POF Rogue Rebarreling

[LRRPF52]

My POF, the barrel nut doesn’t even touch the outside of the barrel past the threads. From the factory the barrel has .03” on either side. Both of them were like that.

Yes. I’m talking about the barrel nut tightly fitting on the upper receiver threads, using the aluminum receiver as part of the hoop stress containment in conjunction with the barrel nut.

You have layers with the AR-15:

Steel chamber wall in the barrel threaded tenon
Barrel extension (needs to be tightly-fit without a relief cut for the thread origin near the barrel extension flange)
Aluminum upper made from higher density billet
Barrel nut

Frank was using all of those as part of the formula for hoop stress containment.

On a normal rifle barrel and receiver, it’s just the thick chamber walls and steel receiver.

When you hog out the tiny AR-15 threaded tenon for a .473” case diameter and don’t increase the diameter of the steel like on an AR-10, you have to compensate for it somehow.

Different thread pattern and length with the extension can be part of that, but meat has to come from somewhere.

Part of the formula for hoop stress containment with the Revolution is the upper receiver and barrel nut tightened down on the threads.

This is probably what Frank was referring to when he said he was afraid to do the AR-15 chambered in .308 initially.

 

[TheWatchMker]

Yes. I’m talking about the barrel nut tightly fitting on the upper receiver threads, using the aluminum receiver as part of the hoop stress containment in conjunction with the barrel nut.

You have layers with the AR-15:

Steel chamber wall in the barrel threaded tenon
Barrel extension (needs to be tightly-fit without a relief cut for the thread origin near the barrel extension flange)
Aluminum upper made from higher density billet
Barrel nut

Frank was using all of those as part of the formula for hoop stress containment.

On a normal rifle barrel and receiver, it’s just the thick chamber walls and steel receiver.

When you hog out the tiny AR-15 threaded tenon for a .473” case diameter and don’t increase the diameter of the steel like on an AR-10, you have to compensate for it somehow.

Different thread pattern and length with the extension can be part of that, but meat has to come from somewhere.

Part of the formula for hoop stress containment with the Revolution is the upper receiver and barrel nut tightened down on the threads.

This is probably what Frank was referring to when he said he was afraid to do the AR-15 chambered in .308 initially.

The thread pattern is standard though and the barrel nut is aluminum. So not really reinforced over anything else on the market.
It’s probably a 2a fit on the threads too. So seems like all standard. Nobody did it so they were first but nothing really different here.

 

[Ape_Factory]

The Revolution has a billet upper and the Rogue is forged. Forgings, generally, are more dense with optimized grain structure and are usually stronger than machined billet.

 

[LRRPF52]

The Revolution has a billet upper and the Rogue is forged. Forgings, generally, are more dense with optimized grain structure and are usually stronger than machined billet.

Yup. Generally true. Some manufacturers I know use higher-density Aluminum alloys that have superior strength characteristics than forged 7075. If you look at some of the aerospace-grade upper 7000 series billet, they get interesting.

To me, it comes into play more with slop-development over time with pin boss/lug engagement. The higher-strength, harder aluminums do noticeably-better maintaining that vault-like lock-up over time.

In this case, POF is relying on tight-fit 7000 series Aluminum to contribute to hoop stress. A thing I would watch over time is egging out of the chamber. Carbon steel would help increase the chamber strength as well in that regard. So would an AerMet barrel extension with longer length threads, using smaller peaks and valleys.

 

[donwin]

I had fired about 1500 rounds through the first POF Rogue barrel. Most of which was without the large aluminum "heatsink" barrel nut that did not actually touch the barrel only the threads of the reciever. I have a picture of it if you want to see it later. It does not actually clamp over the barrel in any tight way. For a while when I ran it to make it work as a heat sink I squirted in heatsink paste into the gap between the heatsink barrel nut and the barrel, I don't know if it helped any with heat transfer, but I don't see how the aluminum sink which didn't touch the barrel was reinforcing the chamber area from "egging out". Brass was ejecting just fine after the first 500 rounds through that rifle and the stock extension was removed just fine and the extension was removed without issue.

If anyone has any more info on if the stock heatsink actually reinforces the barrel not form anecodotes and hearsay let me know.

Back to my new barrel. I have put 200 rounds of 165 and 150gr through the barrel so far. The first 100 rounds were rough, not good consistent groupsings. I cleaned and brushed the barrel down. Now its showing signs of settling in. 1.5 inch group at 100yds with super cheap Aguila 150gr FMJBT. Here is a rapid fire 8 round group from a cooled down bore at the end of the last range session.

Also note the huge brake. I tried shooting it without the break for the first 100 rounds. It was too snappy a recoil for extended range sessions.

 

[LRRPF52]

If anyone has any more info on if the stock heatsink actually reinforces the barrel not form anecodotes and hearsay let me know.

Frank literally told me this in-person at SHOT when we talked about the introduction of the Revolution when it debuted. He said he was always scared to do an AR-15 chambered in .308, but had been mulling over it for years. He finally sat down and did the engineering and drafting for it, and committed to move forward.

I specifically asked about hoop stress, because a .473” case head and larger body diameter eats away into the chamber wall thickness when you limit yourself to AR-15 barrel outer dimensions around the chamber, using an AR-15 sized barrel extension.

He said he used the receiver and barrel nut to add to the formula of containing the hoop, with tight tolerances and stronger alloys.

He then supported the durability of the system by pointing out their videos of it being shot in the full auto mode of fire.

However, they were using Russian steel case garbage, underpowered ammo.

My natural question is, how durable is the pressure containment system if run with full-power M80, 168gr, 175gr, 178gr, etc. I didn’t ask him that because he had already let me see up his skirt more than I ever expected. It was a very open and transparent conversation about critical details of the system design.

I don’t think most shooters will ever find the limits with the system, but I’m not most shooters.

I also remember the DPMS people freaking out when one of their reps took a DPMS GII small frame (larger than Revolution with more wall thickness around the chamber) to a week-long high volume shoot course and burned thousands of rounds through it. They immediately seized the weapon, removed the barrel, and sectioned it to analyze the chamber dimensions.

Not sure why they did that, because they ran the GII through pyramid-testing with 10 base rifles, 100k rounds until finalizing the design.

 

[donwin]

Frank literally told me this in-person at SHOT when we talked about the introduction of the Revolution when it debuted. He said he was always scared to do an AR-15 chambered in .308, but had been mulling over it for years. He finally sat down and did the engineering and drafting for it, and committed to move forward.

I specifically asked about hoop stress, because a .473” case head and larger body diameter eats away into the chamber wall thickness when you limit yourself to AR-15 barrel outer dimensions around the chamber, using an AR-15 sized barrel extension.

He said he used the receiver and barrel nut to add to the formula of containing the hoop, with tight tolerances and stronger alloys.

He then supported the durability of the system by pointing out their videos of it being shot in the full auto mode of fire.

However, they were using Russian steel case garbage, underpowered ammo.

My natural question is, how durable is the pressure containment system if run with full-power M80, 168gr, 175gr, 178gr, etc. I didn’t ask him that because he had already let me see up his skirt more than I ever expected. It was a very open and transparent conversation about critical details of the system design.

I don’t think most shooters will ever find the limits with the system, but I’m not most shooters.

I also remember the DPMS people freaking out when one of their reps took a DPMS GII small frame (larger than Revolution with more wall thickness around the chamber) to a week-long high volume shoot course and burned thousands of rounds through it. They immediately seized the weapon, removed the barrel, and sectioned it to analyze the chamber dimensions.

Not sure why they did that, because they ran the GII through pyramid-testing with 10 base rifles, 100k rounds until finalizing the design.

I don't believe POF is as transparent anymore as your conversation you had with the founder. All the website mentions is the HS barrel nut is compatible with all AR15's and POF mentioned to me I would void the warranty by changing hand guards and changing the heat sink barrel nut to something else. When asked they said that was their policy. I did anyways and many other shooters have too.

I am not an engineer nor do I understand the cumulative stress of 178gr 180gr vs Wolf etc but the original barrel has had hundreds of those rounds through it and kept its baseline accuracy. Egging I cannot speak of as the rounds ejected fine and it looks externally ok without me possessing any tools to be able to detect abnormalities on the rifle chamber surface.

 

[TheWatchMker]

Frank literally told me this in-person at SHOT when we talked about the introduction of the Revolution when it debuted. He said he was always scared to do an AR-15 chambered in .308, but had been mulling over it for years. He finally sat down and did the engineering and drafting for it, and committed to move forward.

I specifically asked about hoop stress, because a .473” case head and larger body diameter eats away into the chamber wall thickness when you limit yourself to AR-15 barrel outer dimensions around the chamber, using an AR-15 sized barrel extension.

He said he used the receiver and barrel nut to add to the formula of containing the hoop, with tight tolerances and stronger alloys.

He then supported the durability of the system by pointing out their videos of it being shot in the full auto mode of fire.

However, they were using Russian steel case garbage, underpowered ammo.

My natural question is, how durable is the pressure containment system if run with full-power M80, 168gr, 175gr, 178gr, etc. I didn’t ask him that because he had already let me see up his skirt more than I ever expected. It was a very open and transparent conversation about critical details of the system design.

I don’t think most shooters will ever find the limits with the system, but I’m not most shooters.

I also remember the DPMS people freaking out when one of their reps took a DPMS GII small frame (larger than Revolution with more wall thickness around the chamber) to a week-long high volume shoot course and burned thousands of rounds through it. They immediately seized the weapon, removed the barrel, and sectioned it to analyze the chamber dimensions.

Not sure why they did that, because they ran the GII through pyramid-testing with 10 base rifles, 100k rounds until finalizing the design.

As someone who is in the process of modeling the whole gun to reproduce so i can have different uppers and doing it with access to scanning CMMs and an XRF.
I promise you both of my samples are basically no different from any other AR in terms of material or the heat sink nut adding reinforcement(it does have space in between the barrel and the nut).

I also made my own barrel and have had 2 others made for me and have shot it with 308, 6.5 and both of them pushing the bounds of their respective load.
They were fine. Ive also run it suppressed with 18" and full powered loads no problem.
there's nothing special going on there. I'm sure its on the engineering edge but works just fine.

 

[LRRPF52]

I don't believe POF is as transparent anymore as your conversation you had with the founder. All the website mentions is the HS barrel nut is compatible with all AR15's and POF mentioned to me I would void the warranty by changing hand guards and changing the heat sink barrel nut to something else. When asked they said that was their policy. I did anyways and many other shooters have too.

I am not an engineer nor do I understand the cumulative stress of 178gr 180gr vs Wolf etc but the original barrel has had hundreds of those rounds through it and kept its baseline accuracy. Egging I cannot speak of as the rounds ejected fine and it looks externally ok without me possessing any tools to be able to detect abnormalities on the rifle chamber surface.

Yeah Frank died in an auto accident a few years ago while driving on the freeway.

 

[LRRPF52]

As someone who is in the process of modeling the whole gun to reproduce so i can have different uppers and doing it with access to scanning CMMs and an XRF.
I promise you both of my samples are basically no different from any other AR in terms of material or the heat sink nut adding reinforcement(it does have space in between the barrel and the nut).

I also made my own barrel and have had 2 others made for me and have shot it with 308, 6.5 and both of them pushing the bounds of their respective load.
They were fine. Ive also run it suppressed with 18" and full powered loads no problem.
there's nothing special going on there. I'm sure its on the engineering edge but works just fine.

I’m not saying you will or won’t have chamber egging, just relating what the engineering considerations were for pressure containment. My understanding is that a stronger steel alloy was used for the barrel extension and bolt.

Stronger barrel extension helps with hoop stress and bolt thrust on the lugs.

Higher strength alloy for the bolt deals with the lug root strength under bolt thrust.

If I was doing it, I would not use a stainless barrel extension, for example. That’s just me.

 

[donwin]

Thanks for bringing up safety concerns LRRPF52, I know you bring them up for the sake of others safety. I googled and it seems several precision barrel makers overbuild their barrels for the reasons you have described like Kriger. Here is another discussion I found on a search about pencil barrels and it is interesting too. https://www.snipershide.com/shooting/threads/minimum-ar-barrel-thickness.7063357/

I specifically asked Paul Ross to make my barrel similar to the profile and taper of the Faxon pencil barrel for 308. He said as a maker it was personally thin for him but he would oblige my request. Will shoot some more through the pencil barrel and I will report back on how it does with more 165gr 168gr pills before I work up to 175 178.

 

[donwin]

LRRPF52, I am reqouting this image of the old stock Rogue profile and the new pencil barrel for reference. As you can see the new barrel starts with the identical profile over the chamber, it is the same thickness as the stock barrel. Major differences to the pencil as it begins to taper rather than stay at medium profile out to the .75 gas block and not taper down much more from there.

Where do you think the chamber area would get bulged out if it were to or the headspace would change? Or were you saying you think the stock barrel would "egg out" without the stock aluminum barrel nut?

View attachment 8606874View attachment 8606876Here’s some weight pictures of my custom barrel from Paul. 19inch pencil barrel 1 oz less than the 16. Having it installed now!

 

[LRRPF52]

The peak pressure is in the center of the propellant column. You can’t generate any higher pressure than that point because of expanding volume as the projectile moves forward.

In the standard AR-15 barrel tennon, there is a relief-cut in the threads before the shoulder. That is the weakest place of the chamber walls if cut that way.

White Oak Armament dealt with it using smaller threads that go longer, with a longer barrel extension in front of the flange like on an AR-10. This moved the relief-cut forward of the center of the powder column.

Even 5.56 chambers egg-out with high round counts, but civilian shooters replace their barrels way before they ever get near those counts because of extreme throat erosion that comes before you hit those numbers.

 

[donwin]

I’m not going to worry about it “egging out” as you say in the short term or within reasonable barrel life, as mobility and lightweight is top priority in this build not dragging out a barrel with high round count longer than it should.

Here’s some accuracy updates with cheaper ammo:

Much better than the 4+ moa provided by the terrible stock POF barrels.

 

[Ape_Factory]

An update on my end. Haven't had a lot of time to shoot the 308's in my collection and I'm averaging about every three months. I did a few experiments and tried out a few new bullet/powder combos. This is going to be a pretty transparent post and I've included all of the full targets so be kind.

I am no wizard behind the rifle and I should probably take a class. I went out on Saturday and I was clearly just off by a country mile. So much so I actually stood up and walked away for a bit. I could visibly see it in my follow through and how the rifle was moving under recoil. I could see the errors as I was shooting. It was also in the high 90's which didn't help my patience or lack thereof. Sometimes you just want to get the testing over with and get out of there.

Anyway...this was a little experiment I did in March, same bullet, powder, load, dimensions but just different cases, all out of a POF Revolution DI, 16.5" factory barrel. PMC Bronze, LC 07 and LC 13 which had a shorter case length. I can shoot 5-shot sub-MOA groups with this load all day long every day. I've shot one 10 shot group sub-MOA. So this one was a bit of a disappointment but it was most likely me or possibly my RCBS dispenser which I had to send back for a replacement. I almost always load to max mag length and find an average, settling on an overall cartridge measurement at the ogive using a Hornady comparator set and calipers. I don't get ultra-precise and I work up loads to run on a Dillon 750.

Here's the entire target, shot at 100 yards. Top left is PMC Bronze. Top right is LC 07, and bottom left is LC 13. Bullet is a Sierra 169 SMK over 43 grains of IMR 4046. Normal velocities for this load are around 2526ish. PMC was 2497, LC 07 was 2526 and LC 13 was 2527 and all are 10 shot groups shot in fairly rapid succession. I don't sit there and let the barrel cool down. I just keep firing with mirage being the only thing that usually holds me up.

PMC Bronze 1.493 MOA

LC 07 1.197 MOA

LC 13 1.691 MOA

Same load, PMC Bronze cases, loaded on a Dillon 750 progressive. Shot this group in late May. A better shooter could knock a good bit off the group size.

Here's a 155 grain Sierra Palma over 44 grains of IMR 4046 load, .696 MOA.

Here's a Berger 185 Jug over VV550, 42.5 grains. Super slow at 2320fps but came in at .737 MOA. The rest of the groups weren't incredible and I maxed out at 2414 with 44 grains.

Here's the whole target for the above. I haven't tried any other powders other than VV for the 185's in the POF. Got good results with Varget and my Sig Cross but didn't try that powder with the gas gun.

Anyway, point being, it's not a precision rifle but it's likely more capable than I am given how frequently I shoot it. Factory barrel. The only changes I've made are a heavier buffer, Geissele SSA trigger and a Riflespeed gas block. I run the Hux Flow 762 100% of the time

Here's a full target from this past Saturday. I was not having a good shooting day and the poor results were completely on me. Which hurts as loading components are through the roof. I priced out 8 pounds of IMR 4895 and it was just shy of $400. Fucking ridiculous.

Gratuitous photo.

 

[LRRPF52]

I don’t see anything wrong with any of those groups. 10 rounds inside of 2” consistently is superb for a lightweight .308 gasser.

I would hold onto that blaster and enjoy it, as long as it runs reliably too.