Can somebody please explain to me.......

[bwaites]

I think every hunter has to make a decision where that distance is for him. So long as the kill is clean, and the animal suffers as little as possible, I have no problems.

When you examine the risks, an arrow in flight for 50 yards takes as long to arrive as a Grendel bullet does at 400 yards. (300 FPS divided by 150 feet, or about .5 seconds. vs 2500 FPS divided by 1200 feet, or a little tiny bit less than .5 seconds) I know, the bullet really isn't going 2500 FPS on arrival, but the arrow is going 300 FPS either, they both slow down quite a bit in their respective flights.

The arrow has considerably less energy than the bullet does, and yet, we don't complain about bow hunters taking 50 yard shots if they are appropriately skilled. I don't see a problem with an appropriately skilled rifle hunter taking a 400 yard shot, or an even longer one under the right circumstances, and I don't consider them a "Hail Mary" shot when done properly.

[elkbow]

if you are really going to keep to 300 yard shots and can even go longer on mid sized game like deer, I would go with the 6.8, reason being isn't the barrel cost, its the overall cost of ammo, brass, bullets, etc. I think the Grendel is a great round, don't get me wrong, and has more long range capabilities than the 6.8, however that doesn't justify the cost of ammo or to reload (not including the wolf junk), i look at things in many ways, like resale, reloading, ammo, bullet selection, availability, etc.

well I don't really as I have one or two of everything lol

[LRRPF52]

With the Prvi Partizan at $12.95 a box, the Grendel is cheaper to shoot than 6.8, since everything else is the same cost-wise. There are more and more factory hunting loadings available, and coming onto the market, and Grendel ammo from Hornady is on the shelves at Cabella's and a growing number of gun stores. There are 3 within 15 min of me that carry it on the shelves.

There are more companies who jumped on the bandwagon with 6.8, and in the rush, an unsafe chamber got SAAMI-spec'd somehow, and you have to figure out which one you have or make sure that you DON'T get a SAAMI chamber in 6.8, or it could kaboom on you since it has an 80 degree leade-to-rifling hand-off. This is why the 6.8 SPC II chamber is the one everyone is pointing out to go with, rather than the dangerous one. That makes ammo manufacturers really leary about loading higher-pressure loads, and many 6.8 owners have noticed that their 115gr bullets aren't going the speeds claimed by the makers on the box, or in the original guns that had correct chambers. Many report 200fps less MV, so guess what...they resort to hand-loading, and stick to...small rifle primer brass to handle the pressures. I would do the exact same thing if I owned one, so factory ammo is out for me either way with these calibers, especially if you're an accuracy nut and get a warm and fuzzy when your bullets fly through a hole where your aiming reference is.

In the long run, it was prudent for AA to insist on the exact chamber dimensions of the Grendel, rather than let everyone and their brother to make "their improvement" on it, since so much R&D had been performed by AA on more chamber dimensions than we can shake a stick at.

[elkbow]

you would have a hard time finding a SPC I chamber anymore from a decent vendor, even if you had a 1:10 twist with a SPC II chamber, will run all Tac loads, there are so many more options for ammo for the 6.8

I've shot some of the factory 6.8 stuff, but never chrono'd it, but my handloads exceed their numbers with no pressure signs...., and I agree, i'm in to handloading, working a round up that I want for a particular situation, for example hunting, and the bullet choice that shoots accurately in my barrel...

I agree on the chamber pressure for the Grendel, one of the reasons why I like the 7.62x39 bolt that others don't, it has a deeper recess...

all that being said, I would still stick with the 6.8, until the ammo is on par with availability and the range of bullets equal to that of the .277, for his purposes that this thread is about, the 6.8 is the way to go...

[Variable]

....(not including the wolf junk).....

Have you shot any of Wolf's (Prvi Partizan) 120gr. MPT?

[Variable]

I agree on the chamber pressure for the Grendel, one of the reasons why I like the 7.62x39 bolt that others don't, it has a deeper recess...

:confused: I must be misreading you there? The Grendel bolt is actually recessed deeper than the 7.62x39 bolt.

[elkbow]

:confused: I must be misreading you there? The Grendel bolt is actually recessed deeper than the 7.62x39 bolt.

oops, yep backwards, the less recess is on the 7.62 bolt, which should allow for higher pressures of the round, thanks for correcting that, not the first time i've brain farted on that

[elkbow]

Have you shot any of Wolf's (Prvi Partizan) 120gr. MPT?

yes sir!! What I have shot of it is awful dirty though. Plus it uses lage rifle primers where Lapua & hornady brass uses small rifle primers. The MPT shoots alot better than the Wolf SP 123 grain but the brass is the same, I'll stick with my handloads. And again, almost all Wolf stuff is junk in my opinion.

[bwaites]

oops, yep backwards, the less recess is on the 7.62 bolt, which should allow for higher pressures of the round, thanks for correcting that, not the first time i've brain farted on that

Not so much, actually. The Grendel bolt was specifically designed for maximum strength, and the steel was changed from the Carpenter 158 used for 7.62x39 bolts to a much stronger alloy. 7.62x39 bolts failed regularly, even at 7.62x39 pressures, and it was one of the issues associated with making it run in an AR. (Along with feeding issues because of mag incompatibility due to case taper.)

Alexander significantly upgraded the steel, and that, in combination with appropriate pressure levels, improved the bolt life. 7.62x39 bolts used by others in 6.5 builds have been less successful. Several years ago I kept a running tally of all the bolt failures and the causes, as well as where the bolts originated. EVERY AA bolt that failed, except one, failed in hand loaded situations. 7.62x39 bolts failed without any significant pattern. They failed with factory ammo, hand loads, or a combination. The one AA bolt that failed with factory loads failed with a steady, almost exclusive, diet of Les Baer 123 ammo. Since others shot that without issues, I never could come to any real conclusion on the cause. Maybe just a bad bolt. Les Baer's old Sierra 123 load was very warm in comparison to other factory loads, though!

[LRRPF52]

So if I'm going into either a 6.8 SPC or a Grendel, and am trying to narrow my choice down, and I know I'm going to hand-load my hunting and or target loads, the Grendel is the obvious choice, since I have Lapua brass, Hornady brass, and plenty of sources of throw-away brass.

I keep hearing how many factory loading there are for 6.8 SPC, but factory loading for me are what I go to for a SHTF rig where cost is the main factor. In other words, I ain't shelling out $20 per box of 20. The rest is hand-loads for me in these types of guns, and you won't find brass in the quality and longevity range of Lapua. If I need SHTF ammo, I can afford to buy the 120gr MPT brass-cased loads from Serbia (Wolf doesn't manufacture anything, they are a distributor) for $12.95 a box, or the steel case once it comes out at probably half that price or less. This favors the Grendel again.

Projectiles: I have plenty of hunting and target projectiles to choose from with the Grendel-more than enough to work with in even an above-average shoot schedule. Hunting & TGT projectiles include:

85gr Sierra Varminter
90gr Speer TNT
95gr VMAX

100gr Lapua FMJ
100gr Lapua FMJ Cutting Edge
100gr Sierra Varminter
100gr Nosler Partition Flat-Base

100gr Lapua Scenar
100gr AMAX
100gr Hornady SP
100gr Berger

100gr NBT
100gr Barnes TTSX
100gr Barnes Tipped TAC-TX

107gr SMK
108gr Scenar

120gr Norma FMJ
120gr Remington Core-Lokt
120gr Swift A-Frame
120gr NBT
120gr Speer Hot Cor
120gr Sierra Pro-Hunter
120gr SMK
120gr Berger

123gr SMK
123gr AMAX
123gr Scenar
123gr Nosler Custom Competition

125gr Nosler Partition
129gr SST
129gr Interbond
129gr Interlock Spire Point
130gr VLD
130gr Swift Scirocco

I kept it at 130gr and under, since the longer bullets take up a lot of case capacity, even though guys have used them without issue. Most shooters will not be loading 140gr VLD's, let's e honest, at least not in an AR-15. Given this list, I still hear that the 6.8 SPC has more projectiles available for it, and that the Grendel is limited on choice of projectiles to select from. There are plenty of even 120gr bullets and custom bullets from GS, North Fork, etc., that I didn't even include. I frequently see the picture entitled: "6.8 SPC Bullets" with 34 projectiles depicted, to include the Elite Ammunition Brass solids, 4 solids from GC Customs, a 120gr Barnes Solid that doesn't look like it would fit in mag COAL, and even 2 130gr pills that are meant for the .270 Winchester, that would never fit in a 6.8 case in the AR, unless you went past the ogive into the neck.

If I expanded the list above based on those parameters, I would lose track of reality as we get into the 140gr class bullets, some of the the 120 solids like the GMX, the 156 Oryx, etc. I feel that is an impractical representation of what is realistic in the AR15 platform, so I left them out. There are 34 pills of all different shapes and sizes in the above list, to include several FMJ's, without listing any GS .264", or other exotic projectiles that most will not buy or experiment with. But we're expected to believe there is a larger selection for the 6.8 for some reason. Every claim I have researched about the 6.8's superiority to the Grendel has been found to be untrue, aside from industry support, which the 6.8 clearly enjoys more of.

I think we're spoiled, more than anything..."But I want a 117.2gr Uber whatever...ah ha ha ha wa wa wa!"

I went through this whole decision process over the years before pulling the trigger, and the Grendel was my choice for several reasons that the 6.8 won't ever be capable of matching. Sectional density is the biggest one, along with Lapua brass, and multiple brass sources. That is just my decision, not the "right" one, but the one for me. I think within 300yds, most people wouldn't know the difference between the two firing the same types of projectiles, but I wanted more versatility in projectile selection/capability, and I know from my .270 that .277 pills need crazy velocity to do what .264" pills do for trajectory and wind deflection.

[elkbow]

Not so much, actually. The Grendel bolt was specifically designed for maximum strength, and the steel was changed from the Carpenter 158 used for 7.62x39 bolts to a much stronger alloy. 7.62x39 bolts failed regularly, even at 7.62x39 pressures, and it was one of the issues associated with making it run in an AR. (Along with feeding issues because of mag incompatibility due to case taper.)

Alexander significantly upgraded the steel, and that, in combination with appropriate pressure levels, improved the bolt life. 7.62x39 bolts used by others in 6.5 builds have been less successful. Several years ago I kept a running tally of all the bolt failures and the causes, as well as where the bolts originated. EVERY AA bolt that failed, except one, failed in hand loaded situations. 7.62x39 bolts failed without any significant pattern. They failed with factory ammo, hand loads, or a combination. The one AA bolt that failed with factory loads failed with a steady, almost exclusive, diet of Les Baer 123 ammo. Since others shot that without issues, I never could come to any real conclusion on the cause. Maybe just a bad bolt. Les Baer's old Sierra 123 load was very warm in comparison to other factory loads, though!

thanks for the info, I had read quite a bit about failed bolts for 7.62x39, even in that cartridge....but the 7.62x39 bolt is a little less recessed than the standard Grendel bolt, correct?, which should with a deeper chamber and strong bolt allow greater pressures? Also, I think the superbolt that ARP makes will handle about anything thrown at it. I'm going to try their new barrel/bolt combo for my next Grendel build and see how their chamber and 5R rifling does for accuracy, looking for a hunting rig, don't mind carrying around my 24", but like the 18" size and I use mainly 16" in my 6.8's, two being 16" (well actually 3 as I have another coming in today, the Bison 16" BSP that i'm going to try subsonic) and one being 20"

[bwaites]

thanks for the info, I had read quite a bit about failed bolts for 7.62x39, even in that cartridge....but the 7.62x39 bolt is a little less recessed than the standard Grendel bolt, correct?, which should with a deeper chamber and strong bolt allow greater pressures? Also, I think the superbolt that ARP makes will handle about anything thrown at it. I'm going to try their new barrel/bolt combo for my next Grendel build and see how their chamber and 5R rifling does for accuracy, looking for a hunting rig, don't mind carrying around my 24", but like the 18" size and I use mainly 16" in my 6.8's, two being 16" (well actually 3 as I have another coming in today, the Bison 16" BSP that i'm going to try subsonic) and one being 20"

Theoretically, more steel should be stronger, but if you use the inferior steel of Carpenter 158, all bets are off, and most 7.62 bolts were/(are?) built with that. In addition, the shallower bolt face creates issues with the extractor claw, which needs to be deeper to grab the thicker rim of the Grendel case. If you take metal off the top of the claw, it weakens it too much causing failure. Thus you have to deepen the face, and make the cut towards the tail, to leave enough meat on it to be stronger.

ARP's bolt may be the answer, but he has made a completely different chamber and barrel extension.....with a .297 neck! If he would just use a standard Grendel chamber I would probably eventually buy one, if for no other reason than to see just how strong the Lapua brass is! The other issue will be what happens for parts, since he is the only one building that bolt and barrel extension, but since it is essentially a custom build, that's the price you pay to play.

[LRRPF52]

I looked at the SCAR-Heavy bolt in 7.62 NATO, and they used a much smaller bolt design than an AR10. They use some type of steel that appears to have a higher Chromium content, but I don't know which one-looks like 9130 to me, and several metallurgists have listed Carpenter 158 as the better alloy for AR15 bolts compared to 9130. I talked with Bill A. about this in some detail at SHOT, and he pointed out how 9130 has sulfur content in it, which is by no means a high-strength element.

The word is that FN has experienced several endurance failures with their SCAR-17 7.72 NATO bolts, which is what that bolt was screaming into my face when I looked at it personally. "I WILL BREAK! I WILL BREAK!" That is what I heard it literally saying to me...

The Milspec Colt 5.56 bolts take an insane amount of abuse, and hold up very well, even though I feel that the AR15 bolt geometry in even a 5.56 is on the risky side of low-mass, barely supported lugs, and definitely a cam pin hole that has hardly any support.

None of these are true with the original AR10 7.62 NATO bolts. The AR10 takes a beating and asks for more.

[stokesrj]

I can't offer any insight into ARP but I can offer some experience on 5R rifling. It is as good as it gets but no better than standard six groove if all other variables are held constant. I have a couple of nearly identical Kriegers with 5R and six groove. They shoot identically too. There is no advantage, and there is no disadvantage. I will say my best shooting Garand has an Obermeir 5R barrel on it, but it was smithed by Don McCoy, double lugged, tuned op rod and all that stuff and it shoots good, but again, no better than my friends Don McCoy with a Krieger six groove.
Bob

[elkbow]

yea copy that on the rifling, i think it would be hard to tell a difference and some barrels from lot to lot just shoot better or worse...

bwaites, copy that on the ARP design, but there are some things I like like the throat and neck, but thats debated as much as upper/lower fit lol, ARP is also usually a bargain, the .264/6.5 barrel/bolt combo is $285

[pinzgauer]

did find that they do offer a 20" bull version of the 6.5 Grendel. Oh.......the cat's meow.

The 20" Bull (Wilson Air Gauge) I built was one of the most accurate rifles I ever owned. Nothing exotic, just shot great with a wide variety of ammo. The JT rifles seem to really like the factory Hornady. (Though most Grendels I've shot do).

[rsilvers]

There are more companies who jumped on the bandwagon with 6.8, and in the rush, an unsafe chamber got SAAMI-spec'd somehow, and you have to figure out which one you have or make sure that you DON'T get a SAAMI chamber in 6.8, or it could kaboom on you since it has an 80 degree leade-to-rifling hand-off. This is why the 6.8 SPC II chamber is the one everyone is pointing out to go with, rather than the dangerous one. That makes ammo manufacturers really leary about loading higher-pressure loads, and many 6.8 owners have noticed that their 115gr bullets aren't going the speeds claimed by the makers on the box, or in the original guns that had correct chambers. Many report 200fps less MV, so guess what...they resort to hand-loading, and stick to...small rifle primer brass to handle the pressures..

The reason for the pressure spikes was not the chamber so much as bores with cross-sectional areas below SAAMI min. The shorter lead in the SAAMI chamber, by itself, it only a 1000 psi difference. That works out to about 20 fps. Rifle factories shoot SAAMI proof rounds in SAAMI chambered rifles, and they are 72,000+ PSI.

[rsilvers]

Of the other options out there the Grendel and SPC are the only real options because the other .30 cal options are just not really realistic for hunting applications unless you go back to the WSSM case. The "Blackout"; A remake of the 7.62x39, Really? I get better velocities out of my 10" Encore with the Grendel. The "Whisper"; a ballistic joke. Neither are really "useful" for "legal" hunting purposes much past 100 yards, especially the whisper.

This is not hunting ammo and was designed for barrier-blind use. But even a 6 inch 300 BLK barrel will do this out to 200 yards, and a 16 inch much farther. It makes a 0.6" diameter hole that is 20-24 inches deep in 10% gel.



A video:

http://www.youtube.com/watch?v=hRw-ypBgrKo

[Variable]

Thanks for posting over here Robert. While I prefer the Grendel for a lot of stuff, I do like the 300BLK also. I see them like screwdrivers or golf clubs. More than one tool for the bag.

Do the 300 uppers run equally well both sub and supersonic without having to adjust the gas in a given upper? I'll likely be buying one when I get my other projects wrapped up.

I hated reading that you guys are discontinuing the 762SD. That is by far my favorite can of the ones I own. I've recommended it over and over to anyone who asked, and some that didn't.LOL!

[rsilvers]

When you put a can on a 5.56mm, the cyclic rate may change by over 200 rpm. With 300 BLK, it is much less. So when people say 300 BLK is good to suppress - most interpret that as "It works with subsonic ammo." While that is true, it is more than that - the rifles don't go out of their optimal reliability range of cyclic rates with full power ammo while suppressed.

Adjustable gas is not needed. Noveske who makes their Switchblock for 5.56mm does not even offer it for their 300 BLK rifles.

I am not sure why we discontinued the 762-SD - but it was probably because it was selling in smaller numbers than the newer 762-SDN-6 - which is the same thing but with all Inconel baffles, is shorter, and has a 51 tooth mount.