Polycase Ammunition

The place to discuss ammunition, reloading, ballistics, loads, and chamberings.
User avatar
Darrell
Posts: 6586
Joined: Mon Aug 18, 2008 11:12 pm

Polycase Ammunition

Post by Darrell »

Guns & Ammo had a write up about the new Polycase ammo--the cases are nylon with zinc bases, IIRC, while the bullets are a copper powder in an epoxy base.

Interestingly, since they can't make functional hollowpoints by injection molding the epoxy and copper, they came up with a sort of straight flute tip, rather like straight flute drill bits. They claim that the flutes cause significant upset in gelatin or flesh. The bullets are light but fast for their caliber. Here's a video of their 9mm 74 grain at work in 10% ballistic gel:


https://www.youtube.com/watch?feature=p ... uTgf8OfDrQ

http://www.polycaseammo.com/
Eppur si muove--Galileo
User avatar
PawPaw
Posts: 4493
Joined: Fri Jan 02, 2009 8:19 pm

Re: Polycase Ammunition

Post by PawPaw »

Interesting, and it's certainly innovative. But nothing we haven't seen before. Like the other poly-cased ammo that came out, and flopped.

Shooting is all about cost effectiveness, and perceptions. (We'll pay more for premium ammo if we perceive an advantage, like premium hunting ammo, or match ammo). However, a good portion of us reload better ammo than we can buy, and we're set in our ways.

Again, it's certainly innovative, and I wish them all the luck. I hope they sell it by the box-car load.
Dennis Dezendorf
PawPaw's House
User avatar
D5CAV
Posts: 2428
Joined: Tue Aug 19, 2008 2:48 am

Re: Polycase Ammunition

Post by D5CAV »

I'm not sure what the advantage is other than cost. There is still a case that has to be ejected.

Caseless ammunition has more promise. There have been multiple tries at caseless ammunition, but they never caught on for a number of reasons.

The caseless rounds I'm familiar with were in the late 1980s and early 1990s, those forgotten days when I was a Centurion of the Imperial Legions in Germania protecting the Empire from the Barbarian Hordes. I believe there were earlier tries at caseless ammo that go back to the ancient days of Vietnam. I'm sure experiments are going on now.

Here are the advantages of caseless ammunition:
1. Lighter weight
2. No ejection port or very small ejection port (propellant gets burned, bullet goes down the barrel - no case to eject)
3. Fewer jams and/or faster cyclic rate (no ejecting case to get in the way of fresh round)

Here are the disadvantages of caseless ammunition:
1. Shelf life/ durability with no protective case
2. Heat dissipation (no ejecting case to carry away some of the heat)

The first issue was on its way to being solved, but the second issue never got close to being solved, so not a lot of effort went into solving problem No.1

Polymer cased ammo should give adequate protection to the case, but will still have an issue with heat dissipation. Nylon has a lot less heat capacity than brass, so less heat is removed from the firearm when the empty case ejects.

Fewer rounds fired before the gun gets too hot to shoot is not a good thing.
None are more hopelessly enslaved than those who falsely believe they are free.” Johann Wolfgang von Goethe
User avatar
evan price
Posts: 1912
Joined: Tue Aug 19, 2008 10:24 am

Re: Polycase Ammunition

Post by evan price »

PCA/Natec put this polymer case stuff out ten years ago. It sucked. Gun gets hot, case gets soft, base separates. Jam.
Sic gorgiamus allos subjectatos nunc

http://ohioccwforums.org/
Ohioans for Concealed Carry:THE source for Ohio CCW information and discussion!
User avatar
Yogimus
Posts: 4922
Joined: Mon Apr 18, 2011 6:32 am

Re: Polycase Ammunition

Post by Yogimus »

The biggest issue isn't with the 1st 15 rounds fired but with the 20th one you let sit in the chamber.
User avatar
PawPaw
Posts: 4493
Joined: Fri Jan 02, 2009 8:19 pm

Re: Polycase Ammunition

Post by PawPaw »

Yogimus wrote:The biggest issue isn't with the 1st 15 rounds fired but with the 20th one you let sit in the chamber.
All that's true, but I'd remind the assemblege that we've been using polymer case shotgun ammo for sevearal decades now. I've been in dove fields, shotgun ranges, sporting clays fields, where the shotguns get plenty hot. IIRC, back in the early '60s when we went from paper shells to plastic hulls, we had the same concerns and the shotshell manufacturers managed to figure it out. In my very humble opinion, the old Winchester AA hulls from the '70s were the very best shotgun hulls ever devised. Easy to reload, sturdy as hell, and as durable as anything since.
Dennis Dezendorf
PawPaw's House
User avatar
D5CAV
Posts: 2428
Joined: Tue Aug 19, 2008 2:48 am

Re: Polycase Ammunition

Post by D5CAV »

PawPaw wrote:I'd remind the assemblege that we've been using polymer case shotgun ammo for sevearal decades now. I've been in dove fields, shotgun ranges, sporting clays fields, where the shotguns get plenty hot. IIRC, back in the early '60s when we went from paper shells to plastic hulls, we had the same concerns and the shotshell manufacturers managed to figure it out. In my very humble opinion, the old Winchester AA hulls from the '70s were the very best shotgun hulls ever devised. Easy to reload, sturdy as hell, and as durable as anything since.
Disagree on the first point. Comparing polymer rifle shells and polymer shotgun shells is not appropriate for the following reasons:

1. The old paper hulls actually have less heat capacity than the plastic. The plastic hulls are better at removing heat from a gun than paper hulls.
2. The old formula PV=nRT still holds for both shotguns and rifles. The cup pressure in a shotgun is about 5x less than any modern rifle. Since P is lower, so is T.
3. Most people don't shoot anywhere close to as much ammo through their shotguns as through their ARs and AKs. Even on a dove field on opening day, someone might go through 200 shells in a morning vs. 1000 rds in an hour (or 10 minutes, like this bubba did to his AK): https://www.youtube.com/watch?v=lND51FkLuFU
4. This only works for automatics. The dwell time in any other action means the heat goes into the nearest heat sink, which is the gun itself. Do that experiment sometime. Shoot a .308 out of your favorite battle rifle and out of any bolt action. In the time it takes you to rack the action, the .308 case has cooled down to the same temperature as the rifle, while the .308 out of any battle rifle will burn.
5. If you get your shotgun hot enough to do something bad to the polymer shotgun shells, your paper hulls (and your fore end) would be on fire. Melt temperature of HDPE is almost 400 deg F. Ignition temperature of paper/wood/cardboard (cellulosic materials) is less than 500 deg F. Ignition temperature of HDPE is about 650 deg F.

Agree completely on your second point. I don't miss paper shells at all, and favor Winchester AA (especially since Remington discontinued "Blue Magics").
None are more hopelessly enslaved than those who falsely believe they are free.” Johann Wolfgang von Goethe
User avatar
Darrell
Posts: 6586
Joined: Mon Aug 18, 2008 11:12 pm

Re: Polycase Ammunition

Post by Darrell »

My interest was more in the projectiles--I'd been wondering, before I ever heard of Polycase, what a bullet with a spiral flute (like a drill bit) would do to flesh or gelatin.
Eppur si muove--Galileo
User avatar
PawPaw
Posts: 4493
Joined: Fri Jan 02, 2009 8:19 pm

Re: Polycase Ammunition

Post by PawPaw »

D5Cav wrote:2. The old formula PV=nRT still holds for both shotguns and rifles. The cup pressure in a shotgun is about 5x less than any modern rifle. Since P is lower, so is T.
No fair, I've been drinking for an hour. Nix that , make it two. I didn't know math was involved.
Dennis Dezendorf
PawPaw's House
User avatar
Netpackrat
Posts: 13983
Joined: Fri Aug 15, 2008 11:04 pm

Re: Polycase Ammunition

Post by Netpackrat »

D5CAV wrote:Agree completely on your second point. I don't miss paper shells at all, and favor Winchester AA (especially since Remington discontinued "Blue Magics").
Try the STS hulls. Admittedly, my shotgun reloading experience isn't all that extensive, but those are all I will use.
Cognosce teipsum et disce pati

"People come and go in our lives, especially the online ones. Some leave a fond memory, and some a bad taste." -Aesop
Post Reply