Stony Point modified case's

[big_genius29]

I am in need of a modified case for my Stony Point COAL gauge, and being the cheap dutchman in which I am, they look very simple to make.

Just drill out the primer pocket and tap a hole. But I do not have a tap that size, it seems to be a wierd thread pitch. It looks like 5/16, but alot finer pitch than what I have a tap for.

Also, is there any modification that needs to be done to the case mouth?

[PA-Joe]

No sure about the thread size but you need a fired case so the bullet can float.

[wogpotter]

You need a fired case anyway as the whole point is having the case exactly match the chamber of the gun it's reloading for.

I've thought the exact same thing, but never got round to actually doing anything about it. My plan was to take either a standard case for the tool, or the tool itself to Lowes & use the gauges they have (for free of course) in the hardware dept to figure out the exact spec for the tap.

[jepp2]

I just checked mine and it was a perfect 36 tpi. But it didn't want to even start in my screw checker 5/16 X 32 hole, so it may be metric...

[Whisper 300]

No, it is not metric.
I will go down to the shop later today and get the exact size but memory - and it is not good- says it is a letter size drill and oddball tap that I got online at Enco.

Gary

[dahermit]

I checked my stony point cases. 5/16-24 pitch, drill size "I" (a letter size). That is the standard for fine threads, nothing odd ball about it. It is just that people, other than machinists, are not aware of any thread pitches other than coarse threads and fractional drill bits.
The Stony Point "special" cases are not any thing special, they just use a standard case, drill through the primer pocket with an I drill and then tap with 5/16-24. The cases still have the head stamps on them.

[jepp2]

There may have been a design change. The set I have were distributed by Hornaday after they took over Stony Point. Mine are definitely not 5/16-24 pitch. They are 36 tpi.

[wogpotter]

I don't think there has been a thread change with the change in distribution. I have an original (alloy slider) Stoney Point tool & later bought a Hornady case for a different caliber & both the old & new cases have the exact same thread.

[Mal H]

I just checked my gauge and it is 5/16 - 36. Got it roughly 11 years ago.

[Whisper 300]

Just checked what I use and it is a 5/16" 36 tpi tap

Letter drill "I" or closest fractional bit is 17/64

My stoney Point unit is the older one, got it a number of years before Hornady's takeover of the stoney point line.

If this is a duplicate post, my bad, did it once and seemingly no joy on the posting so I tried again.

Gary

[Mal H]

5/15" ?

[mehavey]

5/15" ?

What's 1/498th of an inch amongst close friends?

I have an original (alloy slider) Stoney Point tool

Just for calibration, has anyone experienced problems with the new(er) plastic slider ?
I don't 'think' I have had any issues (5 different cartridges) over the last several years, but just checking....

[Mal H]

More like 1/49th of an inch, but what's a factor of 10 amongst close friends?

(Ok, now we're getting silly (er)!)

[Unclenick]

Mal H and Mehavey have it right. 5/16-36. Machinery's Handbook says the minor diameter for an inside thread that size is 0.282" min to o.289" maximum. I recommend you drill for the middle of that. A letter K drill is 0.281" and a 9/32" drill is 0.2812", and a letter L is 2.900, so nothing exactly fits the recipe. However, most drills make the hole a couple or three thousandths oversize, so either the K or the 9/32" may work as-is. If your drills are slightly undersize, as some I have are, you could start with the K or the 9/32", then lightly clean the hole out using the L drill as a reamer (assuming it is undersize, too). Otherwise you could buy an actual 0.2850" chucking reamer, and follow the K or the 9/32" drill with that.

I bought one of these taps together with a letter J drill bit from Champions Shooter Supply in New Albany, Ohio some years ago. They were bagged together, but it didn't take long to discover the letter J was too small, and gripping the case hard enough to force the tap to cut anyway was hard to do without scoring it.

You can get the taps and drills from MSC. They carry all the unusual sizes, here.

[F. Guffey]

If you can drill a hole through the head of the case why stop there, once the primer pocket/flash hole is drilled out you are through, leave the Sinclair/Hornady tool new in the box.

I drill the flash hole to a diameter that will accommodate a cleaning rod, I then seat a bullet, chamber the test case then use a cleaning rod inserted into the primer pocket/flash hole hole to push the bullet out until it stops against the lands. I then use the test case as a transfer by setting it up in the seater die.

Once the seater plug is adjusted down to the bullet, I measure the seater stem height above the seater die with a dial caliper, then adjust it to .000, as in off the lands for that bullet.

I use datums, I then determine the length of the chamber from the head of the case to the rifling contact point, means nothing to anyone else but I only have to determine that measurement once if I keep the test case I used for a transfer.

F. Guffey

[dahermit]

I checked my stony point cases. 5/16-24 pitch, drill size "I" (a letter size). That is the standard for fine threads, nothing odd ball about it. It is just that people, other than machinists, are not aware of any thread pitches other than coarse threads and fractional drill bits.
The Stony Point "special" cases are not any thing special, they just use a standard case, drill through the primer pocket with an I drill and then tap with 5/16-24. The cases still have the head stamps on them.

Whoops! Checked my StoneyPoint gage again. It is 5/16-36. But, I must have made some of my own "special cases", they are 5/16-24. I am getting older and more error prone.

[big_genius29]

Thanks guys.

Now to try to find a tap. I checked Grainger and they called their tap manufacturer and the finest they make is 32tpi.




Now that we have the thread size figured out now what should I do to enlarge the case mouth so a bullet slides in and out easyer than what it does?

I am wanting to make a modified case for .223 and 30/06. would drilling them out .001 or .002 over work? Or would that be a major PITA?

[F. Guffey]

I am a big fan of bullet hold, I want all the bullet hold I can get, some shred the neck, to me the case with the shredded neck look like squids, but I make a test case then use it as a transfer, that is I retransfer the dimensions of the chamber to the seater die, no Sinclair tool, no modified case except the one I drilled the flash hole/primer pocket out for the cleaning rod.



F. Guffey

[dahermit]

what should I do to enlarge the case mouth so a bullet slides in and out easyer than what it does?

Use a case that has been fired in your rifle. Just do not resize it and the bullet will slide in and out.

[Unclenick]

Originally Posted by Big_genius29

Now to try to find a tap. I checked Grainger and they called their tap manufacturer and the finest they make is 32tpi.

Why not just click on the link at the end of my last post? It's why I put it there. Scroll down the list far enough to get to the "5's" (it's by numeral and not by diameter) to find a choice of 5/16-18, 20, 24, 27, 28, 32, 36, 40, 48, 56, 64, 72, and 80.

Originally Posted by Big_genius29

Now that we have the thread size figured out now what should I do to enlarge the case mouth so a bullet slides in and out easyer than what it does?

Fire a normal load in the case in your gun. Drill and tap the fired case. The limitation is it will always be for that particular gun chamber, and not all guns chambered for the same cartridge. However, that also makes it more accurate in that gun, as the universal adapter case is new case size and will always be short by the amount of headspace in your particular gun for any neck-sized case.

Mr. Guffey's method has the same advantage. You can use a fired case that is the actual chamber size, and that is married to that gun.

If you want to make a new-size case into an adapter case for all guns in that chambering, you can expand the neck with a mandrel a couple of thousandths over bullet diameter. Mandrels are available from Sinclair, as is a die body that holds them. They are normally used to prep cases for outside neck turning, but may be used to expand a case mouth for loose fit, too.

Another method is to fire case and then size only the shoulder back using a Redding Body Die or a full length sizing die that uses neck bushings, but leave the neck bushing out so the neck stays the same.

Another method is to take a new-size case and split the neck with a hacksaw blade or a Dremel cutoff disc. That makes the neck flexible enough to let bullets slip through. Just be sure to get any burrs from the cutting off completely.

The most accurate measure involves measuring from the breech end (outside bottom) of the case head to the shoulder datum (the case comparator inserts for your gauge will do that) and then the distance from the bottom of the head to the bullet ogive (the bullet comparator inserts for your gauge will do that), subtracting the former from the latter to get a difference number. Then you adjust the seater die to achieve that difference between the two measures, whatever length case you have. That compensates not only for differences in case length, but for the adapter not filling the chamber 100%.

[big_genius29]

Thanks Uncle Nik, I read through the reply's to quick to even see your link.



I would like the idea of using my cleaning rod instead of the COAL guage, although it would work for my AR, my 06 is a semi auto so the cleaning rod trick will not work for that one.

[IllinoisCoyoteHunter]

Here is how I make a gauge for my bottleneck rimless cartridges:

Take a case, grind the rim off, and cut a slit on each side of the case neck down to the bottom of the shoulder (I use a dremel). Make sure you can slip a bullet in and out of the case neck, but make sure it is a fairly snug fit. "Seat" the bullet by hand so it is seated long. Put dummy round in chamber and close the bolt. Open bolt and you will find case will be stuck in chamber because you ground the rim off. Take a cleaning rod and enter from the muzzle. Lightly push on the tip of the bullet to free the dummy round. Now measure with your comparator (or calipers). This measurement is you COL (not coal, as that is natural resource ) with the bullet seat so it touches the lands. Subtract from this figure the amount of jump you want. Thats it. I do this method a couple times to check and make sure my figures are accurate. Good luck!

[F. Guffey]

big_genius29, no rules, you can shorten the cleaning or you can use a brass rod with two 90 degree bends, with the short rod you could 'carefully' with control use the bolt to seat the bullet.



F. Guffey

[brickeyee]

5/16-24 just happens to also be a common size of set-screws on older doorknobs.

I have had the tap and die for many many years (and of course have two of each so the first will never break).

Damn you Murphy.

[Mal H]

Originally Posted by brickeyee

5/16-24 just happens to also be a common size of set-screws on older doorknobs.

Are you sure? We have a bunch of those old door knobs in our house and the set screws appear to be about a 10-24. I didn't gauge them, but 5/16" would be a huge set screw.