Accurate Molds Tolerance Questions

[Saltbager1]

Hello Guys, long time lurker first time poster. Ive been looking to getting into casting my own boolits for quite some time now. I have been reloading for quite some time but I have never ventured into casting. My father has casted his fair share of fishing weights so he has the majority of the equipment already. I just need to purchase the molds and the sizing kits.

My only concern is that I am not sure what size to order. I spoke to Tom at accurate molds and he told me that for 9MM, most people order .357”. Which, as you all know is .002” Larger than the bore diameter. Now, from all the research I’ve been doing states that you want to be .001” over the bore diameter. I’m assuming that the bullet will be sized to .356”.

Here is where my questions begins. Firstly, I plan to powder coat the bullets. My question is, should I be ordering the .357” diameter or the .356” diameter knowing that the powder coating will add to the diameter.

Also, knowing that I will be powder coating and sizing, should I be ordering the +/- .001” or something else?

[Targa]

You have researched well, I would go with the .356 cavities and a .356 sizing die from Lee’s or my preference, NOE’s sizing body kit and a .356 sizing bushing. Either work well I just prefer the versatility of the NOE.

[murf205]

Welcome , Saltbager1. You will like this place. Lots of nice people and a ton of knowledge too. As for your question, you can order the .357 mold then pc them and then size to suit your gun. Even if your boolits drop at .359 and uyou powder coat another .001, you can still size to .356 with no problem. Just buy a push through sizer and if the boolits need it , you can add a little gun oil to help the process. You’re not going to hurt the powder coating by sizing it. Good luck.7

[ryanmattes]

When I started, I bought a mold that dropped a little fatter, around .359, and I bought push through sizers in .356, .357, and .358.i cast and coated (with HiTek), and I loaded ladders with each size to figure out what my particular guns like. I settled on coated boolets sized to .357, and they shoot great, no leading, and cost me less than a penny each.


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[Bigslug]

Check the 9mm sticky thread currently at the top of the handguns subforum Lot of good info on that one. 9mm presents certain unique challenges that it's good to be familiar with before you dive into the pool.

I've slugged about half a dozen different 9mm bores and gotten .356" on all but one, which was .355" on a Springfield 1911 target model evidently put together by their "A" team when they were having a very good day. Short version, .357"-.3575" probably is what you want to cast at; do your PC thing, then size to .357"

[ryanmattes]

I've slugged about half a dozen different 9mm bores and gotten .356" on all but one, which was .355" on a Springfield 1911 target model evidently put together by their "A" team when they were having a very good day. Short version, .357"-.3575" probably is what you want to cast at; do your PC thing, then size to .357"

Every Sig I've ever slugged comes out .356. Also came out .356 in a S&W and a CZ.

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[reddog81]

.356 or .357 mold will work. PC will add a little to the diameter. And then you can size to .356 or .357. I think most people go .357 for 9mm.

Some people swear that .356 is best while others insist the .358 is the way to go.

[lobogunleather]

There is the stated mold diameter. There is the manufacturer's tolerance to be considered. There is also the alloy used to cast the bullets to take into account.

In my experience, the harder bullet metals will always drop from the mold at a larger as-cast diameter than the softer alloys. I regularly cast handgun bullets using salvaged wheel weights (mostly 1980s and earlier) but I also cast rifle bullets from alloys of WW and linotype metal. The harder the metal, the greater the as-cast diameter, regardless of caliber.

My .309" molds for .30 caliber will deliver as-cast bullets from .3085" to .310" depending on the alloy in use. My .358" molds for .38/.357 will drop as-cast from .358" to .360" with different alloys.

Then there is another factor to consider, and that is "spring-back" during sizing. A .358" bullet cast in wheel weights can be run through a .358" sizer die and be pretty close to .358", but the same bullet cast in linotype may "spring-back" after sizing and mic-out at .360".

I have no experience with powder coating so I can't comment on results, but I suspect there will be some measurable variations added to the process, and those will vary depending on alloy, mold, and sizing methods.

The real proof is always found at the range. The finished cartridge must fit and feed without difficulty (chambers do differ in dimensions). Degrees of accuracy can only be ascertained by test firing under controlled conditions. What works well in one firearm may not work at all in another.

A final thought to be kept in mind: Sizing cast bullets never results in improved performance. Sizing causes removal or displacement of metal, and that is antithetical to best accuracy. The best possible results will come with bullets that drop from the mold within a narrow range of tolerance applicable for the cartridge and firearm in question and lubed (or coated) without significantly changing that narrow range of tolerance.

We must never assume that our firearms have bore, groove, or chamber dimensions within SAAMI specifications. Every gun is produced with machine tools that are subject to wear within each manufacturing run, every chamber is different, every bore is different, and every rifling groove is different. Tolerances in manufacture can become cumulative and create combinations that require careful adjustments in ammunition to achieve best results (undersized chamber or forcing cone, maximum or minimum headspacing, short or long throating, under- or over-sized bore or groove diameters, etc, etc, etc). There really is no simple one-size-fits-all solution, only another challenge to be dealt with.

[44Blam]

Hey Saltybagger -
This is all part of the fun. First of all, you have a gun that you can slug the barrel. BUT don't forget the guns that you will buy in the future... Some of those you will not expect. One example is that I have a 125 grain boolit that I shoot in 357 sig, but I also found that it shoots really well in 350 Legend... I never saw that coming...

Anyway, order it fat and size it. That way if you want .355 you can size down or if you want 357 you just push though to make sure it is good.

[Tar Heel]

First and foremost you should know that throats in 9MM handguns vary considerably. I learned the hard way that my cast .356 RNL would not chamber in half of my guns due to .355 throats and/or no leade. If you know a .356 RNL (or whatever) will chamber in YOUR gun(s) then no problem.

The way to avoid this entire chambering issue with multiple or a single handgun is to shoot TRUNCATED CONE bullets like the ones in the image above in reply #4. No kidding. As you are aware, .001" is like the Grand Canyon to a firearm. With the truncated cone bullets, there is no lead in the leade, it's all still in the case mouth waiting for the big moment. I use the Lyman #356402.

I still shoot RNL bullets in my 9mm guns, but only in certain guns with larger throats (longer leade). Accurate #7 has become my choice for propellant in the 9mm with cast bullets. It's a perfect marriage of pressure/time curve and barrel length in the 9mm using cast bullets.

Have fun.

Attachment 285654

[white eagle]

size your bore order what you want and size what you need

[Cosmic_Charlie]

I heartedly recommend powder coating your 9mm boolits.

[Burnt Fingers]

9mm loading is not as easy as typical straight wall pistol cases like 45 ACP and 10mm/40 Short and Weak.

It's a tapered case to start and it can be very sensitive to seating depth and sudden spikes in pressure.

It took me a couple of months to really figure the little sucker out and now I have no problems.

I load for multiple 9mm firearms. I size my bullets to .357 and normally use Hi-Tek coating. I have also powder coated them.

All my 9mm molds are 358-359 molds.

Personally if I were starting out and knew what I know now I'd just order this mold https://www.mp-molds.com/product/357...d-multichoice/ in .359 and be done with it.

I have the same mold in a no lube groove version and cast them by the thousands.

[Saltbager1]

Guys,

Thank you all for the tips and information.

I think that I am going to order the .357” mold with the +.002” tolerance. That way, in theory, they won’t come out less than .357”. However, if they are over, I can simply size them. Also, knowing that I will be adding powder coating, I should have a few thousandths to “play” with.

I am also going to be ordering a mold for a .50 Beowulf. I think that I will order that mold in .502 with the same +.002” tolerance.

I was thinking that I was going to order a single cavity mold to try, but for the price difference, it makes more sense to me to just buy the 5 cavity mold.

When I’ve been reading about resizing, I’ve noticed that there are quite a few methods. I guess that I won’t know the method that works best for me until I try a bunch of bullets that have been cast by my hand.

What is the preferred methods by the masses? I’ve read a few places that you only want to resize by a maximum of .002” at a time. Is that true?

[ryanmattes]

For coated, push through sizing is the fastest and easiest. I already have a bunch of Lee push through sizers, but if I didn't, I'd probably look at getting the NOE die body and bushings for each size. It ends up cheaper in the long run, and NOE makes excellent products. The bushings are $10 each, and you can get them in .001 increments from .354-.362.

Again, I'd recommend getting .356, .357, and .358 bushings, and doing test loads with each size to see what your barrel likes. Worst case, you spent $10 on a die you don't need now, but might use later for a different gun. And if your gun likes .357 but you're dropping at .359 and then coating to .360, you might want to run them through the .358 die first, and then the .357, to avoid displacing too much metal.

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[Bigslug]

. . .The way to avoid this entire chambering issue with multiple or a single handgun is to shoot TRUNCATED CONE bullets like the ones in the image above in reply #4. No kidding. As you are aware, .001" is like the Grand Canyon to a firearm. With the truncated cone bullets, there is no lead in the leade, it's all still in the case mouth waiting for the big moment.
Attachment 285654

Tar Heel makes a good point. When ordering your mold, consider what your powder coating is adding to the diameter OF THE NOSE, and how that might be decreasing the room you have to work with IN THE THROAT for easy chambering.

Tar Heel's truncated cones are one way to deal with this.

A rounded ogive that tapers quickly enough is another. The NOE/Ranch Dog TL357-135RF is what I use and it works quite well, but then, I'm not PCing. The Accurate 35-135D is effectively the same slug. Bumping your seating depth shorter until the complete full diameter shank disappears from view has done the trick for me on this type of bullet, but again - I'm not powder coating.

A third option to deal with a tight throat is a bullet that takes a quick step down in diameter right outside the case, then presents whatever nose profile you like from there. Yet again, I'm not a powder coater, but this might neatly address any possible issues of your paint causing throat interference while enabling you to still keep something of a meplat. 9mm examples of this would be the 35-125A, 35-125E, 35-130A, 35-135 V and 135X (both powder-coat designs), 36-136N, you get the idea.

Just do some quick math with those blueprints adding the length of the bullet's nose to that of the case to determine your final overall cartridge length, and you'll be stylin'.

[murf205]

I was in a similar situation when I ordered a .358 Accurate mold for my 38 spl/.357 mag revolvers. The mold drops at.360 and with pc, it is .361 which is perfect for the 38 S&W guns I have. You may not have a 38 S&W but you never know and you will have a mold that is a lot closer. Like ryanmattes said, you can always squeeze 'em down and the NOE die body and bushings are a great tool. Good luck

[Larry Gibson]

For many years I cast and shot thousands of .356 sized bullets in many different 9mm handguns and numerous sub-guns with no problems what so ever. I used 115 - 124 gr cast lubed with Javelina over 4 gr of Bullseye. I got not leading and excellent accuracy. Then I read all the hull-a-ballou about using .357 and .358 sized bullets in the 9mm. The last few years I've used the Lee 356-120-TC lubed with BAC over the same 4 gr load of Bullseye. I sized the bullets .358 and in some guns with some brass they functioned okay. In other guns I began having chambering problems because the chambers with some brass would not accept a bullet that large. I then sized them at .357 and that seemed to work okay except in some newer made barrels with .355 - .356 groove diameter barrels chambering problems began after numerous rounds were fired.

I noticed a small ring of lead came out on a cleaning patch pushed through from the muzzle on one of those. Further inspection/measurement revealed the throat just in front of the chamber shoulder was only .356 in diameter. Obviously a small amount of alloy was being scraped off each shot because the .357/.358 bullets were being scraped by the sharp chamber shoulder. Thus after shooting numerous rounds the alloy buildup began preventing the slide from completely closing as the round was headspacing on the built up alloy instead of the chamber shoulder. The problem was solved quite simply by sizing the bullets .356. There was no leading and accuracy was the same, perhaps a bit better. Functioning was 100% even after a lot of rounds were fired w/o cleaning the pistol.

Unfortunately in pistol barrels (not revolvers) with minimal throat length and diameter accuracy is as good with bullets sized to that diameter or to groove diameter. Sizing .001 - .002 over groove diameter many times in such pistols does not improve anything but can cause problems instead.

I have gone back to sizing .356 for the 9mm cartridge for ammunition to be used in multiple firearms. If your .357/.358 sized bullets give 100% reliability in your pistol(s) then drive on. However, what works in some just may not be applicable in all......

[243winxb]

Different alloys produce as cast bullets larger or smaller depending on the alloy antimony content.

Ask the mold maker what alloy the mold is regulated at. https://www.thehighroad.org/index.ph...56-120-tc.317/

[243winxb]

Guys,

Thank you all for the tips and information.

I think that I am going to order the .357” mold with the +.002” tolerance. That way, in theory, they won’t come out less than .357”. However, if they are over, I can simply size them. Also, knowing that I will be adding powder coating, I should have a few thousandths to “play” with.

I am also going to be ordering a mold for a .50 Beowulf. I think that I will order that mold in .502 with the same +.002” tolerance.

I was thinking that I was going to order a single cavity mold to try, but for the price difference, it makes more sense to me to just buy the 5 cavity mold.

When I’ve been reading about resizing, I’ve noticed that there are quite a few methods. I guess that I won’t know the method that works best for me until I try a bunch of bullets that have been cast by my hand.

What is the preferred methods by the masses? I’ve read a few places that you only want to resize by a maximum of .002” at a time. Is that true?

Lyman- sizing down more then .003" hurts accuracy.

I like sizing with my Lyman 450 better then Lee push thru. The Lee requires a Alox coating before sizing & after.

Powder Coating, no idea? Maybe cast, powder, size?