casting alloys and twist rates

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jcnull2305

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Just wondering:

For you veteran castificators out there, is there a magical alloy formula for casting accurate bullets for a given twist rate? I've read plenty here how pure lead can produce great results in a 1:48 twist barrels. I also know some change up the alloy to add a bit of hardness for faster twist rates.

So, for the sake of supposition, Let's say I'm thinking of swapping my 1:48 twist rate .54 cal barrel in my Hawken for a 1:36. Should I continue to use pure lead, or will a 1/40 or 1/20 be better. What if I don't want to use sabots in my 1:28 twist 50 cal? Should I use an alloy in that for cast bullets?

Getting ready to order some Accurate i molds for .50 and .54 because I love me some fat meplats. I may order a faster twist barrel for my Hawken .54.
 
Are you going to hunt? Or target shoot? Harder alloys are great for targeting but not so much on game. I like the 40:1 (1/40) lead:tin alloy for all around use. Its hard enough that it will resist fouling at slightly higher speeds and still performs well on game.
 
These are hunting loads. I should'a made the distinction. Good catch
 
Just wondering:

For you veteran castificators out there, is there a magical alloy formula for casting accurate bullets for a given twist rate? I've read plenty here how pure lead can produce great results in a 1:48 twist barrels. I also know some change up the alloy to add a bit of hardness for faster twist rates.

So, for the sake of supposition, Let's say I'm thinking of swapping my 1:48 twist rate .54 cal barrel in my Hawken for a 1:36. Should I continue to use pure lead, or will a 1/40 or 1/20 be better. What if I don't want to use sabots in my 1:28 twist 50 cal? Should I use an alloy in that for cast bullets?

Getting ready to order some Accurate i molds for .50 and .54 because I love me some fat meplats. I may order a faster twist barrel for my Hawken .54.
Rumor has it 40-1 will keep your conical on your powder while hiking about/Ed
 
Thanks, Ed. And If I used a 40-1, that will shrink less than a pure lead bullet. So I could used the same mold with just a bit more to size
 
Thanks, Ed. And If I used a 40-1, that will shrink less than a pure lead bullet. So I could used the same mold with just a bit more to size
Ideal is as cast , why you need actual bore dimension and a custom mold for it .The advantage of ordering from Accurate mold ,builds it for your barrel so you don"t settle for the average . Adding alloy to the pure lead increases dimension ,the lead doesn't shrink ;) /Ed
 
What I read on the LASC web site is that pure lead shrinks an average of 1.13%, and the alloys shrink less dependent on hardness.

Copied this from the LASC Web site.

Alloy shrinkage of cast bullets
Composition, %
Brinell
Shrinkage

Type Metal

Tin
Antimony
Lead
Hardness
Linear, %
Linotype
4
12
84
18
.65
Monotype
9
19
72
26
.65
Lead
--
--
100
5
1.13
Tin
100
--
--
7
.90
Antimony
--
100
--
50
.47


I have an Accurate Mould, 54-510M, and had it cut for pure lead close to my .541 needed size. I figured that since the 40-1 would shrink less than lead, I'd only have to size it a bit more. I may be going back to the drawing board.
 
Last edited:
Hey Ed, I copied this from Tom's FAQs on the Accurate Molds Site:

"Why does the order form require that I select a casting alloy?

In order to produce the requested bullet diameter, I need to know how much tin is in the alloy. All applicable alloys shrink as they solidify. The more tin, the less shrinkage. The alloy choices in the drop down menu are listed in order of expected shrinkage, from greatest to least. If you intend to use varied alloys, choose the most appropriate one that's highest on the list, so that other alloys with more tin will be a bit larger."
 
I dont have the math skills to figure out and account for shrinkage. But ordering an Accurate mold didnt require it. When you know what size your bullet needs to be for a specific barrel, you can have the mold built to drop at nearly that exact dimension. Having sizers is almost just a backup when you order an Accurate mold.
 
I dont have the math skills to figure out and account for shrinkage. But ordering an Accurate mold didnt require it. When you know what size your bullet needs to be for a specific barrel, you can have the mold built to drop at nearly that exact dimension. Having sizers is almost just a backup when you order an Accurate mold.
Neither do I. The way I read it is that since I ordered my mold for pure lead, the mold will drop a pure lead bullet at nearly the correct diameter I need, and the alloy will drop a little larger, so I will have to size it a bit. But that's a good issue. Better too large than too small - within reason.
 
What I read on the LASC web site is that pure lead shrinks an average of 1.13%, and the alloys shrink less dependent on hardness.

Copied this from the LASC Web site.

Alloy shrinkage of cast bullets
Composition, %
Brinell
Shrinkage

Type Metal

Tin
Antimony
Lead
Hardness
Linear, %
Linotype
4
12
84
18
.65
Monotype
9
19
72
26
.65
Lead
--
--
100
5
1.13
Tin
100
--
--
7
.90
Antimony
--
100
--
50
.47


I have an Accurate Mould, 54-510M, and had it cut for pure lead close to my .541 needed size. I figured that since the 40-1 would shrink less than lead, I'd only have to size it a bit more. I may be going back to the drawing board.
Get older you will forget what you read too ! :wall:
 
Neither do I. The way I read it is that since I ordered my mold for pure lead, the mold will drop a pure lead bullet at nearly the correct diameter I need, and the alloy will drop a little larger, so I will have to size it a bit. But that's a good issue. Better too large than too small - within reason.

You can also get a mold that will cast a bullet just a little larger than you need, and then run it through a sizer to get the exact dimension.

I have a Lee mold that casts a 450 grain .515 diameter bullet, and then size it down after casting.

Lee Precision .515 Cal. 450 Grain 2-Cavity Bullet Mold LEE 90255
 
Get older you will forget what you read too ! :wall:
Jeeze, Ed. That doesn't make me feel any better. I'm 50, and I have to run down the list of my kids' names (5 of them) before I hit the right one!

DO you guys have anything on alloy and twist rates? If I go faster, should I go harder? (Don't do it @michiganmuzzy - act like you're all grow'd up, now...)
 
the bullet speed will be more of an issue on the softer lead alloy than the twist rate. The faster you push a lead bullet the more likely you are to strip lead off and leave it in the rifling(leading). So harder bullets can be shot faster without stripping. Im sure twist rate plays some part in how easily stripping(leading) occurs. But then so will the bore condition, type and depths of grooves, lotsa things that are mostly minor factors. Mainly the hardness and speed. Faster bullets oughta be harder. But to what extent, imo, you need to shoot lots of different bullets at lots of different speeds with and without wads to figure that out for your rifle
 
Does the powder coating leave a different type of fouling?
 
It probably leaves some slight deposits. But its a lot harder than lead so it wont leave much. Almost nothing if you use a good fitting wad. The powder(coat) you use can be of different hardnesses too.
 
I plan to start powder coating bullets sometime soon.

I have started doing some experiments with powder coating during the last few months.

I discovered this week if you size the bullets before powder coating you do not have a problem with the sizer scraping off the powder coat.
 

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