Results 1 to 10 of 10
  1. #1
    Join Date
    Sep 2014
    Location
    Texas
    Posts
    4,862
    Downloads
    2
    Uploads
    0

    Interesting Polymer Coated Bullet Findings and some more gun industry drama

    For all the reloaders in the house... I found this today online. A lot of people are starting to use polymer coated bullets in their range ammo because they are, well cheaper, by a lot. There are also commercial loads available out there.

    Then people started accusing Shooter's World Powder of being 'temperature sensitive' which is something that isn't exactly a compliment.

    Here is the response from the company, which I found very interesting.

    Hi Folks!

    We have been recently inundated with questions about Clean Shot being temperature sensitive.

    The predominant complaint involved Clean Shot and polymer coated pistol bullets. The claims were that as the temperature rose, velocity dropped. And conversely, as temperature dropped, velocity rose.

    To a Ballistician, that's counterintuitive. Normally, as temperature rises, propellant pressures rise with it. It's part of Boyle's Law (PV=nRT).

    So, with all due haste, we tested Clean Shot at 75 degrees F, and 125 degrees F. We shot Berry's plated 124gr RN, Hornady 124gr FMJ, and a polymer coated 124gr RN. All 9mm. We tested all these in laboratory conditions, from a test barrel.

    Now, please bear in mind my history. I'm a competitive rimfire shooter from days-gone-by. I'm also an engineer, a tinkerer, a bullet caster since I was 17, and unverified internet rumors claiming "farmer" status. I digress...

    I know a lot about bullet lubricant.

    So, I theorized before the experiment: What happens to plastics when they get cold? (they get hard and brittle). What happens to plastics when they get hot? (they get soft and pliable). I wondered if this polymer attribute might have some effect upon ballistics...

    The Findings:

    When testing plated or jacketed bullets, between ambient and 125 degrees F, there is virtually no change in either pressure or velocity output. However, when using polymer coated bullets, I witnessed a SUBSTANTIAL loss in pressure at elevated temperatures. Likewise, I witnessed a loss in velocity at elevated temperatures. Keep in mind that my test barrel has a SAAMI min-spec bore/groove, lead and throat. Not so, with competition and production guns. With longer leads, more pressure can bleed off before gas sealing. I SUSPECT this might cause even more velocity loss when shot from a standard firearm.

    How could this be possible? Well, it could well be that polymer bullets, because they're essentially coated in plastic, change their lubricity with changing temperatures. Jacketed and plated bullets seem to not exhibit this trait.

    Could it be that there are some polymers out there that don't change their frictional coefficient with changing temperatures? Dunno. Do some polymers exhibit more temperature/frictional coefficient change than others? Dunno.

    But what I can say today, right this very minute, is that polymer coated bullets dropped from 1072 fps at ambient to 1041 fps at 125F.

    And plated or jacketed bullets changed no more than 10 fps between ambient and elevated temperatures. In fact, the Hornady FMJ changed only 5 fps between temperatures...

    The truth shall set you free.


    The bullet type and specific type of coating actually induced the problem, not the powder. Very interesting.

    The source:

    https://www.facebook.com/groups/2797...2/?__tn__=CH-R

  2. #2
    Join Date
    Sep 2014
    Location
    Texas
    Posts
    4,862
    Downloads
    2
    Uploads
    0
    This was sort of like that whole Fire Clean thing all over again... except the one side smacked down the other side with some cold hard facts thus killing this thing in it's tracks.

  3. #3
    Join Date
    Sep 2014
    Location
    Texas
    Posts
    4,862
    Downloads
    2
    Uploads
    0
    Paging Former11B...

  4. #4
    Join Date
    Oct 2014
    Location
    SC
    Posts
    2,315
    Downloads
    0
    Uploads
    0
    Were the people accusing SW of having temp sensitive powder ONLY shooting poly coated bullets? Or was it everyone? Seems like the trend would’ve been noticed early on based on who was having issues if it’s the former. If it’s the latter, I wonder if it was actual loss in velocity/pressure or people just jumping on the bandwagon

    And it kind of seems obvious to me that the different coating might have some unintended consequence; everyone knows that lead requires different loads than FMJ; I don’t see why it’s not safe to assume the poly bullets ARENT identical until testing proves otherwise. Reloaders are loathe to share load data online and simply say “work up according to a manual....” yet they’re shitting the bed over this.

    Seems a tad silly it went as far as it did

  5. #5
    Join Date
    Sep 2014
    Location
    Texas
    Posts
    4,862
    Downloads
    2
    Uploads
    0
    Quote Originally Posted by Former11B View Post
    Were the people accusing SW of having temp sensitive powder ONLY shooting poly coated bullets? Or was it everyone? Seems like the trend wouldíve been noticed early on based on who was having issues if itís the former. If itís the latter, I wonder if it was actual loss in velocity/pressure or people just jumping on the bandwagon

    And it kind of seems obvious to me that the different coating might have some unintended consequence; everyone knows that lead requires different loads than FMJ; I donít see why itís not safe to assume the poly bullets ARENT identical until testing proves otherwise. Reloaders are loathe to share load data online and simply say ďwork up according to a manual....Ē yet theyíre shitting the bed over this.

    Seems a tad silly it went as far as it did
    Apparently they were shooting coated bullets (not specific as to what type of coating) and they knew enough to be dangerous with opinions but not enough to really know the facts.

    I just saw this post a little while ago so apparently the rumor mill started to flow a few days/weeks back and eventually was laid at the foot of Shooter's World with the masses of shooting ninjas and gun industry bravado laying blame on the powder company.

    That is until they got slapped back in line. On that level alone I think this is beautiful. There are too many people with big egos who think they know more than they really do...and to see them get a humbling makes me smile inside.

    Internet bravado just got taken down a few notches. It's wonderful!

    ---

    As far as the bullets themselves go, I was doing tests using cast and coated bullets for 300 BLK a while back. I recently resumed and am now doing about a 1000 round test to see if the kinks are worked out. So far so good. After about 300 or 400 rounds zero leading issues and accuracy is fairly good especially for 50 to 75 yard targets and plinking around. Keep in mind I am shooting with irons so no precision shooting here so far. I would say with some effort one could make ammo that is high 1 to 2 MOA at 100 yards with those coated bullets.

    Just based on my own limited experience though cast and coated bullets are a different animal from FMJ or plated. This was obvious within the first ten rounds. They are SUBSTANTIALLY faster velocity wise. The FMJ loads from a loader's manual, with similar grain cast bullets will give you a few hundred faster fps at the muzzle so you have to back waaay off to get subsonic speeds.

    Tuning those in for subsonic use is very possible but you have to work through a lot more issues, at least I did until I wrapped my head around the principles of it all.

    It's basically a whole new ballgame. That said with coated bullets you can shoot for about 1/3 or so the total price.

    The thing that I find interesting though is depending on the type of coating used that BULLETS can be temperature sensitive. It's fascinating.

    Note however that not all coatings are created equal. Other coatings might not behave the same as others. There are multiple types of coatings that people use. I would be interested to see more testing done on this.
    Last edited by alamo5000; 20 April 2019 at 21:30.

  6. #6
    Join Date
    Sep 2014
    Location
    Texas
    Posts
    4,862
    Downloads
    2
    Uploads
    0
    Quote Originally Posted by Former11B View Post
    I wonder if it was actual loss in velocity/pressure or people just jumping on the bandwagon
    He proved that with FMJ or plated bullets the powder wasn't temp sensitive with a 50 degree temp variance. He also proved that with coated bullets it does happen. He was able to replicate it, but in doing so he showed that it wasn't the powder that was at fault.

  7. #7
    Join Date
    Sep 2013
    Location
    WA
    Posts
    3,812
    Downloads
    1
    Uploads
    0
    Huh...ya I havenít evolved I guess into the polymer coated bullet world..for the extra work or about same price I donít see the attraction.


    Plus, I was reading something the other day on barfcom I believe, dude was getting peopleís attention, as whoever/whatever coated bullets had nitroglycerin in the mix. They were wondering how stable/longevity of them sitting around loaded...


    Iím still a copper fmj/plated boolit kinda guy...

  8. #8
    Join Date
    Sep 2014
    Location
    Texas
    Posts
    4,862
    Downloads
    2
    Uploads
    0
    Quote Originally Posted by mustangfreek View Post
    Huh...ya I havenít evolved I guess into the polymer coated bullet world..for the extra work or about same price I donít see the attraction.


    Plus, I was reading something the other day on barfcom I believe, dude was getting peopleís attention, as whoever/whatever coated bullets had nitroglycerin in the mix. They were wondering how stable/longevity of them sitting around loaded...


    Iím still a copper fmj/plated boolit kinda guy...
    That's the thing. It's not the same price and it's not hardly any extra work at all. Once you get a formula down its easy.

    Especially for unsuppressed pistol range ammo it's easy. It's not harder it's just that the materials are different and need to be loaded accordingly.

  9. #9
    Join Date
    Oct 2014
    Location
    SC
    Posts
    2,315
    Downloads
    0
    Uploads
    0
    Quote Originally Posted by alamo5000 View Post
    He proved that with FMJ or plated bullets the powder wasn't temp sensitive with a 50 degree temp variance. He also proved that with coated bullets it does happen. He was able to replicate it, but in doing so he showed that it wasn't the powder that was at fault.
    That was my point/question, although I wasn’t making it here. The bandwagon question was more pertaining to people repeating info without the actual experience. You’ve got people who won’t touch RE15 because they read its temp sensitive but have no experience with it, yet they live in the South and it’s actually fine to use (just an example).

  10. #10
    Join Date
    Mar 2013
    Location
    The Unfree State (MD)
    Posts
    2,583
    Downloads
    3
    Uploads
    0
    Hunters who tried poly coated bullets decades ago knew this to be fact. Colder temps, coating is harder and bullet flies faster. Really screws up your holdovers when you ran your numbers in the summer then get 75-100 FPS more in January. Not sure how anyone could blame the powder when the gain/loss curve is backwards.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •