OBR's fluted chamber XRETARDN... What's the point?

[taseal]

I don't get it... here is what they have to say about it
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
XTRAXN™ Technology
(ex-tracks-en)

The Leaders in Black-Rifle Innovation Have Raised the Bar, Again!

LaRueTactical is proud to announce XTRAXN™ Technology and yes, there is a patent pending.

In an industry full of hype and less-than-useful gadgets, every once in a while there is a breakthrough that works. While the fine-details of XTRAXN™ Technology are close-hold, we will say that this evolutionary process results in higher-reliability with a wider range of ammo and operating conditions. Simply put, we just made one of the best guns in the world better!

So, what is it? The process is not a coating or a lubricant. What we can tell you is - XTRAXN™ Technology provides excellent chamber release properties, gives longer life to the extractor components, and makes the entire operating system run smoother.

XTRAXN is a proprietary chamber feature added to reduce frictional forces caused by pressure-expanded cartridge cases bearing against chamber walls. Facilitates reliable extraction through a wide range of temperature / chamber pressure extremes. XTRAXN extends extractor life, while having no effect on the firearm's accuracy. All this, and it dovetails well with the OBR's world-famous accuracy.

If you have a PredatAR and OBR rifle on order...don't worry, you'll be one of the first to get this. Going forward, all LaRue PredatAR and OBR rifles will include XTRAXN™, without an increase in cost during this introduction.</div></div>

so it's a fluted chamber as far as I know...

what benefit does this give? here is my thought process on this

round is fired. brass starts expanding to fireform, but becuase of the fluting, it goes past the chamber's dimensions into the fluting area.

now the extractor starts pulling out the base but because the brass overflowed (even by little) into the fluted slots, it has to work extra hard to pull that brass out

brass comes out, falls on the floor.

now lets fast forward to the handloading bench.

My handloaded lapua brass is now all fucked up because the fluting messed up the dimensions of the brass. it's almost impossible to reload.

what gives? I'm so confused behind this technology

 

[noz455sd]

Re: OBR's fluted chamber XRETARDN... What's the point?

I thought HK has been doing this for awhile...I know my P7 has flutes but maybe this is something different

 

[TenZero]

Re: OBR's fluted chamber XRETARDN... What's the point?

HK-91s & -93s had fluted chambers to facilitate extraction. F's up the brass, but on a Mil rifle, you don't care. Maybe Laroo's flutes are less aggressive than the HK's. I dunno.

 

[BCP]

Re: OBR's fluted chamber XRETARDN... What's the point?

A friend of mine has a zillion PTR rifles, some with this and some without and the only marks it makes on his brass are carbon-soot sort of marks. But then he shoots light handloads or milsurp light ball so his cases are thick and pressures somewhat low. I would imagine if you used a lighter or softer brass and a hot load the brass could expand to fill the flutes.

Personally I don't see the point of it. It was invented for recoil-operated machine guns not DI ARs.

 

[taseal]

Re: OBR's fluted chamber XRETARDN... What's the point?

what's it supposed to help with? accuracy? reliability?

 

[jaycoux]

Re: OBR's fluted chamber XRETARDN... What's the point?

taseal,

Are you saying you actually had your brass destroyed by your OBR with the new chamber?

For what it's worth, I was shooting yesterday and there was a guy there shooting a predatar 7.62 with the xtraxn chamber. I picked up all of his brass and looked at it (around 30 pieces) and it was fine. He was shooting hornady tap or something like that.

Seems like the only people who have actually had an issue with this technology are the guys running super hot loads.

I have one of the original OBR's and have never had an issue with it. I'm not sure why they decided to use this little gimmick, but as long as it doesn't destroy brass I may order another one.

j

 

[zinny]

Re: OBR's fluted chamber XRETARDN... What's the point?

people on arfcom have reported difficulty reloading brass from OBRs with the xtran chamber. Its supposed to help with the reliability of extraction. think less surface area as the brass will not 100% conform to the flutes leading to an easier extraction.

 

[Tantrum]

Re: OBR's fluted chamber XRETARDN... What's the point?

It doesn't destroy the brass. Tassels question sounds purely philosophical.

 

[BCP]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: taseal</div><div class="ubbcode-body">what's it supposed to help with? accuracy? reliability? </div></div>

You can read about it online if you Google for 'chamber fluting'. I think the old Pederson Rifle (Garand competitor) had a fluted chamber because the original wax-coated-cartridges were impractical.

I honestly have no idea why Larue did it.

 

[JCB]

Re: OBR's fluted chamber XRETARDN... What's the point?

The bolt in HK G3 style rifles does not rotate. The combination of the flutes with the delayed roller lock mechanism allows the gas from the fired cartridge to float the brass in the chamber aiding in the extraction.

 

[Falsecrack]

Re: OBR's fluted chamber XRETARDN... What's the point?

I have an OBR 7.62 on order (been 4 mo. and counting) that should be here in a couple of months. I didn't discover that the original design had been altered until about a month ago. I too can't figure out why they decided on this Xtraxn business, but I will say that if it screws up my brass AND lessens accuracy/dependability, i'm going to be pissed. I hate it when the supposed evolution of anything infact turns out to be a backward step.

 

[taseal]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Falsecrack</div><div class="ubbcode-body">I have an OBR 7.62 on order (been 4 mo. and counting) that should be here in a couple of months. I didn't discover that the original design had been altered until about a month ago. I too can't figure out why they decided on this Xtraxn business, but I will say that if it screws up my brass AND lessens accuracy/dependability, i'm going to be pissed. I hate it when the supposed evolution of anything infact turns out to be a backward step. </div></div>

I doubt anything will suffer. the messing up of brass was only my own speculation. That might not be the case.

Those are some crappy wait times btw.

 

[Falsecrack]

Re: OBR's fluted chamber XRETARDN... What's the point?

Taseal
I wasn't speaking to your post per se, but more toward the entire brew haha concerning this newly released system. It was actually on Arfcom that I originally stumbled onto the discussion of this issue. If I remember correctly, there was photographic evidence of the fluting damaging the empties. I was more agreeing with you on the overall question of "Why". Especially given the reputation of OBR/Predatar's accuracy and ruggedness. And yeah, the wait was so long that afterordering, I tried to mentally block it out of my mind so the wait wouldn't seem so long.

 

[K_4c]

Re: OBR's fluted chamber XRETARDN... What's the point?

Kinda like buying a can.... But some things are worth the wait...

 

[Falsecrack]

Re: OBR's fluted chamber XRETARDN... What's the point?

Ah, a Can. They're so unattainable (illegal) here that it's the "wait" afterward (prison) that concerns me more. Everytime I see a can in someone's kit, I get green with envy.

 

[taseal]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: K_4c</div><div class="ubbcode-body">Kinda like buying a can.... But some things are worth the wait...

</div></div>

well what if a company offered a very similar can, but with a shorter wait?

 

[K_4c]

Re: OBR's fluted chamber XRETARDN... What's the point?

Similar.... But not the same.

 

[austinwft]

Re: OBR's fluted chamber XRETARDN... What's the point?

Reloading -XTRAXN Chamber

No trouble reloading brass from an XTRAXN chamber. The 31st & 33rd post, <span style="font-weight: bold">austinwft</span>, is my detailed experience.

 

[IATigerHawk]

Re: OBR's fluted chamber XRETARDN... What's the point?

This round is from my PredatAR, same technology.

I can tell you, you would have NO issues reloading this round.

Not quite sure I can tell you how much it helps, but I have never had a round of Wolf or any other lethargic round get stuck. YMMV.

 

[BCP]

Re: OBR's fluted chamber XRETARDN... What's the point?

Some have posted that they have issues some haven't. If I had to guess I would say it depends on the flutes in your particular chamber and your own personal load.

Like I said earlier I don't understand why they did this and when you're spending 3k+ on a rifle...you should have some say in that rifle's chamber.

 

[K_4c]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">when you're spending 3k+ on a rifle...you should have some say in that rifle's chamber. </div></div>

+1

 

[33shooter]

Re: OBR's fluted chamber XRETARDN... What's the point?

My 18" 7.62 OBR has it. I shot the rifle 2 days ago and was holding less than an inch on my groups when I did my part at 100yds. I shot 155grn TAP, 168grn TAP, and 175grn FGMM. No issues from any of those. The brass had slight marks that were visible but none that I could feel by hand. All rounds fired were with a can.

 

[Turk]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: K_4c</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">when you're spending 3k+ on a rifle...you should have some say in that rifle's chamber. </div></div>

+1 </div></div>
Doesn't make sense; try telling AI or Sako what chamber you want and let me know how that goes for you!

 

[jakhamr81]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: K_4c</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">when you're spending 3k+ on a rifle...you should have some say in that rifle's chamber. </div></div>

+1</div></div>

You do. Its your money, if you don't want what Larue is making, buy something else. HHate to sound like a smart ass but it seems pretty simple.

 

[BCP]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jakhamr81</div><div class="ubbcode-body">Hate to sound like a smart ass</div></div>

LOL it's okay that's basically what I was saying anyways.

When I look at the GAP and OBR rifles I see two genuinely great rifles...but only one that I can have my way. Just my 2cents.

 

[K_4c]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jakhamr81</div><div class="ubbcode-body">Hate to sound like a smart ass</div></div>

LOL it's okay that's basically what I was saying anyways.

When I look at the GAP and OBR rifles I see two genuinely great rifles...but only one that I can have my way. Just my 2cents. </div></div>

Oh but when they shoot as sweet as the OBR does... it's hard to hold back.

 

[Grump]

Re: OBR's fluted chamber XRETARDN... What's the point?

Listen, folks, I ratted brass from H&Ks two decades ago when LC 7.62 brass was a bit hard to find.

Resizes fine. Shoots fine. No difference in accuracy. More aggressive fluting and grooving that pictured above, and you could *feel* the edge of the fluted to non-fluted portions the case had contacted.

What's it for? Read the Fabulous sales pitch. It said everything.

As I understand things, the AR system, like the old M14 and M1 Garand types, has a tendency to bust extractors. Though more rare than with the goofy-shaped Garand-style extractors, being one of the more common failures, it was deemed worthy of some investigation and a bit of evolutionary product improvement.

Me, I wonder if the broken AR extractors are partially traceable to the heat load the BCG gets from direct impingement. But I also have no problem with treating an extractor and its spring as a "maintenance item" to be replaced every 10,000 rounds or so.

If a part other than the accuracy level of a barrel won't last 10K rounds, I'm not sure that I would consider the design adequate. And I've seen an AR extractor spring get jam-inducing weak in only about 5,000-6,000 rounds.

That chamber design won't help THAT problem.

 

[captnmo]

Re: OBR's fluted chamber XRETARDN... What's the point?

I've got a PredatOBR on order and I talked to them about this. They didn't want to talk much about it since they're holding it pretty close. But he did tell me that the reports they are getting from reloaders are that it's not a problem.

 

[Wolvenhaven]

Re: OBR's fluted chamber XRETARDN... What's the point?

I don't get why they're being so secretive about it, to me it looks like they just slightly twisted HK style chamber flutes to allow the gas to float the brass out of the chamber. The marks on that brass above are pretty much identical in length, width, and spacing to .308 HK flutes and my guess is the twist to them is to help with clearing them off the flutes because the bolt rotates(unlike an HK). They're probably a lot shallower than HK flutes but this isn't new tech, it's been around for 50+ years, if it helps make the rifle better, more power to them though, it's great to see different design principals come together to make a better firearm.

To the guys who have this chamber on your rifles, I recommend picking up a .308 HK chamber flute brush if they didn't include one for the rifle, it makes cleaning out the chambers much easier. I have no idea how important those flutes are to the function, but if they're anything like how required they are in HKs, they need to be kept pretty damn clean.

 

[cz777]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TenZero</div><div class="ubbcode-body">HK-91s & -93s had fluted chambers to facilitate extraction. F's up the brass, but on a Mil rifle, you don't care. Maybe Laroo's flutes are less aggressive than the HK's. I dunno. </div></div> 308 shell casing has no taper ..for the gas to break lose the cartridge will help make ar system more reliable ...this is a step in the right direction ..but care of this chamber needs cleaning the flutes better like 410 shotgun bore brush ...i wish others who make the ar barrels will do this as well ....

 

[Awesymoto]

Re: OBR's fluted chamber XRETARDN... What's the point?

If a 240 doesn't need chamber fluting, I will pass.... And CZ777 what do you mean a .308 has no taper, it does, but it's slight.

 

[gunhappy_ie]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wolvenhaven</div><div class="ubbcode-body">
To the guys who have this chamber on your rifles, I recommend picking up a .308 HK chamber flute brush if they didn't include one for the rifle, it makes cleaning out the chambers much easier. I have no idea how important those flutes are to the function, but if they're anything like how required they are in HKs, they need to be kept pretty damn clean. </div></div>

Dam..... like they arent expensive enough already without increased demand in the market

 

[gunhappy_ie]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cz777</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TenZero</div><div class="ubbcode-body">HK-91s & -93s had fluted chambers to facilitate extraction. F's up the brass, but on a Mil rifle, you don't care. Maybe Laroo's flutes are less aggressive than the HK's. I dunno. </div></div> 308 shell casing has no taper ..for the gas to break lose the cartridge will help make ar system more reliable ...this is a step in the right direction ..but care of this chamber needs cleaning the flutes better like 410 shotgun bore brush ...i wish others who make the ar barrels will do this as well .... </div></div>

If its step in the right direction why to my knowledge was this technology confined to roller locking guns or its derivatives and why didnt HK use the design in the 417 ?

From owning/researching the delayed roller locking system, fluting the chambers worked to increase reliability for this particular system. Im unsure of the name of the US manufacturer making Hk clones (PTR I think) but problems ive red about on other forums are that there chambers arent/werent fluted.

I have to agree that it does sound like a gimic !

GH

 

[InfiniteGrim]

Re: OBR's fluted chamber XRETARDN... What's the point?

Its a very light spiral fluting. As for reloading purposes people say there is no problem, but one guy was having issues with redding dies.

 

[cz777]

Re: OBR's fluted chamber XRETARDN... What's the point?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Awesymoto</div><div class="ubbcode-body">If a 240 doesn't need chamber fluting, I will pass.... And CZ777 what do you mean a .308 has no taper, it does, but it's slight. </div></div>yes but very slight true ....it's next to zero with fluting a next to straight cased cartridges would help .....

 

[GunDudeUSA]

To all the guys who saw this post last year,

What's your experience with reloading so far, with your Larue OBR with EXTRAXN?

 

[cz777]

The bolt in HK G3 style rifles does not rotate. The combination of the flutes with the delayed roller lock mechanism allows the gas from the fired cartridge to float the brass in the chamber aiding in the extraction.

this is the key if done right ..it does makes extraction easier and less stress on the parts ..its a plus if done with fine grooves for floating the casing with gas -a shake lose of the cartridge works nicer and smoother for overall working of the weapon ..

 

[cz777]

If a 240 doesn't need chamber fluting, I will pass.... And CZ777 what do you mean a .308 has no taper, it does, but it's slight.

but it's slight next to zero look at French 7.5 or any comboc calber ....

 

[hydro556]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: K_4c</div><div class="ubbcode-body">Kinda like buying a can.... But some things are worth the wait...

</div></div>

well what if a company offered a very similar can, but with a shorter wait?

The waiting time corresponds with the quality he delivers. They have worsened with the panic, but there's always been a line for LT.

some of the best guns available, period. But some hate that, and even more are just bandwagoneers.

 

[bustin]

The 308 has .017" taper in 1.55" Tapered cases don't work so well in ARs and tapered cases as commonly chambered are not very accurate. The more play in headspace the more a tapered case lays in the bottom of the chamber and points the tip of the bullet up making it start crooked in the bore. A case with less taper aligns the bullet better. Big reason the 308 is more accurate than the 7.62x39.

 

[USMAGator]

To all the guys who saw this post last year,

What's your experience with reloading so far, with your Larue OBR with EXTRAXN?

I'm up to 4 loadings with a batch of LC brass, it all resizes and shoots just fine. The brass does have markings that indicate slight spiral fluting of the chamber, but it has had no negative effect that I can notice on reloadability, reliability, or accuracy.

 

[GunDudeUSA]

I'm up to 4 loadings with a batch of LC brass, it all resizes and shoots just fine. The brass does have markings that indicate slight spiral fluting of the chamber, but it has had no negative effect that I can notice on reloadability, reliability, or accuracy.

Thanks! That helps.

 

[2ndPanzer]

SVT-40's have a fluted chamber as well... It's a really old just in case thing. Nothing new. Brass from that or the HK's reload and size fine. Just look funny.

 

[bm11]

99% sure it's there to increase reliability when running suppressed. If you check George's "gas guns and suppressors" thread, most of the issues stem from chambers getting dirty and causing FTE's.

 

[KevinB-KAC]

99% sure it's there to increase reliability when running suppressed. If you check George's "gas guns and suppressors" thread, most of the issues stem from chambers getting dirty and causing FTE's.

I would suggest its also for certain high pressure rounds (M993).

I've reloaded brass from an OBR (with Extran) with no issues.

 

[338AILM]

I don't get it... here is what they have to say about it
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
XTRAXN™ Technology
(ex-tracks-en)

The Leaders in Black-Rifle Innovation Have Raised the Bar, Again!

LaRueTactical is proud to announce XTRAXN™ Technology and yes, there is a patent pending.

In an industry full of hype and less-than-useful gadgets, every once in a while there is a breakthrough that works. While the fine-details of XTRAXN™ Technology are close-hold, we will say that this evolutionary process results in higher-reliability with a wider range of ammo and operating conditions. Simply put, we just made one of the best guns in the world better!

So, what is it? The process is not a coating or a lubricant. What we can tell you is - XTRAXN™ Technology provides excellent chamber release properties, gives longer life to the extractor components, and makes the entire operating system run smoother.

XTRAXN is a proprietary chamber feature added to reduce frictional forces caused by pressure-expanded cartridge cases bearing against chamber walls. Facilitates reliable extraction through a wide range of temperature / chamber pressure extremes. XTRAXN extends extractor life, while having no effect on the firearm's accuracy. All this, and it dovetails well with the OBR's world-famous accuracy.

If you have a PredatAR and OBR rifle on order...don't worry, you'll be one of the first to get this. Going forward, all LaRue PredatAR and OBR rifles will include XTRAXN™, without an increase in cost during this introduction.</div></div>

so it's a fluted chamber as far as I know...

what benefit does this give? here is my thought process on this

round is fired. brass starts expanding to fireform, but becuase of the fluting, it goes past the chamber's dimensions into the fluting area.

now the extractor starts pulling out the base but because the brass overflowed (even by little) into the fluted slots, it has to work extra hard to pull that brass out

brass comes out, falls on the floor.

now lets fast forward to the handloading bench.

My handloaded lapua brass is now all fucked up because the fluting messed up the dimensions of the brass. it's almost impossible to reload.

what gives? I'm so confused behind this technology

I get range brass fired from OBRs with fluted chambers and other rifles without fluted chambers. I use a .308 winchester Dillon carbide die which seems to be on the smaller side like a small base die. Using an RCBS Ammomaster press that I use to size 50 BMG brass with a Dillon carbide die, the brass shot through the OBR with fluted chamber is more difficult to size than the other .308 brass or the 50 BMG brass shot from a semi-auto Barrett.

 

[Lunchbox27]

 

[bigjake83]

I get range brass fired from OBRs with fluted chambers and other rifles without fluted chambers. I use a .308 winchester Dillon carbide die which seems to be on the smaller side like a small base die. Using an RCBS Ammomaster press that I use to size 50 BMG brass with a Dillon carbide die, the brass shot through the OBR with fluted chamber is more difficult to size than the other .308 brass or the 50 BMG brass shot from a semi-auto Barrett.

So I've dealt with this issue first hand, and have actually called Mark LaRue out on AR-15.com about this specific issue.

Be prepared for stuck cases and hydraulic dents, and the reason for this is because there's so much inconsistency with LaRue products and his chamberings, that's why you'll see some people claiming they have no issue reloading them and others can't even get them halfway up the sizing die.

This is also why Mark doesn't give any reloading advice, and neglects to mention to potential buyers that his rifles are chambered in a way that fire formed brass can't be used from his 308's.

The only way around this issue is to have Forster make you a Custom FL Sizing Die, also be cautious of expedited work hardening of the brass if you're bound and determined to reload brass from that chamber you'll need to anneal each and every time. This is why I don't even mess around with LaRue barrels I just pull them and have a custom Barrel spun up by a Compass Lake or Craddock.

 

[_Windrider_]

So I've dealt with this issue first hand, and have actually called Mark LaRue out on AR-15.com about this specific issue.

Be prepared for stuck cases and hydraulic dents, and the reason for this is because there's so much inconsistency with LaRue products and his chamberings, that's why you'll see some people claiming they have no issue reloading them and others can't even get them halfway up the sizing die.

This is also why Mark doesn't give any reloading advice, and neglects to mention to potential buyers that his rifles are chambered in a way that fire formed brass can't be used from his 308's.

The only way around this issue is to have Forster make you a Custom FL Sizing Die, also be cautious of expedited work hardening of the brass if you're bound and determined to reload brass from that chamber you'll need to anneal each and every time. This is why I don't even mess around with LaRue barrels I just pull them and have a custom Barrel spun up by a Compass Lake or Craddock.

It’s also just one more reason to not buy anything from LaRue.

 

[bigjake83]

It’s also just one more reason to not buy anything from LaRue.

I can't argue the genius behind his Free Floated Handguard design and the true Monolith top rail on the OBRs, but that's where it stops!!! That's why I always tell people who ask me about owning a LaRue rifle to find a Pre-XTRAXN with the LW50 Barrels or one that's been well used on the cheap and have a custom Barrel spun up by a competent Smith and you'll have a Sub Half MOA rifle.