New rifle

35 Whelen

Active Member
Good day gentlemen. I ended up scratching a serious itch this past week. I bought a CZ 550 African Classic in 375 H&H...I have read good things about it and using cast bullets, from mild to wild. I love the molds that Tom puts out at Accurate, in that you can tweak his dimensions. I e-mailed him last week about some changes to a bullet mold. I have always loved the profile of the 352 Saeco in .35 cal and wondered if he could enlarge the meplat of a design he had 38-315G and increase it from .180 to .225
I got his reply yesterday and he responded with " The 38 - 320J and JG are now in the catalog. I quickly opened up his web page and found a great looking bullet...even had the letter J behind it, reflecting my last name...coincidence or not...I don't know. This is what Tom came up with and I personally think its going to be a great bullet in that cartridge. I would like to start off somewhere around 1800 fps and would like to ask the members here for their opinions and advise on where I should start?

Here's a couple of pics of the new round.
38-320JG 1.png38-320JG 1.png38-320JG-D.png
 
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Ian

Well-Known Member
He does that. Many of the ones with "G" in the catalog number are mine.

Ok, I gotta bring it up....you're not going to make a chamber cast first and determine the throat size/shape and neck diameter before ordering a custom mould for the rifle?
 

35 Whelen

Active Member
I haven't placed an order with Tom yet Ian. The rifle is coming from the Yukon so it will be a couple of weeks getting here. I have read on a few sources that a chamber cast for throat dimensions is recommended. I have some cerosafe, just never done it and a bit reluctant to muck things up and do it wrong. Worth the effort?
 

Brad

Administrator
Staff member
I did a pound cast on my CZ 550 in 375. They have a pretty large and long freebore. This makes it a bit harder to go faster than 2200 fps with accuracy. As pressure builds the bullet wants to rivet into that huge freebore then squeeze back into the throat.
Mine does well in the 1800 fps range with the 38-265D which is the bullet in the banner for this forum. I use a charge of 2400 with some Dacron, the exact charge escapes me right now. Groups under 2" at 100 are easy and recoil is very manageable.
Great rifle and cartridge.
 

Ian

Well-Known Member
Make an impact impression, much easier and more reliable IMO. It's only worth it if you know what to do with the information the cast gives you, otherwise a two-diameter bullet with a two-diameter fit will do fine for low-velocity work. .375 H&H typically has a 3/8" long, 4° included-angle taper throat for which a two-diameter cylinder is about as far from ideal fit-wise as you can possibly get.
 

35 Whelen

Active Member
Thanks Brad.....I hear they have a generous throat . What did your's mic out at? And what bullet nose and body diameter did you settle on. Im hoping for .378 on the sized bullets.
 

Ian

Well-Known Member
And what bullet nose and body diameter did you settle on
I'm trying to expand your thinking past the 2D bullet.

Brad's bullet has a tangent ogive, no parallel nose :eek: What to do? Select a nose shape that fits the throat shape in the right places, forget about bore dimension entirely (It's unimportant), and size the body to .005" below throat entrance diameter. Bore and groove sizes don't mean anything.
 

Brad

Administrator
Staff member
I have mostly sized to .378. That works fine to a point but when I try to step up the velocity, and pressure, I get some accuracy issues.
I need to redo my pound cast and get better measurements. I think I could do as well with a .376 bullet and possibly improve accuracy too.

That large freebore makes matching pressure curve, alloy, and bullet design even more important.

I have the MP 378 bullet with a similar design to the 30 Sil. I have not shot enough to really get a feel for what that bullet wants. I always seem to have too many guns and not enough time?
 

Ian

Well-Known Member
Brad, I would think that the throat entrance diameter would allow you to load as large of a bullet as the chamber neck and brass would allow. That MP bullet looks custom-made for the .375.
 

Brad

Administrator
Staff member
If I seat the 265D long enough it gives me a distinct ring where the diameter is cut. It has a large freebore but the end of the throats seems kinda sharp. Will see if I can get a mockup made and post a photo.
The MP mould is perfect, I have no doubt about that. I just need to get more work with it. Best of all the bullets just fall out of that mould and checks snap on nicely, way easier than my 30 Sil.
 

35 Whelen

Active Member
Thanks Brad..... I've been lucky when ordering molds I guess with Tom and Al at NOE, even with bore riders such as the 360009 for my Whelen and the .358 Win and have always been a good fit. This filling the throat is new to me and might take me a bit to figure this all out. Can you send a link to the bullet you are using please. I went on the MP sight and couldn't find it....
 
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Brad

Administrator
Staff member
Here are the 265D and MP bullet as cast. These were dropped into the throats and driven into the throats with a cleaning rod and hammer. I then used a rod to remove them by dropping it down the bore.
Notice that the 256D on the left contacts the bore first right in front of the forward groove. Far as I can measure the shiny band you see is at .379. That bullet, if seated long, shows a groove being cut above the front groove if sized .379. I think that bullet would do better at .377 or .379. Need to make a couple new sizers and test that?
On the left you can see that the MP bullet contacts the rifling AND the rear of the throat. Near as I can measure the shiny ring to the rear runs .377. I think .377 or .378 would be right with this bullet too.
I like to treat the MP bullet the same way I treat the 30 Sil. Seat it to give .050 jump or so. Give it an ability to self center in the throats and lands rather than force it into contact that may, or may not, be straight.
The neck area on the 375 tends to run really big. For a dangerous game rifle it just needs to be that way as it must always feed easy and always extract. That makes it a bit harder to get top end accuracy with cast as our lead bullets are easily riveted into that space if pressure curve isn't right for the alloy and bullet.



IMG_3302.JPG
 

fiver

Well-Known Member
maybe I can muck up the thinking a little here.
look at the 375449, it comes from the lyman mold at 379.
but the nose shape, if you notice, looks like it belongs in a saami 45-70 throat.
in other words the nose rolls over into nothingness in the rifle but it does/can butt up against the free-bore, and it avoids the 2 diameter thing all together.

think the opposite of a ranch dog mold and more like a lever gun type for the 45 colt or 44-40.
then if you want more nose length just change the secondary taper to the 4* and flatten it at the start of the rifling.

this bullet is designed pretty much for the 375 H&H.
notice the difference in how much air gap would be around it's nose shape and the throat metal and then between it's shape and the bullet Ian transposed over the saami throat?
I bet money this is a very accurate bullet in a 375 even though it might not look the part.
that minimal air gap and a strong base will get you down the road every single time.
 

Ian

Well-Known Member
Hmmmm, that jax bullet looks a lot like the .224 63 SMP...that I actually bought some of to try in my MVP after your recommendation and doing a pound cast and blowing up some pictures on the net.
 

fiver

Well-Known Member
I was gonna ask if you ever got some of those and give them a run.
the one I show above is actually for the 375 H&H though.
I have come to the conclusion that matching jacketed profiles to the throat pays off as much as cast profiles, they aren't as picky about run up when they do match.