Lyman 450 Questions

[Dakooz]

I've just received my first sizer...a used Lyman 450.

Strangely the head of the pressure screw is standing proud from the sizer quite a bit so that it does not sit flush on my bench. This makes me wonder if this is the correct part.


There is also no seal that I can see on that end of the screw which may be okay but wonder if a simple metal to metal seal is enough to keep it from leaking. I have not put in any lube in it yet.

Any thought/comments would be appreciated.

[rush1886]

Gonna take a stab in the dark here, and say you're probably just fine. Sounds like the pressure screw probably just worked out/away from the piston it works in tandem with, to squeeze the lube thru the sizer body.

You're going to need to back that piston up and out of the sizer body to install the lube, so on a flat surface and using moderate pressure, try to push against the screw, moving it and the piston towards the top of the body. You'll likely need to do this incrementally, to get the piston out of the sizer body anyway. A quick squirt of kroil or similar into the cavity may be useful if the piston and the cavity are dry.

Not 100% familiar with the 450, but my guess is that no seal or o ring is required on the end of the pressure screw, in as much as it, as already talked about, squeezes itself inward to the sizer body, in tandem with the piston. A good, flat, metal to metal surface is all that should be necessary.

Good Luck!

once bench mounted, the screw will simply work itself against the bench or mounting plate surface, to move the piston up and out. there is a possibility of a loose or missing "e clip" inside the sizer body, which would serve this purpose, again not familiar with the 450.

[Dakooz]

Thanks for the reply.

I disassembled it last night. There was no lube in it which made it easier. The head end of the screw is definitely thicker than the recess that it fits into. I found some pictures of screws on the internet and the head thickness does appear to be thinner. Mine is also slightly concave on the end too.

Maybe someone has a spare screw and can measure the correct head thickness.

[Ed_Shot]

I put a new Lyman kit in my 450 about 18 mo. ago replacing the original factory parts from my 1968 450. I do remember replacing broken pressure screws a couple of times. Anyway, if it helps, the head of the old pressure screw I replaced measures .121 in thickness at the head and it does fit flush in the old bottom plate which I replaced. On my 450 the pressure screw and bottom plate are just held in from the bottom by being bolted to the bench. As I recall, the bottom plate in the replacement kit did not fit as tightly as the original part and I used a piece of cardboard between the bottom of the 450 and the bench to act as a gasket. I don't know if the Lyman replacement kit parts have different dimensions but it works great and was money well spent.

[JonB_in_Glencoe]

I've had a few different Lyman 450s. One of them had the issue, of which you speak. I was using while label BAC lube at the time. It leaked quite bit out of the bottom of the pressure screw, til I made a gasket out of paperboard.

[Dakooz]

I checked the pressure screw head thickness and it came out to .310 I don't have a Lyman 45 to confirm but I think the screw is for that model.
I went ahead and ordered the correct screw from Lyman.

Thanks everyone.