Reaming Out the Gas Check

[Uncle Grinch]

I have a Lee C324-175-R mould that I plan on converting to a PB boolit. It currently throws boolits that mic at .325 to .326 just above the gas check shank. It shoots barely OK as is without GC's.

What I plan on doing is reaming out the gas check part of the cavity with a 21/64 drill as I don't have any reamers of the needed size. I realize that 21/64 drill is actually closer to .328, but I will be sizing the boolits down to .325 .

Any thoughts on this?

[MT Gianni]

Drill straight and don't wobble. Let us know how it works. It has been done and I am considering it myself on a sc Lee Soupcan. Gianni.

[trk]

Take the drill you intend on using and drill a hole in another piece of aluminum.

THEN MEASURE the diameter the hole. You might be surprized. It's easy to make a hole larger, not so the other way.

[grumpy one]

Drill bits normally cut oversize - the amount depends on the material you are drilling, and how they are sharpened. Under some conditions they also are prone to drilling trilobally, which gives you a sort of triangular hole with rounded vertices, much bigger than the nominal drill size.

Your best chance involves an evenly sharpened drill, a drill guide (see previous post) and clamping both mould and drill-guide down to the drill table. Even then, it's a risk.

[MtGun44]

I reamed my revolver cylinder throat using one of MSC's 0.001" step sized
reamers. You can probably do a much better and proper sized job
taking the GC shank out with a reamer. It should center up on the
original bore center, and if you do it in a drill press and let the mold
float a bit in your hands to self-center, I'll bet you have success. MSC
reamers should be around $10-15 or less if you buy their Chinese versions.

My guess is that with a drill you'll just make an irregularlly shaped
(trilobed is very common, as previously mentioned) oversized hole,
trashing the mold.

Good luck either way. :)

Bill

[dragonrider]

Another vote for the reamer istead of the drill, run slow and use a lot of oil. You should be able to find a reamer at MSC as mentioned above.

[Buckshot]

...................See the "Removing a Bevel" thread below.

BTW, ditto everything said about a drill bit.

............Buckshot

[kodiak1]

Find a friend with a milling machine and do it like the pro's.
Ken

[grumpy one]

Ken, to follow that recommendation you have to put the emphasis on the word "pro". I'm no pro, and if I did it that way there'd still be a risk. To mill the bevel out requires setting up the cutter concentric with the mould cavity, within say .001 Total Indicator Reading, using a lever-type indicator set up to read on a driving band - and that's the easy bit. Then unless you are remarkably fortunate you won't have a reamer the right size and you'll have to bore the cavity. The tiny boring bar is going to be pretty springy, and may be disturbed by the mould joint-lines, causing some nasty outcomes immediately downstream of the joint line each time it's crossed. Normal boring heads are also difficult to manage for increments much below .001 on radius - though there are exotic ones that will do better. I'm pretty sure nobody in his or her right mind would pay for that kind of work on a bullet mould - you could probably buy at least ten moulds for what it would cost.

[Uncle Grinch]

I only paid $14 for this DC Lee mould, so it's not like I have a lot invested in it.

I thought about the problem we had with some of the Ranchdog 460-360 moulds that had too small gas check shanks. Somebody made a reamer from a machine bolt head and I used it to open up the GC shank ever so slightly.

This sound like what I need to do with my 8mm Lee.

[joatmon]

I did a cavity cast (cerosafe) miked the cast above the bevel and miked my bits till I found the right size and debeveled a 6 cav 358-158RF on a drill press and it turned out nice,shoots good.

[hornetguy]

I took out the bevel base feature on a Lee 375 mold. It was a single cavity. I posted pics of it in this forum a while back.
I used a mill at work, with an adjustable boring bar. It turned out really nice, if I do say so myself. It was my first attempt at doing it.
Let's see if I can get them to upload again...
These are boolits cast before and after.
I imagine a gas check removal would work just as well.

[lathesmith]

Removing the gas check shank from the mold sounds like a relatively simple job for a 4 jaw lathe chuck and boring bar. Or, like Hornetguy I removed the bevel from the base of my Lee 375 mold. I accomplished mine with a twist drill(I hate bevel base bullets). I did this by hand, aluminum is very soft and it don't take much pressure to remove the metal. I did not like the idea of clamping it to a mill table, too easy to "waller" it out. A GC shank may be a bit more difficult to align by hand, I don't know, but it shouldn't be a big deal.
Lathesmith

[Uncle Grinch]

Well, I modified one cavity today. I took a 21/64's drill and mic'd the end of it at .3285, so I moved up the shaft about an inch and it mic'd .3265. That's where I used at cut-off wheel to chop off the bit.

Placed the bit in my press and secured one side of the mould. Opened it up and turned the chuck by hand until it cleaned up the GC.

Cast a few boolits to see how they look... not too bad. I'll know more when my .325 sizer from BullShop shows up.

[Uncle Grinch]

Here is a photo of my modified Lee 324-175 PB bullet.

Still haven't had the chance to shoot any yet.