Hollow point mod ?

[Digger]

Been playing in the loading room again and was mixing up some of Miha's 125 gr for 9mm and got to looking very closely .......
Inherited my father's old wooden tool chest full of his pieces from his tool and die making days at an aircraft company , found what I believe to be a few counter sink bits in the drawers....

What the heck ! .. found one that seem to be close and started to play around and here are the results .....as you can see the original on the left ....it gives a double angle to the HP cavity and sharpens the edge some what.
They shoot very accurately function smooth so good or bad ?
I have yet to experiment with softer alloy like 50-50 ww , stick ons as this is still range lead alloy so I am still a little hard I believe and it only takes a couple of seconds per boolit to do this little trick as I put my drill in a vise in the vertical position on slow rotation and just touch it with the round.
not precise I know but fun to experiment any how.....
To all the Knowledge out there , I ask ,,,another small step forward or backwards?
digger

[GeneT]

Been playing in the loading room again and was mixing up some of Miha's 125 gr for 9mm and got to looking very closely .......
Inherited my father's old wooden tool chest full of his pieces from his tool and die making days at an aircraft company , found what I believe to be a few counter sink bits in the drawers....

What the heck ! .. found one that seem to be close and started to play around and here are the results .....as you can see the original on the left ....it gives a double angle to the HP cavity and sharpens the edge some what.
They shoot very accurately function smooth so good or bad ?
I have yet to experiment with softer alloy like 50-50 ww , stick ons as this is still range lead alloy so I am still a little hard I believe and it only takes a couple of seconds per boolit to do this little trick as I put my drill in a vise in the vertical position on slow rotation and just touch it with the round.
not precise I know but fun to experiment any how.....
To all the Knowledge out there , I ask ,,,another small step forward or backwards?
digger

That's a combination drill and countersink you've got there. You can certainly HP with it, but you'll need accurate seating (assuming you're processing loaded rounds) and drill depth to get uniform weight. I don't think the smallest diameter (tip part) of the hole does anything for you, performance wise - but that's just my guess.

GsT

[Fixxah]

Why do all the extra work? How do the originals shoot? They look sweet though.

[Shooter6br]

I used a similar method I used my case trimmer(Foster) to drill the HP. There is a good video on how to do it on Ammosmith .com. As for alloy I use 20-1 for welocities 900 to 1200. I use 25-1 for 850 to 1000. Good article on alloy is Glen Fryxell sight. I also use lead pencils of a given hardness to determine related hardness (scratch test)

[Charlie Two Tracks]

I think they look great! It will be interesting to see what the difference in expansion is. Makes them look a little meaner

[Digger]

So that's the proper name for it ......combination drll/countersink .....thank you much .
The small tip works good for a pilot shaft so to speak and the angle seems to be right ......

It is fun as I usually grab each round and wipe the lube off .. so this time I just set it on the drill for a second or two and then wipe .
I know doing it free hand is imprecise but the result is good for the moment , maybe later will set up a press method.

digger

[JFrench]

Looks like a lathe center drill with one end broken.
James

[Buckshot]

...........They come in different sizes too. From 5/0 (smallest) to #10 and with angles of 60º, 82º, and 90º. Yours is a 60º #2 plain type. They also come as a 'bell' and 'radiused' type, besides plain which is most common.

...............Buckshot

[a.squibload]

Looks good.

Check this out:

http://castboolits.gunloads.com/showpost.php?p=889051&postcount=88

Using a hand drill works for the jig, but hard to get the right speed.
Is pretty consistent once you set the depth.
Haven't shot 'em, seems like they should work OK.

[excess650]

So that's the proper name for it ......combination drll/countersink .....thank you much .
digger

Its a centerdrill.

[XWrench3]

That was my original thought also, a centerdrill. My brother is a machinist, and i pick up a little on his language. By the way, the boolits look great. Dont you just love fiddling around with stuff?! It is half the fun of doing things yourself.

[Digger]

Okay guys , this could be getting carried away a little bit but just found some more in the drawers ,,,,
As Buckshot described ....
All are 60 degree # 2,3,4,5 and 6 , with more playing around I found out #4 works in the 40 and 45 cal Miha hp boolits.

This just could be too much fun ....:bigsmyl2:[smilie=w:
digger

[JTknives]

Its a centerdrill.

its a center drill, yep. its used in mills and lathes for starting a hole. because its thick the center does not walk. it allows you to drill a hole right where you want it.

[theperfessor]

You can also make a cup point with a ball nose endmill or get a 90* drill-mill for a true inverted cone point. The possibilities are endless.

[theperfessor]

The extended parallel point on common centerdrills creates a small reservoir to hold lube when a "dead center" is used in a lathe tailstock. It also provides tip clearance and ensures that the surface of the cone and not the tip of the center bears the load. The tool was originally designed to make center holes in shafting that would be turned between centers in a lathe.

[Digger]

Yes ! .. the knowledge the gentlemen here put forth is outstanding !!

[white eagle]

yeah I thought it was a center drill too but who knows you can call it what you feel like

[Digger]

Just wanted to thank every one for the technical advice given , ... always learning , ,
digger

[Ole]

Why do all the extra work? How do the originals shoot? They look sweet though.

Silly goof, he can re-melt the drilled-out lead to make more boolits! :kidding:

[a.squibload]

Yeah, save those shavings!
Drilling a pretty good HP in 158gn 38s dropped their weight to 155, no big deal balistically but
not gonna throw lead away at any rate.

[Digger]

Oh definitely saving the shavings !! ......:mrgreen: