bullet mold designation vs. actual weights

[leathersmith55]

New to the site, but I'll jump in with a question that's probably been covered before. I searched around a little and didn't find what I needed, so here's the deal. I've loaded lots of pistol ammo, but new to casting bullets and loading for 45-70 rifle. I have an Ideal brand 405 grain mold (457-193), which throws 418 grain bullets with wheel weight lead. My question is: do I need to account for the extra 13 grain bullet weight, i.e. 420 grain bullet when selecting my desired load from the loading manual tables, or is it within an acceptable range? I've looked for load data for a 420 grain bullet using IMR 4198 but haven't found anything I'm real sure with. Not interested in hot loads at this point, but something on the lower pressure side. Any assistance would be appreciated.

[Outer Rondacker]

Welcome to the sight. Asking questions and learning sharing and just enjoying is why we are here. First its the mix that will determine the weight. The mold is an general or perfect condition number. 420 is fine. Just start off low on the reloading ladder. Your bullet weight is only off by 3%. Do your basics and you will be fine. You know how to reload and if you start low all will work out. Enjoy and others will be alone shortly to correct my what ever I did wrong. Once again welcome to the sight.

[shortlegs]

13 gr of unique under that boolit is sweet! About 1100 fps and no recoil. It packs a punch though. IMR 4198 is good but has more recoil. Use data for 405 gr boolit. My bullets from Lyman 457193 mold weigh 420 gr with my alloy but I use 405 data under trapdoor info. If going hotter use 420 data to be on the safe side.

[shortlegs]

Welcome to Cast Boolits, by the way! I too am new to this site and have learned more than I thought possible after casting boolits for about 40 years. I now know how little I know. You will fine a wealth of knowledge here and people willing to share it.

[Grmps]

leathersmith55 - welcome to CB If you decided to start casting to save money, forget it. You won't, you'll just shoot more.

Short answer, the softer the lead/alloy the heavier the boolit. Published load data is just a starting point. Every firearm is a little different and has a "personality of its own". It is always safer to used load data from a heavier listed boolit.
You need to do ladder tests and play with powders, boolit diameters and alloys to see what works best for your gun.

Casting boolits (lead bullets) properly is a science, once you know the basics, not a hard science.
There is a lot of good information here
http://www.lasc.us/Fryxell_Book_Contents.htm
1. Boolits need to be cast .0005 to .003 over the slugged diameter of your barrel for accuracy and to avoid leading. If the fit is wrong nothing else will work right.
a. slugging a barrel (it is safer to use a brass rod or a steel rod with a couple of coats of tape to avoid damaging your barrel http://7.62x54r.net/MosinID/MosinSlug.htm
b. chamber casting https://www.brownells.com/guntech/cerrosafe/detail.htm?lid=10614
or pound casting http://castboolits.gunloads.com/showthread.php?356251-Pound-Cast-instructions-(for-rifle-chamber)
2. the right alloy needs to be used for the velocity and purpose of the boolit (don’t fall into the trap of going with to hard an alloy
Economical way to easily test lead hardness
http://castboolits.gunloads.com/showthread.php?355056-Easier-pencil-lead-hardness-testing
https://i.imgur.com/TGUQsIe.jpg
Some alloys harden over time
http://www.lasc.us/Fryxell_Book_Chapter_3_alloySelectionMetallurgy.ht m
different alloy’s different end sizes
https://i.imgur.com/emuBC2T.png?1
Lead alloy calculator
http://castboolits.gunloads.com/attachment.php?attachmentid=45784&d=1341560870
3. velocity the bullet needs to be pushed hard/fast enough to get the proper spin, have the proper velocity to accurately reach the target but not so hard as to be dangerous or strip the lead off in the grooves instead of spinning the boolit..
Powders range from fast to slow, you need to choose the right powder for your application.
Loading manuals list the best powders for certain calibers and boolit weights.
Link to free online load data
http://castboolits.gunloads.com/showthread.php?337910-CB-load-data-online-sources

[gwpercle]

I use load data for the weight designated on the mould. Lyman 457193 , 405 grain.
So I go to Lyman Cast Bullet Manual 45-70 and use the data listed for that bullet , regardless of what the bullet actually weighs. Never load maximum loads without working them up...the actual weight of 420 grains just may affect maximum loads but many things besides bullet weight affect loads and all must be checked and worked up to.
I could find no data on 420 grain boolits either but there is 450 grain data.

You could also use data for a 450 grain bullet , this data would be safe with a bullet weight of 420 grains, and would give you a place to start development. I would still drop below maximum and work up...you can't be too safe .
Gary

[leathersmith55]

Thanks to all for the speedy responses, and great info.

[JBinMN]

Thanks to all for the speedy responses, and great info.

LOL You **** betcha they were...
;)

And WELCOME! to CB.GL forum!
:drinks: