"Tit' on boolit base

[kelbro]

New mold with a new issue for me.

Is this from cutting the sprue too early or too late?

Sprue plate too loose? It's plenty sharp.

Does it affect accuracy? Had some unexplained erratic shots yesterday.

[BOOM BOOM]

hi,
It could definitely affect accuracy, especially if it is off center.

[Bad Water Bill]

This is time for pictures to be posted so someone can help.

[NSP64]

What mold, how many cavities are affected?
Have you weighed the boolits?

[kelbro]

RCBS 44-250K mold. Weights are very consistent at 262-263 gr. It's just enough to keep the boolit from sitting flat. One or two swipes across a file and it's gone. May be able to get pix later today.

[Bret4207]

I've had these before.I put it down to the spure plate being a little loose and me striking it at an angle. I did have a few sprue plates that were not flat that would do it. It may be just me, but it tend to happen more if you wait a little too long.

[Gtek]

Close mold, swing plate into position. Take very strong flashlight and shine down 45 degrees on back side, see if any light leaks in center. I have taken plate off and pushed on known flat plate with 600 wet to confirm, plus you can lube pin going back on. Gtek

[kelbro]

Thanks. The plate was a little loose. I tightened it down a little. I cast about 400 with this mold yesterday and it may be a while before I cast any more to see if it's fixed. It didn't happen on every boolit so I thought that it must be a consistency thing. Mold was kept hot, melt stayed at 680 +/- 10 for the entire session.

[44man]

I will be a little different!
I have the same mold but I have never found anything around the sprue cut to mean anything with any mold unless you need to seat a GC flat. You don't want a "tit" there.
I have experimented with the RCBS boolit a lot and it is hard to make accurate. But I have the same trouble with all Keith styles and I can only relate it to a poor bore alignment depending on the shoulder to pull the cylinder in line.
I fooled with it over and over to find as I made the boolits harder and harder, accuracy kept getting better. I got the very best groups at 28 to 30 BHN.
Take one of your boolits and stick it in the muzzle. See how much you can move it back and forth? The nose has no guidance at the forcing cone.
These are some targets, first is 22 BHN and next is 28 to 30 BHN, 25 and 50 yards. SBH.

[44man]

Yes, I know, I am that way, can't help it after thousands of Keith styles in every weight and every caliber. I never made them shoot like I want, some were a total disaster. I have been fooling with them for over 56 years and the old original 358156 and the 429421 were the best. I was actually shooting under 1" at 100 yards with my model 27 (8-3/8" ribbed barrel and a scope.) and the 358156 HP long ago. I was shooting over 400 yards with the 429421 using a flat top and model 29 back in 1956.
Just maybe I had perfect throat to bore alignment with those guns. I kick myself every day for selling them.
I feel any Keith needs a perfect gun. I really think the old guns were better. I could buy, sell, trade guns and all would shoot but today you need to depend on the boolit nose to align things. Variation from gun to gun is too much.

[williamwaco]

That is quite common with a loose sprue plate.

Not to say that there couldn't be other causes.




Happy New Year.


.

[NoZombies]

I also would suspect loose sprue plate.

I've not noticed a difference in accuracy as long as I have good base fill out otherwise.

[grouch]

Usually if you cut your sprue with a gloved hand instead of beating it with a stick that lump disappears
Grouch

[357maximum]

Sounds to me like you are being a bit inconsistent with the timing on WHEN you cut the sprue. The ones with that lump should have been cut a few seconds sooner. This is all conjecture without pics to back it up however.

I have been using the BaBore method wherein you fill the mould in a consistent manner with the ladle, give it a timed rest in front of a fast fan, and then cut the sprue . This has helped in my consistency in a substantial way both in boolit wieghts and accuracy. I cut the sprue when it leaves just a little ...small....consistent divet on the base. You do not need a metranome to do this, just count it out each and every time. The goal is to leave a nice consistent but small divet in the base not a huge crystalline looking crater. The less antimony in the mix the better this method works for me. YMMV

[DLCTEX]

Cut the sprue just as the sprue flashes dull. It's best to have lubed the mould and sprue plate with Bullplate (or a good substitute) to prevent smearing. I also use gloved hand to cut sprue and push down slightly while opening the plate. No tits.

[kelbro]

Thanks. I do a 10 count before I cut them with a gloved hand. The sprues usually change color and 'suck in' at about 7 or 8 seconds.

New mold, just need to discover its idiosyncrasies.

[DLCTEX]

I'd say you are letting the sprue harden too long before cutting.

[wallenba]

After cutting through the sprues, but before you open it up, park the sprue cutter so that a flat part is over each 'bump'. Then press down and hold for a second or two before opening. This helps me control some molds that tend to leave spue bumps.

[kelbro]

Good advice. Thanks all.

[BulletFactory]

I had a mold do that when it was too tight as well.