I find that I cannot edit my prior postings and that makes me uneasy continuing this exercise. I was going to add the following to Part 1 and change the title, but I am unable to do that.
Well, here the the second part of the section.
Load selection
Now we get to the most difficult part of ammunition making, selecting a load. We have all our components, now we need to make them work together to product a superbly accurate powder. The method I am going to discuss here is what I use to come up with my load. It is part research and setting parameters and part testing and validation. I will describe the exact steps I used to come up with my current .308 LR load.
I selected a bullet for its weight and BC first. I wanted a bullet that would have a BC and weight combination that would allow me to reach 1000 yards at a minimum of Mach 1.2 at Sea Level. This bullet is from JLK, it weighs 180 grains and has a long boat tail, It has a claimed BC of .575, but for my calculations I used .525. While I trust Swampworks to claim a good number, I know that BC values change with velocity and I would rather err on the conservative side. Using this figure in JBM, I found that by having a MV of 2750fps, the bullet will be just above Mach 1.2 at 1000 yards between May and September in Houston. According to JBM, by upping the MV to 2800, I would have a year round load above Mach 1.2.
So the low end was 2750, preferably 2800 FPS in a .308 with a 180 grain bullet. This is going to be difficult for a regular length barrel, this is hot 30-06 territory and midway into .300 WM and .300WSM territory but to help me achieve this, I made sure that my barrel would be as long as possible. I had selected 32 inches of barrel and provided my smith with a dummy cartridge made up of a Lapua case and a bullet seated the way I like them to be and that is with the first part of the bearing surface not quite at the neck/shoulder junction in the case. I never want the bearing surface to touch or go below the donut that may form there. My smith chambered the barrel to this cartridge and he provided me with a small seating guage for seating. The guage shows me how to seat a bullet so that it is just at the lands. I know from experience that JLK VLD bullets like to be seated about .020 into the lands. So, I adjusted the seating depth to seat the bullet a little longer using the micrometer and then verified with a Stoney Point bullet comparator.
Just so you know, I had specified the barrel twist from the barrel maker so that it would allow me to properly stabilize the bullet length I wanted and just a little more in case I wanted to go for the 200 or 210 gr bullets, keeping in mind the length of the barrel. In my case, that worked out to 1:11.25.
Next I pored over reloading manuals and the Hogdgon web site looking for a load that would provide a velocity that would reach my minimum MV, without being maximum. I also kept in mind that my 32 inch barrel should provide an extra 200FPS over a 24 inch barrel. So for my 180gr bullet, I needed a load that would give 2600 FPS in a 24 inch barrel and I would let the extra 8 inch take it above 2800FPS. Please remember that we are talking about a .308 here, even though the velocities in question are approaching 300 Winchester Magnum levels. At the Hodgdon website, I found that a max load of 45.0 grains of Varget should produce about 2660FPS.
After I received the rifle, I took it to the range one weekday afternoon, with 100 prepped and primed cases, a chronograph, my spare press, my RCBS Chargemaster, an extension cord and an inverter (just in case,) the seating die and some Varget powder. The next part will be controversial, but that�s what I do and it works for me. After almost 30 years of handloading, I developed an appreciation for the process that is difficult to describe. I use handloads only in my rifles. I only handload two calibers anymore, .223 and .308 and I only use one powder, Varget. This is been going on for many years.
I believe that bullets have accuracy nodes at different velocities. This is why people using the exact same bullet X will seem to clump into groups with similar velocities. For example, let�s say the loading manuals say a starting load will produce 2400 FPS or thereabouts. Groups of people using different components will find that bullet X is very accurate at around 2500 and as they continue to increase the load, the accuracy falls off. So they stay at 2500 and they enjoy a very accurate load. Another group of people have found a great accuracy load at 2630FPS and so on. The trick is to find such a node at or above our threshold.
So at the range, I loaded a bullet with a charge midway in the load range: 42gr. Fired over the chronograph, it showed the extra 8 inches were providing additional velocity, but I was not where I wanted to be. Next load was 43.0 and showed greater velocity, but not there yet. When I reached was 44.0, I was now above 2750, approaching 2800. I decided on an additional .5 grain and the next shot was with 44.5gr which produced 2840fps (this confirmed that I got 200FPS more with the 32 inch barrel.) I loaded 4 more rounds at 44.5 and shot those over the chrono; Average was 2840 with an ES of 16 and an SD of 6. Time to break away from the chronograph and do some groups. I was firing slowly, what with preparing a case and noting the velocities on the chronograph so the barrel was not very hot, just like it would be in a match about halfway through a match.
I had a big cardboard as a target and I simply aimed at a dot of ink at the bottom; remember this rifle is dedicated to LR and I was shooting at 100 yards. I then fired my 5 shots the very best I could, just holding the target dot on the inkspot. The group formed some 3 feet above the dot. The five shot group produced a single hole with another hole almost separate but still touching it. I know exactly which shot that was, I messed it up. The C-to-C group was in the .3s for the 5 shot and almost in the .1s for the 4-shot clump.
The ES was in the mid-teens and that�s seating the bullets on the spare press, outside at the range. The SD was in the mid one digits. But more importantly the group size was nothing short of phenomenal. And to top it all off, I now have a load that has the bullet nicely above Mach 1.2 at 1000 yards and it was not even a max load. Mission accomplished.
Now let me introduce you to my first rule of competition handloading: Once the load is good enough leave it alone and go shoot.
Load production.
Earlier, I explained how I selected my components. The Lapua cases are little jewels when they come in the boxes. I found they are already chamfered so very little preparation is needed out of the box. I just check the mouths to make sure there are no dings and I load them directly. If there is a ding (and I have not seen one in all the Lapua cases I have purchased over the years, I have an appropriate sized mandrel to deal with that.
I measure the cases using a Stoney Point comparator to record where the shoulder is, or rather the datum point on the shoulder according to the comparator. I compared this to my fired case dimension and found that it was just a few thousands shorter. Since I like to set my case shoulders back by .002 from a fired case, the differences between brand new case and resized fired case was almost within the margin of error of my measuring procedure. This has two benefits, 1- A new case is virtually the same dimension as a resized firing case using the Redding Full Length Small Base bushing die so very little work here. 2- It allows me to use the excuse that I am fire forming my cases if I have a bad day, nobody has to know the difference is about .001.
As I said earlier, I try to load my match ammo as close to the match as possible. Usually this is one or two days before. At this point, my cases have been prepped and all I need to do is charge the powder and seat the bullets. Using my RCBS Chargemaster, accurately measuring the powder is very fast. Just as a note, I always close the cover over the pan while the load is being metered out. I wait for the counter to change back to the load before I carefully open the cover and pick up the pan, making very sure that no additional powder falls into the pan. Using an aluminum funnel I pour the powder into the case and then I tap the case 3 times on a piece of wood on my bench; not two and not four, three taps. This settles the powder the same way for all the cases. Next, I place the case into my single stage press with a bullet on top and as I lower the handle, I turn the case in the shellholder to make sure the bullet is in straight as it gets captured by the sleeve in the die. I push the handle to the bottom, then back to the top, I extract the case and for good measure, I check it in a cartridge case and in my special seating guage. I twist the case between my thumb and forefinger holding the cartridge where the bullet goes in, to make sure there is no shavings of anything in that area. The completed cartridge goes in the case. In the past, I used to check for runout. I soon gave that up with these components and the Redding Competition Seating die.
I keep my ammo in MTM boxes and at matches, I keep it out of direct exposure to the Sun. Varget is supposed to be temperature insensitive, but why push it.
When I return from a match, I dump the fired cases in the vibrating tumbler for a few hours. This allows me to inspect each and every case. Earlier, I explained how I resize with the Redding Small Base Full Length Type-S bushing die, bumping the shoulder by .002 from a fired case. I use Imperial Wax as a lubricant. After the box is resized, I put the resized cases back into the tumblers for another hour. This does not clean the now empty primer pockets, but it can clog up the flashholes. I make sure the flash holes are clear. If I decide the primer pockets need cleaning, I will do the entire box on my RCBS Trim mate. The cases go back into the MTM box with flash holes up. This way I can see if there is a case that is longer than the others and deal with it.
It is always a good idea to sample the box for each loading. I pull a half-dozen to check for length, but I see very little growth shot to shot. Because I rotate the boxes and I run many boxes, I simply keep track of the growth and when the box reaches above maximum length, it�s time to either trim or retire the cases. I find this load does not enlarge the primer pockets anyhere near as quickly as on my .223 load. This is either due to the case or the load, I think it�s probably a combination of both. If I trim a box, I will also lightly chamfer/deburr the cases. LR shooting is not something that one does every week and send 20,000 bullets down range per year. For me, once a month plus state matches and other specials add up to about 1,200 to 1,500 LR rounds fired per year. With my system of going through multiple boxes at the same time, it will be a few years before I retire cases, if I only get 5 loads with them. I expect to get closer to 10 or more and that will last me even longer.
