Rossi Rifleman

Okay, here is what I came up with…





A .310", 160-grain bullet. I don't know if your M94 AE is unique or if all are cut the same way but it is really usual to see a rifle with just a step and no freebore leade. This is like what you see in semi-auto pistols. Based on all the time we have spent on this, I'm confident that the numbers are right.

In a nutshell, the chamber offers little support. Think of the point where the step meets the bore/groove as a sizing ring. No different from a Lee bullet sizing die or the steel ring in the base of Lee Carbide Pistol Factory Crimp Die. At this point in the chamber, the bullet is going to experience quite a bit of stress as it is going to be sized to the bore and groove diameter without any foreplay!



What I've done is placed a tapered top band that is .310" at the base and then reduces to .308". This should help with the sudden reduction in bullet size. I've also given it a bore rider nose at the upper end of the top band. There is a 90° drop from .308" at the upper end of the top band to a .301" bore rider. This bore rider should provide support as the cartridge is seated in the chamber and help with the size reduction the bore is going to cut. Here you can see that as the bullet moves .050" forward it is fully engaged in sizing.

Thanks!!! That looks great, and I actually understand what you did getting it past that abrupt step. I don't understand the reason for the sharp step, but I remeasured dozens of times, did two casts, seated and measured oversized bullets, etc, and I'm confident that's the way it was built.

Now, to get the mold cut do I just send these three pics to the machinist?

Thanks again, I really, really appreciate all the work you put into this and explaining it to me. I'll provide the full report once I get the mold and shoot some groups.

Wow man, that is really impressive work!

Micheal, the passion you have for this sport, your hobby/art, is remarkable. And your generosity for sharing your knowledge and wisdom is beyond reproach.

Thank you so much for posting process. Heck, I'm even starting to understand what you're talking about.

klr wrote:Thanks!!! That looks great, and I actually understand what you did getting it past that abrupt step. I don't understand the reason for the sharp step, but I remeasured dozens of times, did two casts, seated and measured oversized bullets, etc, and I'm confident that's the way it was built.

Now, to get the mold cut do I just send these three pics to the machinist?

Thanks again, I really, really appreciate all the work you put into this and explaining it to me. I'll provide the full report once I get the mold and shoot some groups.

You're welcome. I will PM you a detail drawing of the bullet. Depending on who you send it to, the may want a mold cavity drawing which I will provided if needed.

I could probably get this run on NOE but I would want to change it a bit to accommodate trimming the brass to the SAAMI length length .

NOE makes a great mold, but I've already sent Tom at Accurate an email so let me see what he says. Right now he has a three week turnaround time and spring deer culling starts soon.

klr wrote:NOE makes a great mold, but I've already sent Tom at Accurate an email so let me see what he says. Right now he has a three week turnaround time and spring deer culling starts soon.

\
Sounds good. I will redraw it with SAAMI length brass and give it to NOE. Might be some M94AE guys looking for a bullet.

Ranch Dog wrote: At this point in the chamber, the bullet is going to experience quite a bit of stress as it is going to be sized to the bore and groove diameter without any foreplay!

What I've done is placed a tapered top band that is .310" at the base and then reduces to .308". This should help with the sudden reduction in bullet size. I've also given it a bore rider nose at the upper end of the top band. There is a 90° drop from .308" at the upper end of the top band to a .301" bore rider. This bore rider should provide support as the cartridge is seated in the chamber and help with the size reduction the bore is going to cut.

Last night I was thinking about this tapered section and lack of foreplay. Both of my NOE molds cast about .002" over the plan dimensions. Accurate has a tolerance of +.002 on the body and -.002 on the nose for bore riders. Given this, casting temps/methods, and alloy, I'm wonder just how possible it will be to cast that .308-.310 tapered portion. Most likely it will end up oversize and just sized down to a flat .310 when I run it through my sizer? At that point it will get the slam-bam-no-foreplay-ma'am treatment.

Maybe I'm just over thinking it.

This is where all the doubt plays in. The best thing to do is talk with whoever is going to cut it and let them know that it is a bullet drawing, what alloy you are going to be using, and then see what there thoughts are on being able to drop a bullet to the drawing.

I need to move on to other things but here is one way to deal with it. Change the nose to a simple tangent ogive with the base of the nose being .308". That is about the only way to insure that the nose positively gets past the step when you close the action.
Actually, I don't know if that would do it as you are going to have the bore engraving at .301".

Alright, I'll see what the mold guy has to say about dropping a bullet to this spec. I won't take any more of your time, but again, I really appreciate the time you've spent with me on this. I've really learned a lot.
Thanks!