Hornady OAL tool modified case
- Thread starter 762willdo
- Start date
jepp2
Gold $$ Contributor
Always an option to make your own.
B23
Gold $$ Contributor
I haven't always had the best luck with the Hornady store bought modified cases fitting my chamber snugly. They usually are slightly undersize and seem to wobble around a bit not fitting in the chamber like I'd like and I get inconsistent readings so I always take a piece of brass that's been fired in my gun for that perfect fit and drill/tap that for my OAL tool.
46and2
Silver $$ Contributor
If you get a 5/16-36 tap you can make a oal case for every cartridge you own.
No there’s not…..
RegionRat
Gold $$ Contributor
It isn't too difficult to drill and tap your own, but if you are not used to doing machine work it may require a few words of advice.
A cartridge case isn't very rigid so getting it held where the drill will be straight and to take the torque of the tap is the issue.
What Bill Norris is showing in terms of using a conforming wooden clamp will help prevent damage to the case. You don't want to just slap one in a vice and clamp down on it since the grip required to drill & tap will probably mean you squeeze down too hard and damage the case body. You can also add a layer of two sided tape to help conform the case to the clamp and add grip against the torque.
Using a method like Bill's above will conform like a soft jaw on the vice and help give you enough grip to torque the tap as needed.
Once you have a decent conforming clamp, it is a fairly easy job to drill and hand tap. A small drill press and vice makes this a breeze, but even hand tools will work if you are up to it.
The tap is 5/16-36 TPI and can be found at better hardware stores or even Amazon.
The drill can be an L size or 7.25mm or close to it. Some sellers bundle the drill with the tap.
https://www.amazon.com/dp/B09Q85QT2...lja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1
Once you have this drill and tap, you can make these dummy cases whenever you want and they can fit as once fired instead of virgin brass or however you like.
Here is an article on making them, but don't squeeze a case into a die too hard or you will be sizing it down. Use the conforming clamp method Bill is showing.
https://ultimatereloader.com/2019/09/25/making-an-oal-gauge-modified-case/#:~:text=Drills and Tap,3/16″ should work.
A cartridge case isn't very rigid so getting it held where the drill will be straight and to take the torque of the tap is the issue.
What Bill Norris is showing in terms of using a conforming wooden clamp will help prevent damage to the case. You don't want to just slap one in a vice and clamp down on it since the grip required to drill & tap will probably mean you squeeze down too hard and damage the case body. You can also add a layer of two sided tape to help conform the case to the clamp and add grip against the torque.
Using a method like Bill's above will conform like a soft jaw on the vice and help give you enough grip to torque the tap as needed.
Once you have a decent conforming clamp, it is a fairly easy job to drill and hand tap. A small drill press and vice makes this a breeze, but even hand tools will work if you are up to it.
The tap is 5/16-36 TPI and can be found at better hardware stores or even Amazon.
The drill can be an L size or 7.25mm or close to it. Some sellers bundle the drill with the tap.
https://www.amazon.com/dp/B09Q85QT2...lja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1
Once you have this drill and tap, you can make these dummy cases whenever you want and they can fit as once fired instead of virgin brass or however you like.
Here is an article on making them, but don't squeeze a case into a die too hard or you will be sizing it down. Use the conforming clamp method Bill is showing.
https://ultimatereloader.com/2019/09/25/making-an-oal-gauge-modified-case/#:~:text=Drills and Tap,3/16″ should work.
AlNyhus
Silver $$ Contributor
I put the case into a Wilson case holder and then hold the case holder in the lathe chuck. An interrupted thread tap like the Sandvik Coromant style makes tapping the hard brass case head much nicer as it clears the chips easier.
After you do a fair number of these, you develop a pretty good feel for brass quality/hardness.
Good shootin' -Al
After you do a fair number of these, you develop a pretty good feel for brass quality/hardness.
Good shootin' -Al
Absolutely spot on RegoinRat. I place a thin piece of tape around the case prior to clamping into the jig and clamping the jig to the table on the press. Once the hole is drilled I remove the bit from the press and install the tap. I put a little cutting oil on the tap and inside the hole in the case head. I MANUALLY start and run the tap into the case (do not run the motor on the press for this) Secondly, I spray the case down with brake cleaner to remove the oil and lastly, I wait til after the case is finished to resize it in my F/L bushing die with the bushing removed because I want the modified case to fit in the chamber exactly like a regular case I'm loading. If these steps are followed one can turn out a good quality modified case.
Lougler
Silver $$ Contributor
Attachments
WSnyder
Silver $$ Contributor
I do a fair amount of these for people. For a cartridge I haven't done before and don't have a prepped bushing in the drawer I use a short chunk of 1" Alu round stock and put it in the chuck in the lathe. Drill then taper bore for the brass. Tap the brass into the bushing, drill, tap and remove. Doesn't take much time at all once you've done it a time or two 
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.