Arsenal Mold Casting way small

[oley55]

I ordered a 5 cavity aluminum mold from Arsenal (mostly because they were immediately available) for 9mm. A 358-130-RF-PC, https://arsenalmolds.com/products?product_id=195
My as cast with my personally processed COWW plus 1.5% pewter/tin is only .355"-.3555" (measured with analog and digital micrometers). My normal casting temp is 700-720 degrees but I did try at a low of 660 and high of 770 and saw little to no difference in size.

I have been using a Lee TL356-124-2R, but have had to beagle the mold and then bump them to consistently hit my PC'd target diameter of .358". That's a good bit of fiddling hence the reason for ordering a .358" mold. I have a new Sig P320 M18 and the barrel slugs at .356". I was still getting some fouling until I realized my unsorted mixed brass was swaging down some of my bullets. Since then I have sorted and pin gauged my selected/sized brass and have run a couple hundred rounds with great results.

An FYI, I found that a .351" minus pin gauge that will slip into the case to or nearly where the bullet's bottom will be ensures all loaded rounds with those fat .358" bullets plunk every time.

For some reason Jared at Arsenal has not responded to my call/email from last week so I sent another email and called this evening, but now his voice mail is full. I am assuming he has something personal going on and will get back to me soon.

All that said, the .355" as cast from a .358" mold seems WAY off and with the radiused base I do not have the required tools to measure the diameter (although while typing this I just realized I should be able to get a close measurement from an open half).

Any ideas if I'm doing something wrong and thinking wrong?

Edit added: I tried to measure the mold cavity using pin gauges held on an angle to try and get the end of the pin down in there. It is not accurate because a .354" and .355" were both close but the .354" (.3538" actual) seemed to block the light best.

[dannyd]

Unfortunately some of his moulds do cast small and he is probably not going to answer your email or return your calls.

As a backup and if you have some spare cash in the mean time, look at MP moulds for the 135 they have just for pc too.

I know that's not the recommendation you may want, but I have several of the Arsenal moulds. with one lemon that cast way to small. I just put it on the shelf and moved on because your property not doing anything wrong it's just the mould.

[Dusty Bannister]

Any chance your mold is too cool for the alloy temp you are running? I realize you say you tried a melt temp of 770 but did you preheat the mold or run long enough to get good and hot so the sprue puddle remained fluid longer than usual. We are going into fall, so the ambient temps might also affect how hot the mold and melt will be as casting if outside in the elements. I know your location is FL, but with the weather changes, that could be a factor.

[T.J.Smith]

I've got this mold and mine cast at .358. It also powder coats great. I would want another mold that is correct in bullet diameter.

[Wheelgun]

The Arsenal molds I have, fortunately, drop correct size, and are great. But if you’re waiting on an email, good luck!!

I have a mold that casts too small also. I use a hot plate to get the mold HOT. I then cast wide open, fast and hot, they come out VERY frosty, but I get the size I need.
You may want to try that, it might help.

[dannyd]

The Arsenal molds I have, fortunately, drop correct size, and are great. But if you’re waiting on an email, good luck!!

I have a mold that casts too small also. I use a hot plate to get the mold HOT. I then cast wide open, fast and hot, they come out VERY frosty, but I get the size I need.
You may want to try that, it might help.

I am going to have to try that.

[dannyd]

Just looked I have 6 Arsenal moulds and the only one that cast small is a 38 special double end wadcutter 148. I can make it work, but it's time consuming, so I purchased MP mould and use it.

[gwpercle]

The Arsenal molds I have, fortunately, drop correct size, and are great. But if you’re waiting on an email, good luck!!

I have a mold that casts too small also. I use a hot plate to get the mold HOT. I then cast wide open, fast and hot, they come out VERY frosty, but I get the size I need.
You may want to try that, it might help.

This may work ... "Frosty" doesn't hurt a boolit and may in fact help with powder coating to stick . Give it a try , nothing to loose .

All my NOE moulds cast to size stated on mould ... none of mine cast undersized .
Try the telephone ... The Squeaky Wheel Gets the Grease ... be nice but make a pest of yourself long enough and you will usually get taken care of !
Good Luck
Gary

[dannyd]

I have two stinkers from NOE; their copy of H&G 51 and the first mould guide for the new Lyman pot. The guide really sucked, so everyone has their one off. But I do have four other NOE moulds that work great.

I have 55 moulds but only three stinkers.

[oley55]

I use a hot plate and defiantly had everything up to temp at each temp point before I measured for diameter. But as suggested I will give it another go at "fast and hot" but my practical brain tells me really hot lead shrinks more than colder lead when it cools. And for that matter, don't metals expand when hot and I assume an aluminum block expands in all directions when heated. Wouldn't that expansion also include the mold cavities/ i.e. making them smaller as the aluminum expands outward? Just wondering out loud.

gwp, called a week ago and it went to voice mail and I left a message. Called this week and the mailbox was full.

[Dusty Bannister]

Yes, the metal does expand in all directions. The cavity will expand as the mold block expands. The temp of the alloy can remain the same as long as the blocks are hot enough. Just try it and know for sure. Antimony content is also a factor as that expands on cooling as well. Pretty sure you are well experienced in that though. Your COWW is between 2 1/2 and 3% antimony, and the tin has no affect on expansion. If you thin it with soft scrap, you will have less expansion, but you did not state doing that.

[Hickok]

Not trying to be a know it all, just hoping my experience can help some one.

My learning curve with the 9mm in various pistols.

I got away from sizing 9mm to .357" and .358", it was simply a hassle with failures to feed, getting a mold to cast large diameter and a big headache. The hassle surpassed the joy!

I have a SIG M17 and a SIG M18 (Great pistols, but the PVD finish sucks) a SIG P365 and a gaggle of Glocks.

I bought a Lee Universal case expander, then got the NOE expander plug .359" x .355" and used to expand all brands of 9mm brass. No more swaging down of boolit diameter by tight brass.

I now size ALL my cast 9mm boolits to .356" after powder-coating. I mainly use the Lee 356-120-TC, cast of either ACWW or 50/50 ACWW/pure lead....seems to make NO difference after PC.

My load chrono's 1140FPS (+ or -) from a 4 in barrel, with Unique powder.

No leading in any brand of pistols, accurate and jam free. Just had my M17 out after installing a Holosun RMR sight, and 100 rounds shot, and a couple patches through the barrel and it was clean.

Using correct NOE case expander, Sizing boolits to .356" with PC, has made casting and shooting in all my 9mm pistols a satisfying effort. I am very satisfied with the results mentioned above. Others may disagree, but FINALLY, I can use one standard cast 9mm recipe in all my pistols....It all came together and works for me.

Not saying anyone else is wrong...just my results.

[oley55]

Hickock, I hear all of that but my M18 slugs at .356". Don't remember exactly where (except like everywhere) cast boolits need to be a minimum of 1 thousands over. I also have an older Taraus PT92 circa 1985 that also slugs at .356" while several of my Sons' various 9mm's slug at .355".

Note to others about casting hot n fast, it didn't quite workout. I did get the mold hot enough off the hotplate that the boolits hadn't fully hardened after 30+ seconds and left some shiney behind in the cavities. Those actually miced at .357". But smearing lead and waiting over 30 seconds between casting and sprue cutting ain't gonna work for me.

Don't be surprised if you see a listing in the future for a really skinny Arsenal .358" mold in the fer sale section, but still hoping Jared at Arsenal responds........

[flatnose]

Hickock, I hear all of that but my M18 slugs at .356". Don't remember exactly where (except like everywhere) cast boolits need to be a minimum of 1 thousands over. I also have an older Taraus PT92 circa 1985 that also slugs at .356" while several of my Sons' various 9mm's slug at .355".

Note to others about casting hot n fast, it didn't quite workout. I did get the mold hot enough off the hotplate that the boolits hadn't fully hardened after 30+ seconds and left some shiney behind in the cavities. Those actually miced at .357". But smearing lead and waiting over 30 seconds between casting and sprue cutting ain't gonna work for me.

Don't be surprised if you see a listing in the future for a really skinny Arsenal .358" mold in the fer sale section, but still hoping Jared at Arsenal responds........

Sadly there is almost no chance of him replying. I have a couple of decent molds from him but if it is wrong you are just stuck. Mp molds is exactly the same. If you get a bad mold you are just stuck. Many here know this already. May I suggest going to Accurate molds and you will have a great mold that will give you the diameter you want and he backs it up. Unless it is too small for his boring tools I would never go anywhere else. Sometimes you have to just accept defeat. I have thrown away Lee molds and MP molds and one from Jared.. Sure it hurt but they were no good and they truly dont care.

[bruce381]

try making a cast then lapping with it with valve grind compound you can open a AL mold up 2-3 thousands easily

[oley55]

Sadly there is almost no chance of him replying. I have a couple of decent molds from him but if it is wrong you are just stuck. Mp molds is exactly the same. If you get a bad mold you are just stuck. Many here know this already. May I suggest going to Accurate molds and you will have a great mold that will give you the diameter you want and he backs it up. Unless it is too small for his boring tools I would never go anywhere else. Sometimes you have to just accept defeat. I have thrown away Lee molds and MP molds and one from Jared.. Sure it hurt but they were no good and they truly dont care.

It seems you were correct about him. I'll get over the lost money spent, but will never ever buy from Arsenal again and will gladly share my poor experience whenever I can.

[Jeff Michel]

Arsenal got me on a undersized mold as well. Never got a reply either. He had his chance. I think if he continues to poison the well here, he's going to have a tough time giving giving his molds away. I confident that Tom at Accurate appreciates all the business that Arsenal is sending his way.

[MT Gianni]

What does your barrel slug at? You might be ok with 0.356" pc'd. Sometimes you have to give up on a mold, sorry.

[Mr Peabody]

Why not send it back? Certified mail is cheap and a little note inside could help fix the problem.

[tja6435]

Sadly there is almost no chance of him replying. I have a couple of decent molds from him but if it is wrong you are just stuck. Mp molds is exactly the same. If you get a bad mold you are just stuck. Many here know this already. May I suggest going to Accurate molds and you will have a great mold that will give you the diameter you want and he backs it up. Unless it is too small for his boring tools I would never go anywhere else. Sometimes you have to just accept defeat. I have thrown away Lee molds and MP molds and one from Jared.. Sure it hurt but they were no good and they truly dont care.

I’ve had problems with 2 molds from MP, one where the alignment pins wouldn’t stay put when the mold was hot and another that wouldn’t drop the boolits because the cavities weren’t centered perfectly(or close enough to centered). In both instances I communicated and sent pics to document the problems, Mihec sent me new blocks both times, on his dime. He even sent me a sprue plate one one of mine had a big warp in it now I think of it. MP molds takes care of their problems in my experience.