.277 Fury/NGSW Round

[jrumann59]

Also, if this round is adopted in the civilian market its users may need to follow this kind of storage practice. Again, good information. Thanks a lot.

Honestly if there is an issue with galvanic corrosion, I can see it being a rare round for civilian uses. Besides the fact the NGSW is shorter than legal limit barrel and the civilians will be getting at least a 16" barrel I think the brass cased ammo will be the most common.

 

[Some Guy]

I did forget to add, yeah if you dropped the rounds in salt water, galvanic corrosion between the SS, aluminum, and brass will occur. But you are likely still talking the time span of weeks to cause serious issues. Just a regular freshwater environment like your pack/rig got rained on (several times) would likely take months for it to be a serious concern.

Thanks. It sounds like if stocks are properly maintained, and if inventory is planned so there's enough to operate but not to create storage challenges, the round would be good to go.

Regarding the the ballistics, round comparisons and barrel replacement ideas, etc., this has been a very enlightening string. The MDS Brain Trust again demonstrates its might.

 

[Some Guy]

Honestly if there is an issue with galvanic corrosion, I can see it being a rare round for civilian uses. Besides the fact the NGSW is shorter than legal limit barrel and the civilians will be getting at least a 16" barrel I think the brass cased ammo will be the most common.

You're probably right. I doubt I'll ever use this round or the XM7/Spear. It'll be too expensive for me for many years, I think.

AR-10 or similar platforms with proven and less costly ammunition will likely to continue to be used by civilians until there's enough of the Sig Spear weapons and Fury ammunition out there. The Spear's ain't cheap, and personally I can barely afford ammunition as it is.

 

[jrumann59]

Depending on the stainless steel used for the base galvanic corrosion may be less likely and to address this they could always use a an adhesive or epoxy "insulator" between the two metals to inhibit the possibility even more.

Mixing Brass and Stainless-Steel Fittings

Mixing brass and stainless-steel fittings is not very common and shouldn't be overlooked. Learn why in this blog post by Brennan Industries.

blog.brennaninc.com

 

[jrumann59]

You're probably right. I doubt I'll ever use this round or the XM7/Spear. It'll be too expensive for me for many years, I think.

AR-10 or similar platforms with proven and less costly ammunition will likely to continue to be used by civilians until there's enough of the Sig Spear weapons and Fury ammunition out there. The Spear's ain't cheap, and personally I can barely afford ammunition as it is.

yeah right now its $80/20 rounds or there abouts.

 

[Some Guy]

Depending on the stainless steel used for the base galvanic corrosion may be less likely and to address this they could always use a an adhesive or epoxy "insulator" between the two metals to inhibit the possibility even more.

Mixing Brass and Stainless-Steel Fittings

Mixing brass and stainless-steel fittings is not very common and shouldn't be overlooked. Learn why in this blog post by Brennan Industries.

blog.brennaninc.com

That was a good article. The cited Wikipedia anodic index is interesting. I think the aluminum washer would be the challenge because aluminum is pretty far from brass and chrome-alloy steels on the scale.

I wonder if the round build includes an adhesive insulator as you say.

It would be interesting to visit a factory where these rounds are made.

 

[jrumann59]

That was a good article. The cited Wikipedia anodic index is interesting. I think the aluminum washer would be the challenge because aluminum is pretty far from brass and chrome-alloy steels on the scale.

I wonder if the round build includes an adhesive insulator as you say.

It would be interesting to visit a factory where these rounds are made.

Maybe a paint but I do not see how a paint can keep tolerances with in spec. The biggest concern will be reloading, when new and packed full of gunpowder and round the cartridge will be gas tight and the presence of any moisture will be very, very low. The problem could arise when you de-cap and clean a used case introducing solvents and humidity. The added area between the two cases will be huge for holding onto moisture also I do not know how you would go about filling the powder correctly with out separating the two "cases". Reloading could cause a lot of inconsistencies in the round.

 

[smokey]

I'm still just over here wondering how badass a 80,000-100,000 psi 6.5 grendel would be.

 

[Some Guy]

Maybe a paint but I do not see how a paint can keep tolerances with in spec. The biggest concern will be reloading, when new and packed full of gunpowder and round the cartridge will be gas tight and the presence of any moisture will be very, very low. The problem could arise when you de-cap and clean a used case introducing solvents and humidity. The added area between the two cases will be huge for holding onto moisture also I do not know how you would go about filling the powder correctly with out separating the two "cases". Reloading could cause a lot of inconsistencies in the round.

I am not a re-loader. But I think your point about civilians using brass cases instead of the Fury cases is validated due to what you say here. It sounds like it would be difficult to re-load the steel, aluminum and brass Fury casings.

 

[smdub]

I don't think galvanic corrosion will be an issue. Primers are already steel. They are nickel plated. Nickel/brass are basically neighbors on galvanic corrosion charts. Far worse is steel on copper. Comblock calibers don't seem to have big issues as all with storage around the neck/bullet interface in long term storage. They all use some sort of coating/plating on the steel. This issue has been solved.

Since military primers and necks both typ have sealant I suspect the Sig round will have it on the web joint too.

I'm still just over here wondering how badass a 80,000-100,000 psi 6.5 grendel would be.

Now you are getting the idea behind it! Could run some numbers in Quickload or GRT.

 

[lazarus]

Also, if this round is adopted in the civilian market its users may need to follow this kind of storage practice. Again, good information. Thanks a lot.

It won’t be. Sig SAAMI spec is I think at like 68k PSI and they are loading a traditional brass case.

 

[lazarus]

I'm still just over here wondering how badass a 80,000-100,000 psi 6.5 grendel would be.

A 65k 6.5 Grendel would be awesome. Granted you can load to that pressure level in a bolt gun. Not that I am willing to load for my Howa what I can’t safely shoot in my ARs. But just too bad it couldn’t be spec’d 10-15k higher.

 

[smdub]

You you go to different steel bolt and locking lugs you'd be able to squeeze more out of 6.5 Grendel. I'm sure the limit was backed down to 52ksi due to bolt thrust limits on standard AR parts. There have been high pressure big case ARs before though that used more exotic material for the bolt. I can't remember the caliber it was though. Some wildcat I had never heard of... (fellow on Weapons Guild was looking for parts to something odd.)

 

[lazarus]

You you go to different steel bolt and locking lugs you'd be able to squeeze more out of 6.5 Grendel. I'm sure the limit was backed down to 52ksi due to bolt thrust limits on standard AR parts. There have been high pressure big case ARs before though that used more exotic material for the bolt. I can't remember the caliber it was though. Some wildcat I had never heard of... (fellow on Weapons Guild was looking for parts to something odd.)

Bolt thrust limits on standard AR parts with less material in the lugs…

Most bolt guns the case will fail before bolt thrust is going to sheer the lugs. But again, I don’t want to load anything that would be unsafe in my ARs. Though I am willing to load longer than will chamber in my ARs. That’s a fine problem to have.

 

[Park ranger]

I don't think galvanic corrosion will be an issue. Primers are already steel. They are nickel plated. Nickel/brass are basically neighbors on galvanic corrosion charts. Far worse is steel on copper. Comblock calibers don't seem to have big issues as all with storage around the neck/bullet interface in long term storage. They all use some sort of coating/plating on the steel. This issue has been solved.

Since military primers and necks both typ have sealant I suspect the Sig round will have it on the web joint too.


Now you are getting the idea behind it! Could run some numbers in Quickload or GRT.

Primers are brass, not steel. At least the ones I use.

 

[jrumann59]

Bolt thrust limits on standard AR parts with less material in the lugs…

Most bolt guns the case will fail before bolt thrust is going to sheer the lugs. But again, I don’t want to load anything that would be unsafe in my ARs. Though I am willing to load longer than will chamber in my ARs. That’s a fine problem to have.

Hasn't that been the problem with many larger calibers in the AR15 platform, usually not enough meat between the bolt face and lugs usually leading to premature lug failure especially on cheaper bolts.

 

[lazarus]

Hasn't that been the problem with many larger calibers in the AR15 platform, usually not enough meat between the bolt face and lugs usually leading to premature lug failure especially on cheaper bolts.

In general, yes. Better heat treated bolts fair a lot better. Also possible to move to alloys of steel that are even stronger. But not something you'll likely normally see in your average AR15 bolt.

In many cases, the failures are when things are exceeding SAAMI specs and/or a lot of rounds down range. The M855A1 was/has the same issue with its higher pressures. M4s are just fine...until you start talking M4s with MANY thousands of rounds will eventually crack bolt lugs. So they've been sourcing stronger bolts which appears to have solved that issue.

I can't think of an AR caliber I'd shoot a LOT of rounds down range, or exceed SAAMI specs, with other than 5.56/.223. Now, I don't want my 6.5 grendel bolt cracking. And I don't plan to only own the rifle for a few years. Then again, I am probably shooting 50-80 rounds a year through it. About 200-300 through my Howa in 6.5 Grendel. If the lugs fail in 5,000 rounds, that's 100 years for the AR...

Now if I make things spicy, that might be 1,000 rounds and a bigger concern.

Maybe the only other one some day I might shoot a lot, is 300BO. But frankly if I get an AR in 300BO some day, less concern. The lugs have the same meat. The bolt thrust is only very slightly higher than a hot 5.56 for 300BO. And frankly if I am volume shooting, it is likely to be 80-90% subs, which are going to be applying a lot lower bolt thrust.

If I ever get a thumper like a 50BW or 450/458, I doubt I'll be shooting it very much. $$$, even reloading. Though I think all three have rebated rims. So the bolt material is about the same. But it is a lot more bolt thrust than what the AR bolt was designed for.

 

[RangerWillrett]

yeah right now its $80/20 rounds or there abouts.

I'm seeing under $30 for a box of 20 for the civilian version already on the market. 200 rd cases is coming in under 300. https://ammoseek.com/ammo/277-fury

 

[jrumann59]

I'm seeing under $30 for a box of 20 for the civilian version already on the market. 200 rd cases is coming in under 300. https://ammoseek.com/ammo/277-fury

The Mil-spec is going to be higher, bi-metal case and additional parts. Civilian with brass case should fall in line with other rounds od similar size.