Lapping a lube die

[hogstad7]

I have a Ruger Redhawk 44mag. Bore slugs at .431" and throats at .432- .433".

Bought a .430" Lyman lube die with it. I had not even heared about slugging the gun, as this was around the time I got into casting.
Bore leads and so-so accuracy at 25y, with .430" quenched ww. Borrowed a .431" die from a friend, and got some improvement. But still not good enough.

I am considering lapping my .430" die to .432-.433. My only concern is lube leak between the die body and the stem. This will be the first time I am trying lapping.
Do you think it would be a problem?

Mold is NOE 429421 dropping at .434

[OS OK]

These dies have a tight tolerance to keep that lube where intended. Hand lapping is not an accurate way for this application. The center section couldn't be increased to match and keep tolerance either in any way I'm aware of. Magnaflux like a set of engine heads and turn down to size…it's over my head about 3 feet!
First time I ever heard of this question…just buy the size die you need…save a boatload of time, frustration and money.

charlie

[runfiverun]

it's a simple procedure and there is about 10 different way's to do it.
depending on the tools you have on hand it's either fast or a little faster or maybe too fast.
.001 is about 1/2 the thickness of notebook paper.

get a dowell, cut a slit in it with a hack saw.
wrap some 800 grit wet/dry sand paper around it.
put some oil on the paper.
work it all into the hole and spin the dowel in a circle. [rolling it up and down your leg works]
give it about 8-10seconds of spinning.
measure by pushing a boolit through it.
when you get close, polish the die with a bore mop and some flitz or tooth paste or a paste made of baking powder.

[country gent]

It can be done and its not hard to do but removing a couple thousandths can be time consuming. You want a lapp 2-3" long Perferably lead but brass or copper will work also. you wand a light snug fit. A piece of flat stock to impregnated the lapp. Once your lapps are made spread a small amopunt of 240-280 grit clover compound on the flat stock sthinly and evenly, roll lap on this with some hand pressure. It is easier to roll between 2 plates. WOrking slow and with a high feed thru front to back work lap thu sizing die with 3/8-1/2 turns and a feed thru so lines look about 45* angle. Do not go in out of either end keep die entirely on the lap. Rotate die 180* every 8-10 strokes. then another lapp impregnated with 320-400 grit and work to even finish. LAst lapp and 600-800 grit impregnated to finish size. The thru holes will need to be checked to insure they arnt sharp after this.A little lapping compound on a piece of felt or rubber can be used to chamfer these edges.

[hogstad7]

Maybe my question got lost in translation. Im not asking how to lap, but how much I can lap before lube leak becomes a problem.

[country gent]

SO sorry I would think .002-.003 total should be okay before a new pin needs to be made up. A gage pin in the new dia can be cut to length and used also. If you lap the die to .432 then a .431 pin should do fine. some of this will depend on lube used also. softer lubes will push thru a smaller gap than harder lubes

[454PB]

It all depends........

If you use a heater on your lubrisizer, it may leak. If you don't use a heater, and the ambient temperature is 70 degrees or below, and your lube is the viscosity of commercial stick lube, it shouldn't be a problem.

The other alternative is to have someone make a new center pin for the sizer die.

[hogstad7]

I use BAC in a 450 without heat. Room temp is usually around 20C degree.

A fellow shooter in the gunclub is a machinist, so he could probably make me a new stem if the leak is to bad.
Was just curious about your experiences.

[Geezer in NH]

I Love the Pin Gauge solution. Great Idea!!

[JonB_in_Glencoe]

I've lapped out a couple lyman dies .001 as well as .002
I didn't notice any leakage.

[hogstad7]

I have now lapped the die .0025" and sized 100 bullets with BAC at 20c degree roomtemp and no heat. Havent noticed any lubeleak yet.

[Mal Paso]

I have now lapped the die .0025" and sized 100 bullets with BAC at 20c degree roomtemp and no heat. Havent noticed any lubeleak yet.

You haven't lubed enough yet. The pin fit on the unaltered Lyman dies I have is not tight enough to stop a little seepage.

As far as buying one, Lyman and RCBS list .431 as their largest 44 Die so it's either lapping or custom.

Best of luck with your project!

[EDG]

Be sure to keep avoid tapering the hole if you can. Lap it to size and if it leaks you can buy gauge pins in .001 increments for about $3.00 each. You might have to cut off the gauge pin but you can get a good fit.
I think any clearance more than .0015 will leak if you use high pressure.

Maybe my question got lost in translation. Im not asking how to lap, but how much I can lap before lube leak becomes a problem.

[DougGuy]

If your machinist buddy has pin gages, check your cylinder throats for variance between throats. Having the throats even with each other, is *THE* single most important part of your cylinder.

When throats are uneven, they create large variations in pressure which translates to differences in recoil in the shooter's hands, causing the tighter throats to shoot to a different point of impact than the looser throats. It's better to ream or lap them to the largest throat and try to get them within .0002" of each other, THEN size the boolits to fit in the throats with a light drag fit. They should go through the throats from the front with finger pressure and each throat should feel the same amount of resistance as the one next to it.

[Don Purcell]

Buffalo Arms has custom made lube dies with center pin for RCBS/ Lyman and Saeco sizers for $48.00. May sound pricey but they will make what you want plus you will have the right center pin.

[gnoahhh]

I have a slight advantage over the average hobbyist- I have a lathe. In the past I made a bazillion custom diameter Lyman/RCBS dies (well maybe not a bazillion, but over a dozen anyway) for myself. I learned a couple things in the process: 1)explore the world of letter, number, and metric drill bits- there's a pretty good chance a drill bit diameter exists that's awfully close to the size hole desired. 2) a couple minutes with fine and extra fine grit paper wrapped around a rod is all that's needed to polish a thou or two. (Therein lies the advantage of spinning the die and not the lapping rod- much better control can be had in the process.) 3) a close fit of the center pin is necessary, as is a perfectly square end that contacts the bullet base. I don't like to go over .001" slop. It's nice if it "pops" when withdrawn from the die. 4) You don't have to use hard as nails material for a lead bullet sizer die, which makes honing to finish diameter way easier too. I actually made some out of brass in a quick and dirty attempt to prove the worth of a particular diameter. Years later they're still in use and haven't changed materially in diameter from wear.

Then, I made the switch to a Saeco machine and those dies are a challenge to make by an untrained hobbyist. What Buffalo charges is a small price to pay to avoid that challenge. (But the old Lyman sizer stays bolted to the bench, too.)

[454PB]

Yes, I make my own sizing dies for Lyman, RCBS, Star, and Saeco. I use mild steel and some of my dies have sized 10,000 boolits with no dimensional change.

Star OEM dies are as hard as woodpecker lips.