Help me think this through

C

Charles E

curmudgeon
I'm going to get a reamer for a new wildcat. Like most wildcats, it's not needed, but there are these 200 pieces of RWS 7.5x55 cases just sitting there. Great brass, and just about the right size for a 600 yard benchrest rifle if you like .30s, as I do.

But . . . maybe even give it a try at 1,000. Which suggests blowing the body out to the .010 per inch taper of an Ackley, and a 33-degree shoulder. That should give just about dead on .30/06 capacity, using a shorter, fatter cousin.

I DO want to fireform a case that has a crush fit. I do NOT want to expand the neck up & create a false shoulder.

Which suggests to me that what I should do is use a couple of cases as a headspace gauge. Chamber by running the reamer in until a (couple of) case(s) are a crush fit, which is exactly where I want to start with fireforming.

As always, there may be a few more barrels, but there won't be a lot of barrels, and they will always be for my own use. No "customers" . . .

What am I losing by not getting a go-gauge?
 
Repeatability.....

I've done,
-go-gage (no longer an acceptable option IMO)
-handful of cases (acceptable but a pita)
-three shoulder-bumped cases (better)
-one shoulder-bumped and lead-filled case (actually pretty effective)
-go-gage but set to .009 under (the very best option IMO)

The 40.00 for an undersized go-gage is AlMOST even worth it if you do your own machining. It really just depends on how patient one is by nature. The other thing with having a go-gaged chamber for reference is that you can then easily establish oal of cases because you have a baseline. With wildcats it's alwas been a bitofa' fiddle-diddle finding the actual end of the neck, especially when running reamers in deeper and shallower.

some thoughts/rambles anyway

al
 
I'm with Al on the minus Go-Gauge. Repeatability and you'll be guaranteed a crush fit. Pretty much the same idea used on our PPC chamber/brass combo's. Charles's application is a single purpose wildcat intended to be chambered for his brass so it doesn't need to match anything else.
 
why not just let me have the brass....i can shoot it in my k31's and we can deal on some rws 300 win mag brass....

makes it sooooo much simpler.....


mike in co
 
Snyder got it..... IMO crush fit is imperative and the easiest way to accomplish this is to chamber short and bump (reset the shoulder) every piece of brass. Going with .009 short ensures that every brand, lot and type of brass may be accommodated.

Regarding the single-purpose, YES...... the purpose is raw intrinsic accuracy. Being able to slop in off-the-shelf ammo isn't important to me.

Again, my opinion only.

al
 
I completely agree with the crush fit. You can chamber .009 shallow by just doing the math.
why spend more money on a one time guage. Also, a neat way of checking trim length
can be done by drilling out the primer pocket, chamber the case ( without extractor) and
look thru it with a bore scope
 
Basically nothing IMO. Sure a gauge is nice so that you know where your at, but as you stated your creating your own "home brew" cartridge that only you are using. So long as your not stretching out case webs I can't imagine why it would be an issue. As with anything being conjured from thin air, there's a learning curve. Spending the dollars on a gauge only to watch it rot in a drawer after you revise the chamber due to some unforseen nessessity is just money wasted imho.

I would have to think you've aquired enough skill to chamber a cartridge within the normal SAAMI limits. That being said does a "X" cartridge shoot better or worse when chambered within those headspace tolerances? I have to say a firm no is the answer. A 308 set at GO+.001" isn't anymore accurate than one set at GO+.003".

Give it hell and good luck.
 
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