Powder Coat Bullet Accuracy

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Powder Coat Bullet Accuracy

Post by 10sandxs on Sun Feb 28, 2016 3:50 pm

As the accuracy of powder coated bullets has been the subject of discussion of late, Al and I did a methodical study to determine the effects of powder coating on bullet accuracy.  To accomplish this, bullets were cast using a 5 cavity NOE mold # 453-200-SWC and a mixture of Wheel weight and linotype which when water dropped and aged gives a hardness of roughly 14 brinnell. Bullets from this mold and allow combination drop at 216 gr +/-.5 gr when I do my part well. 



These bullets were weight sorted into groups of +/-0.3 gr and the heaviest group was used for testing.  Of this group, half were lubed and sized with White Label Lube X-Lox2500+.  The other half were coated with polyester powder coat (red) sourced form www.powederbythepound.com.  Un-sized bullets were coated by the “Airsoft BB dry tumble” method and baked for 20 minutes at 420 degrees F. Thickness was determined to be between 1 and 3 thousandths by measuring coated and uncoated bullets prior to sizing.  Once baked and cooled, these bullets were sized using the same sizing equipment (Star) that the previous bullets had been lubed and sized in.



These bullets were loaded using IMI Match brass which had been cleaned and prepared using normal loading methods.  The load consisted of 4.5gr of Titegroup over a Federal Premium #150 Large Pistol Match primer seated to a depth of 1.230 +/-0.002 and crimped to 0.001 less than the body diameter with bullet seated.



This load was initially ransom rest tested from a base bolted to a concrete floor at an indoor range at 50 FEET.  Three ten shot groups ranged from 0.431” to 0.615” for this load.  The ransom rest on the indoor 50 YARD range consisted of the rest clamped to a 700 lb. (approximately) concrete and steel bench.  The test protocol consisted of firing 5 ten shot groups of powder coated and traditionally lubed cast bullets.  Previous 50 FOOT ransom rest testing indicated that within 1 or two “fouling” shots, the groups had stabilized and no significant effect was observed when switching between lubed and coated bullets (long line to short line simulation)



The test program was performed using two guns, a 45 I built on a Caspian frame and slide with a 5” Kart Exact Fit Barrel.  This was the gun used for 50 FEET ransom rest testing.  The second was a Rock River 6” gun that has shown excellent accuracy (>1.5”) in numerous previous ransom rest sessions.  The second set of experiments with the Rock River was conducted for reasons discussed below.  There was effectively no difference observed in the accuracy of these two guns.



Groups from the 50 YARD range were somewhat disappointing, ranging from a minimum of 2.065” to a maximum of 3.669”.  Interestingly, these extremes were fired using the same gun/ammunition combination so user error or rest stability are possible factors. In many cases groups were reasonable with the exception of one or two flyers.  To get a better understanding of the overall accuracy potential, group sizes are reported as both 10 shot and 9 shot groups.



Rock River powder – 2.466+/-0.072* and 2.153+/-0.235



Rock River lead – 2.825+/-0.578 and 2.356+/-0.522



Caspian powder – 2.589+/-0.672 and 2.008+/-0.426



Caspian lead – 3.088+/-0.289 and 2.231+/-0.422



* 4 groups, ran out of ammo.



In both guns for both 9 or 10 shot groups, power coating was MORE accurate in these tests by between .25 and .5” on average.  Of course there appears to be some issues with either load development or ransom rest technique/anchorage which may not be allowing the guns/ammo combination to be performing to their highest level.  I've also attached a graph of the average group sizes for all conditions for both 9 and 10 shot groups.



It should also be noted that while the average powder coat group size is better across the board then the lubed group size, the difference is still within the margin of error.  I interpret this to mean that while power coat may (or may not) increase accuracy, it certainly doesn’t negatively affect accuracy.



Now with all that said, I’m open to questions, critiques, comments or suggestions for future experiments.  Some things I’m planning, are to optimize load data for the range and bullet, chronograph testing to determine velocity and distribution. 

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Re: Powder Coat Bullet Accuracy

Post by Ghillieman on Mon Feb 29, 2016 9:41 pm

Very interesting, I'm glad you did this test.
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Re: Powder Coat Bullet Accuracy

Post by rich.tullo on Tue Mar 01, 2016 10:54 am

Great test hope you do it again with a better Ransom Rest set up. 

I also think you came to the correct statistical conclusion: the difference in coating had not difference in accuracy. 

If you have more data with a better test i would be happy to do a Z test for you.
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Re: Powder Coat Bullet Accuracy

Post by 10sandxs on Tue Mar 01, 2016 11:26 am

Thanks rich, I'm going to try some different loads once the weather gets better at a local ransom rest.I'll let you know what I come up with.

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Re: Powder Coat Bullet Accuracy

Post by KevinB on Tue Mar 01, 2016 11:32 pm

Certainly in my plans for 147 gr. 9mm run and gun stuff now.

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Re: Powder Coat Bullet Accuracy

Post by noylj on Wed Mar 02, 2016 7:05 am

If you fired enough groups for statistical analysis, you should report the S.D. and do a student t-test at 90 or 95 "confidence" level to see if there is any real statistical difference.

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Re: Powder Coat Bullet Accuracy

Post by 10sandxs on Wed Mar 02, 2016 8:03 am

I tried to attach the data file but it didn't work. The standard deviation (1 sigma) is reported as +/- after the group size. Looking at it graphically with 1 sigma error bars, it's pretty obvious they are stastically equavelent. Yes, i could do all kinds of various stastically calculations to prove it, but I don't feel the need to prove the obvious, ive got ammo to load and a famity to follow. If you like I'll send you the data file and you can crunch numbers till your hearts content. There are some potential outlier groups that you could examine if you want.

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Re: Powder Coat Bullet Accuracy

Post by BE Mike on Wed Mar 02, 2016 9:50 am

Thanks for sharing all the hard work. I've been wondering about coated bullets and their application to bullseye shooting for a long time. So much "accuracy" testing on the internet involves 5 yds. and is useless IMHO.
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Re: Powder Coat Bullet Accuracy

Post by troystaten on Thu Mar 03, 2016 12:29 am

Nice write up, a friend of mine did a comparison limited to 25 yards and two hands and sandbags from a bench with 3 different pistols (2 Wilsons and one Salyer built bulleye pistol) and there was very little difference between powder coated bullets (bayou brand and conventional lead bullets, most of the groups for both types of bullets where all in the 1 inch range for 5 shot groups. The conclusion was that for his skill level it made no difference and the cleaner powder coated bullets where the way for him to go.  Of course your results may vary and maybe at 50 yards there might have been a difference.

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Re: Powder Coat Bullet Accuracy

Post by lablover on Wed Mar 09, 2016 6:00 pm

I like this..I was on the fence to powder coat and now I think I'm going to...Also, this makes me want to cast my own hence the PC interest.

Now to go buy a mold...Pot...lead..read till my eyes bleed....I LOVE IT

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Re: Powder Coat Bullet Accuracy

Post by PaladinPrecision on Sun Nov 26, 2017 6:05 am

10sandxs wrote:
These bullets were weight sorted into groups of +/-0.3 gr 
My best guess is that the weight sorting of the bullets had the largest quantifiable difference. Often people (at least in USPSA) just throw cast bullets down range without regard for weight. 

Thanks for sharing!

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Re: Powder Coat Bullet Accuracy

Post by troystaten on Sun Nov 26, 2017 4:59 pm

Nice write up, would like to see the same test at 50 yards.  One of my shooting buddies did a simmilar test at 25 yards comparing reloads with a 185 grain magnus button wadcutter and 185 grain Bayou coated SWC and the accuracy was very similar between the two bullets.


Wow I did not read the entire post, I had replied to it earlier in more detail.


Last edited by troystaten on Sun Nov 26, 2017 7:06 pm; edited 1 time in total

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Re: Powder Coat Bullet Accuracy

Post by Gary Wells on Sun Nov 26, 2017 5:59 pm

Great Test challenge & conclusion. Many thanks for this interesting data. Hope to see more testing of this subject.

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Re: Powder Coat Bullet Accuracy

Post by igolfat8 on Thu Dec 21, 2017 10:06 pm

Just to clarify, Bayou bullets are not Powdercoated bullets. Bayou's coating is applied as a liquid paint to the bullets and actually it's more akin to a stain than a high solid paint. The Bayou baked coating has a rougher surface texture than powdercoat paint. When chronograph testing identical loads of Bayou and powdercoat painted bullets you can expect 50-100 FPS higher velicity from the Powdercoated bullets.

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Re: Powder Coat Bullet Accuracy

Post by Jon Eulette on Thu Dec 21, 2017 10:43 pm

I shot this group at 50 yds with some of igolfat8's coated bullets. I think they'll shoot ;l)
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Re: Powder Coat Bullet Accuracy

Post by Rodger Barthlow on Wed Jan 17, 2018 7:54 pm

I'm a little late to this discussion but was wonder if the Bayou bullets leaded the bore?

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Re: Powder Coat Bullet Accuracy

Post by igolfat8 on Wed Jan 17, 2018 8:01 pm

The short answer is no. Bayou bullets have HyTek liquid paint coating, which is a bit different than powder coating. It’s not as durable as powder coat paint but it certainly works to keep lead out of your barrel. The only downside is it will leave lead deposits in comps and barrel ports.

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Re: Powder Coat Bullet Accuracy

Post by S148 on Wed Jan 17, 2018 8:02 pm

Rodger Barthlow wrote:I'm a little late to this discussion but was wonder if the Bayou bullets leaded the bore?

Nope.  I've had no leading with anything hi-tek coated from Bayou or other vendors.

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Re: Powder Coat Bullet Accuracy

Post by Rodger Barthlow on Wed Jan 17, 2018 8:06 pm

Thanks for the info. I'll give them a try

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Re: Powder Coat Bullet Accuracy

Post by Gary Wells on Wed Jan 17, 2018 9:24 pm

I had opportunity to do a visual AQL this last weekend and was quite surprised at the smoothness of the top coat. These were 200 gr SNS hard cast lead bullets which were also coated with red Hi-Tek . I was also advised that they cut out or cut down considerably on bore leading.

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Re: Powder Coat Bullet Accuracy

Post by Cheapshot on Sun Jan 28, 2018 2:40 am

Thanks for the testing, I have decided it is time to make my own now after following this thread.

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Re: Powder Coat Bullet Accuracy

Post by igolfat8 on Sun Jan 28, 2018 8:44 am

If you want to roll your own here is more information than you would ever need to join our group of coated boolit makers. Have fun...

http://castboolits.gunloads.com/forumdisplay.php?184-Coatings-and-Alternatives


Last edited by igolfat8 on Tue Jan 30, 2018 8:20 am; edited 1 time in total

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Re: Powder Coat Bullet Accuracy

Post by Cheapshot on Mon Jan 29, 2018 11:52 pm

igolfat8,
  Great site and a plethora of information. Thank you for the link.

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Re: Powder Coat Bullet Accuracy

Post by igolfat8 on Tue Jan 30, 2018 8:44 am

David,
Here is a short comparison of the two most popular current coating methods:

HyTek:
Easier to apply to bullets in bulk. 
Dry paint is mixed with acetone or MEK solvent then applied to bullets
You can dump bullets on non stick aluminum foil to bake them.
Takes only 8-10 minutes to bake them at 385*-400*F in an inexpensive toaster oven 
Requires 2-4 coats of liquid paint
Size bullets +.001" - +.002" above slugged bore diameter AFTER baking
The least durable coating of the two methods
Leaves zero leading in your barrel
Will accumulate lead deposits in barrel popple holes or external compensator ports
HyTek is the coating used by most commercial casters.
Bullets have a rougher surface texture than powder coated bullets.
Velocity is ~50 FPS faster than lead or jacketed bullets



Powder Coat:
Is easy to apply using the Dry Tumble Shake Method
You can't dump bullets in a pile to bake them because they will stick together in a glob.
You must pick bullets out of shaker container and stand each one on its base before baking
Takes only 10-20 minutes to bake at 400*F in an inexpensive toaster oven 
Requires only one coat of powder paint
Size bullets +.001" - +.002" above slugged bore diameter AFTER baking
The MOST durable bullet coating!
Leaves zero leading in your barrel
Will not accumulate lead in popple holes or comp ports.
I am not aware of any commercial casters offering true powder coated bullets.
Bullets have a glass smooth surface texture.
Velocity is ~50 FPS faster than HyTek coated bullets


Both Coatings:
Neither coatings will harm or wear barrels over time. I shoot 15K+ rounds per year and have been shooting coated bullets exclusively for 6 years with zero wear or accuracy degradation.

Neither coating will smoke when bullets exit barrel.

It usually only takes a couple patches of Ed's Red to clean the bore.

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Re: Powder Coat Bullet Accuracy

Post by 10sandxs on Tue Jan 30, 2018 9:20 am

Federal syntek is powder coated lead... I know the company that does it, but haven't had a chance to see the line...

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Re: Powder Coat Bullet Accuracy

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