Resizing reamer Specs

ntsqd

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In pure theory squeezing the brass .004" when .002" will give you brass that chambers every time, all of the time, is just working the brass that much harder.

I'm not qualified to comment on what the reality of this really is. Have one of each made and try both? Then you'd know for that specific chamber. Do so enough times and you could likely predict a trend.

Were I to guess I'd say that the eargasplittenloudenboomers might need .004" while the pip-squeaks may only need .002", BUT that is only a guess.
 

Mikecr

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When I wanted to build on a wildcat (26wssm Imp), I didn't ask machinists what to do.
I measured my brass, ran numbers in Quickload, filled out reamer prints and ordered what I wanted. The reamer maker (Dave Kiff @ Pacific Tool) made the set to my prints. That's what he does very well.
He's not me, building a gun, shooting and reloading it with my plan. All that's on me.
When I fire-formed my brass in my new chamber, I created my cartridge. I validated QuickLoad and reloaded per my plan. All worked out perfect.

Reamer makers are just good machinists, same as action makers, die makers, and barrel finishers. I used 4 separate machinists to finish my system, and each did their part -per the customer. They provided no inputs nor held influence about whatever I was doing.
After all, how much would they really know about what I'm doing?
My guess: about as much as Leupold or Berger, whom I did not pester to recommend a scope or bullet.

I will suggest that each specialist in the gun building endeavor is useful in their area.
Reamer makers can help you with choosing throat length & leade angle for the bullet you chose(it all begins with a bullet). A die maker may have particular experience about sizing for certain attributes of YOUR chamber & cartridge. An action maker might point out a better model for reliable function, with possible tweaks to port length or something.
Would I go with a reamer maker's ideas about sizing, or a die makers? Personally, I would go with the die maker, or neither. And for my build, that's kind of the way it went..
I sent a brand new shiny sizing reamer along with my fired brass, and body die blank, and reamer prints. I had suspected that my die maker might hold common notions of sizing that I do not agree with. That he would go too far (for my own good). So to stay on my sizing plan, I sent the die maker over-expanded cases(without his knowledge). That is, cases that were taken to pressures well over SAAMI max, and my intended use.
The die maker did do his own thing,, my sizing reamer was not used, and I got what I wanted. Perfect!
My seating die blank(Wilson) was cut using my chamber reamers(rough/finish). The barrel finisher did that.

Anyway, as mentioned I had measured my new brass and for a grand experiment I set my chamber as 'fitted'.
This is no more than 1thou over any new brass dimension, and why I know today how much brass springs back.
It's not 4thou, or 2thou,, it's less than that. And as far as brass growth, you set that with your chamber clearances, breach support, and load pressures. These I had accounted for up front (a plan), before ordering anything.
I only tell you this so that you can know the potentials here.

My 26wssm Imp. has the same H20 capacity as a 260AI. IMO, it is the best overall capacity for 140gr 26cal bullets.
My mid-node with a 28" barrel is 3025fps, 140VLDs, 47.4gr IMR4350, right at SAAMI max (65Kpsi) per QuickLoad.
I had worked up all the way to 3380fps, finding another node near there, but not as accurate. That's where I produced over expanded brass for my die maker. I'm sure his plan would have worked for that, but it was never my intent to run that hot.
I've gone through 2 1/2 barrels at mid-node and ~80 reload cycles using the same 50 wssm cases -with ZERO body or neck sizing.
Since I only went with 35deg shoulders, I do have to bump them(began at 9th reload). That's where my die maker trick came in, and what my sizing reamer would have done; to allow bumping without body sizing.
Next reamer, I'll go 45deg shoulders, or maybe even 60deg(haven't decided), and see if I can remove bumping forever.

From my perspective, you do not have to move brass ~4thou up & down with reloading.
I KNOW YOU DON'T
If you want to, that's your plan, then fine. But, you don't have to.
 
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phorwath

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I'm thinking that JGS has already manufactured two or more in many different cartridge chamberings, prior to advising 0.004". Already been there, done that.

With their business reputation on the line, maybe 0.004" is the path of least resistance, all things considered.

I know building a resizing die reamer, and building a custom resizing die using it, is an expensive route to go. I also think a 0.004" reduced reamer will cut a resizing die that works brass less than most standard resizing dies do with factory cartridges. So casing life isn't apt to be any issue at all.
Resized cases that won't chamber, on the other hand? Total loss on investment.
 

Earl Fouraker

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Feb 18, 2007
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Florida
Mike and Paul, thank you for your inputs. Their is lots of knowledge on this website. I appreciate you taking the time to answer.

I have a background in long range revolver shooting. The age old practice with shooting cast bullets is to size the brass onlyfar enough down to hold the bullet.

thus aligning the cartridge better with the cylinder as it makes its way the throat. I never really thought about it much, just accepted the theory.

That’s why I was having a hard time sizing rifle brass that far under size.

But with my thinking about the subject over the last few days, it seems to me that a rifle cartridge at 60k+ psi, upon ignition, will swell to fill the chamber completely prior to releasing the bullet.

This will (in theory) Align the cartridge with the chamber.

If these things are true, I guess it comes down to how much you want to work your brass and how much tolerance you need to account for debris or dirty brass you might encounter in the field.

Prob a reason why nobody neck sizes anymore
 

ntsqd

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I know next to nothing of internal ballistics, but I do think that there is a sliver of time immediately after firing pin contact with the primer where the pressure rise is low. It isn't until the bullet has started to engage the rifling that there is enough resistance to bullet motion for the pressure to really ramp up. Something has to hold the bullet in the correct alignment during that admittedly very small fraction of time.

For me that has long meant that the case base and the case neck needed to be a good fit in the chamber. I do not see the section of the case between the datum line and roughly where the belt would be if the case were a belted mag case as all that important to this alignment UNLESS one or the other ends is not doing it's job.

Kent Duckworth, the "worth" of Cosworth Racing Engines, is famously quoted to have said "Don't read, you become mis-informed." But how many of us can afford the time and money that it would take to develop ALL of this on our own?
 
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D-mon

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Aug 11, 2003
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Scotland
When you ream a die blank with your sizing reamer, I presume the finish will not be perfect. How much does the final internal polish removes out?
 

L.Sherm

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When you ream a die blank with your sizing reamer, I presume the finish will not be perfect. How much does the final internal polish removes out?
It shouldn't be any different than a chamber.
 

J E Custom

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A well cut chamber has a nice finish so polishing should not be necessary. Polishing can alter the dimensions and the idea is to closely match the chamber. The first time you fire a case, it is fireformed to your chamber, but you have to adjust the die to get the fit you want from then on.

You can always back off on the die but if it is to large you will have to grind the die or the shell holder. After you cut the die, the recommended size, it won't be that size any more because of spring back as mentioned.

Dangerous game rifle dies are 6 to .008 thousandths smaller than the chamber but they will still not under size the case unless you adjust it all the way down.

J E CUSTOM
 

Rardoin

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Jul 22, 2020
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South Louisiana
Stick with JGS's recommendations. It WILL work fine....from experience. Al and Dan Warner must be doing it wrong too since my WTC die inserts have correlated to the same resize reamer suggestions by JGS. But hey....Al and Dan are just machinists:).
 

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