While I was waiting for the barrels to arrive I got started on the brass and dies. The dies I started with were RCBS and Hornady New Dimension. I set up the full length sizers to push the shoulder back to SAAMI minimum minus .002?. By the way, donít change shellholders after you set up the dies or you might change the headspace. For my two shellholders, the difference is .002? and one shellholder makes firm contact with the bottom of the die, while the other does not. The Hornady dies reduce the shoulder diameter from .457? (fired) to .452?, and size the ID of the case mouth to .260?. The RCBS dies reduce the shoulder diameter to .454? and the neck to .260?. After working on barrels 1 and 2, I purchased the Lee Collet die set so that I could size just the neck. It initially sized the neck ID to .262?, but I polished the decap mandrel down to .260? to give the neck a tighter bite on the bullet and match the other dies. I like the Collet dies, and itís nice not having to mess with lube before and after sizing cases.
The Wind Course. Notice that the lanyards hanging at the bottom of the Kestrels are whipping in the wind. Cell phone photo courtesy of Todd.
The concentricity of my loaded ammo is typically .002? or .003?. The worst Iíve measured was .005?. Iím not saying thatís great, Iím just sayiní thatís what it is. By comparison, Federalís 308 Gold Metal Match averages .004? whenever Iíve checked it. I donít think Iíll get the concentricity any lower without turning the necks.
The brass (300 pieces) arrived in six 51-piece bags and was made by Remington. I started sorting them by weight, in .5 grain increments. What I ended up with was the following, shown in Table 1.
I checked them for length and trimmed those that were over 2.031?. Most fell in the 2.029? to 2.031? range. Then I chamfered the case mouths and deburred the flash hole. Finally I full length sized them all and primed them with Winchester WLR primers. I was going to buy GM210 primers but Sinclair was out and the nice guy that answered the phone said that he used the WLRs in his long range rifle. When I handload the ammo I keep the brass segregated in its half-grain groups.
I checked the jam lengths for the following bullets in barrels 1 to 5.
I do have two types of 140 grain A-MAX bullets, some older ones and the new AMP versions. The jam lengths and overall lengths differ between the old and the new. For example, barrel #3 has a jam length of 2.836? for the old 140 A-MAX and 2.866? for the new 140 A-MAX. The old A-MAX is 1.367? long and the new AMP A-MAX is 1.379? long.
Each barrel was checked for accuracy using six to eight different types of the above listed bullets. The Alpha Industries 10 round magazine that I use can handle cartridge lengths up to 2.89? so I can load all these rounds as far out as I need and still cycle them through the magazine.
I happened to meet Troy Lawton (AMU) at an ammo meeting. I asked him if he had any recommendations for 260 loads. He recommended H4350 and mentioned firing the 142 SMKs at 600 and the 107s or 123s at 200 and 300. I did use H4350 for my loads that I took to Texas. H4350 is part of the Hodgdon Extreme line of powders, known for their temperature insensitivity.
We arrived at Accuracy First on a Monday morning, with the prospect of three windy days in the 70s, followed by a rainy or snowy day. As such, we decided to spend as much time outside the first three days and then have more classroom time on Thursday. Mr. Beaufort and I decided to mix our shooting between the school guns (LaRue 18? 308 OBR rifles with Horus Tremor reticles) and our own rifles (my 260 and his 338 Lapua Magnum) with Horus H58 reticles. With that plan in mind we headed to the 100 meter range and zeroed our rifles. This was my first exposure to shooting in real wind Ė not the gentle breezes of Virginia but the full blown winds of Texas. The wind blows dirt and sand into everything. Thatís eyes, ears, bolt, safety, magazine, pockets, ammo boxes Ė well, you get the idea. My safety became non-functional at this point due to blowing sand. The bolt release also became barely functional. We left the 100 meter range and headed out to one of the ranges to ďtrueĒ our guns. The concept here is to shoot the gun at a distance where the bullet goes transonic (around 850 meters with the 308) and see what its drop is. You tell the computer what the drop is at that distance and it will adjust the velocity or BC to match what you just found. I trued the rifle at 1045 meters, where my come-up from the 100 meter zero was 9.5 mils. My bullet wasnít transonic there but it was far enough out to be useful. Using the environmentals of the time I told my Kestrel that my muzzle velocity was 2775, that my bore height was 2.91?, that the barometric pressure was 27 (IIRC), etc. and that it took 9.5 mils to hit at 1045 meters. It figured out that I would need a G1 BC of .64 for that to be true. Based on that, the Kestrel made a range card in 10 yard increments. Using a Vectronix Terrapin L5, we lased our targets or milíed them to determine their range and then the Kestrel told us our mil holds. At 790 meters I held 6.2 mils and hit one out of five shots. My hold at 475 was 2.5 mils, at 520 it was 3 mils, at 700 it was 4.8 mils and at 890 meters my hold-over was 7.3 mils.
Monday afternoon we grabbed the OBRs and headed to the Golf Course. Todd would tell us what ďparĒ was for each station and then we would mil the target, determine our range and make a wind call. If the target was more than 600 meters away, Todd would tell us the distance. If the range was less than 600 meters, we had to mil the targets to determine their distance. The targets were either 12 inch steel circles or 12 inch circles on top of 16 inch steel squares. The OBR I was using had the Tremor reticle. Hash marks in .1 mil increments were used to determine how far away the target was. For example, a 12 inch plate that appeared .6 mils high (or wide) was 508 meters away. Once we had the range, we used the Kestrel to determine wind speed. Then we determined if the wind was full value, no value or somewhere in between. Based on that, we made a wind call. Todd had formulas for this, and the reticle had wind dots that helped us with our holds. At one location, Todd pointed out how the wind became audible at 16 to 18 mph. I hadnít noticed that Ė of course, I had my hard ears on. One, to protect my ears from a 338 with a muzzle brake, and two, to keep the wind from blowing off my cover. The first plate was a par 2 and I hit it on the second shot. The second plate was at 705 meters and was a par 3. I hit it on the third shot at 6 mils elevation and holding 7 wind dots into the wind. I think most of the stations were par 1 to par 3 and as I look at my notes I see some 4s and 5s. On a positive note, as I got to the end of the course, I hit the 743 meter target (a par 3) on the second shot. The last shooting location was at the top of a steep hill. We were encouraged to hear that the Marine Snipers ran from station to station. Twenty-five years ago I would have tried that, minus gun and gear, but those days are long past. So with all the speed of a glacier, I eased my way to the top of the hill and got one shot off Ė a hit Ė before the sun dropped below the horizon and my reticle disappeared into the darkness. That ended day one.
We headed to the Cattle Exchange restaurant, ate a trough full and then finished it off with bread pudding. For what itís worth Ė itís really not pudding Ė itís more like cobbler. I made a mental note that it took two Cokes to wash all the grit out of my teeth. Mr. Beaufort said, ďI think I got a rock stuck in my moustache.Ē I have no doubt.