Anyone shooting the newer POF with the E squared chamber?

[RugerJB]

I've gotten an email recently from POF in regards to my 308 I bought from them 6 months ago, with an offer to "upgrade" my chamber to the new design.

I do reload for this rifle and what I'm wondering is have any of you noticed any adverse effects to cases with this chamber?

On one hand I can see a potential benefit with making the extraction a bit less violent. I'm thinking I should see less case stretch and extractor wear on my brass thereby extending it's life.

On the other hand that does absolutely no good if this gas that is forced into the case shoulder deforms the shoulder.

I'm just a bit apprehensive about spending $ on an irreversible modification if it destroys cases. What do y'all think?

 

[Gtscotty]

I don't have any experience with the E^2 chamber design, but it seems like the case neck would be forced into the chamber groves adding an extra dimension to the reshaping of fired brass. I can see how the new chamber design would aid extraction, but have you asked POF how the new chamber cut affects the "reloadability" of brass fired in the chamber?

 

[MCMXI]

I have a couple of POFs including a P308 and P415 but I don't experience "violent" ejection. I've received emails from POF regarding their new e2 extraction but don't consider it to be a worthwhile investment. My P308 has a 20" barrel so maybe a 16" or shorter barrel would benefit from an e2 upgrade.

 

[redbullitt]

Never really had an issue with my POF. I might consider an upgrade, but it runs so well now that I would hate to change anything.

 

[RugerJB]

My rifle is the 16" version. To which I have done basically nothing to except put a vortex viper pst 4x16x50 in gggaz QD mount, and a Harris bipod on. The only issue I've ever had with it is ejection failure when it was brand new.I had some stovepipes,I had some double feed. I didn't try to put too many rounds through it at the time because I figured there was some sort of gas issue with it. So I sent it to POF and like everyone else I know that's had this issue, they replaced the entire gas piston system and shot 100 rounds through it and sent it back to me inside 2 weeks without charge. Since then no FTF or FTE. It is a pleasure to shoot in all aspects!

As of yet no reply form POF. Hopefully they will get back to me sometime Monday.

As far as the violence of extraction is concerned I should have worded that a bit differently. I should have said something like.... Potential benefit of making the extraction process a bit less stressful to the cases with regards to case stretch and case head wear.

I really haven't experienced a violent extraction such as broken extractors or ripped off case rims, and to be fair I haven't put my spent cases into my wilson chamber gauge yet either. I mostly just noticed what the extractor has done as far as case head wear. At this point it's not too bad but will they survive 3 more reloads? Maybe, but I'd like more than that if I can get it. Especially when it takes so darn long to sort and prep the cases as best as possible.

I guess we will see what POF has to say, even though it might be a bit biased for a sales pitch

JB

 

[Slamfire]

How far up the throat do these flutes go?

For the gas lubrication system of the roller bolts to work, the flutes have to go forward of the case mouth.


Also, the flutes for the roller bolt go down to the last third of the case, to break the friction between case and chamber, and the last third of the case performs the case seal function.


Even used in 9mm sub guns.


This is Xtran technology, AR15 action, 223 chamber, much shallower flutes, and spiral cut.




I think the whole idea, breaking the friction between the case and chamber “breech friction” is a great idea. When breech friction gets high, the case won’t extract. All automatic gun mechanism will function better with less case friction. To prove this, just create a high case to chamber friction, as an example, glue the case in the chamber. The mechanism won’t be able to extract the case.

However, the cost of making chamber flutes must be complicated, this thread SVT40 chamber threads at the Practical Machinist Forum makes me believe this is not a simple process.

Curious to see some fired cases of this POF system.

 

[RugerJB]

From what I can tell they're only to the shoulder in the chamber and not completely down the length of it. Essentially there are 4 grooves cut down where the neck of the case will sit ending on where the shoulder will sit

 

[MCMXI]

Exactly. The four gooves are only in the neck region of the chamber. The theory is explained in the link below.

http://www.pof-usa.com/esquared.html

RugerJB, I thought you might have a 16" bbl version. As I said, the upgrade might be worthwhile for you given that your rifle is probably harder on case heads and the extractor.

 

[RugerJB]

Thank y'all for the input I do appreciate it. Also thanks for sharing the pics slamfire. I've never physically seen those before. Thankfully the cuts POF makes are shallow and only in the neck area.
As far as my extraction is concerned, I think you're right 1858. The shorter barrel should net higher pressures with the same cartridge compared to your 20", unless they've reduced the gas that enters the system somehow. I'm not sure if they've done that or not , but I agree any help to extraction should help preserve case life.

I've got the response that POF sent me here:
We have seen no case deformation throughout the testing of this feature and have zero customer complaints as well. We have not seen any significant change in the cleanliness of the upper receiver. I hope this helps, please let me know if there is anything else we can do for you.

So I guess there's gonna be an upgrade in the future. I hope I don't regret it

 

[MCMXI]

I have to wonder how the cuts in the neck of the chamber are made. Broaching after finish reaming would require some sort of clearance for the chips. Maybe they use RAM EDM . RugerJB, if you decide to go with the upgrade please report back.

 

[RugerJB]

I will probably wind up getting it done. I guess worst case I'll have to turn the necks of all cases fired which won't be fun, but that's a worst case scenario. It's not going to be for a bit anyway as I'm going to be away for a while with work. But I will post pics of spent brass when it's all done