Lead Bullet Sizing

Slug the bore and size 1 and 2 mils over bore.
Test both and get the one that works.

Cast bullets is a lot of tinkering, start the right way, slug the bore.

Its pointless if you d not do it the right way. Your next post will be asking why your bullets are tumbling or why you have barrel leading.... slug te bore, size accordingly, start the right way.
 
Quigly said:
How does slugging the bore really help when a commercial rifle may have a bore that is not exactly the same diameter all the way through. What if there is a tight spot and all you're getting is the diameter of the tight spot. Slugging a bore is more appropriate for finding those tight spots, so that you can either hand lap them down or fire lap them down. I'm better off measuring the land diameter at the muzzle as one poster suggested. That's what I will do between naps, thank you.
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You know what? Slugging the bore isn't actually the best way to do it... my comment is truthfully more of a comment on how lazy you are. You're asking for advice and when multiple people give you the same advice you say it's too much work. You're not looking for advice you want someone to tell you "sure go ahead. It'll work perfectly!" The best way of sizing a cast bullet for your rifle is to do a pound cast of the throats and lead. Then size to the largest that will chamber reliably. Next best is a chamber cast but they shrink so may give inaccurate readings. However, slugging the bore is the "lazy" way. However, that's apparently too much work for you. Good luck. You're gonna need it. May want to invest in chore boy copper scrubbing pads now before you start shooting cast.
 
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Quigly said:
Hello All,

I bought three RCBS Moulds. My question is what diameter do I size the bullets to for optimum performance.

1) 458 caliber mould 405 grain flat point gas checked
2) 458 caliber mould 300 grain flat point gas checked
3) 30 Caliber 180 grain flat point gas checked

I have a couple of 308 win rifles, and a couple Marlin 45-70s I would like to fire them in once I get them cast and sized. If anyone can help me out I would appreciate it.
Mike
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First of all, Mike, I have not done any precision cast bullet shooting at all. Have only loaded for hunting and target practice.

My limited experience has often been to just load the bullets as they come from the mold. As long as the loaded rounds will chamber, and are larger diameter than the groove diameter of the barrel, the bullets will be sized to the correct diameter by the bore. Accuracy is usually good enough for hunting out to 200 yards. I have had very little leading, even at velocities over 2000 fps in 9.3 and 30 cal rifles.

If they are smaller than the groove diameter they will almost certainly lead the bore, and accuracy will not last very long, if they are accurate at all.

Just give them a try as cast, and see what happens. Load development with cast is where you are going to have a much steeper learning curve. ;)

Best,
Ted
 
Quigly said:
Hello All,

I bought three RCBS Moulds. My question is what diameter do I size the bullets to for optimum performance.

1) 458 caliber mould 405 grain flat point gas checked
2) 458 caliber mould 300 grain flat point gas checked
3) 30 Caliber 180 grain flat point gas checked

I have a couple of 308 win rifles, and a couple Marlin 45-70s I would like to fire them in once I get them cast and sized. If anyone can help me out I would appreciate it.
Mike
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The standard is
1. .459
2. .459
3. .309

Might not be optimal.

Generally speaking, with cast bullets - bigger is better. The best accuracy usually comes from the largest diameter bullet you can chamber, and it will lead-up less too.
A lot of people shoot .460" or even .461" bullets in 45-70. A lot of people shoot .310" in their 30 cal rifles. Not all rifles will chamber bullets that big, that's why you need to check it.
 
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aric84 said:
Not everyone approaches this hobby the same way and telling someone HOW they are supposed to go about their hobby is a great way to discourage people from learning and enjoying it. Maybe some should spend more time experimenting and less time patronizing...

As for the OP, let us know how you make out!
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That's the thing with shooting cast boolits...experimenting has been going on since rifled barrels were invented, literally hundreds of millions of rounds and the smart ones wanting to join this aspect of the shooting sports will heed the advise of those before us that have learned the hard way. Shooting cast can be the most frustrating thing to ever try and for sure the cheapest way to success is to take good advise as it was intended, especially if you ask for it.
 
I've found that the bore dimensions aren't as important as the throat dimensions. Slugging the bore is helpful, but it's not the only way or even the best way to go about determining what cast bullet diameter to choose.

I've found this video on youtube, this guy's philosophy for cast bullet sizing is the same as mine: "the largest bullet you can fit in the throat will shoot the best" . Watch the first 2 minutes if you don't want to watch the whole thing.

 
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I've been shooting almost 100% cast in all of my rifles for the last 4 years. With precise casting practices and lots of testing I have many loads that will hold a minute of angle out to 200 yards of I do may part. I even shoot cast out to 500 yards with very good results.

I generally slug the throat and size my bullets at 1-2 thousands over that.

OP if you don't want to slug your bore that's fine but remember an undersized bullet can and will pack your bore with lead. If you don't notice it and fire roo many rounds you will be sorry.

When I first started loading cast I decided not to slug the bore of my rifle and loaded bullets taht SHOULD of been 1 thousand over the bore diameter. I proceed to shoot 20 rounds with a softer alloy then I'd use now.

They all tumbled and hit the 100 yard target sideways, I fired 4 groups of 5 before I realized what was going on. The bore of that rifle was absolutely packed with lead, took me the better part of a month to get the lead out and man was I sorry I didn't slug the bore.

Cast shooting especially in rifle cartridges can be a very involved process to become good at. It's labour intensive and you'll often have to do lots of testing before you find a good load.

If you are unwilling to slug that bore that's OK just pay attention to your bore and watch for leading after a few shots. If you have leading, you either need a larger bullet, a harder or softer alloy, different or more lube or a combination of all of them.
 
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I shoot several hundred rounds of lead in rifles every month and I don't have any more cleaning problems than I would if it was jacketed bullets instead. People make it harder than it needs to be.

- The biggest mistake is shooting cast in a bore that's already fouled with copper jacketing. Start with a clean barrel and it's a lot easier.

- The bore needs to be sealed to prevent flame cutting. To seal the bore, you need a bullet that's bigger than the bore. Undersize bullets will flame cut deposit melted lead in the barrel, and bullets that are flame cut don't shoot well, expect key holing and poor accuracy.

- Most modern factory rifles are fairly consistent in bore dimensions. The older rifles is where the largest deviation in bore size occurs. The 38-55 was mentioned earlier - some of these older rifles have generous throats and bore dimensions to start with, and some of them have eroded or corroded a bit over the years too. The older rifles aare generally the ones that benefit the most from slugging a bore.
 
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