sizing die size question for installing Hornady gas checks using Lyman gc seating tool

  • Last Post 18 March 2021
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Michael S posted this 21 February 2021

  I think I found a way to ask my question that will be better explain my confusion.


  So I have the RCBS 38/357  38-158-SWC mould and I am loading it in several guns. Revolvers and lever action rifles. The dia for 38 cal is .357" but one normally sizes the cast bullet .001" or .002" bigger. I have a old Ruger Vacaro is .357 mag that needs the bullets sized to .359" all the rest of our 38cal guns take the .358" sizing

  I am using the Hornady brand of gas checks and using the Lyman gas check seat tool in my Lyman 4500 lube and sizer.  I put the Lyman GC seat tool in the lube and sizer and place a GC on the bullets shank and then place the cast bullet into the size die lip and then my wife pulls the handle so the top pounch makes contact with the bullet. I then pull the handle until I feel the GC seat on the bullet. I then raise the handle and most of the times the bullet with GC installed lifts out of the size die some. We remove it and set it aside and seat the rest of the GC. 

  Then we remove the Lyman GC seat tool and plug in the heat cord for the lube and sizer. Once the lube is heated we lube and size all of those cast bullets.

  My question is; do I used a different diameter size die to install the gas check on the bullet we will be sizing to .359" ? or is the diameter of the size die to install the GC's going to be the same? And I just use two different size dies the .358" and .359" for the size and lube portion?

  I hope I have explained this quandary well enough that ppl will understand what I am confused on. My wife and I plan to put gas checks on the 6.5's and 25cal and 38cal and the 45cal cast bullets we casted last night on date night.


GOD, United States of America, US Marine Corps, Family, Self

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Coydog posted this 15 March 2021

I install GC with my 450 and use the same set up and have no problems with Lyman , Hornady , Gator checks. They all go on with the dies in use . I put the GC in and then the boolit and then press on . I also use the spacer under so the boolit dose not go all the way down so to get the GC set and crimp on. 

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corerf posted this 17 March 2021

You want the check sized same diameter as the gas and driving bands “usually”. Some tapered exceptions apply (rifle specific).

For .358 checked, size and lube in same .358 die. Same for .359

I usually just flip a bunch of checks on the table and fk get press bullets on top. That installs them till the sizer gets to crimp them.

I am unfortunate in that my current supply of checks in 44 ( example) I have been using are loose enough to not even snap on the bases so I have to pass them through the sizer die (crap Lee mold, check shank Diameter is under by .004) They seat and crimp when lubed. I think the only times you would need to apply a with install tool is A: large tight gas check shank, B: weak fingers (not being demeaning, they can be hard to install) or C: want to keep the entire bullet as cast, unsized but lube in a second oversized die to prevent sizing but apply lube.

Only a few of my molds have shanks that are dimensioned correct for a H gas check to snap on. None are made by Lee. Regardless of alloy too!

NOE- they all fit perfect!

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Michael S posted this 17 March 2021

  Thank you for your reply in the thread and thank you to the guys who talked to me in PM about this as well these last few days. This answer saves me from having to use two different H+I dies for GC seat and size and lube of bullet.  

GOD, United States of America, US Marine Corps, Family, Self

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MarkinEllensburg posted this 18 March 2021

Why not seat all checks with the .359 die installed. Then size what you will use in the Ruger. Switch dies and size the rest. I find the occasional check that I need to use the seating tool for and just place it as needed. 

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