30-30 311440 mold dimensions question

[Chris]

Thanks guys for the mold recommendations. Always useful to know what works and there is a common thread among the various molds. I have a RD mold in .44 and it's alright but I prefer the standard lube grooves. Just old-fashioned I guess, also still using a Lyman 450. Heck I still prefer ash snowshoe frames to aluminum.

Back to getting an education: I understand the concept of filling the void with a forward drive band. Is there a better term for that little ring ahead of the crimp groove? Looking at the pound cast from my marlin 30-30, the void measures about.06 inches ahead of the crimp grv. and then tapers quickly to the bore. Attached photo.

The diameter of this band is about .33". Most of the molds at accurate spec the band at about sizing diameter, so between .310 to .312. Would it be useful to increase the diameter as much as possible to make closer contact with the sides of the chamber? Of course all that lead will get smooshed down upon entering the bore.

Next question: If Tom can make dimensional changes on request, why not have him change the dimensions of the forward band to fit exactly? In my case make this band .06 long rather than try to stick a .10 inch band into the hole? Of course can trim brass if need be to fit.

 

[fiver]

your not using a forward drive band to fill the void.
the RD molds use the nose to guide the bullet into the throat on the other side of that void.
it's the same principle I use in my AR rifles.
what your doing is ignoring the void and making the bullet strong enough in the transition section of the nose to the drive band to take up the rifling on the other side of it.

 

[Chris]

Thanks Fiver. I'm not understanding this... Ian showed in his drawing a lack of support in the void. Should we not fill the void as many mold designs appear to do?

Maybe to help me understand you could comment on 3 case studies of Accurate molds, please offer your own examples to illustrate your point? Two have a fwd. band, one does not. Could you comment on the advantages and differences of each mold? Assume all dimensions are equally made to conform to the rifle throat/bore. I'm not getting this and possibly others may not either. Sorry to be slow on this but I'm trying.

RD design: https://accuratemolds.com/bullet_detail.php?bullet=31-165D

Non-RD design: https://accuratemolds.com/bullet_detail.php?bullet=31-165RG

No forward band: https://accuratemolds.com/bullet_detail.php?bullet=31-165W

 

[fiver]

no problem that's why I keep explaining it.
when it clicks your gonna have a good idea about bullet designs for many other things besides the marlin.

okay let's start with the RD design.
it has a full diameter drive band in front of the crimp groove, but if you look closer you'll see it doesn't have any sort of bore riding capability except for that very short section right in front of that band.
so what happens is what I explained above.

the second one is an RG design.
it works much the same way as the Dog design does, only with a much longer nose.
it relies on the drive bands with a short interaction section on the nose like a keith bullet does.

now the final one.
turn the page back to Ians picture and compare that design to the open spaces in his drawing.

Bullet Design Details | Accurate Molds

accuratemolds.com

here is a design I use in my 30 cal bolt rifles.
it's based of the Winchester 308's throat..
if you look at it you'd think wow! look at that big o'l chunk of drive band there, it'd be perfect for my rifle.
and it'd actually probably work pretty good if you seated it deep enough to feed.
not because of the big drive band but because of the nose and front edge of that drive band getting a run up into the throat.
now slip that same bullet into Ians drawing.

 

[Ian]

Looking at that pound cast,, the throat is so dang short a Barlow design is about all you will be able to get to chamber. I was wrong, your rifle does NOT have the really long throat so typical of 60s and 70s era 336s.

You can't fill that .330" void with lead unless you make a heeled bullet, so the only solution is to bridge the gap between case mouth and ball seat with the body diameter portion. .311" is about as large as you would want to go on the body or else you get too tight in the loaded chamber neck. Most cartridges don't have this problem but the .30-30 has a relatively close-fitting chamber neck so you can use that to your advantage to steer the back end of the bullet straight. On the front end you will need to closely fit the front band into that abrupt taper and fit the base if the nose into the bore diameter....but don't worry about trying to make a bore-rider fit, it won't do much good and will cause clambering problems due to the case taper as I mentioned earlier.

Maybe this photo will help.


Left to right, my 1966 336 pound cast, a NOE/Arsenal 311-165 (similar to AM 31-165W) crimped in the top lube groove, same bullet crimped in the second lube groove (VERY hard to close the lever in that one!), a bore rider with .304" nose showing scuff marks (this is NOT what you want, it has NO support in the tapered part of the throat and relies only on the tops if the lands to pilot the front straight across that big gap, then a compound, concave tapered bullet ( MP 30-180 Silhouette), the blue bullet is one I cut myself to fit a throat such as yours, then the reamer that makes that throat, and last an MP 311-140 group buy mould which has a very short, fat, round nose and doesn't fit any part of the chamber or throat well as you can see from the peeled up lead.

With your short, abrupt throat you might be better off with the 31-165 RG spec'd at .311".

 

[fiver]

yeah that's the new school throat designs.. my Winchesters have something similar [only with more taper] and so does my Ruger 308.
that's why I mentioned the 165-A and using it in the 308.
unfortunately there isn't a 30-30 design with that same feature and we mostly rely on a near nose ride bullet that feeds through the gun.
in a bolt gun we got options, if we single feed we got options [shrug]

 

[Bret4207]

It can be real tough to follow all this Chris, I know I have to let it go and then come back and re-read it a few days later most of the time to start to get it and even then I'm only getting part of it. But if Fiver says something is a particular way, it usually works out to be right on the money.

 

[JWFilips]

Could always work the throat with a finish reamer! That is what I did on my Savage 340 30 WCF
I was fortunate to find a guy on the site across the street that loaned me the use of his! Just paid for shipping both ways!

 

[Ian]

Could always work the throat with a finish reamer! That is what I did on my Savage 340 30 WCF
I was fortunate to find a guy on the site across the street that loaned me the use of his! Just paid for shipping both ways!

The issue is finding a throating reamer with a .303" pilot.

 

[Chris]

Thanks for your help with this, and your patience. It's particularly useful to use drawings and photos, and I think I have the concepts down but these are things I never thought about before. I was going to study chamber molds from other rifles and compare with molds that shoot well in them. However I ended up with a houseful of energetic little grandboys and believe me you can't hear yourself think. So maybe tomorrow.

It had occurrred to me that some chamber work could move things in a good direction. I recall when I was learning to shoe draft horses my instructor was adamant that you shape the shoe to fit the hoof, not rasp the hoof to fit the shoe. Does that apply here?

So could we use my short-throated Marlin as a case study? Why not ask Tom to shorten the forward band on the RD 165 to about half, in my case I think about .05" rather than the present .08?Keep all other dimensions the same except make band diameters .311. Is that practical and in keeping with the concepts you address? https://accuratemolds.com/bullet_detail.php?bullet=31-165D

As an example, I found another bullet to use in discussion: https://accuratemolds.com/bullet_detail.php?bullet=31-160B

It has a skinny fwd. band, and a nose of about the same length as the RD, but the drive bands need set to .311. The nose ahead of the fwd. band is set to engrave on contact and maybe that area could be opened a bit. I would be very interested in your reaction to these ideas.

Brett, I'm going to be mulling this over for a while. I took a quick look at the pics in the Accurate catalog and I'm already starting to look at them with a different eye.

 

[fiver]

your gonna want to size to 311 most likely anyway.
that 165-D doesn't look too bad [if those numbers are gonna work with yours out there on the nose]

 

[Ian]

Most of the time the most convenient thing is to work around the needs the gun presents. Sometimes you can't win and it's time to break out the reamers, lapping compound, lathe, files, holy water, or a case full of Bullseye and a long string.

 

[RicinYakima]

You forgot the martinis and gin and tonics.

 

[fiver]

that's for the walk home.

 

[popper]

The '041 and RD have the drive band. Mine has a tad longer throat, the RD shot accurate when jamming the lands but was a problem unloading. I've shot full power from the tube magazine with no setback, just an FCD crimp and no crimp groove, haven't trimmed brass anymore. The 170 & 184 works great, bit more accurate if I use a washer to nose size enough to get centered in the bore, seated long. The 165a doesn't shoot well in mine, does in 308mx. Difference in chamber design.
So, the one with drive band is OK, forget the crimp groove (NOT NEEDED, taper or fcd crimp with proper neck tension), seat to be just off the lands/bore. Bolt lock lug is the lever and jamming the nose into the bore is hard on it. This is the original RD GC full power load, accurate but jamming the lands and had to use a cleaning rod to clear the loaded round. Lubed with LLA IIRC. My one and only real deer hunt and double hitching the lever to seat a round is a pain. Bottom ones are GK's friend. About 60 yds

 

[Ian]

Poor Ken.

 

[popper]

Yea, he got 'shot down' in the election. Looking at that pound cast, not sure that is really all the neck end but it does look like this one.


This is where I washered the nose to prevent jaming lands. Dark line aft is where the bore starts, lands are beveled. Slight reductio in ogive dia forward of that line wold allow not jaming. I'd keep the taper of the front band as that part isn't sized. This shoots good enough for me so I won't get another mould made. Without the 3 or so thous. sizing I seat 100 thous deeper. Never did a pound cast of it. Lost the washer someplace so I just seat deep, good enough for me.
Interestingly, Micheal did load the 308MX with the 165RD but I couldn't get good results with it. A version of the 165A worked well. ~2400fps, leverE powder. Chrony test. Shows difference in fit.

 

[Bret4207]

Sometimes I look at the castings people make of chambers and then the targets they shoot and then I read the theories on what a "properly" supported bullet should look like and I wonder how anyone managed to even hit the paper...

"It only matters when it does." Bass's best rule!

 

[Ian]

True, but not often and when starting out with a particular rifle it's good to take a proven approach if you know one that usually works out well. The danger to our thought processes is getting myopic about ANY one particular approach and beating our heads against a wall trying the same thing over and over, so always hedge your bets.

If you keep velocities reasonable, you can get away with a lot of techniques and situations which are less than ideal, so it's also important to recognize that what "works" in one situation probably won't work as well in another.

 

[fiver]

I haven't found too many rifles that don't have the extra neck length like Popper shows.
there is the occasional one that hangs out where saami likes to show them, but for the most part trimming brass down to the minimal book length is something I don't bother with anymore.
maybe back to maximum, or squaring up case mouths, but down to minimum?? noo.