How good is your base?

[FabMan]

I have been casting and powder coating for years, but am paying more attention to the Accuracy of my rounds. Boolit base does effect accuracy and some of mine have imperfections from running them thru a sizing due and distributing excess material to the base. If there is a little Lead flashing at the flat base it is deposited unevenly and this should cause accuracy issues. Spruce cuts are not always the best with small voids.
My typical reload groups are approx 20% larger than factory FMJ. Lots of variables to throw in there. Are perfect bases possible?
How good does the base have to be for good handgun accuracy?

[charlie b]

For plain base bullets usually need to remove any flashing before sizing or coating. My cast pistol loads used to run neck and neck with jacketed as long as they fit the bore correctly. Is it possible you are sizing too much as well?

Would also help to know what bullet and what pistol you are casting for.

[Bazoo]

Pends on the gun and distance. It makes a lot of difference as the distance increases. My GP 100 will cut 1 5/8" groups at 25 yards with bullets of not perfect bases. Dunno what factory does really as I rarely shoot it. I'm not overly joyous with that accuracy but I'm not unhappy either.

Some folks consider 25 yards long range for a handgun. I shoot them out to 100 and expect at least 6" at 100. Some folks expect 2" at 100 and can get it. Maybe one day I'll be there too.

[El Greco]

Clean bases? Why?
Too much work for a paper punch. I’m a lazy old man.
267759

[FabMan]

My main issue is with plain based molds of all makes and styles. I have surface ground some spruce plates and squared up the molds. Adjusted temps, alloys and dwell time. I still get some flashing. And voids on the base. I size one or two thou over bore size. Is it possible to have good bases without gas checks? As far as accuracy, there are too many variables including me. My quest is to have better looking boolits.

[44Blam]

Perfect base is my first check when casting. If there is a hole or the base is not sharp it goes back immediately. If I am casting HPs, the next check is the nose / hp fillout. If it isn't perfect - back in the pot.

Then I look at the rest of the boolit, if it is not wrinkled it is a good one. Keep it.

When casting I am more lenient with pistol rounds (I'll get the occasional wrinkle) but with rifle rounds I only keep perfect boolits.

It has been a long time since I saw lead pushing past the base but I do remember it. I would cut it off with my pocket knife when I saw it.

[Winger Ed.]

Spruce cuts are not always the best

I put gas checks on my .30 cal. stuff and sometimes get sprue cuts and bases I'm not happy with.

What works for me is lay a sheet of 400 grit wet or dry sandpaper on the table top
and pull the base flat across it for about 2-3 inches.

I never bothered with short range hand gun rounds, but try it, it might work for ya.

[monadnock#5]

Pends on the gun and distance. It makes a lot of difference as the distance increases. My GP 100 will cut 1 5/8" groups at 25 yards with bullets of not perfect bases. Dunno what factory does really as I rarely shoot it. I'm not overly joyous with that accuracy but I'm not unhappy either.

Some folks consider 25 yards long range for a handgun. I shoot them out to 100 and expect at least 6" at 100. Some folks expect 2" at 100 and can get it. Maybe one day I'll be there too.

I agree with this. What your goal might be also enters into the equation. Are these for a match? Maybe someone at the range you'd like to beat just once? My scoped Super Redhawk is one thing. With most of my other pistols, keeping them all in the black, or consistently ringing the 12" gong at 75 feet makes me happy.

[FabMan]

These rounds would be used by my son for IPDA matches. Nothing serious tho. He’s just starting out. 9mm, .40, .45 ACP. I am playing around with 147 grain 9mm too. I cut back on my tin to decrease flow out of the flat base. Reduced temps and rotated molds to keep them cooler. I think I need to be happy with what I have and just cull the imperfect ones.

[metricmonkeywrench]

Somewhere abouts on one of my devices I have a link to "reading" bullet bases to tell you what's going on based on the finished cut, something to the effect of a smear is cutting too hot, a divit is too cold finned is loose/warped sprue plate etc. About the only time I can see this reading being of any value is the moment between knocking open the sprue plate and dumping the bullets. I have taken others advice and cast merrily away until I meet my goal then cull. Trying to make any since of visual clues during final culling would be too late to adjust anything.

[Burnt Fingers]

Wow, I cast, coat, size, and shoot many thousands of boolits every year and get no flashing on the base of the boolit.

1. What diameter is your mold dropping?
2. What diameter are you sizing to?
3. What is your alloy?
4. Do your molds have lube grooves?
5. How are you sizing?

Something is failing for you to get flash due to sizing.

[Conditor22]

use spray case lube
size right after PCing
don't size down more than .002 at a time (if needed use sizing dies in .002 increments to get down to the desired diameter
Make sure the boolits have complete fillout when casting if not add a little more tin or raise the temperature of the pot -- always preheat your mold
ANY defects on the perimeter of the base can throw you boolit off when it leaves the barrel

[kevin c]

I need bullets in bulk, up to thousands each month. I can't baby each slug individually to maximize accuracy, and my application (action pistol sports) doesn't need it anyway. They may be nigh on perfect out of the cavities, but they aren't by the time they're loaded into the cases.

So my 95-3-2/96-3-1 alloy isn't hardball tough to resist dings the way commercial producers need, and with the tumbling and dumping for coating (twice) plus the drop into a bucket for sizing, the slugs do get rough handling. Inspection shows some marking up of the perfect-out-of-the-mold bevel bases, but hitting a 6"X11" target at ranges of 5' to 75' doesn't need a perfect boolit base (though that doesn't mean I don't try to cast as well as I can).

[RogerDat]

Weight of bullet would I think indicate void or even oversized sprue teat. Weight may offer a quick way to sort bullets into a "high accuracy" pile. Assuming one has a digital scale suitable for bullet weighing.

For the lead pushed down by a push through sizer there is a hand or power drill chamfer tool available from NOE that is I recall less than $20. I use hand one just to clean off edge from sizing and maybe provide a tiny bevel on bullet base before applying gas checks.

[FabMan]

The flash on the base is due to casting. I’m sure everyone gets at least some on plain bases.
Even a little flash is curled over to the base during the sizing process. I use 6 and 8 cavity molds as I need bulk and have time restraints. My 9mm cast around .359 and I size them to .357 to fit most barrels. I could drag the base accross an abrasive to clean them up I guess. I’m gonna shoot some groups with a few near perfect slugs to see if the effort is worth it. I will leave perfect bases with no Imperfections to others that have more time than me.

[fredj338]

Perfect, probably doesnt exist. Good bases though are very doable. I will trim any flashing if it happens. I toss them back if the bases show any void or edges not uniform. Most of the calibers I cast will beat FMJ with open bases.

[blue32]

For pistols - whatever. But for rifles, if it doesn't have a square base I'm not wasting a check on it. There's enough to put a rifle boolit off course at 100 let alone 300 meters but its not worth the alloy to me if I can't make the best cast possible.

[FabMan]

Just a thought, what if the thin flashing that was turned down to the base by sizing burned off in the barrel and it exited flat? I can’t imagine 2-3 thousands lasting the whole trip down the barrel. I did look at some supposedly good bases with a magnifier and still see issues after sizing. I do powder coat everything.

[country gent]

My best bases are from nose pour moulds. They are very sharp and clean very flat with the sprue cut on the nose.

Several thoughts on this are ( ive never powder coated 1) If sizing after coating is the added size creating an issue/ Or sizing down to compensate for it? It used to be accepted that sizing over .002 created problems. 2) A light lubricant applied sparingly might help. A water soluble would aid clean up after sizing a dish soap or wire pulling lube might help. How are you sizing nose up or down? With base down the major force should push up into body or grease groove.

Another lace to look for the cause is fit between ejector pin and sizer die body. To much clearance between the 2 will allow lead to flow into the gap. The pin should be a very good fit under .001.

[wv109323]

You should not have flashing on your bases when they drop from the mold. It sounds like your sprue plate is loose or warped. I would work on eliminating the flashing when the bullet is cast.
You can improve your bases by standing the bullets on their base when baking the powder coat. I know it is time consuming but it gives you a flat square base and the pc fills in some voids.
But I think you are over thinking the issue. For the distance of action pistol shooting , I don't think it is worth the time to be overly strict on your boolits. The fit to the bore is much more critical.
I shoot NRA bullseye. I cast up some 200g. swc . I then picked out the bullets with the worst bases I could find in the pile. I loaded them up and fired them through a Ransom rested wad gun. These bullets grouped 3" at 50 yards. I normally average 1 1/2 to 2 1/2" with sorted boolits. My thoughts are close ranges like sction pistol you will never be able to tell the difference in your dcores.

[cstrickland]

I cast for 9m action pistol . I shoot action steel matches. I cast , water drop, powdercoat water drop, size and load. I only cull out anything that does not have fill out be it driving bands or a rounded bottom. I typically have very very few. Maybe only 1- 2 per K . My bottoms some times have small nibs . I have even had ones that caused the bullet to sit slightly off when powder coating, and I have never noticed any difference for what I shoot.

unless you are shooting for bullseye or similar then you should be more than fine.

[cainttype]

The OP states the flashing is from sizing in post #1.... Sizing base-first will eliminate base flashing from lead displacement.

[Bazoo]

Polishing your sizing die will eliminate help flashing from sizing.

[FabMan]

Just to clarify, the flashing starts at the mold, at the base. My nose first push thru sizing dies take that extra material and curl it down creating an edge. I’m talking about very small flashing, not something obvious you would return to the pot. Check out your flat bases with a 5x magnifier and see how imperfect some are. Gases exerted on these imperfections as the slug leaves the barrel may cause issues, especially with longer range rifle shots. I’m not a perfectionist by any means, just looking for an easy way to smooth out the base for bulk casting. I did try a RCBS motorized outside case chamfer tool and that worked somewhat well.

[charlie b]

If you need a 5x magnifier to see the flare I don't think it will be a problem unless you are shooting several hundred yards, like with a .45-70.

My rifle bullets get a gas check, seated square to the bullet base.

Take your bullets and shoot them and see if you have an accuracy problem. Compare to commercial loads. Sorry, noticed you already did that, 20% bigger groups with your cast. 1" compared to 1.2" I'd probably be happy with that.