i'm working on makeing bump dies. on another site i asked the question about what steel to use. i want to use 12L14 or 1144. it was sugested that i use o-1 and harden it. i wanted to use the others because of the fine finish that can be achieved. i'm just a hack hobby machinist. this leads to my question; anyone use the steels that i mentioned with good results, not hardened??
steel for bump dies
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- Last Post 04 February 2021
When I was making bump dies I was concerned about strength and stretching so I used drill rod for the first ones and then, later, I used old stainless shot out barrels for die material. 416 R stainless worked very well and gave a nice finish. If you use 7/8's or larger stock you don't need to worry about heat treating and after bumping thousands of hard bullets I never detected any wear in the die. Don't waste your time heat treating. Spend your time getting the correct dimensions. I ended up having a separate throater reamer made up to throat the gun barrel and then made the bump dies off that same reamer. Leaded steels are usually pretty soft so I didn't use them. I was bumping hard bullets cast of monotype at 30 BHN.
Don't worry about using a soft steel because it might stretch while under pressure. Contrary to popular belief, all steels from softest to hardest (or weakest to strongest) have virtually the same elastic modulus (stretch the same if under the same stress up to where they permanently deform -- yield point.)
Softer steels will wear faster and permanently deform under less stress (lower yield strength), but these aren't concerns in a bump die as Tom points out.
i make most of my bump dies from aluminum ... 2024 or 7075 preferred but 6061 actually seems fine ... for the die body ...
seems to work just fine for a thousand squishes or so.. i get bored and go to another project about then anyway.
consider that lead doesn't like to gall on aluminum. and of course aluminum is fun to cut ... and doesn't rust.
and don't forget threaded cold rolled from Ace hardware ... 7/8-14 is available.
but yes stainless barrels make a really nice die body ... i have a ruined genuine po ackley 25 cal varmint barrel i could send you some chunks from that for postage if that would help.. give your dies some history ( g ) ... pm me if .
thanks ken but i have 5or 6 junk bbls. just bought a junk rem. 22 bbl. at local gun shop last week for $5.00
I agree with Ken about using the 7/8'sX14 threaded rod. I've bought it from various sources and it all seems to be the same stuff. I started using it because my old lathe isn't of the quick change type. I can cut any thread in existence but I have to make a gear change that takes a while. I had a piece of this stuff laying around years ago and gave it a try, worked great. I, being in love with wildcats, have always been in the need for case forming dies and am too tight to spend money if I can make it myself. I have several sets of form dies ,neck sizers and such, made from the threaded rod, some of which have been in use for over 20 years and are still in fine condition. They seem to burnish inside after some forming use.
David a. Cogburn
Pacific makes blank sizing dies that come bored to sammi bore specs. Simply align throating reamer then cut.
LBT bullets that are designed for long free bores are perfect designs for taper bumping.
Bumping bullet for better alignment does work. I bet bumped powder coated would work even better. Anything to reduce lead fouling sounds good.
i noted the method that i plan to use on another site; and i'll explain it here. anneal old unused or useless dies to soften and make boreing out easier. drill close but under .625 (or whatever size you choose) . used boreing bar to finish to .625. i have .625 TGP steels so that is the size i chose to bore to. depending on the fit; loctite or epoxy the .625 round stock into the bored hole. drill and ream to your size for bumping. i will use reloading dies because of the alignment between the bore and threaded top. the top is already threaded to utilize for the top punch/ ejection rod. at least that is what i think will work
Yes, you must locate the center on any project before turning or boring. After annealing some reloading dies you will get an awful scale inside and that scale is heck on reamers or boring tools. Most of you guys try to make everything expensive and complicated.
David a. Cogburn
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