Author Topic: 12 ga mould...(First pour) (Read 2713 times)

Victor3 · « **on:** February 16, 2009, 03:48:33 AM »

Hope this thing will cast an accurate slug for my Dom 75, considering I've been whittlin' on it for the past five hours...

Double D · « **Reply #1 on:** February 16, 2009, 03:58:56 AM »

The sprue hole is going to give you problems. You may have to make a larger sprue hole or at least a tapered one. If that doesn't work you can always machine the top down to make it shorter. The Mould also needs vent lines. Looks fine otherwise

Victor3 · « **Reply #2 on:** February 16, 2009, 04:07:40 AM »

I just wanted to get the cavity and base plug done last night. I used blanks I already had squared up for a larger mould. I'll cut it down and add vents (and maybe a sprue cutter).

Double D · « **Reply #3 on:** February 16, 2009, 04:47:28 AM »

Having been there done that, I though I would warn you, but it sounds like you have yours under control. I didn't.

I found this mould in a box the other day. I forgot I had it. I made it back in the early 80's. You can see why I forgot it. Originally the projectile was shorter but I had problems with lead freezing in the sprue hole. I have no Idea why I made the body longer and did not shorten the the top, that was 25 years ago, I was 30 something--okay nearly 40.

Yes precision machining techniques were used to make this mould. 1 inch silver and deming drill in chuck in the tail stock. Well the blocks were dialed in, in the 4 jaw. I am going to be at a loss machining here in Cut Bank, no shade tree.

The base plug in my mould never worked right. It wouldn't release completely and it finally cracked.The base plug material might be my problem. I am going rebuilld the base plug with a new design. I am going to copy your deep plug design to shorten my slug. Your mould looks to be aluminum, what is you base plug material.

Evil Dog · « **Reply #4 on:** February 16, 2009, 05:19:20 AM »

Uh.... why not save yourself a bunch of time and trouble and just buy a used Lyman 12ga slug mold? They come up of flea-bay quite often.

Victor3 · « **Reply #5 on:** February 17, 2009, 01:04:37 AM »

Quote from: Double D on February 16, 2009, 04:47:28 AM

The base plug in my mould never worked right. It wouldn't release completely and it finally cracked.The base plug material might be my problem. I am going rebuilld the base plug with a new design. I am going to copy your deep plug design to shorten my slug. Your mould looks to be aluminum, what is you base plug material.

I think the problem with your plug is that it looks to have little or no taper/radius near the bottom. You don't want any straight diameter on it. This will cause it to stick in the lead. It should also have a pretty smooth finish to help it release.

I made mine from brass. There's .003" clearance between it and the hole in the block. I'm going to add a slot in the bottom of one block under the plug's flange so I can loosen it with a screwdriver while the mould is still closed. This will prevent damage to the projectile's skirt as the plug and bullet are removed.

Cat Whisperer · « **Reply #6 on:** February 17, 2009, 01:10:28 AM »

Quote from: Evil Dog on February 16, 2009, 05:19:20 AM

Uh.... why not save yourself a bunch of time and trouble and just buy a used Lyman 12ga slug mold? They come up of flea-bay quite often.

They are way UNDERSIZED to allow the slug to go through a full choke. Sloppy!

Victor3 · « **Reply #7 on:** February 17, 2009, 01:49:11 AM »

Quote from: Evil Dog on February 16, 2009, 05:19:20 AM

Uh.... why not save yourself a bunch of time and trouble and just buy a used Lyman 12ga slug mold? They come up of flea-bay quite often.

The problem with 'stock' 12 ga moulds is that...

1. They cast light slugs (~1oz).

2. Standard Foster/Brenneke slugs don't generally shoot all that accurately from rifled bbls.

3. Lyman's Diabolo (skirted "airgun pellet") shaped slug uses a shot wad as a sabot and is too tight a fit to be loaded from the muzzle in my bbl (I tried it).

http://www.ballisticproducts.com/prodinfo.asp?number=1244112

I may get one of the Lyman moulds and modify it to make the OD of the slug larger and ditch the sabot. It might be very accurate with a light load.

Aside from the above, I just wanted to design and make my own bullet. I'm funny that way...

Double D · « **Reply #8 on:** February 17, 2009, 01:50:06 AM »

Yes, I think that was the problem part of the plug was cylinder section. It had a pretty good finish until the last casting session when it started sticking and got tossed in a box for 15 years.

Rickk · « **Reply #9 on:** February 18, 2009, 02:30:23 PM »

I measured some slugs out of my Lyman hollow base mold . This is the 475 grain "conventional style slug" Lyman # 2654012 mold... not the 525 grain sabot "pellet gun" style.

I cast them with soft lead, and they measure pretty much .700 dead on.

Rick

Frank46 · « **Reply #10 on:** February 18, 2009, 04:45:02 PM »

Saw the NRA show on the tube this evening. One gent was making his shells out of aluminum. Had part of the rifling preengraved on the base of his projectiles. Estimated length by calibrated eyeball was between 6-8 inches. Had the nose tapered. Said he was getting good accuracy from them. But when asked about digging them out of the backstop there was the problem. They were so close together that they were hitting the previously fired ones and shattering them. I have some odds and ends of aluminum here and a lathe to make them up. Not too many hill which to fire said projectiles and recover them usually by long handled shovel.Maybe instead of useing round balls made of zinc, we make them shell shaped maybe fly truer. I watched one mortar crew digging up their shot. Some where near the surface but here in louisiana they better bring in an excavator cause them shells will penetrate our soggy soil. Frank

Cat Whisperer · « **Reply #11 on:** February 19, 2009, 12:18:57 AM »

Frank -

We'd love to see some pictures of your shells! Before and after firing too.

Victor3 · « **Reply #12 on:** February 19, 2009, 01:08:05 AM »

Quote from: Frank46 on February 18, 2009, 04:45:02 PM

Saw the NRA show on the tube this evening. One gent was making his shells out of aluminum.

One problem with aluminum is its tendency to gall under pressure. Leading in a bore is bad enough, but 'aluminuming' would be much harder to get out. You might have to clean your bore with Draino or some other caustic solution to remove it.

Victor3 · « **Reply #13 on:** February 19, 2009, 01:22:45 AM »

Quote from: Rickk on February 18, 2009, 02:30:23 PM

I measured some slugs out of my Lyman hollow base mold . This is the 475 grain "conventional style slug" Lyman # 2654012 mold... not the 525 grain sabot "pellet gun" style.

I cast them with soft lead, and they measure pretty much .700 dead on.

Rick

My bore is .725".

Rickk · « **Reply #14 on:** February 19, 2009, 02:29:20 AM »

They have a fairly thin skirt, and if cast of soft lead they would probably load easily and expand fully into the rifling.

I recovered one of the 1" machined steel skirted slugs that Mike and Tracy fired into a log out behind my house and even the steel skirt expanded into the rifling.

Rick

Victor3 · « **Reply #15 on:** February 19, 2009, 03:08:52 AM »

Quote from: Rickk on February 19, 2009, 02:29:20 AM

They have a fairly thin skirt, and if cast of soft lead they would probably load easily and expand fully into the rifling.

I'll be trying them out for sure, but I'm not expecting much.

One goal of this project is to obtain some measure of accuracy. I've started with a good barrel in a well made gun. Next step is a good bullet.

Double D · « **Reply #16 on:** February 19, 2009, 04:48:21 AM »

I'm with you here Victor. Obturation has limited use.

My real affection is for Martini's. You do not know how many people jump into the 577/450 Martini and use .458 diameter bullets. They then gripe and complain when they can't get any accuracy out othe Martini.

The Martini does not have lands and grooves, it has the flats and peaks of Henry rifling. There is a minor diameter which is the center of the flats and in the Martini that is .450. Then there is the major diameter the corners of the flat which in the Martini is .464. To get better visualization look at an octogon barrel. It is smaller across the flats than across the corners. To complicate the matter in the Martini the first 8 inches barrel is a tapered throat. The taper is .451 minor/.469 Major to .450/464 in 8 inches.

The guys shooting .458 bullets report minute of cardboard box accuracy at 50 yards with a bullet that is .011 undersized. They are relying on obturation to bump the bullets up. I followed Wolfe's obduration theory and used softer allloys in my 45/70 Trap door and got marginal increaseaccuracy. When I switched to.464 bullets my Trapdoor shot under 2 inch at 100 yards. I tried the hollow base minie style bullets in Trapdoor and got mixed results.

Victor stick to you guns, make the slug fit you bore, .025 is far to much obturation to expect decent results.

RocklockI · « **Reply #17 on:** February 19, 2009, 05:46:11 AM »

Quote from: Evil Dog on February 16, 2009, 05:19:20 AM

Uh.... why not save yourself a bunch of time and trouble and just buy a used Lyman 12ga slug mold? They come up of flea-bay quite often.

That sounds like a good idea . At least a good starting point , you could hone out the dia. shorten the cavity .

Plus the handlage ,squared blocks ect. seems too me to be a good starting point .YMMV

Rickk · « **Reply #18 on:** February 19, 2009, 11:59:24 AM »

Victor,

if you want to try a few 12 G slugs from my mold before investing in one yourself, lemme know with a PM containing a mailing address and I'll send you a few.

Rick

Victor3 · « **Reply #19 on:** February 20, 2009, 03:24:38 AM »

DD - I had no idea that Martini-Henrys had this rifling style. Only one I've shot was a .22 rimfire. Learn something new every day. Thanks much for the details.

My experience with hollow-base projectiles is limited to airguns and BP rifles (and one 20mm bullet mould for a rifled cannon). I've found much the same as you have. You want it to be able to load easily of course, but not so sloppy that the bullet will be able to cant in the bore significantly, nor have to be deformed into the rifling any more than required.

Rickk - Thanks much for the offer. I have a few types of 12 ga slugs here to try. Who knows? They may shoot well out of my barrel. I also have a .700" ball mould that may do well with a patch.

I'm sure I'll find an accurate boolit some kinda way...

Double D · « **Reply #20 on:** February 20, 2009, 01:49:03 PM »

Only the Martini Henry 577/450 has Henry rifling. The Martini Enfield .303 and the BSA .22's all have conventional Enfield rifling that we are familiar with.

Artilleryman · « **Reply #21 on:** February 21, 2009, 06:58:25 AM »

Quote from: Victor3 on February 19, 2009, 01:08:05 AM

Quote from: Frank46 on February 18, 2009, 04:45:02 PM
Saw the NRA show on the tube this evening. One gent was making his shells out of aluminum.

One problem with aluminum is its tendency to gall under pressure. Leading in a bore is bad enough, but 'aluminuming' would be much harder to get out. You might have to clean your bore with Draino or some other caustic solution to remove it.

I have been using a cast aluminum projectile with lugs that engage the rifling for 28 years. I use N-SSA powder charges, and haven't had any "aluminuming" yet. I have used the same mold to cast zinc projectiles to be used with service loads. This has left some zinc in the bore, but it hasn't stayed there long and doesn't appear to cause any problems.

Victor3 · « **Reply #22 on:** February 21, 2009, 07:26:04 PM »

Quote from: Artilleryman on February 21, 2009, 06:58:25 AM

I have been using a cast aluminum projectile with lugs that engage the rifling for 28 years. I use N-SSA powder charges, and haven't had any "aluminuming" yet.

I was thinking hollow-base projectiles that are obturated into the rifling (under a lot of pressure) upon firing. An aluminum projectile like yours, with lugs that ride in the grooves isn't subjected to a tight force-fit in the bore.

Might not be a problem; I'm only going by my experience with aluminum galling in other applications. It's not normally recommended for bearing surfaces.

Victor3 · « **Reply #23 on:** February 23, 2009, 12:12:43 AM »

Getting there. My band saw screams loud enough to wake the dead cutting aluminum, so I didn't shorten the top section tonight...

Scraping vents on the mill...

Cannoneer · « **Reply #24 on:** February 23, 2009, 01:23:48 AM »

Victor,

Did you mull over a lot of different design choices for the nose of your projo, or did you early on in the planning stages of your project settle on a similar (with a shoulder) design to a Brenneke and most other shotgun slugs, because of the bore of your/Dom's 75?

Victor3 · « **Reply #25 on:** February 23, 2009, 02:22:48 AM »

Boom J,

It was a combination of the little I know about bullet design/ballistics and ease of machining the mould cavity. The step between the nose and OD is to hopefully punch clean holes in paper.

I've also shot thousands of these 5mm Sheridan pellets with good results over the past four decades

Double D · « **Reply #26 on:** February 23, 2009, 03:38:40 AM »

Victor,

You need another guide pin on the other side of the mould. The guide pins need to support both sides of the mold.

Are you building this CNC, I'll send you my demensions and you can punch them in.

Cannoneer · « **Reply #27 on:** February 23, 2009, 09:28:04 PM »

Quote from: Victor3 on February 23, 2009, 02:22:48 AM

It was a combination of the little I know about bullet design/ballistics and ease of machining the mould cavity. The step between the nose and OD is to hopefully punch clean holes in paper.

I've also shot thousands of these 5mm Sheridan pellets with good results over the past four decades

I've been reading the March issue of Shooting Times, and there's an article titled "Accurate Air Rifles" that's basically about being able to practice shooting at a cost of pennies instead of the dollars it takes with smokeless; anyway, there's a photo of some of the current match-grade pellets and these look different than the pellets that I remember. The hunting pellet that they show looks like yours, and the ones I remember from greener days, but the M-G pellets have what look like smooth flat faces. If you've ever used these, are they really more accurate than the hunting pellet?

Victor3 · « **Reply #28 on:** February 23, 2009, 10:24:25 PM »

Quote from: Double D on February 23, 2009, 03:38:40 AM

Are you building this CNC, I'll send you my demensions and you can punch them in.

No CNC here, DD. My stuff is all MHC (Manual Hand Crank)

A salesman once hinted that a "surplus stock" CNC retrofit kit to fit my Bridgeport might could appear on my doorstep if I were to arrange a $275K purchase for my employer from him though $:-\$

Victor3 · « **Reply #29 on:** February 24, 2009, 12:24:42 AM »

Quote from: Boom J on February 23, 2009, 09:28:04 PM

The hunting pellet that they show looks like yours, and the ones I remember from greener days, but the M-G pellets have what look like smooth flat faces. If you've ever used these, are they really more accurate than the hunting pellet?

Boom J,

Paper-punching airgun competitors use flat-nosed pellets to make clean holes in the target for scoring purposes. Since they're shooting to short ranges at paper, the crummy BC of these pellets isn't a problem.

In games like field target and silhouette, where they're shooting at metal targets that require more retained energy to make them fall, a round-nosed pellet is used. They're also the most commonly used pellet style for hunting for the same reason.

In most airgun shooting, the Diabolo pellet shape is favored due to its inherent 'drag stabilization' at low velocities. It also takes advantage of an airgun's low power due to the small front and rear driving bands which have little contact with the bore.

Cylindrical pellets aren't popular anymore since they're not as suited to airgun characteristics.

However, in a cannon like mine (with no shortage of power/velocity), the design works. I chose it as a happy medium of paper-punching, BC and simplicity.