Author Topic: .375 CAST - two moulds, two rifles (Read 1422 times)

Cat Whisperer · « **on:** March 05, 2007, 04:12:33 PM »

Looking for loads/experience with .375 diameter.

Two moulds I have are Lyman 375449 (264gr GC) and the RCBS/Saeco 375-300 (flat base)
Two rifles: Ruger #1 in .375 H&H and Ruger #3 in .375Win. both scoped. (Also have a BB 94 in 375Win).

Looking for 100 and 200 yard loads.

BABore · « **Reply #1 on:** March 06, 2007, 07:42:52 AM »

I don't have any experience with the 375 Win., but do with the H&H. I've been using XMP 5744 with an RCBS 375-250GC, NEI 377-280GC, NEI 377-290DDGC, and my own 377-300GCHP. I use CCI 250 primers and a LEE FC. I've checked with Accurate Arms and reviewed their data for my loads. I've used powder charges from 35-45 grs with all bullet weights mentioned. Accuracy has been consistently sub-inch for all bullets. While 5744 is super accurate, it's also a little quirky on its charge weight. Just a 0.25 gr change in powder charge could double group size. I found that it paid to keep searching for the ideal powder charge. I found great accuracy, with the NEI377-280GC at 38.0, 40.0, and 42.0 grains. All shooting was with a Winchester model 70. I'm also looking into using AA 3100 powder, but have no hard data on it yet.

Here's a group I just shot trying out a new bullet.

Cat Whisperer · « **Reply #2 on:** March 07, 2007, 03:25:16 PM »

BABore -
I'm impressed. What is the rate of twist in your Model 70?
Looks like I've got a bit of testing ahead.

BABore · « **Reply #3 on:** March 08, 2007, 02:56:46 AM »

I'm pretty sure it's a 1 in 12 twist.

It was born a Win. Mod. 70 Supergrade in 300 Win Mag. I had it rebarreled by ER Shaw a couple years back. I firelapped it with 35 rounds using the Beartooth/LBT method. It's been a tackdriver every since. It's scoped with a Burris 3-9x40 BallistiPlex. The NEI 377-280 gr is an accurate round even though the bore rider nose really doesn't engrave. It will consistently group 3/4-1" at 100 yards. I was shocked when I papered it at 300 yards. My very first group was a bit less than 3". I've improved that by quite a bit with practice and good wind conditions. This is what drove me to design my own bullet and make a mold. I figured if I had a properly fitting bullet I could best that. I'm still in the load developement stage so we'll see.

Here's my best to date 300 yarder with the NEI 280. For fun, me and my shooting buddy drive golf balls at 300.

Cat Whisperer · « **Reply #4 on:** March 10, 2007, 01:34:34 AM »

So looking through all my moulds - most everything casts to .382 to .384" dia. Ouch. Only sizer I have or have seen is .375".

How do you handle that? Grooves disappear and nose squashes. Custom sizer? Tumble lube?

Larry Gibson · « **Reply #5 on:** March 11, 2007, 10:48:55 AM »

In my 375 H&H I use the Lyman 377449 cast of WWs and water quenched from the mould. They are sized .377" in a Lyman H die. I use Horndy GCs and Javelina lube. In my M70 with 1-12" twist I load them over 49 gr of 4895 with a dacron tuft filler. Dropping back to 40 gr 4895 and 1680 fps give MOOA accuracy. Velocity is 2175 fps and accuracy is sub 2 MOA with the 2.5X scope. Over 36 gr of 5744 with no filler or wad they run 1850 fps with the same sub 2 MOA accuracy. I mostly shoot the 2175 fps load for practice and would not hesitate to hunt deer or even elk with it. Hornady 80 gr RBs with a light coat of Lee's Liquid Alox over 4 gr of Bullseye (no wad or filler) gives 890 fps with 1" groups at 50 yards. A great small game/grouse/ptarmigan load.

Larry Gibson

BABore · « **Reply #6 on:** March 12, 2007, 02:24:29 AM »

Quote from: Cat Whisperer on March 10, 2007, 01:34:34 AM

So looking through all my moulds - most everything casts to .382 to .384" dia. Ouch. Only sizer I have or have seen is .375".

How do you handle that? Grooves disappear and nose squashes. Custom sizer? Tumble lube?

I make my own push-thru sizers and Saeco dies. All bullets go nose first through the push-thru die first. The lubrisizer die is made 0.0005 bigger so it only lubes. This prevents a longer bullet from being bent which can occur with base first sizing. I've sized down bullets up to 0.005" and haven't had any problems. I don't have much use for LLA. It may keep you from getting any leading, but I have never seen it produce good accuracy except in plinker loads. I don't pick a lube just cause it doesn't lead up the tube. Accuracy is my benchmark and I've yet to see a lube that is best for all guns or bullets. I treat it as just another reloading variable.

After noting the bore size through slugging, I first size to fit a fired case. A bullet that will just slip fit into a fired case will support the rear of the bullet while still allowing enough tolerance for case expansion and bullet release. A bullet sized as such is then checked to see if it will still chamber well. In my rifle's case the groove slugs at 0.3755 and the bore is 0.3695. The BR portion of my 300 gr bullet is 0.3705". I size the bullets to my fired case dimension of 0.3780". Upon chambering the BR is engraved in the bore, the front band is just engraving in the throat, and the case neck supports the base with just a slight clearance as ignition pressures expand the case neck. Only direction the bullet can go is straight down the bore.

I had a chance to try some AA 3100 powder with CCI250's this week end with my 300 gr HP. I started on the conservative side and worked up in one grain increments. Results were not impressive until I got the charge up to a decent pressure range. Groups progressively tightened the higher I got. The best load was right at 1.00 inches. Next weekend I hope to work around this particular powder charge in 0.25 grain increments and see if a sweet spot can be found. Didn't chronograph anything, but the data suggests between 2,300 and 2,400 fps.

Cat Whisperer · « **Reply #7 on:** March 12, 2007, 01:09:07 PM »

Larry, BABore -

Thanks for the thoughts. I'm building my own push through sizers, ordered the largest sizers Lee offered under .430 - which was .358". Ordered 3 bodies that I'll drill and ream to .380, .381 and .382". That should give me 1-2 thousandths on the diameter clearance at the neck diameter in the chamber with the 300 gr RCBS. The other option, parallel path, is to open up the gas-check shank on my 264gr Lyman mould, as it casts about .377" give or take. These are good problems as the solution will be a bullet that is fitted.

BABore · « **Reply #8 on:** March 13, 2007, 01:59:27 AM »

Lee dies are pretty hard and will likely tear up anything lesser than solid carbide. Carbide tipped will cut a smaller hole, in hard material, cause the core is soft and compresses some. Also, I've found than trying to ream to size is futile. Even with annealed O-1, I drill, ream and/or using a boring bar to get 0.002 to 0.003" under desired diameter. The die is then finished, in a lathe, with an adjustable lap, with 280 grit clover, or an emery wrapped rod. Final finish is 400, then 600 grit wet/dry. I don't bother measuring, but push through a lubed bullet of the same alloy and hardness I intend to use and measure it with a good 0.0001 res. mic. There is some springback happening, so a 0.381 hole doesn't make for a 0.381 bullet. Go slow and slug and measure often.

My own push-through setup is made from a piece of 7/8-14 threaded rod. The bottom end is bored to accept a 5/8 diameter by 1 1/4 long O-1 bushing. The rest of the length is drilled through to 1/2". A locking nut is positioned and fixed and is tapped on the side for a set screw. The screw passes through the threaded rod and locks in the bushing insert. The bushings are bored to just under size, backbored about 0.010 over, and the entry has a 6 degree lead (12 degree included). Of the 1 1/4" length, there is only about a 3/8" section that is at the sizing diameter. Make finishing to size much simpler and is easier on the bullets. I don't bother hardening the bushings as it just makes finishing harder and usually shrinks and egg's the hole.

Cat Whisperer · « **Reply #9 on:** March 13, 2007, 04:19:28 PM »

BABore -

Cool! I actually picked up a 3' section of 7/8-14 all thread - hmm - 4 years ago! And I once bored an old reloading die to accept H&I dies (but the wall thickness was right-much thin).

Looks like good machining you did on yours. I don't have any O1 on hand but I do have several feet of 5/8"dia stainless that is begging to be consumed.

Thanks for your detailed description and measurements!

Cat Whisperer · « **Reply #10 on:** March 15, 2007, 04:06:47 PM »

Did some machining tonight.

Took a Lee push thru sizer body and chucked up in a 5C collet in the lathe. It is marked .358-A7 (largest size under the .44's they make. So I took the Dremmel tool with a diamond drum and opened it up to where it would size to .376" dia. Pusher I made was .368" dia - leaving .004 unsuported all the way around. Ran a few through lubricated with a little lanolin. Slight fin from sizing the Saeco 771's (which bases were about .383"). Then I took them and sized the lower 5 of 6 driving bands in a .375" H&I die in a Lubriciser. This left me with 5 bands right at .375 and the top driving band and scraper at .376" (fits the throat closer). All that being said, I haven't shot them yet, so I don't know if what I'm doing is good or bad; but they LOOK good. All that sizing and the grooves are much narrower, but are more even than I expected.

I think it would be better to start with something closer to the finished size. AND I need a H&I die that is bigger.

Cat Whisperer · « **Reply #11 on:** March 17, 2007, 12:05:17 PM »

So what diameters give the best accuracy (and for which powders and loading style)?

Am I right in my assumptions (smokeless powder, cartridge loaded) that three diameters are important?

First, bore riding portion (if any) should be right at bore diameter.

Second, portion of bullet that loads into the throat (between rifling and neck of case) should be say 0.0005" on the diameter smaller than the throat.

Third, the rest of the bullet should be at the diameter of the ID of a fired case (to allow for some sizing for tension and some clearance when fired resulting in minimum case stretching).

I would assume that the throat diameter is at or slightly larger than the groove diameter, depending on the rifle.

BABore · « **Reply #12 on:** March 19, 2007, 03:03:55 AM »

Yep! That's pretty much how I set up the bullet engagement for the mold I made. The BR and front band just engrave when chambered. Body diameter is a slip fit into a once fired case. Full 3 point support, matching the gun's geometry is almost a guarantee for accuracy. Alloy, bullet hardness, and lube are the final tweaks.

I've only used XMP 5744 and some AA 3100 to date. Neither seem too fussy. I'm planning on trying some other powders in the 3100 burn rate range too.

Cat Whisperer · « **Reply #13 on:** March 19, 2007, 10:22:44 AM »

Hmmm. XMR5744 is between 2400 and 4227 (on the powder burn charts). And 3100 is about the same as RL22 and 4831/7828. One fast one slow.

So, hard or soft? Do both work, only one slightly better? Or is it one sided?

BABore · « **Reply #14 on:** March 20, 2007, 02:18:24 AM »

I'm using 5744 in the 36-42 grain range for my 375 H&H and a 280-320 grain bullet. I't will get you between 1,600 and maybe 1,900 fps. Accuracy is well below sub inch. I wanted to see how fast I could drive my 300 gr HP, so I went with 3100. It's slower than a normal jacketed 300 gr bullet powder so you can get lower pressure and a full case. I'm playing it safe here. Accurate Arms has 300 gr jacketed data for 3100. I started a grain or so below min and worked up to a couple grs. below their max. The max load is like 83 grains and would be very compressed. Pressure at max load is 40 kpsi. Again, this is jacketed data. Even with a heavily compressed cast bullet load, it would be very safe. Question is will it burn well. So far it has. Best groups are around an inch. Not killer, but adequate for a high velocity hunting load. I'm guessing my velocity is around 2,400 fps. Other powders, of similar burn rate, should work as well. As far as "hard or soft", I'm assuming your talking about bullet hardness. I've only shoot OHT'd bullets. I use an alloy of 50% WW's and 50% Pb. When heat treated it comes out at 22 Bhn. Plenty hard for the velocity and it is more accurate than high antimonial alloys. No gray wash in the barrel at HV. It also expands well and holds the mushroom better.

Cat Whisperer · « **Reply #15 on:** March 20, 2007, 04:22:05 PM »

Well, I'm still not there yet.

Tried making my first H&I die - outside went well but the boring bar I had wasn't small enough (tapered shank) to get in as far as I needed.

More tooling. Hurry up and wait.

Cat Whisperer · « **Reply #16 on:** April 09, 2007, 04:22:55 PM »

Finally got the sizers worked out. Built a push-through (Lee style) sizer to size the Saeco 571 from .384 (base) and .376 (top band) down to .378 (to fit the neck of a fired case). Then I got a .378 Lubriciser H&I die to lube the bottom 3 bands. Using 13 grains of Unique averaging 3/4" five-shot groups at 25 yards. It's a start.

Cat Whisperer · « **Reply #17 on:** April 20, 2007, 05:20:13 PM »

Since I don't have my breech seater done for the .375 H&H for Ruger #1 done yet I've been trying to vary the diameters to which I size to match closely either a fired case or a minimally neck-sized case.

THis has caused problems in trying to seat the bullets. By using the Lee collet neck sizer I've gotten to where I can load a .380 bullet in the case with minimal neck sizing and it leaves the OD of the neck of the case at about .404" (12 thou neck wall thickness) which is about as large as I want to go in the neck of the chamber - 2 or 3 thou clearance on the diameter.

The problem is that both seaters I own are for jacketed bullets. Both the Hornady and the Lee will support a .375 diameter bullet with about a thou or two clearance guiding it into the case - which is a serious interferance fit trying to use a .380-.381-.382" diameter cast bullet.

Fortunately, the Hornady has a floating guide that I can duplicate that has a little more room inside for the bullet.

Looks like machining in the AM instead of range time.

Cat Whisperer · « **Reply #18 on:** April 21, 2007, 01:33:37 AM »

Left is original sleeve and punch, right is new one.

Cat Whisperer · « **Reply #19 on:** April 21, 2007, 03:01:09 PM »

30 rounds seated far out. 14gr of Unique Tumble lubed only with Alox thinned with mineral spirits and coated with mica.

On 1.4" 25 shot group at 25. Better, but not good yet. No leading to speak of in the bore but LOTS in the throat. (Bits sheared off.) Therefore, .381 or so is TOO big. Back down to .378 for next series of tests.

Cat Whisperer · « **Reply #20 on:** April 23, 2007, 05:23:58 PM »

Launched another three dozen today (.375H&H). These were 260gr from group buy Lee (GC variety) fired without GC's. Grouped well but with the ubiquitous flyers. Then I fired two groups, same charge, with GC's - tight groups. I guess I expected that. Everything sized to .378".

Need to work back to .376" sizing and lubing. Tumble lubing alone isn't doing it for stripping chunks of lead. Need also to FINISH the breech seater to have something to contrast these results to. The two groups shot WITH gas checks says accuracy CAN be had; now to do it with out the GC's.

Time to do a little more machining - to make the guide for the Hornady seater that will taper crimp and precisely locate the .376" dia. cast bullets.

Cat Whisperer · « **Reply #21 on:** April 28, 2007, 06:25:25 PM »

Took the Lyman 375449 DC mould to the shop last night and tonight - bored out the gas-check shank. Most of the bands cast to .378 with 50/50 WW and lead with a little tin added, the bases now cast at .381 and are within .0005 of eachother and normal dispersion of as-cast weights overlap (a range of a few tenths of a grain measuring 10 of 'em) so I don't know which one is heavier unless I weigh and mark 50 or so of them. Fist time I've seriously weighed cast bullets.

Range time tomorrow if the weather holds.

Would have shot some today but I did get half the backyard tilled and started planting.

Cat Whisperer · « **Reply #22 on:** April 30, 2007, 01:00:25 PM »

Took the modified 379449's to the range today.

Sized 20 to .375 and 20 to .378".

I alternated rounds/targets. 25 yards. First two 5 shot groups were .375: 0.98 and .378: 0.26" ! Second pair larger, third pair both 0.74". Hot rifle - fast shooting.

Load was 25gr of 3031.

The .378's were seated in Lee neck sized cases (just right, a little tension and lightly crimped). The .375's needed neck sizing from a regular sizer - not as good.

Now that I KNOW I can do a 1/4" 25yard group, it's refine the techniques and tune the load.

If that doesn't get me 1" 100yd 5-shot groups it's try a different bullet design.