Velocity variation between HT and PC?

[igolfat8]

Has anyone else noticed a consistent velocity variation between HiTek and Powder Coatings? I only shoot coated lead in pistols so that is where my testing is based. My Chrono numbers are always 50-100 FPS faster with PC projectiles using the same alloy and loads. The PC feels much smoother and slicker to the touch so I would assume there is less drag going down the pipe.

[slide]

Yes, I have noticed the same thing in pistol and revolvers. I have started work on trying cast in 223. I haven't been able to get to the range because it is flooded. I will be trying powder coat and hi-tek.

[Smoke4320]

Has anyone else noticed a consistent velocity variation between HiTek and Powder Coatings? I only shoot coated lead in pistols so that is where my testing is based. My Chrono numbers are always 50-100 FPS faster with PC projectiles using the same alloy and loads. The PC feels much smoother and slicker to the touch so I would assume there is less drag going down the pipe.

Your chrono is not lying to you.. I have stated many times with PC you should see at least 4% to 5% increase in velocity.. 100 fps in most pistol rds would equate to around a 8 to 9 % increase
biggest reason you cant just take a lubed load and switch directly over to PC'ed .. it will not shoot the same as velocity has increased and barrel harmonics are different now ..
Also means if you want to stay the same velocity you "should" be using less powder per load and "should" have less barrel wear

[Dragonheart]

Some seem unable to comprehend that friction is a big factor in velocity. The fact is the polymer jacket produces less friction than a metal jacket, plated or lubricated alloy, so there is a gain in velocity. I would also mention with less friction gun barrels run cooler.

[psweigle]

Yup. I notice it most in pistol caliber carbines.

[kevin c]

At least for me, the difference between copper jacketed and coated slugs of he same weight, using the same powder charge, is 80 fps through my factory barreled G34's. Now, that isn't all attributable to coating versus jacket, since the coated bullet has a lube groove, and therefore less bearing surface, but I found about half the difference between slick sided and lube grooved coated casts of the same weight with the same powder charge, so it seems that the effect is real.

That's with HiTek. I haven't compared powder coated to HiTek.

[igolfat8]

The gist of my post and velocity numbers is that there is measurably less drag in PC boolits than HiTek coated boolits. Both coatings are slicker than copper and brass jackets but PC numbers show that they are the fastest of all.

[slide]

igolfat8, what barrel length are you shooting? I dug out some old targets that had been chrongraphed. These rounds were shot out of a smith wesson model 66 with a four inch barrel. On the average the powder coat was around 25 to 30 fps faster than the hi-tek. I was using a hollow base wadcutter out of a mp mold. Powder was bullseye at 2.8 grains, target loads. I will try it with a six inch barrel.

[igolfat8]

Hi Benny,
Most of my shooting is from Glock 34's and CZ TSO's. The 34 has a 5.25" barrel +1/2" of threads for its comp. The TSO is 5.25" as well. I am a competitive shooter and average >15,000 rounds per year.

[fredj338]

I don't find the vel diff nearly that high, maybe 30fps from lubed lead to PC or HT.
FWIW, IMO, a slicker bullet would not fly faster, less pressure with the same powder charge = lower vel.

[tomme boy]

Faster because the bullet has MORE drag and an increase in PSI. You use a moly coated jacketed bullet and you loose 50fps over a regular bullet. So you have to ADD powder to get the speed back up.

That is the way it is with jacketed bullets anyway.

[Forrest r]

I always thought the higher velocities were from a better/faster seal of the cylinders/bores.

With traditionally cast/lubed/sized bullets alloy plays a huge role in velocities. Find a load with a specific alloy and then re-test the same load with softer & harder alloys. The velocities will increase & decrease with the alloy/pressure curve. Pc'd bullets tend to take this out of play and obtain higher velocities with a wider range of alloys.

Awhile back I did some testing with a snubnosed 38spl using 10 different bullets and 5 different powders testing 38spl p+ loads. The bullets ranged from 140gr to 160gr. At the end of the day the bullets with the larger bullet bases/longer strait walled bodies had the higher velocities consistently. I'm talking as much as 70fps difference between bullet designs.

Just another opinion

[Dragonheart]

I don't find the vel diff nearly that high, maybe 30fps from lubed lead to PC or HT.
FWIW, IMO, a slicker bullet would not fly faster, less pressure with the same powder charge = lower vel.

I keep hearing PC ain't rocket science, but actually it is, and this topic is basic mechanical engineering. In forming your opinion you have taken into account only one part of the equation, "thrust" from the expanding gas pressure, but you completely ignore drag (friction). Assuming equal mass, velocity can be increased or decreased by more or less thrust (gas pressure), but it can also be increased or decreased by altering the drag (friction); in the case bullet lubricant. At the point of ignition if the bullet has a seal the the gas is confined and expanding, if you decrease the drag (a bullet that produces less friction) the confined gas can expand faster as the PC resistance is less, thereby increasing velocity. The polymer jacket produces less friction than any other coating, plating or lubricant I am aware of with the possible exception of ceramics.

You can easily prove this yourself with a chronograph. Addition proof, measure the barrel temperature you will also find due to PC producing less friction the gun barrels will run cooler. Identical loads altering only the bullet coating, the PC bullet will consistently show an increase in velocity, I found this to be true back in 2012 when I first got into PC. Test for yourself or just take my word for it.

[fredj338]

I keep hearing PC ain't rocket science, but actually it is, and this topic is basic mechanical engineering. In forming your opinion you have taken into account only one part of the equation, "thrust" from the expanding gas pressure, but you completely ignore drag (friction). Assuming equal mass, velocity can be increased or decreased by more or less thrust (gas pressure), but it can also be increased or decreased by altering the drag (friction); in the case bullet lubricant. At the point of ignition if the bullet has a seal the the gas is confined and expanding, if you decrease the drag (a bullet that produces less friction) the confined gas can expand faster as the PC resistance is less, thereby increasing velocity. The polymer jacket produces less friction than any other coating, plating or lubricant I am aware of with the possible exception of ceramics.

You can easily prove this yourself with a chronograph. Addition proof, measure the barrel temperature you will also find due to PC producing less friction the gun barrels will run cooler. Identical loads altering only the bullet coating, the PC bullet will consistently show an increase in velocity, I found this to be true back in 2012 when I first got into PC. Test for yourself or just take my word for it.

Well with lead bullets we get a better gas seal, higher vel. With jacketed that are molly coated, we get less vel, the bullet offers less pressure. So why would a slicker coated bullet be any diff? The diff in vel between conventional lubed & coated is within the std deviation for any given load, about 20fps, why I see very little vel variation using coated vs lubed, HT vs PC.

[Dragonheart]

Fred, I can't explain your results, so all I can do is say that just about everyone that has done a comparison between PC and any other jacket or lube has found that everything being equal the PC projectile has an increase in velocity. Federal has even published these same results in their testing of their commercial line of PC bullets.