Leaving the 6.8...

[Jimla]

AT3 FF-ML 20 Inch Faxon 6.5 Grendel Upper Range Result

https://www.65grendel.com/forum/showthre...ight=Jimla

[Cornbread]

As someone who has both I would go 18”. My 16” 6.8 is faster than my 18” Grendel when loaded to safe pressures.

[LRRPF52]

As someone who has both I would go 18”. My 16” 6.8 is faster than my 18” Grendel when loaded to safe pressures.

What loads and speed are we talking about, and what does that look like at 75yds, 100yds, 150yds, and 200yds?

Every time I’ve run the numbers, the Grendel starting slower will catch up and overtake the 6.8 within pretty close range.

Hornady’s data for the 16” 6.8 SPC with 120gr SST is 2460fps with an inflated BC of .400 G1.

Hornady’s data for the 16” 6.8 SPC with 110gr V-MAX is 2550fps with a BC of .370 G1.

My data for my first 16” AA barrel build with 123gr A-MAX and SST is 2439fps with a Litz BC of .462 G1 (not Hornady’s inflated BC of .510).

You can load the 6.8 SPC faster than that. I can load the Grendel faster than that.

6.5 Grendel with 123gr SST at 2439fps G1 .462 standard atmospherics

50 2347fps 1505ft-lbs
75 2302fps 1448ft-lbs
100 2258fps 1392ft-lbs
150 2170fps 1286ft-lbs
200 2084fps 1187ft-lbs 3.6” wind drift for 10mph full value (hunting vital zone consideration)
etc. It still is supersonic past 900yds.

6.8 SPC 120gr SST .400 G1 BC at 2460fps same conditions
50 2354fps 1476ft-lbs
75 2302fps 1412ft-lbs
100 2250fps 1349ft-lbs
150 2149fps 1231ft-lbs
200 2051fps 1121ft-lbs 4.1” drift 10mph wind full value

With hand loads, I’ve seen guys load the 16” 6.8 SPC chamber with longer freebore into the high 2400-low-2500fps range from 16” barrels.

I can load a 16” Grendel to 2500fps with CFE223 or LVR and still not exceed MAP. Or I can just find my accuracy node and not even worry about pushing pressure because the bullet is going to retain a lot of velocity on its own, no matter what speed I spit it at.

That all said, because of the current ammo climate, I’m actually considering getting a 12.5” 6.8 since one of my local Sportsman’s Warehouses stocks the 200rd cases of Hornady AG and nobody seems to be buying them, or they just happen to be on the shelves whenever I go there every time.

[grayfox]

As far as the 6.8 goes, I had one, well 2, and when I left them for the Grendel I never looked back.
Not to say if someone else likes it that's fine too.

I have mostly 20" Grrr barrels and it's a great length for me.
Easy to hand load for.
They can shoot well lots farther than I can!

Get nice, good barrels, not low-price rack grade, is all I suggest.

[Fess]

I have followed both the Grendel and the SPC since they were introduced. Since the intense rivalry and mud-slinging between the two cartridges has abated somewhat, I thought it might be useful to give a "current day" comparison.

The Grendel has a shorter case and the same overall loaded length, which allow it to use longer, high BC bullets. This gives it the edge when shooting long distance. Both cases hold similar volumes of powder. The Grendel seems to gain relatively more velocity from longer barrels. The SPC has a slightly larger bore diameter and uses slightly higher pressures so it often has slightly higher muzzle velocity given same weight bullet and same length barrels (18" and shorter). In short, the 6.8 SPC and the 6.5 Grendel are pretty close in performance at typical hunting distances (of up to 300 yards or so). For general hunting and plinking, they both work well. The smaller diameter base and thicker walls of the SPC case permit it handle higher pressures before damage to the brass occurs. If my memory serves (not a sure thing), the SPC can be loaded routinely to about 58K psi with good brass life. Bolt life has been a non-issue.

The SPC had much worse teething problems than the Grendel. Remington sent a flawed drawing to SAAMI. First, there is a math error in the SAAMI chamber drawing (numbers transposed on a dimension) for the step-down from the neck to the freebore.* This was exacerbated by errors in a lot of PTG reamers that made this angle closer to 80 degrees than the intended 45. This increased chamber pressure and sometimes even shaved brass from bullets. The SAAMI freebore length is also shorter than what had been used in the prototypes, causing Remington to download its ammo. In the mid-to-late 2000's, a large number of out-of-spec barrels (undersized bore) were produced and this further exacerbated the pressure problems caused by the chamber flaws. These were mostly 1-in-10" twist, 6-groove barrels, so there is myth that only slower twist barrels can be used. Despite this 1-in-10" myth being commonly repeated, many of the barrels currently sold by Bison Armory are chambered in 1-7" to allow them to shoot subsonic loads better. They have no pressure issues.

All of these 6.8 SPC problems have led to several variations of chambers being currently available. All of them are fine with current factory ammo. The first "SPC II" chamber simply lengthened the freebore from the SAAMI 0.059" to 0.100". Later "SPC II" variants fixed the sharp angle problem AND used the longer freebore. These are the chambers that are often used with longer than SAAMI length loads. Several companies have now reduced the freebore to something between SAAMI and SPC II to provide better velocity and accuracy with factory ammo. These include Bison Armory and ARP. ARP barrels tend to be faster than average, possibly due to their increased groove-to-land ratio causing less bullet distortion.**


* the note on the SAAMI drawing says the angle should be 45 degrees, but transposed numbers in the dimensions make it significantly steeper and thus sharper at the beginning of the freebore.

** BTW, although a 50/50 groove-to-land ratio is often seen in the US, a larger ratio is not terribly unusual. For example, my Russian Saiga 7.62x39 has relatively narrow lands and is probably closer to 70/30.

[LRRPF52]

There were at least 3 different types of 6.8x43 chambers when Chris Murray was working on it at the AMU on his own time, before Remington took it to SAAMI.

One chamber would be more ideal for accuracy looking to fulfill the DMR/SPR solicitation that SOCOM was looking for. (That award ended up being the .223 Wylde SPR shooting 77gr SMKs from 5.56 cartridges, not anything 6.8x43). The 6.8x43 DMR chamber actually had a tighter freebore than projectile diameters, but it sure was accurate!

Another chamber was meant to allow more velocity since the SEALs wanted the 115gr going 2900fps, but nobody could safely reach those velocities of course, even after promising the SEALs that it was “no problem". Several tried and blew up a lot of guns in the process at some very well-known companies.

Then there was another chamber that was supposed to be a balance between the 2.

SSA loaded at least 3 different pressure levels, 2 of which exceeded what the action will handle in volume, and this was demonstrated across a fleet of rifles with predictable results, all resulting in failure of critical pressure-containment components.

I’ve heard a more detailed account of what happened with the SAAMI submission. I'll just say that no reamer maker worth their salt would purposely make a reamer with an unsafe hand-off from the case mouth to the freebore. If they see that kind of transition, their first action would be to contact the customer (company having barrels made) and let them know the reamer design has an error, if it was actually present.

There was also a lot of hype where certain segments of the industry saw it as a done-deal for SOCOM’s and the USMC’s new cartridge, so by trying to ride the coat tails of the new momentum, if they could make themselves notorious by fixing some "inherent problem with the design", they could cement their legacy in the history of US small arms.

Ramshot Powders tested the 2 different chambers (SAAMI and SPC II) on their instrumented test breach and barrel, and found maybe 30fps difference. They started with the SAAMI chamber, fired their pressure-tested strings, then reamed it to SPC II and repeated. They got 20-30fps difference with less than 1000psi change in peak pressure. 6.8 forum called foul, said that one of the biggest powder manufacturers with decades of pressure test experience and SAAMI compliance institutional knowledge was doing it all wrong.

There is so much that went on behind the scenes with 6.8 development that has never really been in the open. The consumer can rest assured now that only safe ammunition is produced by the current go-to companies like Federal, Hornady, Nosler, Remington, and Sellier & Bellot.

There are still some guys that think the industry screwed it all up, and that you can chase the .270 Winchester velocities (which has twice the case volume and 65,000psi working pressure from large actions meant to handle it) with 6.8 SPC II Mod X with the right combination of secret sauce and special tweaks to rifling, twist rate, freebore, COL longer than 99% of the magazines out there, etc. There was a guy that was getting over 2820fps with a 130gr from his 22” 6.8 SPC II clipping his mags and loading long, claiming that a combination of the secret sauce allowed him to do this safely.

I looked at my .270 Winchester loads pushing 130gr and 135gr at similar same speeds and wondered what I was doing wrong!

The last thing you want to do is make a cartridge perform to a set of unrealistic expectations like that. It drives you to substitute caution with bravery when at the load bench and behind the rifle.

When I did my first ladders with CFE223 under the 123gr A-MAX in Grendel, I reached some stupid velocities well above what I expected (which departed from the trend line of course). Imagine if I came on here and said, “Guess what guys! 2700fps with a 123gr from a 16” Grendel is totally doable. Work up your own load of course, but this is what I’m getting!”

For the hunter or prepper, you won’t see a practical difference within 150yds between the 2 cartridges. For those that think they can safely load past 55,000psi with a larger case head in standard AR-15 barrel extensions, I would advise to lean towards caution instead of chasing mv.

[Cornbread]

What loads and speed are we talking about, and what does that look like at 75yds, 100yds, 150yds, and 200yds?

Every time I’ve run the numbers, the Grendel starting slower will catch up and overtake the 6.8 within pretty close range.

Hornady’s data for the 16” 6.8 SPC with 120gr SST is 2460fps with an inflated BC of .400 G1.

Hornady’s data for the 16” 6.8 SPC with 110gr V-MAX is 2550fps with a BC of .370 G1.

My data for my first 16” AA barrel build with 123gr A-MAX and SST is 2439fps with a Litz BC of .462 G1 (not Hornady’s inflated BC of .510).

You can load the 6.8 SPC faster than that. I can load the Grendel faster than that.

6.5 Grendel with 123gr SST at 2439fps G1 .462 standard atmospherics

50 2347fps 1505ft-lbs
75 2302fps 1448ft-lbs
100 2258fps 1392ft-lbs
150 2170fps 1286ft-lbs
200 2084fps 1187ft-lbs 3.6” wind drift for 10mph full value (hunting vital zone consideration)
etc. It still is supersonic past 900yds.

6.8 SPC 120gr SST .400 G1 BC at 2460fps same conditions
50 2354fps 1476ft-lbs
75 2302fps 1412ft-lbs
100 2250fps 1349ft-lbs
150 2149fps 1231ft-lbs
200 2051fps 1121ft-lbs 4.1” drift 10mph wind full value

With hand loads, I’ve seen guys load the 16” 6.8 SPC chamber with longer freebore into the high 2400-low-2500fps range from 16” barrels.

I can load a 16” Grendel to 2500fps with CFE223 or LVR and still not exceed MAP. Or I can just find my accuracy node and not even worry about pushing pressure because the bullet is going to retain a lot of velocity on its own, no matter what speed I spit it at.

That all said, because of the current ammo climate, I’m actually considering getting a 12.5” 6.8 since one of my local Sportsman’s Warehouses stocks the 200rd cases of Hornady AG and nobody seems to be buying them, or they just happen to be on the shelves whenever I go there every time.

I did extensive testing in my2 rifles. In my 18” 6.5 the hornady factory ammo was running 2415-2425. My 16” 6.8 factor sst was running 2465. In all my load testing using published load data,ie not hot rodding,the shorter 6.8 was consistently faster or pretty close with a shorter barrel. Obviously the higher 6.5 bc wins out downrange. I find the 18” is kind of a sweet spot. I would not go over 20” as the rifles just get more heavy and awkward for the field.

[The Profit Joseph Sith]

Welcome to the forum OMCHamlin!


I think an 18” 6.5 Grendel can accomplish your goal. Faxon barrels are rack grade so it is luck of the draw whether you get an accurate barrel. With the price of ammunition I think it is cheaper in the long run to buy the best barrel you can afford. If you buy a Faxon and it doesn’t meet your desired accuracy then your out all the effort/expense and still aren’t satisfied.

Lilja has an excellent reputation for accurate 6.5 Grendel barrels. Accurate barrels shoot a wide variety of ammo accurately. Rack grade barrels like Ballistic Advantage, Faxon, Odin, Satern/Liberty are less likely to shoot accurately with a wide variety of ammo. Lilja, JP, Criterion, Shilen get good reviews as do the custom barrels by Precision Firearms or Craddock Precision.

I have two Faxon Group Buy Monster logo barrels from a few years ago. These two barrels have been gtg and met my expectation but neither will produce groups as good as my Shilen Match barrel in 6.5 Grendel. If your looking for accuracy at distance you want an accurate barrel which tend to cost more but a better chance of giving good results. This subject comes up frequently on this forum and the responses are usually the same. You don’t hear about poor accuracy with Lilja, PF or JP but you do with rack grade barrels.

interesting. you dont see Craddock mentioned too often. i have a heavy bull barrel from them in 6.5CM still sitting waiting to be assembled. i have everything but the hand guard. not sure if its going to happen at this point. glad to hear they are good, they always seem to get good reports for what few of them you can find.

kinda curious what accuracy your getting from your faxon's i just finally shot mine later last year and in initial testing i think i hit around .8" @ 100 yrds with the 20" around 1.1" with the little 12" but in its defense it only has a cheap $120 burris optic on it and the mounts i had laying around are a little too short so its kinda funky to shoot ATM. only 2-7x power as well as opposed to 14x for the 20"

i FULLY agree with spend more now to save $ in the long run.

[Wafavre2]

OMC,

If you want the same results as your SPC get a short Faxon barrel. If you want an immediate improvement over what you already have then I would choose 18-20" and a top-tier/Olympic grade barrel like Lilja, Bartlein or Kreiger. Otherwise you will be struggling to see the difference for the effort.

What Klem said!

[VASCAR2]

interesting. you dont see Craddock mentioned too often. i have a heavy bull barrel from them in 6.5CM still sitting waiting to be assembled. i have everything but the hand guard. not sure if its going to happen at this point. glad to hear they are good, they always seem to get good reports for what few of them you can find.

kinda curious what accuracy your getting from your faxon's i just finally shot mine later last year and in initial testing i think i hit around .8" @ 100 yrds with the 20" around 1.1" with the little 12" but in its defense it only has a cheap $120 burris optic on it and the mounts i had laying around are a little too short so its kinda funky to shoot ATM. only 2-7x power as well as opposed to 14x for the 20"

i FULLY agree with spend more now to save $ in the long run.

I’m definitely the limiting factor when shooting but generally factory Hornady 123 grain A-Max or ELD-M were right at 1 MOA (5 shot groups) off a bipod at 100 yards. My reloads vary with the best around 1 MOA to 1.5-2 MOA. What I really like was how consistent my two Faxon chambers were to each other. Checking several bullets for seating depth with a Hornady C.O.A.L. gauge both barrels are within a couple thousandths seating depth with the same bullets.

My Faxon barrels are great barrels for my uses but they don’t produce the consistent accuracy I’ve seen from my Shilen which cost twice as much. If accuracy is your primary concern and you like to shoot tiny groups then I recommend a higher quality barrel. For quick handling AR-15 with an intermediate cartridge like the 6.5 Grendel for all around use I like the QPQ treated Monster barrels whether Faxon or Green Mountain.