On the POF E^2 design...

[Integr8d]

I've been sizing up the new Gen 4 308 as a possible next purchase. But I have a few thoughts that I'd like to bounce off you guys. POF is introducing this new E(squared) chamber design, where the make four cuts in the neck chamber to allow the casing to break free for easier extraction. The idea is that these ports will allow the gas to flow back to do the heavy lifting.

I'm wondering if A: this is a solution in search of a problem.

And if B: this will necessitate more cleaning.

The second question is more pertinent. My only other AR is an Adam's Arms piston upper mounted to a generic (actually produced by Mega) lower with blah blah blah on it. Servicing the rifle has been as easy as one could hope. And that was one of my primary reasons for going with the piston design.

So assuming that this gas will loosen the casing, it's likely that that gas will still be flowing through those cuts as the bullet is traveling through the barrel. How likely is it that I'll be seeing four concentrated areas of carbon buildup around the shoulder area of the chamber? Anyone wanna take bets?

I don't mind cleaning my rifles. It's kind of therapeutic. But one more step is one more step. Plus, I wonder if or how long it'll take before these chambers just get clogged up.

Here's a video that a guy made at SHOT with an animation about half-way in.
POF P308 Gen-4 7.62mm NATO/.308 Win. Tactical AR Carbine with E2 Chamber and Ambi Controls - YouTube
The guy from POF says 'ambidextrious'... *sigh

 

[Razor74]

HK put flutes in their MP5 chambers to help with extraction, but that was with a blow back system. Don't know how it will work in a larger caliber gun.

 

[Rob01]

A. It's an innovation to help the rifles run more reliably and put less stress on extractors, which are know to be an eventual weak link.

B. No it won't. The chambers won't be fouled up. It's been tested. This is NOT A FLUTED CHAMBER.

Brass also isn't damaged like people see in fluted chambers. Below are a couple of pieces of fired brass. You can see the slightest mark on the neck to shoulder junction. No more powder fouling than with any other rifle. The mark is so slight in person that it's hard to take a picture of.

 

[Integr8d]

I'd be interested to see some tests. Something along the lines of removing the extractor from the bolt and firing off the last round in a mag. Do that on both a standard chamber and one with the cuts.

Edited for carelessness*

 

[InkedIan]

A. It's an innovation to help the rifles run more reliably and put less stress on extractors, which are know to be an eventual weak link.

B. No it won't. The chambers won't be fouled up. It's been tested. This is NOT A FLUTED CHAMBER.

Brass also isn't damaged like people see in fluted chambers. Below are a couple of pieces of fired brass. You can see the slightest mark on the neck to shoulder junction. No more powder fouling than with any other rifle. The mark is so slight in person that it's hard to take a picture of.

View attachment 29615View attachment 29616

Huh, I’ve personally never seen an AR style rifle have aproblem with extraction that was caused by the extractor. Going through Marine Corps regular training, EMP classes, pre-deployment training, and personallyowning 3 ar15s, 2 ar308s I’m fairly experienced in this area. I have seen caserims ripped off by extractors from stuck cases but that was by no means afailure caused by the extractor. Seems like a fix to a non-existent problem. Just my opinion.

 

[Rob01]

Huh, I’ve personally never seen an AR style rifle have aproblem with extraction that was caused by the extractor. Going through Marine Corps regular training, EMP classes, pre-deployment training, and personallyowning 3 ar15s, 2 ar308s I’m fairly experienced in this area. I have seen caserims ripped off by extractors from stuck cases but that was by no means afailure caused by the extractor. Seems like a fix to a non-existent problem. Just my opinion.

I have been through all the same as you as well. Breaking extractors is what I was talking about and not trouble extraction per se although this will also help with the possibility of stuck cases so rims aren't ripped off. I personally haven't had an extractor break but I know people who have and I carry a spare just in case. This will take some of the pressure off the extractor and give it longer life and just give one more . This is also being used on the .308 sized cases POF offers as well. There is no downside to this process for the shooter and all it will do is offer one more layer of prevention.

 

[InkedIan]

I have been through all the same as you as well. Breaking extractors is what I was talking about and not trouble extraction per se although this will also help with the possibility of stuck cases so rims aren't ripped off. I personally haven't had an extractor break but I know people who have and I carry a spare just in case. This will take some of the pressure off the extractor and give it longer life and just give one more . This is also being used on the .308 sized cases POF offers as well. There is no downside to this process for the shooter and all it will do is offer one more layer of prevention.

Thank you for the nice professional rebuttal. I'm all for innovation and if it only offers benefits with no down side or extra costs to the shooter, then that's good stuff. While it wouldn't be a selling point for me it's a nice idea if it actually works. Have you or anyone you know shot one of these chambered rifles suppressed? If so, any increase in fouling in the chamber in that case? Seems like this might actually very mildly help prevent/delay case stretching and case seperation with the extra back pressure against the shoulder if it works as described.

 

[tipper]

The brass case does expand to seal off the chamber from the hot expanding gases, this expanding hot gas is what erodes the throat area, an this will let that same hot expanding gas into the chamber eroding the case neck & shoulder area of the chamber. This is not a good thing.

 

[Rob01]

Thank you for the nice professional rebuttal. I'm all for innovation and if it only offers benefits with no down side or extra costs to the shooter, then that's good stuff. While it wouldn't be a selling point for me it's a nice idea if it actually works. Have you or anyone you know shot one of these chambered rifles suppressed? If so, any increase in fouling in the chamber in that case? Seems like this might actually very mildly help prevent/delay case stretching and case seperation with the extra back pressure against the shoulder if it works as described.

No problem. I haven't shot one suppressed but have an email in to someone who has and will get you some info.

 

[Rob01]

Thank you for the nice professional rebuttal. I'm all for innovation and if it only offers benefits with no down side or extra costs to the shooter, then that's good stuff. While it wouldn't be a selling point for me it's a nice idea if it actually works. Have you or anyone you know shot one of these chambered rifles suppressed? If so, any increase in fouling in the chamber in that case? Seems like this might actually very mildly help prevent/delay case stretching and case seperation with the extra back pressure against the shoulder if it works as described.

Here is a 35,000 round 17 month test/evaluation by the San Bernardino Sheriffs with a .308 with the E Squared chamber shot with a Surefire suppressor. This is a third party test.
http://www.pof-usa.com/assets/afteractionreport_pofgen4_jan2014.pdf.zip

After 35,000 rounds shot thru the weapon system the 14.5" barrel still shot 1 to 1.5 MOA at 500 yards with the same three snipers and only loss 84 FPS from when the barrel was new and first tested. This was a long test that helped to show the life expectancy of the weapon system.

Even when springs went bad in the weapon system while shooting brass and steel case Wolf ammo that was supplied, they never once experienced a stuck case in the chamber with harsh use and very little cleaning. The case always came out of the chamber.

From accuracy and function you can see Tipper that nothing was eroded or negatively effected by the E Square chamber.

 

[tipper]

The E Square chamber is new, it dose not say that the chamber in this test is the E Square chamber.

 

[Rob01]

The E Square chamber is new, it dose not say that the chamber in this test is the E Square chamber.

It is an E Square chamber that they were testing. I got that test link from Frank DeSomma the owner of POF and I specifically asked if that was a E Square chamber and he said yes. Do you think they just make something new and put it out on the market for the public to test. I have known about the E Square for over a year now but it wasn't meant to be put out to public yet as it was being tested.

 

[SmimL7]

Do they plan on retro fitting any Gen 3s with the E2 chamber? I have a P-308 does not eject reliably for shit. I can guarantee a few malfunctions per mag with it. On most ARs this new chamber would be unnecessary. With the tight ass chambers on the POF, I can see how this would be a fix for cases getting stuck or not properly ejecting.

 

[Rob01]

Give a call and ask. It would most likely have to be a replacement of the barrel but I am sure POF could let you know for sure.

 

[Razor74]

Do they plan on retro fitting any Gen 3s with the E2 chamber? I have a P-308 does not eject reliably for shit. I can guarantee a few malfunctions per mag with it. On most ARs this new chamber would be unnecessary. With the tight ass chambers on the POF, I can see how this would be a fix for cases getting stuck or not properly ejecting.

If you have not done so already, polish your chamber and you will see a world of difference. I did mine and I have had no more problems with ejection since.

 

[Guest]

I haven't had a single FTE or any other problem for that matter with my 14.5" P308. Shoots consistently sub moa and eats anything I feed it. I haven't shot any steel through it though, all brass.

 

[SmimL7]

If you have not done so already, polish your chamber and you will see a world of difference. I did mine and I have had no more problems with ejection since.

I did this and it remedied my problem for a while. The problem is, as soon as gets a few hundred rounds through it, it starts again until I clean it. Kind of defeats the point in having a piston driven gun. I've shot my other D.I. and piston guns suppressed well over hundreds of rounds without cleanings and never have a problem.

 

[tipper]

I'll be nice, would like you to go to the range an feed your 14.5" p308 5rds each of 6 diff. ammo at 100yd's an show me & the world consistent sub moa .

P.S. I'm bad, I have a dog an he eats anything I feed him & shits every where.

 

[Rob01]

I'll be nice, would like you to go to the range an feed your 14.5" p308 5rds each of 6 diff. ammo at 100yd's an show me & the world consistent sub moa .

P.S. I'm bad, I have a dog an he eats anything I feed him & shits every where.

You got a third party test with the chamber and 35,000 rounds. Some people aren't happy with anything are they?

 

[tipper]

I read that article on pof's site before you had to email a bud to get the info. The crap you are getting paid to push is not secret insider info.
I bought 2 of these rifles from info I myself got here & there, I liked the looks & the fit of them. It's what is on the inside & the function that is not on par with the looks.
They went back to pof & got cleaned, they may have changed the bolts in both if they did it was not on the work order. I will shoot them & get back to you.


P.S. Maybe you can tell me where I can get a print of a standard 7.62 nato reamer that pof will not supply

 

[Rob01]

Sorry but not getting "paid" to push anything. I went to the source to get the info as i was talking to Frank at SHOT about it and figured he would be the best person to get it from. I didn't look at their site. Never said it was secret insider info but it was not public knowledge the whole time it was in development.

You are obviously a pissed off customer so you can send the pissed off at POF if you want but don't come on here acting like an asshole to me. I am just getting the facts out to help people make a decision.

Even if I did know where a reamer info was you have worn on my last nerve and I wouldn't help you if I could.

 

[Guest]

I'll be nice, would like you to go to the range an feed your 14.5" p308 5rds each of 6 diff. ammo at 100yd's an show me & the world consistent sub moa .

P.S. I'm bad, I have a dog an he eats anything I feed him & shits every where.

Well so far the following has shot sub moa @ 100 yds without issue

XM118LR
FGMM 168
FGMM 175
Hornady BTHP Match 168
Hornady TAP 168
Hornady AMAX Match 168

You want me to test anything else send the ammo my way

Sent from my Sprint Galaxy S4

 

[Sinthor]

Help with POF?

Well so far the following has shot sub moa @ 100 yds without issue

XM118LR
FGMM 168
FGMM 175
Hornady BTHP Match 168
Hornady TAP 168
Hornady AMAX Match 168

You want me to test anything else send the ammo my way

Sent from my Sprint Galaxy S4

I have a fairly new POF .308 that I have still just under 500 rounds through and haven't had any issues. Frankly I've been pretty amazed at how well it shoots and how accurately (I have the NP3 coated 14.5" barrel version). I was thinking of getting the E2 chamber upgrade though, just to help increase extractor life and perhaps prevent any future issues I might run into. Has anyone done that or have any feedback/ideas on it?

Also, does anyone have info on any other "POF owner" type threads or forums where I can get more information? I'm not a "know it all" and like getting info from other people or just discussion.

Thanks!

 

[tomthebaker]

I did need to polish the chamber on one of my 2 POF 308's because of nitriding salts.

Since this is not a fluted chamber, would subsonic ammo be safe/no squibs?