264 LBC-AR Cartridge

[kentuckytroutbum]

bwaites-
You may know me from the Grendel forum. I am loading 107 SMKs, 120 SMKs, 120 Nosler BT, and 123 A-max with Win 748, & AA2520.

As I stated earlier, because of the short leade/throat, I having to seat the bullets deeply in the case. When I get close to 30.0 grains of powder, I can feel the powder "crunch" when I seat the bullet which I would prefer not to do. Once, I go over 30.0 grains +/-, I even had the bullet to "rebound" out of the case slightly, increasing COAL, and changing the ogive seating depth. This is probably detrimental to accuracy and pressure constraints. Without a means to accurately measure the chamber and barrel pressures, I will admit that this is conjecture on my part, but I would rather be safe, than push the extreme limits.

I've considered getting a throat/leade reamer to lengthen the throat, and I may end up doing this. Since you have 4000+ rounds through your barrel, the throat has probably eroded somewhat, where you can seat to magazine length. At this time, I cannot do this without running into flattened or cratered primers, because the bullet is jammed into the rifling. I've not had good success using jammed bullets in any of my rifles. My brass is only on its Second loading, so "loose primer pockets" has not manifested itself at this time. I've also considered letting the throat erode to a point where I can seat to magazine length. It is somewhat frustrating, as I'm not subject to similar throat limitations with my AR15 Service rifle that I use for NRA HP XTC matches. Also, I don't like to jam bullets is that I may need to extract a loaded round during the course of a match, the bullet becomes stuck in the rifling, and powder is dumped into the receiver. This has happened with the Grendel, and I am not comfortable doing this.

 

[constructor]

Hmm...well, we'll see.

So far as I can see, only Les Baer is building rifles, all the rest are barrel makers, or upper builders.

It will be a LONG time before those few guys catch up to Sabre, AA, J&T, and all the others building actual Grendels.

As for the 6.8, no one seems to be stepping up and trying to get one of those multiple chambers approved by SAAMI, so its highly unlikely that any of the major manufacturers will build the higher pressure ammo.

As for the use of the 6.8 by SF, it was Rust who said, "Come to think of it, that's probably why the military went with the 6.8 SPC." The military HASN'T gone with the 6.8 SPC. A few units may use it, but the military as a whole certainly isn't using it.

I am just a small custom shop but I do have a class 7 and have been chambering the 264 LBC. I am also using a larger diameter bolt that can handle the 6BR but in this case I am holding a .450 bolt face to make it even stronger, it does require a different extension.
where is that poking stick smilie? ;D

ATK, Federal and Winchester who is somehow tied to FN said at the SHOT show they are waiting for SAAMI to approve the new specs. May happen may not.

As far as the military, some groups use the 308, 300 win mag, 338 lapua, 9mm Hks, some may even use the 7.62x39 so as a whole none of the military is using the same thing. Sure MOST use the 5.56 without a doubt but would you go as far to say they haven't gone with the 9mm, 300 win mag or 338, I mean they are using them but every infantryman isn't carrying one?
The thing is LB posted the chamber drawing for everyone to use, that may standardize all of the other 6.5 G knockoffs, and stop the confusion about whether someone should use a bolt with a .125 recess or one with a .136 recess in order to get the proper headspace.

 

[Rust]

The military HASN'T gone with the 6.8 SPC. A few units may use it, but the military as a whole certainly isn't using it.

The military HAS gone with the 6.8 SPC, they just don't issue it to 100% of the troops. Does it have a FSN? Yes? Is it in the supply system? Yes? Means it is an approved weapon. Means the military has "gone with it"

For example, they don't issue a Ma Duece to every single body and it's an accepted weapon. They don't issue a Mk 23 Mod 0 to every single body and it's an accepted weapon. They don't issue an M-24 to every single body and it's an accepted weapon. Or M240s or M249s. Etc.

Different units have different load outs. The M-16/M-4 is just more common.

 

[Grendelfreak]

Rust, I'm sorry, but the fact that a very few, small number of people have access to the 6.8 does NOT mean that the military has gone with it, anymore than the same can be said of the Grendel, or the Beowulf, for that matter, both of which also can be accessed by people with the right "in".

Let a common Joe in the military try to justify the 6.8 and get it, won't happen. The same Joe can access a .50 if he shows need, he can get a 7.62x51 if necessary.

That fact that a few high profile people continue to test the 6.8, and they should, is good for our military, but it doesn't mean that it has been adopted. Adopted means that it is standard issue, for those with a need. It simply isn't.

It's in the same class as the .45 is now, not standard issue, but available if you are one of those with the right clearances. That doesn't make it adopted.

Perhaps a better comparison would be the SCAR, available to you if you have the right clearances, but not to common Joes.

As one Army colonel said when asked if the 6.8 was a dead issue in the Army, "Dead? Was it ever alive?"

 

[constructor]

Rust, I'm sorry, but the fact that a very few, small number of people have access to the 6.8 does NOT mean that the military has gone with it, anymore than the same can be said of the Grendel, or the Beowulf, for that matter, both of which also can be accessed by people with the right "in".

Let a common Joe in the military try to justify the 6.8 and get it, won't happen. The same Joe can access a .50 if he shows need, he can get a 7.62x51 if necessary.

That fact that a few high profile people continue to test the 6.8, and they should, is good for our military, but it doesn't mean that it has been adopted. Adopted means that it is standard issue, for those with a need. It simply isn't.

It's in the same class as the .45 is now, not standard issue, but available if you are one of those with the right clearances. That doesn't make it adopted.

Perhaps a better comparison would be the SCAR, available to you if you have the right clearances, but not to common Joes.

As one Army colonel said when asked if the 6.8 was a dead issue in the Army, "Dead? Was it ever alive?"

Guess the Colonel didn't have the right clearance huh? ;D
Back to the 264, it will make a fine deer and hog hunting rifle with the new Barnes 100 TTSX
and work well for punching paper with the 123s(SMK or Lapua)or 108 and 100 Scenars, actually the 120 SMK is very accurate but just doesn't have the high BCs of the other bullets.

 

[bwaites]

Constructor,

I've loaded all those bullets, and my rifle flat doesn't like SMK's, of any persuasion.

Barnes give me sub MOA groups, Scenars are a little better, Nosler BT's are the best at 100-600 yards, but I'm hoping the new 123 AMAX kicks it up a notch. No one around me has them in stock yet, and I don't want to order 500 and then find out they don't shoot as well as what I have. Paying shipping on 100 is as much as 500, essentially.

Bill

 

[constructor]

Constructor,

I've loaded all those bullets, and my rifle flat doesn't like SMK's, of any persuasion.

Barnes give me sub MOA groups, Scenars are a little better, Nosler BT's are the best at 100-600 yards, but I'm hoping the new 123 AMAX kicks it up a notch. No one around me has them in stock yet, and I don't want to order 500 and then find out they don't shoot as well as what I have. Paying shipping on 100 is as much as 500, essentially.

Bill

Wow, I never guessed the 120 SMKs wouldn't work, those are kind of universally accurate in all of my bigger 6.5s. I had a 10 twist G so I didn't try any that heavy, mainly shot 100 and 108 Lapuas for target and 100 Noslers for antelope. I want to try the 100TTSX for deer and hogs and since the barrels I am building now are 8 twist 3 groove I could try the 120 class projectiles.

 

[bwaites]

The SMK's will shoot right around 1 MOA, but I've tried several different powders and can't get the 108, 120, or 123's to group any better. The best load I've shot with them is a Black Hills clone using TAC, but even that is just under 1 MOA.

Both Nosler BT 100's and 120's have shot .25 MOA groups, and I'm hoping the new Berger 120's and AMAX 123's will match that because they are so much cheaper!!!

Bill

 

[kentuckytroutbum]

constructor-
You said in a previous post on this thread, that LB has posted his chamber drawing for everyone to use. How do I go about getting a copy of said drawing. IS PT&G offereing a chamber reamer or throat reamer for the 264 LBC.

I am now seriously considering lenghtening the leade/throat on my Grendel to seat my bullets further out, as I cannot achieve magazine length COAL at this time.

bwaites-
Of all of the bullets, from 107 SMKs to 123's, the 123 A-max and 107 SMK has been the most accurate tested at 100 yds, on a Sinclair rest, and a Leupold LR scope. I've not chrono'd them yet as I have been waiting for a 80 deg. F day with no wind, hopefully soon. Of all of the bullets that I've tested, the 123 SMK and Nosler 120 BT have given poor accuracy compared to the others. Goes to show that each rifle is different.

 

[bwaites]

Kentucky,

They certainly are! Everyone seems to have good luck with the AMAX though! I'm hoping it can become my go-to bullet, I like the cost, and all I shoot are coyotes!

Bill

 

[constructor]

constructor-
You said in a previous post on this thread, that LB has posted his chamber drawing for everyone to use. How do I go about getting a copy of said drawing. IS PT&G offereing a chamber reamer or throat reamer for the 264 LBC.

I am now seriously considering lenghtening the leade/throat on my Grendel to seat my bullets further out, as I cannot achieve magazine length COAL at this time.

bwaites-
Of all of the bullets, from 107 SMKs to 123's, the 123 A-max and 107 SMK has been the most accurate tested at 100 yds, on a Sinclair rest, and a Leupold LR scope. I've not chrono'd them yet as I have been waiting for a 80 deg. F day with no wind, hopefully soon. Of all of the bullets that I've tested, the 123 SMK and Nosler 120 BT have given poor accuracy compared to the others. Goes to show that each rifle is different.

PTG does have them, they have .2948 neck, a .135 freebore 1.5 degree throat so they work better with some bullets. If you want hunting type accuracy then sure a longer leade is fine but the 123 Lapua, 120 Amax, 108 lapua and that kind of match bullet has to be set out around 2.370 to get close to the lands and you will never get close with a Berger. The 123 Amax maybe different if it has a steep secant type ogive.

 

[kentuckytroutbum]

constructor-
Thanks for the info on PT&G's 264 LBC reamer. I need to make up a dummy with the 123 A-max seated at the depth and COAL that I want, and compare it to your info, and what PT&G is stating. I load by measuring the ogive, and not necessarily the COAL as I have found differences in the bullet tips, each for Hornady, Sierra, and Noslers. I want my loads usually about 0.015 off the lands. Short line loads, I will seat at the magazine length, and my long line loads at 0.015 off the lands provided the bullet is firmly supported by the case neck, and neck tension is adequate.
Thanks

 

[TX65]

The 264 LBC has .2948" neck diameter with .135" free bore and a 1 degree throat (not 1.5 degrees).

The PTG reamer print is attached to the first post in this thread.

 

[kentuckytroutbum]

The 264 LBC has .2948" neck diameter with .135" free bore and a 1 degree throat (not 1.5 degrees).

The PTG reamer print is attached to the first post in this thread.

tx-
I tried to "click" on the link, and it told me "access is denied." I'll call PT&G and talk to them. Thanks

 

[TX65]

just email me and I will send you the print...

arnekbrennan@mac.com

 

[constructor]

The 264 LBC has .2948" neck diameter with .135" free bore and a 1 degree throat (not 1.5 degrees).

The PTG reamer print is attached to the first post in this thread.

the PDF I have shows a 1 degree 30 minute that is 1.5 degrees, dated 9-25-09
drawn by Dave Kiff print # 19277

 

[TX65]

The 264 LBC has .2948" neck diameter with .135" free bore and a 1 degree throat (not 1.5 degrees).

The PTG reamer print is attached to the first post in this thread.

the PDF I have shows a 1 degree 30 minute that is 1.5 degrees, dated 9-25-09
drawn by Dave Kiff print # 19277

Constructor,,, I see the print you are talking about

 

[rcw3]

The 264 LBC has .2948" neck diameter with .135" free bore and a 1 degree throat (not 1.5 degrees).

The PTG reamer print is attached to the first post in this thread.

TX65

Nothing personal here but you are reading the reamer drawing incorrectly (as are some others on this thread as well) and you are putting out incorrect information in your posts - the free bore on the reamer drawing is .120" (i.e it's not the .135" dimension on the drawing as that includes the 45 degree case mouth taper that is not a part of the free bore - at least in terms of typical reamer and chamber terminology) and the throat angle on the drawing is 1.5 degrees (i.e. one degree 30 minutes which = 1.5 degrees).

Robert Whitley

 

[TX65]

The 264 LBC has .2948" neck diameter with .135" free bore and a 1 degree throat (not 1.5 degrees).

The PTG reamer print is attached to the first post in this thread.

TX65

Nothing personal here but you are reading the reamer drawing incorrectly (as are some others on this thread as well) and you are putting out incorrect information in your posts - the free bore on the reamer drawing is .120" (i.e it's not the .135" dimension on the drawing as that includes the 45 degree case mouth taper that is not a part of the free bore - at least in terms of typical reamer and chamber terminology) and the throat angle on the drawing is 1.5 degrees (i.e. one degree 30 minutes which = 1.5 degrees).

Robert Whitley

Hi Robert,

You are correct regarding .120" and 1.5 degrees on the final print. I have two different prints related to the LBC so was reading the wrong one. Here is the last final print I have since someone said they couldn't download it.

Have way too many reamer prints related to this case over the years. My current reamer I use on bolt guns is a .292 neck and I use a 1 degree throating reamer to set the freebore.

Arne

 

[kentuckytroutbum]

Arne, Robert, Constructor-
Thanks for all of your imput & help on this matter. I talked to Dave at PT&G, and he suggested that I get their .264 Unithroater tool which would allow me to lengthen the throat/leade without demounting the barrel from the AR15 upper. He told me that it would be fairly simple for even a non-machinist to do. Go slowly (obviously) and use a good cutting oil, and then blow out the barrel with compressed air.
Final step would be to clean the barrel thoroughly.

Anybody see any negatives to this approach?

Bill