gas checks wont stay on

[waco]

i have a marlin 45-70
my mold is an RCBS 405 round flat
hornaday GC
the gc shank of the boolit is to small
even after running them through my lyman 450
they just fall off
alloy is 50/50 ww, 22lr indoor range lead with a little tin added
anyone else have a problem with this mold?
is there an easy fix?

[randyrat]

I would figure a way to hone a little bit off the mold but then i've been known to do some real brilliant things and some real stupid things. My thinking would be to "lament" the mold where the gas check fits.
First remove the sprue plate, get the mold hot, set a nut on top and pure some lead until it almost overflows the nut. Then put some grinding compound only where you want make the bullet bigger. Use a wrench on the nut and work it back and forth.
Like i said, this may be one of my stupid ideas....************Take care not to remove too much material.***********
Another idea is to use a different alloy to make bigger boolits.....Softer alloy? or Harder alloy?
Be sure it's not your gas checks in need of softening/ annealing.

[thenaaks]

you might try some really fine sandpaper...like 1000 or 1500 grit. roll it up really tight, then a few swipes on the too small gc shank should open it up. just don't hit the other parts of the mold. wet sanding with the 1500 grit should leave it almost polished so your bullets won't stick. i don't think perfect roundness is an issue...as long as the gc sticks, the sizer will take care of that.

[Will]

If they fall off inside the case they can create a pressure problem and if they fall off when the boolit leaves the gun thet can spin off as much as 30 degrees from aim. When they fall off after firing the have enough force to destroy a chrony or break a nearby window. I speak from experience.

[Leftoverdj]

If you are using spray on graphite mould release, clean it off and try again. Mould release can reduce bullet diameter enough to cause this problem. If the problem really is in the mould, you'll need to lap.

Randy's on the right track, but too complcated. Put a bullet nose first in a spare drill chuck. With the mould in handles, put a dab of fine valve grinding compound in the shank portion of the cavity. Insert shank of the bullet and rotate by hand as you increase pressure on the mould handles. Do not use power to rotate. When the mould is tightly closed and the bullet turns with little resistance, it's time to clean up, casr a few and check them.

On aluminum, you will have opened the shank about .002. Haven't done this on iron, but believe it will be about the same.

[XBT]

If you are using spray on graphite mould release, clean it off and try again. Mould release can reduce bullet diameter enough to cause this problem. If the problem really is in the mould, you'll need to lap.

Randy's on the right track, but too complcated. Put a bullet nose first in a spare drill chuck. With the mould in handles, put a dab of fine valve grinding compound in the shank portion of the cavity. Insert shank of the bullet and rotate by hand as you increase pressure on the mould handles. Do not use power to rotate. When the mould is tightly closed and the bullet turns with little resistance, it's time to clean up, casr a few and check them.

On aluminum, you will have opened the shank about .002. Haven't done this on iron, but believe it will be about the same.

I have opened up an undersized gas check shank on an iron mould using the method described above and it worked fine. I didn’t have a spare chuck handy so I very carefully used a pair of pliers.

It’s an easy fix for an undersized shank.

[GabbyM]

A 45 pistol gas check takes a .425” shank while the 458 rifle takes a .4265” shank.
Maybe a pistol check would fit?

[canyon-ghost]

I don't want to sound off or anything but, have you tried seating the gas check under some extra pressure? Hornady's are supposed to crimp on, I had some trouble with them wanting to fall off and found that if I used my gas check seater and pushed down with some pressure that they'd stay on. I just shoved down on the Lyman about 50# worth on every check. I had about three that wouldn't work at all, just threw them back to remelt. The rest worked as long as I seated them with much determination.

[RayinNH]

Anneal a few first before messing with the mould. They may just be springing back to be loose on the shank...Ray

[rockrat]

You might try straight WW metal. It should cast a bit bigger in dia and might be enough

[waco]

ill take the above under advisement!
waco

[hiram]

Consider beagling just the base end of the mold to make the shank larger.

[Skipper]

Super Glue

[Zeek]

Measure the check shank on a boolit of that caliber that DOES fit the Hornady checks, then order a decimal "chucking reamer" that diameter from a competent tool supply house, and hand ream the too-small shank part of each cavity out to that diameter. Done! The check shank is the most readily opened-up part of a GC mould. Just go slow, use cutting oil, and turn it by hand. When done, wash the mould out with an old toothbrush, hot water, and hand soap and it'll be ready to go.
Zeek

[Blammer]

get gator checks.

ok had to say it.... lol

all good suggestions, I'd pick one an go for it.

[waco]

i found the problem!!!
its the rcbs mold!
like i said. it is an rcbs 45-405 fn
my buddy at work has the same mold.we both usually cast these boolits from wheel weights
he was stunned to hear that my boolits weighed on average 426-428 BEFORE lube and gascheck. he said his where around 410gr.
so........my wheels start turning.
if you look at the gascheck shank of the boolit, it has a slight tapper.
could they(rcbs) have run the cherry too deep into this mold block?
i asked my friend to bring one of his boolits to work so i could compare it to one of mine.
sure enough!
my boolits are about .040" longer than his!
no wonder my checks wont stay, or even go on at all!
will be calling rcbs sometime this week. i hope that their customer service is what everyone here says it is. i have never had to call them about a problem with any of their products.
ill let you guys know what becomes of this.
hopefully a new mold
this one has only cast out about 100 boolits
i was just happy to figure out that it was the mold, not me!

[drobinson]

Waco, how did this turn out for you? I have a RCBS 405 that is doing the same thing.

[waco]

rcbs replaced the mold no questions asked
great customer service

[milsurp mike]

I tried melted wax to get the Chex to stay on and the worked fine.I dont know where the check went after firing but the boolit went where I aimed it.mike