6.8 x 51mm / .277 Fury

[hkguns]

I couldn't find any threads on this, so here goes.

I picked this up on Saturday.

I bought the hybrid brass cases over a year ago and have been waiting for the rifle to hit the streets from SIG.

My Forster dies arrived today.

Quickload says I could possibly push 49-ish gr of H335, using 112gr bullets and be within pressure limits. Obviously I would work my way up to that number.

Reloading data is really hard to come by and I like to reference a few sources before loading some up and tossing them into the chamber.

Has anyone loaded for this cartridge yet? If so, what did you find and if you used QL can it be trusted like you would trust it with 30-06?

 

[hkguns]

Nobody? Not even a smart-@ss comment?

 

[ShootnFool8]

Just let us know, how it goes.

 

[spife7980]

If you have quickload then develop reasonable pressure loads and true the system to the real world.
Then push forward and see how high you can go without rising above the 80k psi.

With a steel case head the brass in the chamber is no longer the weak spot, the whole thing is equal so beware, it’ll go from nothing to a grenade when it does let loose from too much pressure.

I don’t know that anyone on here is doing anything with the hybrid cases that could share besides the one guy who can’t shut up about em. After reading his novels you’ll want to go back to regular brass.

 

[Doom]

I don't know about QL but I do use GRT and what would concern me about either is how well the powder models work going to 80KSI and also how the powers themselves behave. They may be fine but the issue is there is not much data available to qualify them.

As for the round itself I would be concerned about the primers, as we use these primes as indication we are over 65KSI. How will they hold up? Can we use them as an indicator of pressure? I doubt it. With the hybrid case the only pressure indication is hard bolt lift but in a Semi Auto that will be hard to detect.

It is interesting that no-one seems to have published data for 65KSI Fury. As for the 80KSI hybrid case this is a patented design and I suspect that only Sig is going to manufacture the case. At least for some time.

 

[hkguns]

Thanks for the responses.

With the rounds I normally load, I've found QL, to generally fall on the lighter side, as one would expect for safety reasons. I suppose I'll start with QL using a powder I have in stock that seems reasonable for the round. Which is exactly why I chose H335 in my original post.

Shooting for 65 - 70K in my first test rounds should be relatively safe. I'll just ensure I get a good H2O reading on the cases before and after firing.

Not sure me being the first one on here to try this cartridge is a good sign for its longevity.

I haven't seen the novels posted by the one guy who won't shut up about them. Unless he's the one forming them to another caliber. Time to do a better search.

 

[supercorndogs]

Didn't we see a custom action that sheared the lugs using 80k psi loads in alpha brass? Seems like the only thing that stopped it from lodging the boke in his face was the bolt handle hitting chassis.

Around that time didnt alpha put out a statement that their brass showed traditional pressure signs at much higher pressures?

Is running 80k psi in an action designed to run loads under 60k psi a good idea?

 

[hkguns]

Didn't we see a custom action that sheared the lugs using 80k psi loads in alpha brass? Seems like the only thing that stopped it from lodging the boke in his face was the bolt handle hitting chassis.

Around that time didnt alpha put out a statement that their brass showed traditional pressure signs at much higher pressures?

Is running 80k psi in an action designed to run loads under 60k psi a good idea?

Who exactly in this thread is talking about running 80K PSI loads in a 60K action?

 

[Supersubes]

Who exactly in this thread is talking about running 80K PSI loads in a 60K action?

Everyone who’s not shooting a Sig Spear is.

 

[Supersubes]

I don’t know that anyone on here is doing anything with the hybrid cases that could share besides the one guy who can’t shut up about em. After reading his novels you’ll want to go back to regular brass.

Well said.

 

[jbonnie]

At the risk of distracting from the primary purpose of the thread, does anyone happen to know if we can push the .277 fury through Sig’s NG762 suppressor? (Or any other 7.62 suppressor that folks are aware of?) FWIW the Huxwrx folks told me they would not put it through their 7.62 flow suppressors given the higher chamber pressure, which had surprised me not knowing anything about how these things actually work from an engineering standpoint since you can push a .300NM though there. Trying to figure out whether I need to wait for the Sig NG68 to become available or not….. Thanks in advance for any insights!

 

[Farmerbrown32]

Anybody have some load data for the 277 fury? Trying to figure out a good starting point with varget and 110 vmax

 

[Farmerbrown32]

I built a load with the 130grain ballistic tip this afternoon with varget powder and the hybrid case. Average 2900fps and shoots fantastic. Well under sub moa. Super impressed with the sig spear!

 

[XLR308]

Its kind of virgin territory and bucks the known norms but it's out there now.
Your going to get the usual nay layers and put downs regarding the operating pressures but the animal is out of the box so roll with it.
I personally have been contemplating a barrel for one of my kelbly actions in 277 Fury for a light weight hunting rig since it would be a real beast in a short action but I'm waiting to see more Comercial support for the round.

 

[Farmerbrown32]

Settled on the 145 eldx with varget. 2820 fps. Killed pdogs at 705,706 and 736 yards yesterday with it. Really splatters them well. Hope to find an antelope to get with it this weekend. Really happy with how clean the rifle stays even shooting suppressed. Super reliable and shoots very well.

 

[Chris Goodwin]

So this is my first post here, honestly just been doing a lot of reading. I do have an Sig Spear but impatiently bought one when they were just selling them in 7.62x51.

Due to my impatience with Sig releasing the Spear in 6.8x51 I decided to build a AR10. I used a x-caliber barrel, 4140 steel, 20 in, 5R, 1:7 twist, with a high pressure bolt and bolt carrier but it is still limited to 65k psi. I started out with the all brass casing box ammo, 135 gr FMJ and the 130 gr Venari SP. I took down all the necessary measurements, noting the 135 gr is using an extruded powder and the 130 gr hunting had a ball powder.

As you are finding there is no load data for this cartridge. Initially I based my load data on 7mm-08 as it’s a similar cartridge and case capacity. I am not using any programs just my experience handloading.

Down to business. I ran velocity and pressure tests using StaBall 65, H4350, and Reloader 16. H4350 just didn’t match the speed of Staball65 and Reloader 16 I have not completed a complete work up but in the 2850 fps range with low charges. I found a tight 1 to 1/2 MOA load with Staball65 at 49.6 gr and max is at 50.2 but still not seeing pressure signs or popping primers. At 49.6 I am at 2970fps with 130 gr Nosler Accubond. Just to mention fired case capacity averages 57.2 gr water with the all brass casing and the hybrid case.

I recently purchased 1000 hybrid casing from American Reloading. Deprimed and then resized with Forester dies. Following the same methods I did another velocity test working from 48.8 gr to 50.2 gr of StaBall 65 a 130 gr Sierra Gamekimg and the Hybrid case. Velocity ranged from 2882 fps to 2998 fps at 50.2 gr.

Right now I am working up a load for a 130 gr Barnes’s TTSX. All this for an amazing 1 shot kill on some fat wild boars here in Texas.

I just picked up an Sig Cross in 277 Fury and impressed with the 150 gr Accubond box ammo hitting 3000 fps with recoil feeling lighter than a .308 shooting the same grain bullet about 200 fps slower. At some point I hope Sig releases just the 6.8x51 upper, not looking to spend another $4k.
Sorry if this is long winded, just wanting to share. I am not chasing a 80kpsi threshold as some see as more important. My AR10 version has been extremely reliable, velocity is matching the hype of the round, and doing it safely.

 

[layjzay]

Anyone tried H335. this is from load data that i purchased for max load

.277 Fury || .277 | 115gr | Sierra HPBT MatchKing​

Hodgdon H335

45.2gr

92%

71881

90%

3199

100%

Primer is still not as flat as the factory 113 hybrid load but accusracy is so much better. I wiil get my conograph out when I've got so better weather and see if I can go higher. as always load at your own risk..

 

[layjzay]

I couldn't find any threads on this, so here goes.

I picked this up on Saturday.

I bought the hybrid brass cases over a year ago and have been waiting for the rifle to hit the streets from SIG.

My Forster dies arrived today.

Quickload says I could possibly push 49-ish gr of H335, using 112gr bullets and be within pressure limits. Obviously I would work my way up to that number.

Reloading data is really hard to come by and I like to reference a few sources before loading some up and tossing them into the chamber.

Has anyone loaded for this cartridge yet? If so, what did you find and if you used QL can it be trusted like you would trust it with 30-06?

What is your results with the H335?

 

[hkguns]

They're still waiting to be tested, I had a few opportunities to shoot them and decided to start with factory cases, both hybrid and all brass first.

I will update this when I finally get around to it in the spring. Too cold now.

I did send the Brass to AMP to have them analyze it. Alex says it should be listed on their website now.

Pilot #70

Standard Mode:
Hybrid Case - Program 54
Brass Case - Program 55

Aztec code: 070 C

Couldn't believe how much it was to ship the brass to NZ.

 

[northern_wind]

Hey guys, I don't get on here often but I recently decided to start reloading the 277 SIG FURY (6.8X51mm) Hybrid cases. I searched high and low to see if this was even possible, only to find little to no info on this topic as it is a fairly new cartridge with no reloading data on it. I even saw some people saying the Hybrid case was not "reloadable"... All that being said, I just successfully fired some loads I worked up using hybrid cases and thought I'd share some of the results for those wanting to reload this but have been hesitant.

For starters, I bought a 460rnd can of the factory military overrun 6.8X51mm 113gr. solid copper FMJ RR (Reduced Range) SIG offers. My 13" MCX-SPEAR SBR with SLX-MG 6.8 Suppressor consistently shot between 3075-3100fps for the first 60 rounds (3 mags) I put through it while establishing a solid zero. This is a brand new rifle so I suspect once I get a couple hundred rounds on it those numbers will slightly increase. Accuracy with the factory ammo was as small as 3/4 MOA up to 2MOA at 100yds.

Now that I had some once fired cases, I decided to start reloading them. A quick note, I noticed these factory rounds did not make any powder noise when shook in hand like most traditional rounds do. After pulling one of the 113gr factory loads to take a peak under the hood, I measured 53gr of some type of ball powder SIG is using. The bullet is also compressed into the case as the powder was filled up to the neck and the bullet would not seat back down to where it was originally seated from the factory by hand. There is literally no more room in these cases, hence why the powder was not making any noise when I shook them. After studying the ball powder SIG is using, I decided to try some Hodgdon H-335 powder as they looked pretty close if not identical to each other.

Equipment/Components:

RIFLE - SIG MCX-SPEAR 6.8X51mm 13" SBR / SLX-MG 6.8 SUPPRESSOR
DIES - FORSTER SIZING & SEATING / LEE FACTORY CRIMP DIE
CASE - SIG 6.8X51mm HYBRID (ONCE FIRED)
PRIMER - CCI #200 LARGE RIFLE
POWDER - HODGDON H-335
PROJECTILE - 113GR SOLID COPPER FMJ

Without any real min/max data to start with, I decided to go with a lower charge than normal and ended up starting at 45gr just to be safe. Below are the charges and velocity averages.

45gr - 2876fps
46gr - 2916fps
47gr - 2988fps
48gr - 3050fps
49gr - 3089fps
50gr - 3140fps

No signs of pressure on any of these, but I decided to stop at 50gr just because it was getting dark and was 17F degrees out. I know I can push it further up to 3200fps and beyond but until I have a chance to shoot these in warmer weather Im going to call it at 49/50gr. I assume these will all speed up another 50-60fps when the 70-90F degree summer days hit and as my barrel breaks in. I have not tested these for accuracy yet, but will report back on that soon. As always, what works for me in my gun may not work for yours, be safe, smart and load at your own risk.

 

[Chris Goodwin]

Hey guys, I don't get on here often but I recently decided to start reloading the 277 SIG FURY (6.8X51mm) Hybrid cases. I searched high and low to see if this was even possible, only to find little to no info on this topic as it is a fairly new cartridge with no reloading data on it. I even saw some people saying the Hybrid case was not "reloadable"... All that being said, I just successfully fired some loads I worked up using hybrid cases and thought I'd share some of the results for those wanting to reload this but have been hesitant.

For starters, I bought a 460rnd can of the factory military overrun 6.8X51mm 113gr. solid copper FMJ RR (Reduced Range) SIG offers. My 13" MCX-SPEAR SBR with SLX-MG 6.8 Suppressor consistently shot between 3075-3100fps for the first 60 rounds (3 mags) I put through it while establishing a solid zero. This is a brand new rifle so I suspect once I get a couple hundred rounds on it those numbers will slightly increase. Accuracy with the factory ammo was as small as 3/4 MOA up to 2MOA at 100yds.

Now that I had some once fired cases, I decided to start reloading them. A quick note, I noticed these factory rounds did not make any powder noise when shook in hand like most traditional rounds do. After pulling one of the 113gr factory loads to take a peak under the hood, I measured 53gr of some type of ball powder SIG is using. The bullet is also compressed into the case as the powder was filled up to the neck and the bullet would not seat back down to where it was originally seated from the factory by hand. There is literally no more room in these cases, hence why the powder was not making any noise when I shook them. After studying the ball powder SIG is using, I decided to try some Hodgdon H-335 powder as they looked pretty close if not identical to each other.

Equipment/Components:

RIFLE - SIG MCX-SPEAR 6.8X51mm 13" SBR / SLX-MG 6.8 SUPPRESSOR
DIES - FORSTER SIZING & SEATING / LEE FACTORY CRIMP DIE
CASE - SIG 6.8X51mm HYBRID (ONCE FIRED)
PRIMER - CCI #200 LARGE RIFLE
POWDER - HODGDON H-335
PROJECTILE - 113GR SOLID COPPER FMJ

Without any real min/max data to start with, I decided to go with a lower charge than normal and ended up starting at 45gr just to be safe. Below are the charges and velocity averages.

45gr - 2876fps
46gr - 2916fps
47gr - 2988fps
48gr - 3050fps
49gr - 3089fps
50gr - 3140fps

No signs of pressure on any of these, but I decided to stop at 50gr just because it was getting dark and was 17F degrees out. I know I can push it further up to 3200fps and beyond but until I have a chance to shoot these in warmer weather Im going to call it at 49/50gr. I assume these will all speed up another 50-60fps when the 70-90F degree summer days hit and as my barrel breaks in. I have not tested these for accuracy yet, but will report back on that soon. As always, what works for me in my gun may not work for yours, be safe, smart and load at your own risk.

I have been reloading this cartridge for awhile, say 8 months. I started out with the brass casing and later I bought a 1000 hybrid cases from American Reloader.com. I built a AR-10 since at the time the Spear in 6.8x51 was not out. For reference I am using a 20 inch 1:7 twist. In my case I was building for a low pressure load, and I have been very successful. I found that StaBall 65 and Reloader 16 puts fps next to yours easily. 49.6 gr of StaBall 65 in the brass case and 48.6 in the hybrid case equals 2986 FPS with a 130 gr Nosler and 130 gr Barnes TTSX. Building loads for hunting and not just for plinking.

Back when Sig only had the 7.62x51 Spear, I had to have it and hoped they would offer the complete upper later. I didn’t want to spend another $4k on the same rifle. So to feed my curiosity of the true hybrid case ability to fire, I bought the Sig Cross in 6.8/277 Fury. It does not disappoint firing a 150gr Accubond/hybrid case to 3000 fps and is extremely accurate.

As for your loads, I think you are on the right track but wouldn’t try to duplicate Sigs Compressed load. 48 to 50 gr are giving you good numbers. I look for speed and accuracy. Makes no sense just to chase speed if it’s sending rounds down range like a shot gun. The typical Army load and acceptable accuracy is what 2-3 MOA, for me that’s horrible but they are only concerned with sending rounds down range, keeping heads down and any hit on the enemy is a kill.

I would remind that you are probably not going to see the normal pressure signs at the case head, except a popped or pierced primer and case head separation. I can’t imagine case head separation with a hybrid case, pressures would probably blow the gun and you with it. Nothing wrong with a 3100 fps 1MOA load out of a 13 in barrel as long as it’s still safe. I would further recommend you use a CCI 34 primer over the CCI 200. The cases I received was primed and I suspect they were CCI 34 or equivalent.

I have a lot more information to share but many are chasing this 80k psi pressure loads and I feel I found near same ballistics with a low pressure loads. I just finished development of a M118LR clone for my M1A loaded, with a 175 gr Sierra MK. Gonna start to load for the Cross and a 150 gr Accubond with a goal of 3000 fps.

Good luck and don’t blow your face off.

 

[northern_wind]

Chris, thank your for your input and advice on this topic. It seems you have had some experience and success as well reloading the 6.8x51mm Hybrid cases. The CROSS is a great host/rifle that would definitely benefit from this flatter cartridge for hunting and long range shooting.

I realize velocity is not everything and intend to fine tune my powder charge up or down to achieve desired accuracy with a couple bullet types. The initial velocity test was just to get a “ball park” idea of where I need to be to get close to the intended velocities (3000+fps) of this cartridge in the shorter 13” barrel.

For all intensive purposes, the SPEAR is a “battle rifle” not a precision rifle and I don’t intend to make it one. I have other rifles In other calibers I reload specifically for long range/ELR accuracy. I am mainly looking to develop a “cheaper to shoot” FMJ target load for blasting/plinking as well as an “acceptable” semi-accurate Tipped/HPBT load (1 MOA or less) for defensive, hunting and mid to longer range shooting with a better BC.

For the target load I could probably just load the conventional brass cases as the extra pressure/velocity is not really needed for the shorter ranges I would be shooting and would also be less wear and tear on the gun. I did pull apart a couple rounds of the factory SIG 135gr FMJ all brass conventional case to find they are using 48gr of stick powder instead of the ball powder they are using in the MIL hybrid ammo.

I guess the good news is, there are plenty of options between cases, bullets and powder to load for whatever occasion suits your purposes. I did want to ask you what you have experienced with the number of reloads per case with the hybrids? Are you getting 2-3? 3-5? Or are these one and done? I have been annealing my hybrid cases after every firing just to be safe.

Thanks again for all the info, it is greatly appreciated!

 

[Chris Goodwin]

Chris, thank your for your input and advice on this topic. It seems you have had some experience and success as well reloading the 6.8x51mm Hybrid cases. The CROSS is a great host/rifle that would definitely benefit from this flatter cartridge for hunting and long range shooting.

I realize velocity is not everything and intend to fine tune my powder charge up or down to achieve desired accuracy with a couple bullet types. The initial velocity test was just to get a “ball park” idea of where I need to be to get close to the intended velocities (3000+fps) of this cartridge in the shorter 13” barrel.

For all intensive purposes, the SPEAR is a “battle rifle” not a precision rifle and I don’t intend to make it one. I have other rifles In other calibers I reload specifically for long range/ELR accuracy. I am mainly looking to develop a “cheaper to shoot” FMJ target load for blasting/plinking as well as an “acceptable” semi-accurate Tipped/HPBT load (1 MOA or less) for defensive, hunting and mid to longer range shooting with a better BC.

For the target load I could probably just load the conventional brass cases as the extra pressure/velocity is not really needed for the shorter ranges I would be shooting and would also be less wear and tear on the gun. I did pull apart a couple rounds of the factory SIG 135gr FMJ all brass conventional case to find they are using 48gr of stick powder instead of the ball powder they are using in the MIL hybrid ammo.

I guess the good news is, there are plenty of options between cases, bullets and powder to load for whatever occasion suits your purposes. I did want to ask you what you have experienced with the number of reloads per case with the hybrids? Are you getting 2-3? 3-5? Or are these one and done? I have been annealing my hybrid cases after every firing just to be safe.

Thanks again for all the info, it is greatly appreciated!

I can understand that the Spear doesn’t need to precision rifle accurate. I have a mindset that if I can get to 1MOA or better than that’s what I’ll try and obtain. Sometimes the bullet, the powder charge, and rifle just isn’t going to produce those results. As long as it’s consistent group or 1MOA-ish group then ok.

I too pulled apart the brass case 135 gr FMJ and I pulled apart the 130 gr SP hunting rounds. I was taking measurements and notes, building my own loading book on this caliber. In my AR10 build, the 135 FMJ was a very hot load and if ambient temps were high, it would blow the primer and totally ruin the primer pocket. The same round in my cross shot very well and decently more accurate. Once fired brass from either gun still fire formed the case pretty much identically.

With my brass cases I have gotten 4 to 5 firings out of them. Again, loading for lower pressures is helping and not blowing anymore primers but also using a temp stable powder. I live in Texas and high summer time temps, so I like the temp stable powders if I can. Primer pocket wear is the first thing I have seen going first. I use a go/no go gauge and would recommend one. Also I am annealing too. With my hybrid cases I have some with 3 firings. One thing I noticed with the hybrid and brass cases is once fired the shoulder will push from 1.675 to 1.680 once I resize them, which if I am reading it right is the minimum SAMMI chamber size. I am using Forester Full length sizing die and Ultra Micrometer seating die.

 

[northern_wind]

I am using the same Forster dies as well. Are you finding that the full length sizing die expander ball is producing adequate neck tension for the semi auto? This is something I usually control with a specific sized neck bushing in other dies but I could not find a 277 full length sizing die with bushing as I don’t think anyone makes them yet.

I know for bolt guns you typically want .002-.003 neck tension and for semi auto guns .004-.005 neck tension to help retain the bullet with feeding and recoil in the magazine etc. I noticed my rounds were moving several thousandths out of the case when chambering/dropping bolt on magazine so I purchased a lee factory crimp die to add a little more tension to them. Do you use a crimping die as well?

 

[Chris Goodwin]

I am using the same Forster dies as well. Are you finding that the full length sizing die expander ball is producing adequate neck tension for the semi auto? This is something I usually control with a specific sized neck bushing in other dies but I could not find a 277 full length sizing die with bushing as I don’t think anyone makes them yet.

I know for bolt guns you typically want .002-.003 neck tension and for semi auto guns .004-.005 neck tension to help retain the bullet with feeding and recoil in the magazine etc. I noticed my rounds were moving several thousandths out of the case when chambering/dropping bolt on magazine so I purchased a lee factory crimp die to add a little more tension to them. Do you use a crimping die as well?

I think it’s producing adequate next tension. I think Forester might be able to custom make an expander ball if you wanted more. I thought I had a neck tension gauge for .277/270 but I don’t. But taking an inside measurement I get .003 . I do not crimp but I would be interested in the where you got your crimp. I have not noticed and rounds moving after firing.

I can imagine that if your Spear in 6.8 and my Spear in .308/7.62 are heavy recoiling rifles. With no buffer it just is what it is. On the other hand my Cross shooting the 150gr hybrid, I say recoil is less than .308 and slightly heavier that 6.5 Creed. I honestly expected more recoil from this light weight rifle, but it’s not bad.

I highly recommend getting brass from American Reloading. Can’t beat new cases with primers. Wondering when this cartridge is going to get more support? This is one of the rifles I do a lot of pig hunting with. Decimating one shot kills on large pigs. And it’s a great deer cartridge and I am sure could take an Elk.

 

[northern_wind]

I did not have a chance to measure if the rounds in the magazine were growing or shrinking in COAL yet, I would like to measure that as well.

What I did find though, was that with the bolt locked to the rear and loaded magazine inserted, upon releasing the bolt on the top round in the magazine to chamber, the bolt was causing that first round to grow several thousandths from the inertia of the bolt driving it forward and then stopping abruptly once chambered.

The Lee factory crimp die that I picked up is below, A lot of people swear by these and have nothing but good things to say. You can over crimp the bullets with this so read the instructions and start lighter than you need to, you can always add more.

277 SIG Fury Dies

277 SIG Fury Dies

leeprecision.com

I am still messing with it as I have never had to crimp anything before and this adds an extra step to my normal process. All the calibers I load for are primarily for precision and have been able to achieve the desired neck tension using the various neck bushings in my dies. I guess crimping makes sense for semi auto's as the round is getting knocked around more during feeding, recoil, ejecting etc.