How to drill a hole in the primer pocket?

[quartermaster]

I'm sure that some of you must have had occasion to drill a hole in the head of a casing. I have a tap so that I can make my own modified cases out of a fired case from my chamber instead of buying the generic Hornady ones. I also have a set of Sinclair chamber measuring plugs which I would like to use, and both require a hole drilled.

I have had a difficult time trying figure out a way to hold the case and drill a hole thru the primer pocket without damaging the case.

What works for you guys? I feel stupid asking this question as I know there must be an easy way. It's not the first stupid question I have ever asked and I'm sure it won't be the last.

Thanks in advance. QM

 

[rcmodel]

The only way to accurately drill it perfectly centered is by using a lathe.

Any other method using a drill press or hand drill would be less precise, and not be perfectly centered.

I don't care who ya are.

If you don't care if it is perfect or not?
Take to pieces of scrap wood, clamp them together, and drill a hole one drill bit smaller then the case in the center of them.

Then clamp the case in the split-wood-hole in a drill press vice and drill away.

rc

 

[NeuseRvrRat]

i drilled out some primer pockets to use with the sinclair chamber measuring plugs. i used the case holders that are used with the L.E. Wilson case trimmer. the Wilson case holder is big enough that you can just hold it by hand. i did that and drilled it out with a cordless drill. i guess you could also stick the case holder in a bench vise.

the hornady modified cases are cheap enough that if i need one i just throw it in my next online order if it's a place that carries them. like rc said, i didn't really think i could get the hole centered up good enough without a lathe. i guess i could've put it on the lathe at work, but once again, the things are pretty affordable. good luck.

 

[quartermaster]

It has to be centered enough to make the modified case and the Sinclair plugs work. I don't believe that it has to be perfect, but close. I have a ton of the modified cases from Hornady, but for the $10 cost for the correct tap, a fired case would be much more accurate as far as headspacing goes. I always have to mess around after using the Hornady modified cases more than I care to. I do really want to use the Sinclair chamber measuring tool.

I guess we all got along for a long time before both these items came out and managed to figure out COALs and accurate loads. They just make things a bit simpler. I don't believe that it is worth it for me to buy a lathe, as I wouldn't use it enough to get my monies worth. My reloading room and basement is filled with all kinds of gadgets and tools to simplify tasks.

I believe that with some thought and imagination, there should be a simple solution to drill the hole. I was hoping someone has already come up with it. There is some very innovative members on this forum.

Let's see what happens.

 

[Sport45]

Does it have to be perfectly centered?

If not, all you have to do is put a sizing die in your press upside down. Drop the case in the die and press it down with your thumb. It should grab the case well enough to keep it from turning. If you can't get it back out when you're done unscrew the die and screw it back in from the top. Raise the ram and slide the shell holder into the ram and over the case rim at the same time.

 

[IndispensableDestiny]

I considered using L.E. Wilson case holders, but didn't want to mess them up. What worked for me, at least for .308 was a piece of copper pipe strapping. I folded it in a "U" around the shell and squeezed the loose ends in a vise. Since I used a hand drill, I had to try a couple of times until I had the hole straight (it does matter).

I tried this on .223 Remington, but could not get the case to hold.

I thought of just drilling a hole through the case wall and holding it with a punch. I haven't tried that yet, the brass may tear.

 

[hentown]

The hole doesn't have to be precisely centered, in order for the system to work.

 

[Jaxondog]

I drill case's out all the time for when i shoot wax bullet's. [ keep's the primer from kicking back and putting cylinder in bind] I use my Lyman case trimmer with a cordless drill like mentioned earlier. Work's for me.

 

[Offfhand]

No problem whatever in centering flash holes. Simply use a drill bushing. Several years ago a firm I work for (part time) did some testing of different size flash holes and we simply made our own bushings for different size drills, a simple machining process, even for amateur machinists. They may also be commercially available in primer pocket sizes.

 

[closetgunnut]

I make jewelry (key chains, pull chains and necklaces) from fired cases and I came up with this simple set-up to drill my flash holes.



I drilled holes in a piece of scrap steel and a pair of old vice-grips and attached them using screws and wing-nuts.
I cut a couple pieces of 1/2 inch air hose, slit them open and slipped them over the grip ends. I C-clamp the whole thing to my bench and drill away.

The hose protects the cases and holds them tight and I loosen or tighten the "grip" depending on the size of the case.

Closet

 

[fguffey]

For years, I have made tools, none are tools I made, all are about tools I use in a manner not described in the description of the tool use.

I drill out flash holes and primer pockets, drilling out the flash hole/pocket turns my cases into tools. When I decide to drill the primer pocket/flash hole I cram them into a full length sizer die, instead of lowering the ram to remove the case I remove the shell holder by rotating until it can be removed from the case and ram at the same time, then I remove the die from the press and screw it back into the press from the bottom. After the die is screwed in upside down I secure the die to the press with the lock ring (from the bottom)

The press become the vise/holder for the case.

It is possible to drill the flash hole without removing the die if the reloader understands the hole in the shell holder limits the diameter of the drill, meaning the shell holder aids in holding the case, drilling from the top down could push the case out.

Holding the case (just in case) can be aided with a pair of pliers.

I use cases with drilled out flash holes/primer pockets when deterring the length of the chamber from the bolt face to the rifling/ojive contact, off the lands and converting my seating dies into micro adjust seating dies.

Then there is the neck tension, I use bullet hold, as we have found Aberdeen uses bullet pull with a one of a kind bullet pulling machine, bullet pull? Again, I make tools-out of other tools. If a bullet can be pulled, it can be pushed, I drill out the primer pocket/flash hole to facilitate bullet pushing, and I collect scales, to determine the amount of bullet hold I drill the flash hole/primer pocket, size the neck then seat a bullet, after seating a bullet I stand the case in a L.E. Wilson case gage, I use a spacer to prevent the bullet from bottoming out, then I place the spacer, gage and case on a scale then push the bullet out while reading the scale.

Purpose of bullet pull? I do not know, R. Lee said there is no such thing as too much crimp, then there is cold welding, back to time as a factor, a cold weld? could increase bullet pull (I guess) not a problem, my bullets are not pulled out, my bullets are pushed out, and I am a fan of lag and catch up, in my opinion the neck expands and releases the bullet before the bullet has a chance to take off, back to bullet hold and I do not know unless the design of bullet hold measured in bullet pull could be about recoil, I can measure bullet hold, I can measure bullet hold by pushing the bullet out.

My understanding there was a a wide range of puling pounds necessary to pull bullets, some numbers went up to 500 lbs. I would put that number in the category of nice to know, my pullets are not pulled out of the case, my bullets are pushed, then there is that 45,000 + psi thing, pressure in the case does not get serious until the case is flattened against the chamber wall.

F. Guffey

 

[ranger335v]

I use RC's wood blocks method, works fine.

 

[jmorris]

The only way to accurately drill it perfectly centered is by using a lathe.

Depends on the lathe. If the chuck is out the hole will be too.

If you use the clamp/block method on a drill press and clamp the block to the table before you drill the hole that holds the case, then after the large OD hole put in the case and switch bits to drill the smaller hole they will be as perfectly aigned as your drill bits and drill press allow (until you remove the block).

 

[fguffey]

jmorris, I agree, if Quartermaster had a lathe we would not be having this conversation. Even with a lathe it is possible to center the tapered case in a chuck, I have chamber gages, I could use a die in the lathe to hold the case, again, he has a press, die and shell holder, he has a drill, drill bit and taps, he wants someone to share a method and or technique.


“ I have had a difficult time trying figure out a way to hold the case and drill a hole thru the primer pocket without damaging the case”

While drilling and tapping, think of a die with a stuck case in it. I could remove the die from the press with the stuck case, chuck the die into the press then drill and tap, back to the part where most do not have a lathe, it means little to my friends, I have 5 lathes and grinders, I have three grinders, still it means nothing to my friends.

It is possible to to remove a stuck case in the same manner, rotate the shell holder and remove it from the ram and case at the same time, then remove the die and reinstall it upside down, then drill and tap while using the press as a vise/holder. Everyone else uses a 1/4’ tap, I use a 3/8” tap.

Careful when drillong the case head flash hole/primer pocket, the primer punch/neck sizer plug will have to be raised first, as opposed to 1/4” tap, I use the 3/8” tap, when the hole is drilled to 3/8” the primer punch/sizer pulg assemble can be removed out the bottom of the case. And, I use smaller taps for cases with smaller case head diameters.

F. Guffey

 

[quartermaster]

Some good ideas to try in your posts.

My primary reason for drilling this hole is to be able to punch out the plug after using the Sinclair chamber length gage. This would not require a hole which was perfecfly centered. I was hoping to be able to do the tapping for the Hornady tool that would measure max COAL with a fired case, but that would be my secondary use. That length can easily be determined many ways. The most accurate being done by removing the spring from the bolt, seating a bullet long and keep seating it deeper until you can feel the head hitting the lands.

Hornady will make a modified case for you from a fired case for $15.00. I'm not cheap (maybe a little), but if there was a way to tap it myself accurately without a lathe, I would do it. If I thought I would find enough use for a lathe to justify the cost, I would consider buying one, but I don't see that happening.

I will mess around and try a few things. I would like to drill the hole without damaging the case.

I appreciate all your thoughts and input. QM

 

[rg1]

For drilling brass a drill with negative rake works best. A regular drill has a tendency to dig in and grab and twist the piece being drilled, especially when the drill is just about to completely finish the hole. Take the drill to the grinder and flatten the "front" of the cutting edges taking out the spiral making the cutting edge flat at least or negative angled. Google "negative rake drill". Makes drilling brass safer and prevents grabbing and twisting the workpiece.

 

[fguffey]

"I was hoping to be able to do the tapping for the Hornady tool that would measure max COAL with a fired case"

I have the Sinclair maximum length gage with threaded primer pocket cases, I do not use it, I drill the flash hole/primer pocket to a diameter that will allow the bullet to be pushed out of the case with a cleaning rod. Once the bullet contacts the rifling while being pushed I stop and remove the case from the chamber then use the modified case as a transfer, meaning I do not remove the bullet/plug. This technique works with new or fired (formed) cases. The $5.00 price of the modified case makes it expensive to have a modified case for each (different)bullet being seated. I am the fan of bullet hold, I want my case neck to have all the bullet hold possible, having one modified case makes that practice difficult.

I am the only one that uses transfers to adjust the seater die. I place the transfer into the shell holder, raise the ram then adjust the seater die down to the transfer crimp first then the stem, after adjusting the seating stem I measure the height of the stem above the die, then zero a height gage/dial caliper etc. To adjust the OAL length I raise or lower the stem from .000".

Other methods, shread the neck of the case, again, I want all the bullet hold I can get, anything that reduces bullet hold does not work for me.

F. Guffey

 

[quartermaster]

fguffey, I am still thinking of yout prior post on this thread reguarding neck tension and bullet release. You must be retired to have the time to think of all this stuff. I have been fastenated with your theory of the neck expanding before the bullet heads down the tube. I have some thoughts on that subject and some day when I have time to put them together and write them down, I will either add to this thread or PM you. It might be an interesting topic to start a separate thread on.

You have had a few posts on threads that I have started before and just to let you know, yours thoughts and advise are always welcomed and respected.

QM

 

[jp9mm]

Why not just stick the case on a tapered rod?
Thats what i used to enlarge primer pockets so i could make some snap caps.
Used a hand drill too

 

[CLP]

seems like a lot of trouble to go through for 6 bucks

 

[GP100man]

I run it in the die then slip the holder off the case/ram .

 

[blarby]

Could also just use a flash hole deburring tool, remove the stop stud and bore on through.....

 

[1SOW]

I chamfer crimped pistol brass using a drill press and a drill press vise. It might be applicable to your needs.
1. I filed/sanded down a bolt to be very slightly smaller that the cases and very "slightly" domed. The case can rotate and self-center just a skosh.
2. I clamped the bolt in the vise using a square to get it vertical , put a case on it, and lowered a very small drill bit into the "flash hole "to center the vise & case with the bit, and then clamped the vise to drill press table.
3. Insert the countersink or whatever bit you plan to use.
If you are drilling all the way through the base, drill the bolt/rod end first to allow a through drilled hole. A pilot hole could be done with the small bit used for alignment.

I ended up using a rubber lined pair of pliars to hold the large number of crimped cases I was chamferring. My fingers got sore after a few hundred.

Hope this makes sense.