Mine doesn't have any? Only my hogue grip.

I guess I am just more comfortable with the aluminum receiver. If in testing the polymer receivers prove to be as good or better, I may be ready to make the switch.

Please let us in on the info you have. Why will it not work as an AR lower?

I see this pic alot as a reason poly makes bad lowers.

What it doesn't so is that the failure was due to someone using a buffer that was too short.

The BCG was able to contact the stock tube aria as it cycled.



If you claim that a poly lower, upper or even a poly FCG are a bad idea you need to post pics of why and how it is bad or how failed.

If someone has a Plumcrazy lower and had issues they need to pipe up.



Tell then I take any claims good or bad with a grain of salt.  Especially if a pick is posted of a failure of a part without explaining the full context.



I ran into the same BS claims about factory 308 blowing up Ishapore Enfields.

I have NEVER found ANY pics of a  Ishapore Enfield that was blown up by factory 308 ammo.  However I've seen a couple that were blown up by handloads that owners first claimed to be factory ammo.

Styer AUG has a plastic Fire Control Group.  Seems to work OK, but some of my Aussie Army buddies complained of problems after extended full auto fire.

I don't see how folks can knock it or praise it until someone does some independent testing of it.

Yes but the sear surfaces are HUGE compared to an AR sear surface, with much less stress applied to the sear surfaces than with an AR.  Again, Parts designed as polymer are great.  Parts designed as aluminum, but made in plastic, not so great.  


(ETA, that trigger is horrible by the way, and you know it.   I've fired a full auto AUG at a rental range and...blah...   I've heard the new MSAR's are much nicer...

I would like to see some torture tests of this lower and FCG...

This is interesting...

If anyone wants to donate $5 to my paypal account, I'll BUY one of these plastic lowers.

I'll mount it on my CZ upper and put 10k rds of .22lr through it and report back.

IM me if you want to donate to the "cause".

We should probably give you a few bucks just cause your a Leafs fan. But seriously here, If you had a polymer stripped lower and put a decent parts kit into it, I don't see why you couldn't shoot a bunch of 223 out of it. The buffer and spring are gonna take the pounding, not the plastic lower itself. I really am not interested in a plastic lower but minus a plastic FCG, it should be halfway decent.

Lil Wayne?

my hk ump is plastic and most trigger parts are plastic . my hk navy lower is plastic . if you look at fire control group of plumcrazy you will see the sear is metal and thiers metal imbedded in hammer . im planning on getting one after christmas to play with

HK is to sub guns what the pony is to AR's....errr....M-16...err.....sarcasm....ok I'm changing my name to Bigdouche

it will be ok , drink more koolaid

For what its worth, I know Glocks are proven and tested and yadda, yadda , yaaaaah....but in my career as a LEO out of the 3 duty guns we had the choice of carrying......9mm S&W 5946, SIG P-226(I think....maybe P229?) and a Glock.......out of all the times I was at the police range, the Glocks always had all of the problems. I saw barrels split, blow up, stage3 malfunction etc.....fairly regularly. The Smith, which I carried and the Sig....were much more reliable. In the 13yrs before I got hurt (LOD retired) I never had a malfunction or FTF in my metal duty gun and I shot likely 4K rounds out of it. So, plastic guns....

using a glock as an example of why not to buy a polymer gun is

bigdick.....giggles.....that was sarcasm...not the douche part though

and i forgot the nylon 66

whats sarcasm

now your just being silly.

sorry my name kinda fits

hence the reason I need to change mine to bigdouche, I'm following suit.

People in general have false impressions of what a well engineered plastic part can do.  Generally this probably stems from the plastic shit you buy at Walmart that was designed by someone with absolutely no real knowledge of polymers.  Polymers and composites are the future, don't rule them out because your blender cracked the third time you used it.

That said: I have no idea whether or not this product has been properly designed.  I'm simply saying don't rule it out because of the word "plastic".

I said it for its looks, and feel. Not for function. If this is what you mean in your comment? I've shot my brothers glocks in .45, and 9mm. And I just prefer the look and feel of my 1911 better?

The ONLY proven synthetic lower is Calvary Arms! I would purchase a REAL Carbon Fiber Lower (with carbon fiber mat), that would be tougher than any Aluminum lower. BUT, the only "carbon fiber " lowers available are really CHEAP PLASTIC!

PursuitSS

I think I heard all this plastic guns stuff when the glock started really getting talked about in the 1980s. I think the advantage of Polymers (plastics) over aluminum is that the polymer can give where the aluminum with stress and eventually crack. As pointed out before a polymer firing group was used successfully in the AUG.  FN has built several "plastic' platforms lately I for one would like to get one of these and play around with it. I bet you could build a Super Duper light weight gun.

Hahaha yup!

Three pages of speculation.  If no one here has personal experience with this brand than it is pretty lame to be trashing it.  I plan on buying one (not the LPK though) and trying it out as long as i cant find a connection between them and vulcan/hesse.

AMEN ...

I don't think there is any connection between Hesse/Vulcan?Blackthorne/Velocity and them. It was speculated here awhile back that they MAY be Professional Ordinance resurrected.

Someone posted side by side photos of Professional Ordinance receivers and Plumcrazy receivers. And considering that Professional Ordinance was also out of Lake Havasu, AZ this seems to be a real possibility/probability!

PursuitSS

I love my Glocks, but these guys really are plum-fuckin-crazy.

"Made of a Fiber Reinforced Polymer that is More Durable and Will Outlast any other AR15 on the market today."



You want a polymer receiver? Buy a Kel-tec. At least (I think) they use an alloy FCG.

Plastic? No way,  I wouldn't even consider it for an AR lower.

Someone bought the tooling from PO, maybe?

YOU CAN'T BEAT A GLOCK

Wow that is interesting as my experience has been exactly the opposite. We put 7500 rounds each through 35 Glock Model 22's 40 S&W, and the same number of rounds through 35 Sig Sauer 226's in 9x19. We also had a few Ruger 95's and an HK USP put into the mix. The ammunition was Speer lawman for both calibers. The guns were run through a lot of tac shoots, accuracy shoots and with various strings and rates of fire. No more than 1000 rounds were fired in a day taking place over about 6 hours. The guns were cleaned and inspected at the end of each day. At least two of the sigs had stoppages each day of shooting I think the highest number was four in a day––-still pretty good, But the Gocks had ONE single failure and that was when a primer failed. Again not bad when you consider how many tens of thousands of Speer Lawman was fired. A few Sig mags had to be replaced after they were damaged after hitting the deck (all empty mags were allowed to drop free to the groud as a part of the excercise. One Sig frame cracked towards the end. I do wish to point out all of these guns were fired more than most privately owned handguns probably will be in 20 years.

The part about seeing barrels blow up is very interesting to me I would like to hear your experience with them especially if you saw more than one.

Here is research on the topic:

The Glock kB! FAQ

version 1.04, 14 March 98
by
Dean Speir ([email protected])
Jay L. Swan ([email protected])
Todd Louis Green ([email protected])
with significant contributions from
Walt Rauch ([email protected])

1. What is a kB!? Coined by firearms journalist Dean Speir, "kB!" is shorthand for kaBOOM!, which is the written representation of what happens when one has a catastrophic explosive event in one's firearm, or, for the purposes of this FAQ, one's Glock.

2. What causes a kB!? Catastrophic failures may be caused by a variety of problems, but in general a Glock kB! is as a result of a case failure.

The case failure occurs when pressure inside the cartridge increases to the point that it cannot be contained by the case and the material of the case fails, allowing hot gases to escape from the ruptured case web at damagingly high velocities.

The resulting uncontained forces can blow the magazine out of the gun, emulsify the locking block, cause the tip of the trigger to be snipped off, ruin the trigger bar, rupture the barrel, peel the forward edge of the slide at the ejection port up, and do other nasty things. In general, Glocks tend to contain case failures fairly well, but under some circumstances they can cause injury as well as damage to one's gun. At least one LEO has been injured in a kB! involving a Glock 21 and a Winchester factory overcharge.

Additionally, there is some evidence of there being another cause of a kB!... a barrel failure caused by improper metallurgy.

3. Which Glock models are affected? Speir has documented many instances of kB!s, all of them in the Models 20-something Glock (.40 S&W, 10mm and .45 ACP). Speir has no confirmed cases of Glock kB!s in the 9 x 19mm (Models 17, 17L, 18, 19 and 26) or the .380 ACP/9 X 17mm (Models 25 and 28).

4. Why does a kB! occur in these Glock models? Reports compiled by Speir from various independent laboratories are inconclusive as to one single cause for the catastrophic failures.

There do, however, appear to be several contributing factors which collectively may induce catastrophic case failures:
Firing out of battery. Most Glocks will do this to some degree, especially those improperly maintained.  [editor's note: most semiautomatic handguns of any manufacture may fire out of battery; whether Glocks have a proclivity for this is open to debate]
Significantly overpressure rounds. These occur mostly in homemade reloads or in commercially remanufactured ammunition, but have occurred in factory ammunition as well.
The lack of full case support in the critical area over the feed ramp of all large caliber (.40 S&W, 10mm, .45 ACP) Glock pistols.

       (Ostensibly as a measure to promote feed reliability, Glock chamber mouths are slightly oversized. One can test this by removing the barrel from the Glock, dropping a factory round into the chamber, and observing that there is brass exposed at the six o'clock position. Take a fired case and note that there is a slight engraving if not actual bulge around the case web, which is most pronounced in the area of the case which, upon
       firing, was in the six-o'clock position.)

The use of personally reloaded or commercially remanufactured ammunition utilizing cartridge cases of indeterminable generation. Unlike many rifle handloaders, many of those who reload for handguns do not as a habit separate their fired cases by generation, and each time a case is re-sized and reloaded, the brass "works" and weakens. kB!s have been documented with factory ammunition, but most of them occur with either commercial or homemade reloads.

5. Do kB!s occur in other guns or just Glocks? kB!s do, of course, occur in other guns, but no one appears to be keeping accurate statistics for most of them. Many 1911-style handguns have partially unsupported case mouths, and numerous case separations have occurred in these guns. Early .38 Super barrels were particularly susceptible. Gunwriter Frank James has documented a number of kB!s in HK USP .40 pistols, which do have fully supported chambers.

6. What is the relationship between reloads and kB!s Most kB!s occur with commercially remanufactured or personally reloaded ammunition.

Successive re-sizing and firing of a case result in eventual weakening of the brass, increasing the probability of case failure. The partially unsupported chamber in the Glock exacerbates this problem.

"Hard crimping" or overseating of bullets, particularly in the .40 S&W, can cause dramatic increases in pressure almost to the same degree as a propellant overcharge. [See Annotation #3] Either alone or in combination with a weakened case, these factors can result in a kB!

Some people have also postulated a relationship between the use of cast lead bullets and kB!, arguing that buildup of lead in the chamber can lead to pressure buildups as well. The jury seems to be out on this one as a direct causation, but lead build-up will sometimes cause a round to not fully chamber, and as Glocks can discharge with the action not completely locked up ("out of battery"), this can lead to a catastrophic failure.

7. What can I do to prevent a kB!?

  1. Shoot only new factory ammunition out of your Glock. This is what Glock, Inc. recommends, as do several members of Glock-L. Shooting reloads voids your factory warranty.
  2. Install a barrel with a fully supported chamber. Custom barrel makers include:
     Jarvis Precision
     Bar-Sto ([email protected])
     Wilson ([email protected])
     Briley (http://rampages.onramp.net/~briley)
     For related data, see annotation #3 at the end of this FAQ.
  3. Avoid wherever possible .40 S&W ammunition manufactured by Federal Cartridge Company prior to November 1995. [See Annotation #2]

At an October 1996 G.S.S.F. match, one competitor with a Model 22 had simply switched to a .40 S&W Sigma barrel which he averred not only better allowed him to shoot lead because of the conventional rifling, but that the fully supported Sigma chamber significantly decreased the opportunities for a kB!  Note: This procedure is neither recommended nor authorized.

8. If I insist on reloading for my 20-something Glock anyway, what can I do to minimize the chance of a kB!?
Install a custom barrel. See 7B.
Keep careful track of your brass. Load "Major Power Factor" loads only in new brass. Don't use range pickups. Don't shoot "hot loads" from used brass. Discard used brass sooner than you would normally.
Use calipers or case gauges to keep your reloads within spec. Check for excessive bulging in the case web and make sure your bullets are seated to the correct length. Also check for excessive case thinning or bulging.
The propellant AA#5 has been identified in a disproportionate number of kB!s, not only in Glocks but USP40s with barrels which do provide full case support. A number of Glock-L members have reported kB!s involving this propellant. It is not clear whether these kB!s are the fault of the propellant or the reloader, but it is clear that they are occurring in disproportionate numbers. [See Annotation #1]

       Dean Speir and Frank James have reported that there are at least four discrete propagations of AA#5 in the U.S.A., variously manufactured under the same label by IMI, Olin, Beta Chemical (Norinco) in China and Lovex in Czechoslovakia.

Another poster has identified VihtaVuori N350 as a potential problem. As a rule, you should always track the lot numbers of your propellants, and when using a new lot (or to be even safer, a new canister), you should back off the power of your loads and slowly increase them until you have verified the safety of the new lot.
Don't use cast lead bullets at all, or at least be very careful about lead buildup if you do.
Religiously follow all the other safety precautions associated with normal reloading procedures. Take special care not to load a double charge.

Annotation #1 Accurate Arms' current reloading guide contains the following statement regarding .40 S&W pistols and supported/unsupported cases:

"In recent years it has become very apparent that there exists a situation regarding some pistols chambered for the .40 S&W cartridge. Some of the pistols currently available to shooters may not provide complete support to the case when a cartridge is chambered."

"This information [AA's load data] is safe for use in firearms which provide complete support of the case. Failure to fully support the case with cartridges of such intensity may result in bulged cases, ruptured cases, separated case heads or other consequences which may result in damage to the firearm and/or injury or death to the shooter and/or bystanders."

"If you own a firearm chambered for the .40 S&W, we recommend you contact the manufacturer to determine if the case is fully supported."

"If your firearm does not provide complete support for the case, DO NOT USE Accurate Arms Company data or products to reload your .40S&W ammunition."

"This is the first time Accurate Arms Company has felt it necessary to place such a restriction on the use of our products, but the continued safety and welfare of the shooting public compels us to do so."

Annotation #2 In late 1995, Federal Cartridge of Anoka, Minnesota quietly undertook a redesign of their .40 S&W cartridge case to strengthen internally the area of the case web. While no one at Federal will address this for the record, it has been suggested that this move was dictated by the popularity of the .40 S&W Glocks, and the munitions giant's attempt to hedge against a kB! with any of their ammunition.

Federal .40 S&W rounds which may contain suspect casings may be identified as follows:
Lot number consists of 10 characters (mostly numbers).
In the 7th position, there may be a number or a letter.
If there is a number in that position, the ammo was manufactured with the old style (possibly defective) brass.
If it contains the letter Y (1995) or R (1996), the ammo has the new designed casing and should be okay.
If the letter H appears, then check the next three [3] digits (the last three in the lot number).
Ammo lot numbers H244 or below have the old style casings.
Lots H245 and above have the new style casings.

This information was provided by Federal Cartridge Company in September 1996.

Annotation #3 It was Law Enforcement/Gun writer Walt Rauch who first brought forth information that bullet set-back (such as often occurs in administrative unloading/loading) in the .40 S&W could raise pressures exponentially.

"This was first confirmed via a European cartridge maker (Hirtenberger In Austria) from information given to me by a high level Glock representative. 1/10" set back can cause pressures to double from 35,000 psi to 70,000 psi.

"Note this was achieved with factory ammo and without the detrimental effect of lead build up in the barrels. I also had 'off the record' confirmations of this from two U.S. sources, one governmental and one manufacturer."

I think I will look into getting one of these Polymer lowers and give it a go. Remember, those who hated the idea of the Armalite had a main arguement in that who wanted an aluminum battle rifle?! Once one of us gets a hold of one of these things we can get some data and then argue about it in an intelligent manner.

Don't think so, I read somewhere that that's how Bushmaster got started with their polymer rifle. They purchased the assets of Professional Ordinance. I remember from the side by side photos there were subtle differences as if  someone set out to recreate the molds but being they started from scratch there are minor dimensional changes. It sure smells like either the former owner of Professional Ordinance restarted molding receivers or maybe a former employee.

PursuitSS

why is there no gripes about any of the other polymer rifles... AUG F200 G36 Arctic Warfare.... the Scar or ACR?!

Because they don't have a reputation for braking in half like Professional Ordinance/ Vulcan/ Bushmaster and MAYBE Plumcrazy!

PursuitSS

Probably because those rifles were designed for those parts to be made out of polymer and use the material as appropriate.

An AR15 lower wasn't designed to be made out of polymer... and trying to directly substitute polymer for aluminum without altering the design to compensate for the different material qualities can lead to disappointing results.  The manufacturer of these isn't saying what they are made out of, it's possible they have some material that has sufficient material qualities to hold up in this application.  Won't really know until some guinea pigs buy them and try them.

There's likely a good market for an inexpensive polymer AR lower, but it (probably) needs to be (re)designed to account for the different characteristics of the different material.

Guardian, I can give you one personal experience that affected me, when I was in the academy, we trained with the guns that would ultimately be our personal duty guns. My Company Sgt. was shooting to my left, at the time perhaps 400 rds went through this Glock and the barrel split upon disharge, we both got hit with metal/plastic and they sent us to the emergency room(precautionary only, they wanted to make sure we didn't get anything in our eyes). I was told what happened, I didn't have my witt about me to investigate it at the time, for all I knew, I thought I had been hit with a riccochet off the stantion. I have heard other similar stories from guys on the line. The gun was new. I'm not sure what dept you are with, in the early 90's mine was 38,000 uniformed strong, so that gives you an idea of where I worked and the number of Glocks out there.

do they offer a lifetime warantee like Cav arms plastic lowers?

from earlier in this thread

""Lifetime Unconditional Guarantee. We have registered some of these as machine guns and put close to 9k rounds through one, with negligible wear." "

I am in contact with the owner.  I may have one of these soon.

Were you using factory training ammo? Winchester had some ammo that was overcharged at one point. Also did you see from the study that 1/10th inch difference in the seating of the bullet can result in DOUBLE the pressure. I am guessing you were using a 40 S&W? It is always interesting to hear about these things. I have seen a couple of burst receivers and barrels but they have usually been from reloads and not on a glock. I am not arguing just interested.

Depending on what they offer for dealer pricing from that ad, I might pick one (or two) receiver/LPKs up just to play with them.  If nothing else might end up putting together a .22 build or something.

I'm not seeing where Glock KBs have any relevance to an AR lower...

This is what I thought of during the day....Cav Arms modified the design to accomodate a weaker material.

I can't understand how somebody decided to use the identical shape for polymer part.

Thanks for taking one for the team my man. Let us know how it runs after a few k through it

I have personal experience with these.  The owner is Hal Lockett (d.b.a Omega Performance Products), and I have spoken with him directly back in June when I purchased a stripped PlumCrazy lower from him.

Yes, it's based off of the original POI design (by Hal) which was sold to Bushmaster.  The PlumCrazy lowers are a revision to the POI design.  I'm only aware of the subtle differences though.  I don't have a POI lower to compare my PlumCrazy lower to.  The manufacturing was in Lake Havasu, and that's how the receiver is marked.  I recieved mine directly from Hal Lockett and his current FFL is issued out of California.  He is friendly enough to work with.

Mine is assembled onto a super-light build that weighs in at 4-pounds 9-ounces.  I've done a LOT of lightening on the rifle to get it to that weight, and mainly built it as a novelty to see how light I could go and still function reliably.  

I'm not an engineer or machinist, but the owner of twenty-one complete AR's, sixteen M16 uppers (I'm a retro guy, as you can tell), and God knows how many spate parts.

I DO know that I have been around AR's long enough, and built enough that I was pleasantly suprised with the quality of the PlumCrazy receiver.

I have not put it through a torture test, so I can't vouch for it's longevity.  

I'm happy with it though, and think it was well worth the $100 I spent on the stripped receiver.

Never got a LPK with it, and really don't know if I would have wanted to rely on a plastic LPK.  I wouldn't mind gettng another one, just to see how long a plastic LPK would last, and to see if I could get my complete rifle down to 4.5 pounds.  

And no, I'd never take a hammer to it, like they did in the video LOL.

I'm pretty sure PLUMCRAZY firearms is owned by a guy who tried to start a Youtube smear campaign against Cav Arms (along with Youtube user TMHonfire) to try and sell his shitty Cav-wannabe lowers.

Quick, someone post the video of the guy who made a lower out of a cutting board, mounted an upper, and fired it repeatedly.

I'm too lazy to search for it here or on YouTube.  I know it's out there though.  I'm not sure what ever came of it, or if the guy kept shooting it.  But I do know, that he did indeed make an AR lower out of cutting board material, and actually fired it.

IIRC, he fired the first rounds with the gun mounted stationary, and pulled the trigger with a string, in case it blew up.  But once it didn't blow, nor showed signs of failure, he shouldered it and dumped a mag or two.

There's also a dude over on another board that made an AR lower out of plywood.

Plywood.

Let that sink in a bit.

The plywood lower worked great once the builder inserted a couple of steel sleeves into the takedown pin holes. And that was off-the-shelf-from-Lowe's junk-ass sheathing material, cut with a jigsaw and assembled with off-the-shelf nuts and bolts - not fiberglas-reinforced polynylon composite resin injection-molded into CNC-milled carbide dies.

The stress points on an AR15 are contained mainly within the upper. Of the negligible stress transmitted into the lower, it is transmitted into the front takedown pin and the threaded collar for the extension tube - and I'm fairly certain the fellas that spent upwards of a hundred thousand dollars in R&D, tooling, dies, materials and marketing also thought of this.

I love all the bullshit and FUD spewed by the Gucci Gun crowd on this site, all the irrational hate on an a new, inexpensive alternative to The Way We Waste Our Money. Rather than applauding a new method of solving an old problem and leading to an eventual reduction of costs to the point where this hardware becomes a commodity that can be sold very inexpensively and placed in the hands of the everyman, you guys are sitting in your ivory towers and looking down your noses at any development that seeks to place your special little golden guns into the hands of the unwashed, illiterate masses that dwell within your effluent.

Real populist attitude to take there, guys.