Trying a new plain base bullet and a new-to-me powder coating.
Hybrid coating seems to be much more forgiving of overcure than polyester coatings, and that's important if you need to heat treat the bullets. I've been mostly content with the off-white hybrid powder coating that I've been using, except that it's not very attractive. Hybrids are normally only available in dull colors. My hope was that this "copper" hybrid coating would provide an attractive copper finish while maintaining the physical characteristics of a hybrid coating. Well, as you can see it doesn't look coppery at all, instead it looks butt ugly.
Oh well, as long as I have the bullets made up I might as well shoot them.
Here's the results, with targets numbered in the order they were shot. In general, this barrel did not care for the 115gr. bevel base no matter the coating. The best it could do was 2 MOA, so I will give up on the 115 gr. BB.
#1- 115 gr. BB, hi-tek coating, 31.5 gr. WC844, seated at jam+0 as measured with the rod method.
#2- same as #1 but powder increased to 32.0 gr. and jam+8.
#3- same as #2 but jam+15
#4- same as #2 but jam+10
#5- 115 gr. BB, ugly hybrid PC cured 15 minutes, 32.0 gr WC844, jam+10.
#6- same as #5 except 20 minute cure
#7- same as #5 except 25 minute cure
#8- same as #5 except 30 minute cure
#9- 130 gr. BB, 2 coats hi-tek cured 350F for an unspecified time, air-cooled WW, 32.5 gr. WC844, jam+10. These were an old batch of bullets from several months ago, and some of the coating was rubbing off when the bullets were sized. I suspect the coating was not cured completely, causing poor adhesion and poor accuracy.
#10 & #11- same as #9 except a different batch of bullets with 4 thin coats hi-tek cured 365F for 20 minutes, and air-cooled J.R. brand reclaimed shot (normally 12 BHN). Good adhesion.
The so-called copper hybrid PC seemed to shoot best if cured 25 - 30 minutes, similar to the almond hybrid PC. A 30 minute cure time works out well if you need to heat treat after curing (so far my plain base bullets prefer to be air-cooled).Conclusions, And Things To Try Next Time And Down The Road:
-- this barrel does not like the 115 gr. BB.
-- This barrel does like the 130 gr. BB, as long as the BHN is right and the coating is good. Including last week's groups: 1.40", 1.35", 1.80", 1.95", 1.20". Average-to-date=1.54". That's pretty decent for a plain base at 2700+fps!
-- I could tweak the 130 BB load, but IMHO it's already pretty close to optimal.
-- how 'bout a 145 gr. BB?