New NOE 30cal heavy plainbase

[Ian]

300BLK started the thread based on a different bullet than the NOE 190-grain one. Some guys wanted a 311279 copy, "ish", and made hash of it IMO.

A little story, Cliff's Notes: The 311679 was originally a solution to a specific problem with certain limitations. The problem was match accuracy with rifles having military chambers and particularly large chamber necks. The limitations were needing a relatively heavy bullet which would also feed from and fit in a magazine box, so the Eagan trick of putting as little bullet in the neck as possible was out, and filling the case neck with bullet creates more issues with misalignment at launch. To overcome the alignment and/or riveting issues that a neck full of bullet and excessive chamber neck clearance create, and since shrinking the chamber neck or thickening the cartridge brass necks enough to make desired minimum clearance were both impractical, Ardito's solution was to simply fill the chamber neck up with bullet. This introduced the issue of starting a .314" bullet into a .311" hole without shaving metal, so he simply throated the rifles to accept the larger driving portion of the bullets, and designed a bullet to fit this system. The bullet had a long, bore-riding section to guide the front, a concave, parabolic taper up to the first driving band which ensured centering and support of the middle of the bullet, and a couple of relatively narrow driving bands to stuff back into the case. Very clever. And it worked.

To make this work, the bullet needed to cast .314" on the bands and the rifle needed to be throated to accept the relatively large body portion without shaving off big rings of metal. Who does this? Not many. So Lyman started cutting the mould at .311" or so on the driving bands, I can only guess so that it would work in un-modified rifles. Well, that kind of defeats the purpose, but ok, they can still cash in on the name.

I'm still trying to figure out what that straight-taper nose and ridiculously long pair of body driving portions of the NOE bullet are supposed to fit or how it's supposed to work. I already designed that bullet (less the really long driving bands) years ago (AM 31-190X) and have a rifle whose throat and chamber neck fit it perfectly...and after publishing my experiences and re-discoveries with the "Morse Taper Fit" I'm a little puzzled why anyone else would want to continue that folly.

 

[fiver]

but Loverign went another direction to deal with the long military rifle throats.
he pretty much tapered the entire bullet to run up or stick out into the throat and fill it when it got there.
the numbers could be a little off but each band would take the rifling and re-shape itself into the desired diameter as needed.
this allowed the bands to flatten out and fill the grooves as the barrel pressed everything into place.
he pretty much ignored everything from the case mouth back and focused on the ball seat area and the leade.

take his numbers and fill most of his lube grooves with lead and you end up with many of the newer designs,
except for the nose portion that 'guides' everything into place using the rifling.

 

[Ian]

My thoughts are like yours that the Loverin designs work because the bands are narrow and close together and can tolerate a lot of squishing without deforming the basic core shape of the bullet or creating so much engraving force that the base rivets into the excess neck space. This also generally limits the design velocity-wise.

The MP designs use a slightly different mechanism to take up excess slack in the neck yet not rivet before entering the throat. The square, deep lube groove sides allow the "band" in front to fold back cleanly like an umbrella, displacing lube into the space at the end of the case neck which forms a lube bridge across which the narrow rear driving band and gas check can pass to get into the throat. Those MP bullets also are intended to be sized somewhere around .312-.313", which minimizes the loaded neck clearance.

 

[35 shooter]

Ian and Fiver,

Thanks for all the bullet tech advice. Now I know more about how to read Tom's diagrams.
Slowly learning a bit about what makes cast bullets tick lol.

 

[35 shooter]

OK, all this tech stuff got me doing some research tonight on cg and cp and how to determine it. I'll never look at a diagram of a bullet the same again. I definitly have a much deeper grasp on it all now.
Still have a lot to learn, but at least i can keep up better with what's being discussed from now on in regards to bullet design.

The learning never seems to stop.

 

[fiver]

that's why we get going with this stuff.
if we can let y'all know what we know you can make better decisions and pick up more information to pass back.

 

[Josh]

Ok, with all the excellent advice given here I don't know what else I can add to the discussion. So let me go one at a time.

NOE 311-208

This bullet is the perfect example of what a group discussion will net you if the designer doesn't keep it on track, or if the people contributing to the discussion are pulling in 7 different directions. I see a short blunt nose with no meplat, this is one point in a bullet design where you can move that C.G. back to the rear, there is no downside to making the nose secant and lengthening it out a tick. The nose section will be engraving semi early and hard. You have a .302" nose about half way down the length. I would have taken the nose and kept it .299" at the front, taper it to .300" then start an angle like the UMW. The front band is too narrow and slopes way too much, if the nose was designed correctly this could be a good start to a front band. The grease groove is a radius design, they give up lube capacity and IMO are harder to get right. Now on to the base band, wow, it is huge, I think it needed to be shorter, it almost looks like the NOE 190 gr was given a few thou more base to get the weight. The only think I can say about it is at least it doesn't have that crazy micro band that never fills out.

NOE 311-190 FN PB

A better design in my opinion, it has some potential but a hair more work would have made it a real winner. The nose diameter should have been smaller before the taper and it should have had a single grease groove with a small crimp groove.

Accurate 31-188G

This bullet is pretty close to good, it is Ian's baby and you can definitely see his influence in this design. I think he too my design and made Tom adjust it slightly (possibly because I wouldn't? LOL) I would have added a 0.020" radius to the meplat, it helps aid in feeding. The massive crimp groove is a no start for me, I would have thinned that out and lengthened out the front band some more. grease groove is the "Accurate minimum" which is the steepest he can make it, I like this grease groove, it has enough capacity for most any barrel out there. Gas check shank is pretty Josh standard, I like a straight shank, or a shank with only 0.001" taper (0.284"-0.285") I also do not like a long shank, it is prone to bending under pressure and riveting so I make my shanks about 0.020" longer than the check. Overall a good bullet, one that even with Ian's touches I would run in most any 30 cal rifle.

Ian UMW

I can't say much more about this bullet than I did about the 31-188G, they are so close it I would call them twins. I would adjust the same things on this bullet I would the 188G. Not much more, I will say that this bullet and the bullet I helped design for Hawk and his 7.62x40 WT has swayed me to the long fat taper and thin nose.


I really hope this helps the discussion, I feel like a babe in the woods when adding to a discussion with @Ian and @fiver

 

[Ian]

A crimp groove only needs to be about .015" deep at the absolute maximum, because that's just about as thick as cartridge brass ever gets. Any more than flush and it's kind of a waste. BUT. There's always a but isn't there? In the instance of the 188G there is a secondary reason for the crimp groove, and that is metal displacement. If you don't the metal rolled back by the throat somewhere to go, the whole bullet will distort lengthwise and probably a little bit sideways as well. The goal of the crimp groove is to let that sloped front shoulder fold back without disturbing metal deeper within the core of the bullet. That's the theory, anyway.

I intended to make a round nose with a burr or modified drill bit, but haven't yet. What would really be great is to continue the nose on out to a .120" meplat, but without shortening it that will cause magazine length issues in some .308s. Having Tom radius the nose would make it too wide and move the already marginal GG forward. He just can't go smaller than .180" on the flat part without upsetting his whole production system. So far I haven't needed to mod that yet...but it would be a good idea for feeding purposes.

A straight gas check shank is what I've settled on as well. I absolutely detest a tapered shank (those that go from .285 to .290 or so) because invariably the checks are difficult to get seated fully and there is a roll of lead pushed up in front of the check after sizing which causes all sorts of problems. I tried a Hornady-matching check shank on a couple of bullets and it's great for not deforming metal, but it didn't prove any better than a standard shank and in some instances I think the reduced support can make it a little worse, so I'm content with a .284" straight shank and exactly .020" clearance to the back edge of the rear band after the check is crimped.