe]

Depends on your barrel. My Gree Mountain .38-55 barrel is .375" groove and likes .377" bullets.

[JonB_in_Glencoe]

I had a Interarms Mark X in 375 H&H, and it had a tight chamber.
I recall getting some sample boolits from a member here that were sized to his gun's liking, .378 or .379 I don't recall exactly. It turned out I needed them sized to .376 to get them to chamber with my desired seating depth (where boolit base wasn't below the shoulder).
Anyway, your gun will tell you what it wants, better then us Arm Chair Booliteers, LOL.

[405grain]

ronniet: Would that be a 375 rimless nitro express, (also known as the 9.5x57 Mannlicher-Schoenaur)? If that's the case post some details please. I've been gathering the action, barrel blank, stock blank, reloading dies, etc. to put one of these together. I'll be ordering the chambering reamer and gauges just as soon as my credit card gets a rest from the holidays. Even if it isn't the rimless nitro express, put up some pictures and post some details anyway: it sounds like an interesting project. BTW, if using reformed cases, which is about the only way to get 375 RNE brass unless your sitting on a pile of gold bars, the necks might be too thick and could need turning. Check the neck diameter on a piece of empty reformed brass and see if that might be part of the problem.

[GARD72977]

C Sharps 1885 38-55 really likes .376

[ronniet]

405 grain, check out the post I started last year on the 375 nitro express, just now getting back around to it, took PT&G about 3 months to get a reamer and HP gage to me and and I had other things at the time more pressing.
Am using 8x57 RP used brass, all annealed and necked up and then back down and trimmed.
I think the necks are too thin to turn down , I think it lies in the cast boolits that were given to me.
I have no sizer nor any molds, I will buy some factory branded bullets with a jacket that are supposed to measure .375 and try those.
I did measure the inside case mouths and o.d. too and even my expander ball on my RCBS, which I am thinking is too small too. (used set of 9.5x57 dies) but look perfect. I just cant remember the measurements right now but will do it again and write them down.
Yes its a 375 nitro express aka as 9.5x57 MS which is what my reamer and go gauge is marked.
Link to the post I started last year with great pictures of my other 1891 build and some great load data and brass forming post by members. http://castboolits.gunloads.com/showthread.php?374590-Making-375-Nitro-Express-brass
I just cant believe that the cast bullet users here are using such large o.d. boolits in thier rifles and they chamber.! Mine are measuring .376 -.3765 and they will not chamber when loaded.

[405grain]

ronniet: Thanks for the information. I picked up some unfired LC 30-06 brass from pulled down ammo last year and plan to reform that to 9.5x57 once I get the rifle together. I figure that military brass doesn't have a caliber head stamp, and will last longer. Down-side is the thicker brass will probably need neck turning, but that's OK. I got the Lyman 375449 mold for this project, but haven't cast any yet. I'm planning on this being a cast bullet gun. PTG is the only company that I know of that's making the 9.5x57 chambering reamer, so that's what I'm saving my nickles and dimes for. I'm planning to build this rifle using an Enfield P14 action, with a M1917 bolt, magazine box & follower. The M17 bolt means that the barrel will need a cone breech, but that's actually a plus, and might help feed better. Hearing that your having trouble chambering is of interest. First things first: Since you've got the chambering reamer, take the dimensions off of it and compare to the cartridge specifications for the 9.5x57. Because the cartridge is somewhat of an "improved" case, ie: it has less taper and the shoulder is blown out as compared to all the other cases that it can be formed from, the cases that haven't been fire formed yet should slide into the chamber much easier than what you are experiencing. Are you able to chamber an empty case? The first thing to look at would be the cast boolits that you are using. If the boolit is way too fat it could be preventing the case neck from entering that portion of the chamber. If you can chamber an empty case, when you get some jacketed bullets, make up a dummy round and see if that will cycle through the action. If that works, then the cast bullets are too big. If it doesn't work, then there's some other problem that will need to be figured out.

[ronniet]

This is a copy of the 9.5x57MS reamer Headspace gauge that Dave Kiff made for me in December of last year , it mimics the old Eley cartridge drawing dated 8/1913 that is found around the internet.
PT&G has lightly less length to shoulder but pretty much the same elsewhere . It does show like the Eley that it should be .375 and not over .3755 on the bullet diameter. all mine are measuring over .376 and better , all cast bullets btw.
So I am getting some jacketed ones to see if my load will chamber , as free bore and throat is show as adequate.
Ron

[405grain]

ronniet: I checked the link and went back and read your original thread. The empty cases chamber so that indicates that the bullets are too fat. I'd send you some better cast bullets but I haven't machined up a .377" sizing die yet, and Lee doesn't make a push through sizing die for .375 boolits. Heck, I haven't cast any 375 boolits, and haven't even ordered any 375 gas checks yet either. I usually build the rifle, then make the ammo for it. If everything works out with the jacketed bullets, and you need some case slugs, I can scratch things together and see if I can make you a few.

[ronniet]

405grain,Its either the boolit is too fat to chamber in the barrel or the boolit has made the case neck to fat to chamber.?
I am going to "saw" off the bullet at the end of the case neck and see if that chambers , if it does then its the boolits, if it don't the case neck is too bulged, and will try some 375 jackets which are .375. no I dont need any more cast boolits as yet, I am going to get me a push thru dies and then but some cast that I think I will like to use and size them in the .375 die. did you see the reamer draing that PT&G made for me in the above post? I made some brass from 30-06 and the neck material are so much thicker than the 8x57 ones, both are RP brass too. very thin wall on the 8x57 ones.

[405grain]

I plan on making up my brass from military 30-06. The case necks will need turning. I've been researching this cartridge as I've been gathering materials for the rifle. Several folks have posted that if they form their brass from either 8x57 or 9.3x57 the neck will end up too short when the brass fire forms. The cartridge is wider at the shoulder than a x57 case, and when the shoulder forms the expanding brass causes the neck length to shorten. I haven't even remotely got there yet, but plan to fire form the brass with a small charge of pistol powder and some cream of wheat filler (no bullet). I'll leave the necks slightly long, then trim them to length after the fire forming. I down loaded the reamer drawing and will compare it to the cartridge drawing. I've used several reamers from PTG and have always gotten really good results. I've also compiled a lot of load data on the 9.5x57 from the internet and have been putting that on an excel spreadsheet. There's some jacketed bullet information, but almost no cast bullet data out there.