Another 40 Caliber Mold Question Before Spending Some $$

[DHDeal]

I'm looking hard at the BACO JIM395415E (40 cal elliptical .395" 415 grain) and wonder if I have enough twist for that bullet.

Rifle is a Crossno Hepburn 40-65, 30" 1-16" twist Douglas barrel. The other numbers are .400" bore and .410" groove. Just a SWAG, but I suspect I'll see 1300 fps using Swiss 1.5F or 3F. Brent suggested using about 72 grains of Swiss 1.5F (and that should see me all over the 1300 fps number). Starline brass is what I use most.

Using an online stability/ballistics calculator, assuming this bullet is only 1.4", I'll need about 1-14.5" twist. I do believe this bullet is longer than 1.4" and know my twist isn't any faster than 1-16" per the cleaning rod tight patch scientific measuring method.

FWIW, I will only shoot these to 600 yards as that's all I have. Am I over thinking this or is a shorter bullet going to suit my rifle better? There is always a call to Brooks if necessary.

I've known of this forum for years, but as my interests have been 600 benchrest, I kind of ignored it. I must say I have enjoyed getting back into BPCR's and the knowledge you guys have on the subject.

Thanks again.

[Don McDowell]

I have been shooting the 396415M in the 40-70, with it's 16 twist. Shoots really well to 600 until the wind picks up, then it's not much good.
I think if I was looking for something of the "long pointed" bullets, I would give Brooks the diameter and specify his new postel nose and keep the length at 1.30-1.35

[BrentD]

DHD, I don't have any experience with the .40 and 16 twist. You might be right about it being a bit on the slow side. I just don't know. You could ask them to make that bullet but shorten it slightlly for you, as they will do custom mould cutting. That is probably pretty easy.

The other thing you could try is to shoot it as is and then, if you found the bullet was too long, have the block shortened from the base of the bullet.

I would NOT do a postell nose for any target further than a chicken.

[DHDeal]

I pretty much just threw a mold at this rifle before and it worked (BACO JIM409400M4). I wasn't to familiar with twist rates and these bullets. I learned a lot shooting the 6mm and 6.5mm and their rates if twist for the long for caliber bullets I shoot. To be honest, I just never gave it much thought as a 1-16" is kind of standard for 40/65 and 400 ish grain bullets. Since I just shoot steel at 600 with the BPCR's I never noticed bullet holes in paper. I suspect I might be in for a surprise even though it shoots well. And yes I have noticed when conditions aren't good, the rifle didn't always shoot well. I always chalked that up to me or a "what the heck" shot.

You consider his Postel nose an easy bullet to tune or does he do something like an elliptical? I'm in the fun learning stage right now. When the money is spent, then it becomes work......

Since we're talking molds, what about the KAL molds? Never cast with a nose pour before. I understand there is a learning curve attached to them. Maybe I should stick with a base pour as I know them pretty well.

Thanks Don.

Brent,

I'll give them a call in a few minutes and ask. They have them "out of stock" and that may work as they'll have to make one anyway. I shoot very high BC bullets in my BR rifles. I never shoot anything light for caliber as I tend to run a fast twist. This rifle was made for someone else years ago. I believe his user ID is 40-82Hepburn on ASSRA.

[semtav]

Just had Rick at KAL moulds make me a 1.370 PP Money bullet for my 16 twist rifles. Not sure when I will get around to working up a load for it tho.

[DHDeal]

Just had Rick at KAL moulds make me a 1.370 PP Money bullet for my 16 twist rifles. Not sure when I will get around to working up a load for it tho.

Have you casted any yet? Was it an adjustable mold? I understand he only makes a nose pour.

[Gunlaker]

I would keep the length the same as the 409400m4 and use a 1:16 alloy. That bullet is good and stable to the 600 yard line so I imagine an elliptical of the same length would be too.

BACO might make you a slightly shorter version of that bullet if it's too long. They seem to accept customizations as is evidenced by the 25 or so different .45 cal Money bullets in their catalog

Chris.

[BRUCE MOULDS]

dhdeal,
I had rick at kal make me a custom mould in 40 cal .
it is base pour elliptical, with the nose being 1.5 calibres long.
he has a cad drawing facility, and will draw you the mould and send you a copy for verification prior to manufacture.
he might remember the mould he made for bruce moulds, as a guide.
my bullet is for a greaser chamber, but is mostly patched to bore.
this was done by making it dual diameter,0.395 and 0.405.
add 0.005 to those diameters when patching wet with seth cole 55w.
they slide into the bore with a little friction, and into fired cases as well.
the large diameter is only 0.2" long, and then tapers at 7 degrees to the smaller diameter.
I usually load them about 1/8" in the case.
I shoot them out to 1000 yards.
my bullet weighs about 440 gns and gets about 1300 fps with 83/84 gns of swiss 1.5 or 1.0.
the elliptical and the money nose probably have the lowest drag in the transonic zone.
keep safe,
bruce.
edit to add,
look for a stability factor of 1.8 minimum to avoid windshear problems etc. that will tell you the length you need.
recovered bullets show no sign of having started as 2 diameters.
of interest is that these bullets cast at 12:1 alloy shoot with 7 points less drop at 880 yards than 16:1, suggesting better retention of nose form and hence b.c.

[DHDeal]

Well the GG Money bullet is 1.400" give or take a .001". Brent, I believe stated that the Elliptical 415 grain bullet is 1.417". Not much of a difference.

[Don McDowell]

Not the best picture , but it's obvious Brooks new postel nose is awfully close to most of the BACO money bullet noses.



This bullet is for the 44-77 and it holds well to the 1000 yd line even in the winds at Raton.

[BRUCE MOULDS]

mostly 0.017 will not make a difference.
but when things get dirty, you will trend to getting more vert.
this is because if the bullet wobbles a little bit, it temporarily loses some b.c.
in windshear situations, the yaw of repose will try to alter temporarily, due to forces altering on the bullet, so you need plenty of stability.
also be aware that the time of flight of our bullets allows for some spin decay.
keep safe,
bruce.

[Lead pot]

I don't think in the rotation can slow down to much in the 3 seconds it takes to reach the 1000 yard line. But I might be wrong.

[BRUCE MOULDS]

kurt,
308 bullets have been measured for this an lose quite a percentage (20%?) at 1000 yds in 1 second.
what happens relatively to our bullets can only be speculated at, but you need 1.5 factor at the longest range.
keep safe,
bruce.

[DHDeal]

Not the best picture , but it's obvious Brooks new postel nose is awfully close to most of the BACO money bullet noses.



This bullet is for the 44-77 and it holds well to the 1000 yd line even in the winds at Raton.

I bet that one is easy to patch.

Got my paper in today and couldn't resist trying to patch some GG bullets (it's all I have for now). Went ahead and wrapped them 3 full turns and cut through the patch for a measurement. I cut some more and didn't do bad at all except for those funny grooves showing through. The outside "end" wants to not stick. I suspect I didn't get them wet enough.

FWIW, the paper is Eaton Berkshire Eminence Onion Skin 25% cotton (beautiful stuff). I hope it works as I bought 2 boxes of 500. I usually don't do things half heartedly, or cheaply my wife says.

[DHDeal]

Bruce,
I enjoy your input here. I know that something works, just not always why. It's a little like reading Brian Litz's books. I sometimes have to read it twice.

[semtav]

Have you casted any yet? Was it an adjustable mold? I understand he only makes a nose pour.

No. Its a base pour. He only makes PP moulds but he ll make them either way. Ive got 3 of his base pour moulds. Just got it a week ago so I haven't done anything with it.
I do have a nose pour boomer mould with a cupped base that we got our wires crossed on and I'll probably never use. should cast a few with it just to see what they are like. was supposed to be a money bullet mould but looks like a blunt nosed spitzer. I think its adjustable.

[BrentD]

DHD, I think you were right, the bullet I suggested is a bit long. I ran the numbers through 5 different estimators of max bullet length, and a .40 cal bullet moving at 1300 fps would be better off closer to 1.3". I tend to find that paper patches need to be a bit shorter or twisting a bit faster than a groove bullet. I think they are a little less stable without the grease grooves to give them "fletching" to stay straight.

I know BACO could make you a version of that mould that is 1.3" long or I could draw one up for you that you could send in to them. That's how the one I have was done. Easy as pie and the same price. They make amazingly good moulds too.

Anyway, if you need a drawing and set of dimensions for a prolate paper patch, just holler.

Brent

[Don McDowell]

DHD, that bullet is really easy to patch and wet patched it's easy to roll the paper nice and tight.

[DHDeal]

I ran the numbers too, but just once. I would really need a 14.5" twist, which mine isn't, for that bullet. Anyway, no big deal. 1.3" would probably be 380 ish grains. Not bad.

I was just trying out the wrapping with the GGB's. I didn't do to bad, but I will need a board. I'll get some oak tomorrow. I saw somewhere where someone had a board made up with a built up edge. I suppose the edge was to push the base against? I'm still having issues having the outside edge not sticking to the underlying wrap. I might not have worded that well. I hope a PPB will be much easier to roll on a patch than the GGB.

[BrentD]

You might have seen my board. The raised edge is useless, but I thought it would work well when I started this game 20+ years ago. All you need is a slightly elevated platform. A cheap paperback novel will work as well.

Wrap them dry. Whole lots easier.

this is how I do it (patching board shown too).https://www.youtube.com/watch?v=9AvKalQipeY
Another version. https://www.youtube.com/watch?v=p1DmoZnYIQE