My quest for speed and accuracy with powder-coated cast bullets
- Thread starter Ian
- Start date
Ian
Notorious member
A lot of the hill country is very brushy and overgrown (like my place, can't see more than 20-30 yards any direction except where I've cleared.) Here's the view from my mbr balcony:
My own shooting range is basically a tunnel through the brush and trees. At my boss's ranch we had to use a drone and 2-way radio along with Google Earth to plot a 500-yard shooting lane, and his place is about 60% cleared.
My own shooting range is basically a tunnel through the brush and trees. At my boss's ranch we had to use a drone and 2-way radio along with Google Earth to plot a 500-yard shooting lane, and his place is about 60% cleared.
Ian
Notorious member
Mostly it's hilly, rocky, brushy ranches with combination of thick brush/trees and open areas where I hunt close to home. The photo of my property and the photo of the shooting range on the previous page are good indicators. Down on the coastal areas it's a combination of elm/pecan river bottom (thick brush) and open fields or fields with mesquite and cactus. So...all kinds of conditions.
I went to the MOE rifle stock for my ARs. PRS is too pricey for me. Those carbine stocks just don't work with bags. I got a 24" LR308 upper for your long range stuff - way too heavy for me to carry in the field anymore. No need for a can @ 400. Once they hear the splat or see the legs in the air - they are off.
What does QL say for 18gr. Rx7 under 145 & 170 PB seated 0.020" off the lands in 30/30? I got large ES for those but 185GC did much better.
What does QL say for 18gr. Rx7 under 145 & 170 PB seated 0.020" off the lands in 30/30? I got large ES for those but 185GC did much better.
Ian
Notorious member
Celebrated our veteran's lives today by flying the flag, sending up my gratitude, and doing a little shooting.
The shooting mission was centered around the powder-coated 30 SIL hollow point in WCC '08 brass with 35.5 grains of Reloder 7 (the load my short LR-308 requires). First I cleaned the LR-308, lubed the bolt, and shot five for a group at 100 yards just to make sure it was still "on". Shot #1 nicked the white bullseye and the rest went into 1.7" with no help from me and the MFT ultralight buttstock:
Then I shot two into the sawdust trap just for fun, found them at 38" and retained weight was 122 and 130 grains. This alloy is about 2.5/2.5 Sb/Sn, air cooled and aged to a whopping 12.5 bhn. Not bad for about 2460 fps at the muzzle.
The shooting mission was centered around the powder-coated 30 SIL hollow point in WCC '08 brass with 35.5 grains of Reloder 7 (the load my short LR-308 requires). First I cleaned the LR-308, lubed the bolt, and shot five for a group at 100 yards just to make sure it was still "on". Shot #1 nicked the white bullseye and the rest went into 1.7" with no help from me and the MFT ultralight buttstock:
Then I shot two into the sawdust trap just for fun, found them at 38" and retained weight was 122 and 130 grains. This alloy is about 2.5/2.5 Sb/Sn, air cooled and aged to a whopping 12.5 bhn. Not bad for about 2460 fps at the muzzle.
Ian
Notorious member
Next up was the M1A, I wanted to see how it handled this load with bullets sized about a thousandth smaller than it normally prefers, and with a significant jump to the lands. Had to close down the schuster valve quite a bit to get the bolt working in the happy zone. Not impressive accuracy, but I chrono'd the last eight rounds and got 2541 fps average with 10.8 SD from the 22" barrel. Circled group was first, then the chrono added for the lower group:
Then I sent three at the 100 yard backstop after making a left windage adjustment:
The first two were almost touching, shoulda quit while I was ahead!
Then I sent three at the 100 yard backstop after making a left windage adjustment:
The first two were almost touching, shoulda quit while I was ahead!
Ian
Notorious member
Things I've learned about powder-coated, gas-checked rifle bullets so far:
- The bullets don't need lube up to and beyond equivalent jacketed bullet speeds.
- Full-power, full-pressure loads can be used in ordinary, production-quality barrels without leading.
- Light carbon-fouling akin to shooting jacketed bullets is all I get at high-velocity, one wet and two dry patches gets it all out (five rifles tested so far, repeatedly).
- The first shot from a CLEAN barrel goes in the group, usually in the center. Very predictable.
- Powder coating allows full-power rifle loads with reasonable hunting accuracy in ordinary hunting rigs using bullets of HALF the BHN normally required, making for more effective expansion at extended ranges. This of course extends the minimum hunting range if you don't want excessive meat damage.
- Powder-coating drastically reduces the lead fouling of muzzle brakes and suppressors and virtually eliminates leading of both piston and DI gas systems.
- The coating hasn't proven any gilt-edged, match-winning accuracy yet, but then again I haven't (nor am I inclined to) pursue it to that level given the velocity and alloy concessions that will likely be necessary. This quest was for usable hunting accuracy with appropriate alloys and particularly for semi-automatic rifles which we don't see at many cast bullet shooting matches.
- And for the biggie.....After all this testing at both extremely low and high velocity, I consider the Quest for Extreme Bullet Lube 100% fulfilled. Our dear departed friend Felix Robbins was right all along when he kept indicating that some sort of polymer was the solution to the bullet lubrication challenge. Who knew all those years ago that it would take the form of a TGIC-crosslinked coating?
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Ian
Notorious member
I forgot a few things in the "lessons learned" list. This isn't holy writ but my experience from my own data points so far.
One important thing seems to be the bullet having displacement grooves of some kind to prevent fouling accumulation from the coating. I have never actually tried "slicks" or grooveless bullets coated, but Bama has done a lot of work with them and has battled fouling akin to copper jacket fouling in his bores. I have never had such fouling from my traditionally grooved or micro-grooved bullets. Intuition and lessons taught us by Frank Barnes seem to hold true for all monolithic bullets, even paper-patched high-velocity bullets.
Another important point for loading HV powder-coated bullets is diameter. Typically they shoot best for me when sized somewhere in between the nominal groove diameter and what works well for traditional lubricated cast bullets in the same rifle. In other words, never go larger than throat entrance diameter due to scraping off the coating going into the throat. Often (in my experience with just a few rifles so far) sizing the driving bands for a light scuff-fit in the throat or even a bit smaller depending on throat geometry gives the best accuracy. Bolt-actions with some parallel freebore benefit from a more snug fit and semi-autos with funnel throats from a slightly more loose fit. In all cases, selecting and sizing a bullet for minimum deformation and engraving force until the gas check begins entering the throat has given me the best results. Powder burn rate, crimp, neck tension, and bullet jump all need to be adjusted for the low engraving pressure to yield consistent burn (note how well the fast-burning Reloder 7 worked for my .308s at 50K psi and over 2500fps, not something that would do well with traditional cast bullets and certainly not with copper jacketed!)
Other techniques I use that seem to help are seating the gas checks Lyman-style in an old 45 luber and then push-through presizing the bullets to crimp the checks and reduce the amount of metal moved during post-coating sizing. Coating after applying and crimping checks seems to help check retention and allows the checks to be annealed in the oven (for better or worse?). The only drawback to coating the checks is uneven powder coat on the bullet bases which I believe in some instances degrades accuracy. The bases could be wiped before standing to bake, or other techniques used. Most anything added or refined in my methods would be chasing sub-moa, and my LR-308 has shown repeated sub-moa tendencies without doing anything special like weight-sorting bullets, flash-hole prep, weighing each powder charge, or any other exotic loading routines. Most of my ammo is loaded on a Lee turret press with charges thrown from an RCBS Uniflow straight into the cases.
Spindrift
Well-Known Member
Very good results, Ian! I agree, your quest is fulfilled. I am impressed by the look of the recovered bullets, with the pretty deep HP I expected less retained weight. I actually have ordered the MP SIL mould myself, will hopefully arrive in a few days.
I have learned a lot from this thread. Thanks!
I have learned a lot from this thread. Thanks!
Ian
Notorious member
Sawdust really isn't much of an indicator of performance in flesh, I was just trying to catch them and see what they looked like. Straight WW alloy with a solid, spire point will lose 2/3 the weight as rough/fractured chunks and not mushroom much at all at 2200 fps when trapped in the same media. Diluting the WW very slightly with soft lead and bumping the tin up for this batch to make something like half #2 alloy at 12 bhn (compared to 14-something for straight WW + 2% tin I was using before for these same HP bullets) may have cost a little accuracy but they hold together pretty well I think.
More testing is in order in wet newsprint, I just have to acquire a bunch of it.
More testing is in order in wet newsprint, I just have to acquire a bunch of it.
Went shooting this morning before the next monsoon arrives. AR10 and 300BO carbine, to get some chrony numbers. Had a little problem with the magnetospeed, numbers are way off from optical chrony (bout 1k fps). Got the last round shot and the BO bolt stuck on empty. I was on bench 13! Anyway, not bad getting back to 100 yds. Did about 60 40SW off & single handed, most in the black. Fellow 2 down had a Colt delta elite 45 with comp, he was stacking them pretty good too.
The cast I shoot is basically grooveless and they work fine. Friend got a 200# boar this weekend, have to make sure I'm sighted right, might get asked to go with him soon.
Sure is hard getting a spent primer out of the gas key slot on an AR!!!
The cast I shoot is basically grooveless and they work fine. Friend got a 200# boar this weekend, have to make sure I'm sighted right, might get asked to go with him soon.
Sure is hard getting a spent primer out of the gas key slot on an AR!!!
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Ian
Notorious member
Looks pretty well dialed in on grouping, not bad velocity and great groups for an AR pistol. Better make head shots, I filled a pig full of holes (11 hits according to a witness) with my BO and it ran off as soon as it found the hole in the fence.
I thought DE's were all 10mm auto?
I thought DE's were all 10mm auto?
That target is the 308W. 3 Amax and then cast, just verifying the scope zero, 3" high so need to do that again-oh, blade was on the barrel for these shots. BO carbine got me frustrated with the blade, missed a string of 110 vmax completely, the others were 125 SST, 155 amax, 150 spp. Didn't get to cast as the primer locked up the bolt.