Flex hone to open a Lee size die?

[Wheelgun]

I’m curious about using them for opening lee sizers. Would these be able to open a .311 to say .313 and keep it round??


A buddy says he used one to opened his revolvers throats slightly. Making them all a consistent .358 and keeping them round.
I haven’t handled it to see or been able to check with my pin gages to confirm.

[Tall]

That would be a really tiny flex hone! I do not recall ever seeing one that small. The smallest ones I own were designed to work on drum brake cylinders. I think the smallest ones may be .700" ID.

[BLAHUT]

Yes, With care; check at brownells ?

[DougGuy]

The sunnen hone would keep it round, you can get an Acro lap off fleabay that would work quite well for you with some fine lapping compound. Flex hone is not the tool for a job like this.

The acro lap will cut QUICKLY so don't crank down on the collet real hard, you would likely want to finish .0005" under to allow for springback. Lee does!


That would be a really tiny flex hone! I think the smallest ones may be .700" ID.

I got them in pistol calibers from 500 S&W all the way down to 22 caliber.

[Wheelgun]

This is the link my friend send where he bought his.
Shows 32 up to 45 cal
32 only comes in 800grit, would that be ok?

https://www.amazon.com/Research-07584-Revolver-Chamber-Flex-Hone/dp/B00DB8CLLY/ref=mp_s_a_1_3_maf_3?crid=2VFTDKNB0YKWF&keywords=revolver%2Bflex%2Bhone&qid=1699308119&sprefix=revolver%2Bflex%2Bhone%2Caps%2C274&sr=8-3&th=1&psc=1

[metricmonkeywrench]

Go to the main site, they have multiple sizes/grits, not all are listed on Amazone.

I got a (I believe) 600 and 800 to clean up some .38 dies. I used a bore mop with some automotive rubbing compound to finish them out.

Some folks just use various grits of sandpaper on a split wooden dowel to do this kind of work.

Just go slow whatever method you use

http://www.brushresearch.com/brush-types.php?c1=4

One of the manufacturers (noe?) sells sizing dies and custom make others for specific sizes, I believe they use a Lee die body as the holder.

[Kenstone]

Split/Barrel Lap
Recommended over a flex hone.
A flex hone will flare out (bell-mouth) both ends of the hole.

Barrel Laps:

https://www.mcmaster.com/4548a15/

https://www.mscdirect.com/browse/tn?searchterm=Barrel+laps&refinements=Lap+Diameter+%28Inch%29%3A5%2F16

That MSC lap is pricey though.
.

[hollywood63]

I opened a couple by wrapping some 320 around a 1/4' bolt , removed the lock nut put a little oil; on the emery put the bolt through the die and rolled it on a bench opened it up a couple thou in no time. Was a tip from a member here

[Polymath]

Split/Barrel Lap
Recommended over a flex hone.
A flex hone will flare out (bell-mouth) both ends of the hole.

Barrel Laps:

https://www.mcmaster.com/4548a15/

https://www.mscdirect.com/browse/tn?searchterm=Barrel+laps&refinements=Lap+Diameter+%28Inch%29%3A5%2F16

That MSC lap is pricey though.
.

I've made a number of push-through sizer dies with split dowels and emery cloth (stands up better than sandpaper) When you get close try a few as you can always go more but can never put it back.
Also made Luber-sizer dies the same way, because they were unavailable during the plandemic. Waited 2 years to get a sizer die for a pistol Cal.

[wv109323]

I have opened up two Star sizing dies. The .358 was actually .3577. I used the split dowel rod and sand paper/emery cloth. It took several minutes of lapping to go from .3577 to .3582. Go slow an size boolits until you get to your desired size boolits. I also had to use rougher sandpaper that I originally thought. IIRC I went to 100 grit to get material removed then polished. The sizing die stayed round with the flap rod.

[Wheelgun]

Ok thanks everyone.
I’m going to pass on the flex-hone. I’m thinking about getting one of the laps.

I’d use the rod and emery cloth, but I’m not sure I could keep it straight enough…

[DougGuy]

Ok thanks everyone.
I’m going to pass on the flex-hone. I’m thinking about getting one of the laps.


Do you have a drill press or access to one? If you get an acro lap, chuck it up and adjust the collet to just barely begin to touch the tight portion of the die, this is the only part of the die that actually does any sizing, so leave enough slack to then add some 320 or finer grit compound, and try it. If it's too tight the drill press will start the die spinning, loosen off on the collet a tad if it wants to spin, you are only going to .313" but stop at .3125" and run a boolit through it, mic it and see where you are at. Finish with some 600 grit, you can use the slotted dowel for the finishing stage since it will do more polishing than actual sizing.

[uscra112]

Lee dies are nitrided, not hardened The core material seems like 12L14, from the way it machines for me. (I've had cause to shorten one.) The nitride skin is very hard, but also very thin. I would doubt you could take more than a thou or two on diameter before you were into the soft core. Try it, but don't expect too much.

[Wheelgun]

Ok thank you.
Yes I have access to a drill press. There is one at my grandparents place.
I’ll order a lap and give it a try.
Thanks

[firefly1957]

I would try a wood dowel and sand paper first .

[Ks Muleskinner]

I recently used an Acro lap that I bought off of Ebay pretty cheap to open up a Lee die from .430 to .4365. Goes pretty fast. Worked great

[Dusty Bannister]

When I lap with the drill press, to keep the parts aligned, I remove the belt and hand turn the pulley. If you run the power, it can dry out and end up galling the surface. Wet and not too tight and take your time. Test often.

[lightload]

Has anybody opened up a LL's neck sizing area or chamber? Perhaps doing this for 45-70 set used for cast bullets would facilitate loading .459/.460 boolits.

[cabezaverde]

I have opened some Lee sizers by coating cast boolits with valve grinding compound and pushing them through the die.

[country gent]

Lapping is a very accurate process it is how very precise surfaces are produced. IE surface plates, gauge blocks, pins most precision tools.

You can "grade" your own lapping compound from grinders dust from a pedestal grinder or surface grinder with just 2 clear bowls and some water or light oil.
Put the light oil water in 1 bowl and sprinkle the dust on top let sit very still for 10 mins then carefully drain into other bowl. This sediment layer is normally 2 coarse for most work. continue letting the bowls sit and draining each time the sediment is finer and more even.

As you lap with compound it will slowly break down into finer grits thru natural wear. I normally dont add more compound just water or oil in small amounts to jeep the work wet and flowing.

Working a sizing die will go fast as the actual surface area is very small in most. This ring inside is what is doing the work, Very similar to a burnishing tool.

Even on the nitrated dies if you do break thru the thin hardened surface the 12l14 core is much harder than the lead and will last a long time

[country gent]

Lapping is a very accurate process it is how very precise surfaces are produced. IE surface plates, gauge blocks, pins most precision tools.

You can "grade" your own lapping compound from grinders dust from a pedestal grinder or surface grinder with just 2 clear bowls and some water or light oil.
Put the light oil water in 1 bowl and sprinkle the dust on top let sit very still for 10 mins then carefully drain into other bowl. This sediment layer is normally 2 coarse for most work. continue letting the bowls sit and draining each time the sediment is finer and more even.

As you lap with compound it will slowly break down into finer grits thru natural wear. I normally dont add more compound just water or oil in small amounts to jeep the work wet and flowing.

Working a sizing die will go fast as the actual surface area is very small in most. This ring inside is what is doing the work, Very similar to a burnishing tool.

Even on the nitrated dies if you do break thru the thin hardened surface the 12l14 core is much harder than the lead and will last a long time