Making 8mm Bullets - More

gitano · April 14, 2015, 11:58:46 AM

Making one's own bullets, especially when one wants to 'plow one's own furrow', reminds me of the old adage: "Before you choose to get your degree from The School of Hard Knocks, make sure you can pay the tuition".

Tired, as usual and very quickly, of 'trial and error', I decide to do some math to see why I was chasing my tail on these light-for-caliber 8mm bullets, and if so, if there was some way to start moving in a straight line instead of time and resource wasting circles. As usual, my education grows - painfully. (That tuition is darned expensive.)

I did some cypherin' to determine exactly what the nose length of a bullet of 8mm caliber would be if the ogive radius was 7 times the caliber. Turns out, it's 0.839". That's with no meplat; in other words, going to a 'needle' point. If the meplat is 0.1", (the minimum meplat diameter with my dies), the nose length is 0.621". The finished jacket length of my jackets is 0.610". What that means is that if I were to run my finished bullet to a meplat of 0.1" with no exposed lead, there would be ZERO caliber-diameter bearing surface. I'm pretty sure that wouldn't shoot exactly 'straight'.

Of course, it was never my intent to run the meplat to 0.1" AND no exposed lead. I intended on a relatively large, no exposed lead, meplat proportional to the Speer 115-grain 7mm bullet, and the 130-grain .308 bullet. (See post number 66 in this thread: http://thehunterslife.com/forums/showthread.php?t=16677) However, I am resigned, at least for the foreseeable future, to not having a plastic tip - that works - available for this bullet. Therefore, I have to focus on getting a 'real' bullet, (one that works), made, AND the proper processes and techniques "committed to paper" that results in the CONSISTENT fabrication of that bullet.

In retrospect, and particularly in the context of the 'school of hard knocks' comment, what I should have done is simply purchased the dies, and used 7mm, .30 cal, and 8mm FACTORY bullets, and reformed them in my swaging dies. Here is a picture of what can be done with that approach:

On the left is the .30 caliber Sierra 125-grain #2020 bullet and what it looks like after going through my swaging dies. In the middle is the .30 caliber 130-grain Speer HP #2005 and what it looks like after swaging in my 8mm dies. On the right is a 174-grain Hornady .312 caliber bullet #3130 and what it looks like coming out of the swaging die.

Pretty easy. Don't have to buy jackets or lead wire for cores. The down side is that the jackets I have are extra thick-walled - 0.035" thick. I like that. And pure copper, meaning 'dead' soft. I like that too.

If I was interested in light-for-caliber, as I am, I should have gone with a shorter ogive. 7 calibers is relatively long. I could have had 8, but opted for what was in hand at Corbins. For 125-grain bullets, a 5 caliber ogive would have been fine. The loss in aerodynamics could have been made up by the smaller meplat. BUT... If wishes were horses, beggars would ride; woulda, coulda, shoulda; etc... Just the cost of matriculating at The School of Hard Knocks.

I've been working on a spreadsheet that performs a lot of calculations associated with bullet design and swaging. I'm almost finished with it. When I am, I'll post it here to 'look' at, and provide it to anyone that wants it.

Paul

Making 8mm Bullets - More

gitano