Slightly oversized cast bullets: OK?

[Casty]

This may be a dumb question for you experienced caster guys, but I'd rather be safe than damaged by barrel splinters....:

Would it be OK to load and fire a .459 or .460 bullet in a .458 (groove dia) bbl, black powder, 1:20 lead mix? Seems like it would just make for a nice gas-proof bullet when it obturates (but these are flat based bullets, not cavity, and not gas check), but maybe it would also make for too-high a pressure curve?

What do you say?

[Larry Gibson]

Casty

It is quite safe. It takes little pressure to size a cast bullet. With such the bullet is sized in the 1st bearing length of travel in the barrel. This is very early in the time/pressure curve and is most often un measureable. I know because i have tried to measure such during pressure tests. Most BP loads with that alloy will bump up the bullet before it enters the bore anyways and then it is sized down. I regularly shoot .4615" sized cast bullets in my .458 TD barrels all the time. I also shoot most of my cast bullets at .002 - .003" over groove diameter of the barrel. Accuracy is better that way.

Larry Gibson

[Bomberman]

Two thousands of an inch will not make any difference...actually that seems just about perfect...you want a boolit that is a little oversized. Shoot away!

[MBTcustom]

Not only is it all right, it is ideal. Most guns need boolits that are .001-.002 larger than the groove diameter of the barrel that is kissing them good by on their way to the target and the mold manufacturers make their molds to give you this option. Every mold I own casts boolits that are .002-.005 oversize.
The amount of pressure that is generated by the cartridge is enough to swage any amount of oversize boolit without even breaking a sweat. I once had the idea that I would like to push a sierra gameking through a sizer to reduce the O.D. by .001, I almost broke the press off of the bench trying to get that blanking bullet through a Lee sizer die, and yet I routinely ask my rifle to do worse than that, and think nothing of it. (by the way, don't try to duplicate my jacketed bullet sizing experiment unless you have a buddy with a lathe that can bore the bullet out of the sizer.) on the other hand I have used the same setup to size .013 off the diameter of a .360 cast lead boolit and I pushed that through with no problem.
Based on that experiment, I would think that cast lead boolits don't create near the pressures that J-words do.

[geargnasher]

Casty, read my post on your self-introduction thread, particularly the part about sizing for micro-groove rifling.

If there is one key to success with loading and shooting cast boolits, it is that PROPER FIT OF THE BOOLIT TO THE GUN AND THE BRASS TO THE BOOLIT IS ABSOLUTLEY ESSENTIAL. Unfortunately, there are only some guidelines to get you started, your gun and target will tell you what it likes best, so listen up when you pull the trigger. I've fired as much as .005" over groove dimension in .45 before with no ill effects. It does raise pressure some, but not drastically. Undersized is your biggest concern, for that will cause leading and accuracy issues guaranteed.

Gear

[MtGun44]

Not only safe - but the smaller ones are likely to not work well.
Normal is about .002 or .003 over groove diameter for most rifles.

Bill

[Bret4207]

Casty, read my post on your self-introduction thread, particularly the part about sizing for micro-groove rifling.

If there is one key to success with loading and shooting cast boolits, it is that PROPER FIT OF THE BOOLIT TO THE GUN AND THE BRASS TO THE BOOLIT IS ABSOLUTLEY ESSENTIAL. Unfortunately, there are only some guidelines to get you started, your gun and target will tell you what it likes best, so listen up when you pull the trigger. I've fired as much as .005" over groove dimension in .45 before with no ill effects. It does raise pressure some, but not drastically. Undersized is your biggest concern, for that will cause leading and accuracy issues guaranteed.

Gear

As usual, Gear hit the important stuff spot on. Proper fit demands a boolit large enough to align well in the throat/leade area and fill the grooves. Proper fitting brass, something I never remember to mention, will allow the boolit to fit the chamber at it's proper size. Start there and you have at least 1/2 the battle won.

[btroj]

I would say well over half won Bret. Good bullet fit will overcome many other ills but little can be done to overcome poor bullet fit.
One of the biggest complaints you will see here is people with moulds that cast too small. It is rare to see someone unhappy because the mould they bought casts too big. There is a reason for this.

[bowfin]

geargnasher, I tracked down your post on microgroove rifles, since I have an older .444 Marlin. This answered most every question and concern I had left on where to start.

What little success I have had in life came mainly from taking good advice from others, rather than trying to reinvent the wheel.

[ShrinkMD]

I have a 629 and the Marlin 1894ss, and I want to try and find a load for both. I was going to order some cast bullets in different sizes, so I can just shoot each batch and decide which shoots best. I tried .430, and in the rifle they were all over the place (maybe it was me, but I shoot better than THAT at 50 yds - load was 240 lswc and Unique 10 gr) Hard to tell in the pistol since I'm still getting used to the recoil.

Is there any problem trying to use the larger .431 or .432 in both? I am hoping to standardize some loads, and not looking forward to needing two different sized bullets for my rifle and pistol.

[Bomberman]

I have a 619 and the Marlin 1894ss, and I want to try and find a load for both. I was going to order some cast bullets in different sizes, so I can just shoot each batch and decide which shoots best. I tried .430, and in the rifle they were all over the place (maybe it was me, but I shoot better than THAT at 50 yds - load was 240 lswc and Unique 10 gr) Hard to tell in the pistol since I'm still getting used to the recoil.

Is there any problem trying to use the larger .431 or .432 in both? I am hoping to standardize some loads, and not looking forward to needing two different sized bullets for my rifle and pistol.

First off, you need to slug your barrels and slug your cylinder for your revolver. That way you will know exactly what your guns can shoot. You will want a boolit that just fits inside the throats or is a little larger...enough so you can push them through the cylinder with a little push. If it's .430 then you can safely go to the .432 if you like. Just make sure to load at the low end of the recommend powder charge and work up to where you want it to be and look for signs of pressure.

Also, when trying out loads for accuracy, shoot off of a rest of some kind. Then you will know for sure that it's the rifle/handgun and ammo combo and not your shooting skill. Once you figure out the load you want and are getting good groups, then start honing your skills. Good luck.

[1Shirt]

Better big than small! Agree with Gear!
1Shirt!:coffeecom