Pockmarked and cratered bullet bases --- tin has changed my life

[Dimner]

This one is for the deep recesses of the cast boolit search engines.

I have long been comfortable and successful in bullet casting 30 caliber. Always get nice filled out boolits with straight wheel weights. Especially when using Lyman or RCBS iron molds. Less successful, but still good results using aluminum molds of 30 cal. Just need to be more strict about temperature and cadence/timing while casting.

Well, when doing 22 cal casting, I have never been able to get anything resembling a nice base from an aluminum or brass mold. The bases are always cratered and pockmarked. Torn and ripped. When I turn down the temp, then the fill out goes to hell. No matter how slow I cast. But as always when I cast with iron molds, all is perfect.

This time though, I decided I had to get these brass molds working right. The profile was something that was not available in iron. So I added 1.5% tin to my mix for the first time.

OH MY DEAR LORD

The impact and perfect bullets were instantaneous. its like a choir started singing. It just changed everything that rapidly and that much.

I always knew tin was important for fillout, but never really needed that with 30 cal. But for 22 cal.......you need it. Don't be cheap like me. Get some tin.

[cupajoe]

I have, so far, been able to resist the urge to cast tiny bullets, nothing smaller than .30. Even so a "sweet" alloy is a joy to use, it really shows the mold detail.

[Bazoo]

Yep, you can make bullets without tin but its a frustrating row to hoe. Makes a lot of difference in the amount of keepers and the overall ease of casting.

[GregLaROCHE]

You can cast boolits with good bases using pure lead. Sometimes adding tin doesn’t improve bases. It’s a lot about temperature of alloy, mould and when you cut the sprue. Tin makes good boolit fill out a lot easier. This is my opinion and what I have experienced and learned. Others may have other options.

[bangerjim]

I have added 2% or more to all my alloys for the past many years! Makes a wonderful difference. A little goes a long way, so the cost in null.

That and preheating all my molds to FULL CASTING TEMPERATURE on an electric hotplate rather that the old school way of sitting them on the edge of the casting pot. I also pre-heat all my feed ingots to just below (10-15°F) liquidous temp so they melt in almost immediately in the pot! I have a digital controlled lab plate so I can set the temp easily.

But Sn it an amazing addition. It lowers the surface tension of your melt to allow better fills. That is the reason lino type metal is rich with Sn....to fill in all the letters. Casters that do not use Sn do not know what they are missing. It is a totally different result than just raising the pot temp, as many say the do to avoid the small added cost of Sn.

Glad you joined the Sn choir!

banger

[Tazza]

I found the same, i use range scrap, works great for western action projectiles, the mould fill out is just fine (not perfect), but for other sizes i do, adding a bit of lino for the tin and antimony, the mould fill out is nicer and you can see it by the colour/frosting on the dropped projectile from the mould is different.

[Winger Ed.]

Minor little imperfections don't really bother me for hand gun stuff, but I get pretty particular for the rifles.

I never did all the measuring & weighing, but if the results warrant it, I'll run a few feet of 95/5 solder into a 20 lb. pot.
That usually straights things right out.

[Goofy]

Tin? Don't leave home without it.

[Mal Paso]

My first casting mentor was a Jew and I am a Scott so 1% Tin is the rule.

I can only explain a Scott's view. As a Scott it's important to know the difference between Thrifty and Mean. If you take Thrifty so far that you defeat your purpose, that's Mean. 1% Tin is Thrifty, less than that is Mean.


LOL

[popper]

Guess I'm mean as I don't use tin for anything other than 'terminal' performance. I also don't cast 22s. Remember you are pouring heat, not Pb. Little bullets don't have much so higher mould/alloy temp. Yes, Al moulds cool faster. I don't have rifle moulds with more than 2 holes as I can control heat better.