CJR
06-04-2011, 01:05 PM
Yesterday was a very good day at the range! I got a chance to try my first 3000+fps loads in my 308Win. Load was a 150gr (1 grain lot) LBT LFN PPCB (15BHN), CB initially sprayed with Teflon dry film spray and sized to 0.301"D, PP(Office Depot 100% cotton Vellum, 0.0025" thick) with 50% mixture of wood glue+water with leading edge of PP slightly in front of where ogive starts, PPCB dried, PP tails clipped, PPCB sprayed again with Teflon dry spray, PPCB dried, PPCB slight coated with LBT Blue lube, then PPCB final sized to 0.308"D. Loads assembled with OAL to allow rifle to do final seating of PPCB with PP against rifle's chamber forcing cone. Powder charge was 50 gr. of W748 ( a Lyman jacketed bullet load). Pressure had to be close to 50,000psi according to the manual. All round extractions were normal and primers looked normal, but I will mike the case heads to check for excessive pressure.
I started shooting my 175 gr, Lyman 311291 PPCB loads with 50 gr. and then 51 gr. of W760 and they were grouping nicely with many rounds touching at 100 yards. Then I popped in the 150 gr LBT LFN PPCB and started on a new target. My brother was spotting for me, and after the first shot he didn't see any thing on the target? After about 4 more shots, both of us couldn't see anything on the target. So I walked the 100 yds. to see the target. It appeared that in the well-used backing board there were new holes, at about 4 inches low, with about a 3"x3" group. I need a higher powered spotting scope. To see if those were really my loads, I used a 4" high "Kentucky Windage Correction" hold and started shooting again. This time I started getting a group form that was centered on the target. I kept brushing the barrel after every shot and sometimes would get a little resistance in one part of the barrel but it would clean up with one or two passes of dry brushing. Other times, I got no felt barrel resistance to the dry brushing. The PP must have been shredding a little in the barrel. Anyway, I continued shooting and though my group size never exceeded 3"x3", I did get 3 rounds touching at 100 yds.! Those 3 rounds touching really made my day! Also, I noticed a puff of white smoke about 6 or 7 feet in front of the muzzle which indicated perfect PP disintegration. The barrel was allowed to cool between shots. The surprising thing I noticed was that the barrel was not getting too hot with this max. load?
When the NRA was developing 3000+fps for the 300 Win Mag loads, they had their groups mysteriously open up to 6" at 100 yds. They concluded the PPCB needed more lube to survive and make it to the muzzle. So they coated the PPCB with more lube and all was well again. So, I will try to coat my 3000+fps PPCB loads with a little more lube and maybe look at a different wood glue to use. This is very simple tweaking for 3000+fps loads acting in a 50,000psi environment. Hopefully I can improve load consistency. With what I have now, I could comfortably use this load to take a deer up to a 100 yards.
At home I solvent cleaned the barrel to see what I had. No leading whatsoever, but I did get patches covered with a black substance that was either carbon residue or graphite which is typically used to coat powder granules. I am very pleased with this first attempt at 3000+fps! Back to the loading bench! Life is good!!
Best regards,
CJR
I started shooting my 175 gr, Lyman 311291 PPCB loads with 50 gr. and then 51 gr. of W760 and they were grouping nicely with many rounds touching at 100 yards. Then I popped in the 150 gr LBT LFN PPCB and started on a new target. My brother was spotting for me, and after the first shot he didn't see any thing on the target? After about 4 more shots, both of us couldn't see anything on the target. So I walked the 100 yds. to see the target. It appeared that in the well-used backing board there were new holes, at about 4 inches low, with about a 3"x3" group. I need a higher powered spotting scope. To see if those were really my loads, I used a 4" high "Kentucky Windage Correction" hold and started shooting again. This time I started getting a group form that was centered on the target. I kept brushing the barrel after every shot and sometimes would get a little resistance in one part of the barrel but it would clean up with one or two passes of dry brushing. Other times, I got no felt barrel resistance to the dry brushing. The PP must have been shredding a little in the barrel. Anyway, I continued shooting and though my group size never exceeded 3"x3", I did get 3 rounds touching at 100 yds.! Those 3 rounds touching really made my day! Also, I noticed a puff of white smoke about 6 or 7 feet in front of the muzzle which indicated perfect PP disintegration. The barrel was allowed to cool between shots. The surprising thing I noticed was that the barrel was not getting too hot with this max. load?
When the NRA was developing 3000+fps for the 300 Win Mag loads, they had their groups mysteriously open up to 6" at 100 yds. They concluded the PPCB needed more lube to survive and make it to the muzzle. So they coated the PPCB with more lube and all was well again. So, I will try to coat my 3000+fps PPCB loads with a little more lube and maybe look at a different wood glue to use. This is very simple tweaking for 3000+fps loads acting in a 50,000psi environment. Hopefully I can improve load consistency. With what I have now, I could comfortably use this load to take a deer up to a 100 yards.
At home I solvent cleaned the barrel to see what I had. No leading whatsoever, but I did get patches covered with a black substance that was either carbon residue or graphite which is typically used to coat powder granules. I am very pleased with this first attempt at 3000+fps! Back to the loading bench! Life is good!!
Best regards,
CJR