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6.5 Grendel

OkieStubble

The Men Who Sniff at Goats
Now that my ‘Jack of All Trades AR rifle is complete, I am signing onto another project.

I try to keep my project’s a tad challenging, because if not attempting something that might be impossible, why call it a project? :)

The 6.5 Grendel. I am very enamored by this caliber and it’s ballistics. Since it just naturally seems to adapt to the AR-15 platform, the two just seem synonymous in most conversations that arise concerning this wonderful cartridge.

I am mostly traditional when it comes to most of my firearms, but when I try to think outside the box every once in awhile, it seems to be with a rifle.

I purchased a LWRC M4 a couple years ago, looking to make it a full sized, lightweight,all around, Jack of All Trades AR, which while not perfect at any particular set up, like long range or CQB and while not designed to specifically do either of these as a designated sniper or SBR, it isn’t really short for CQB and it doesn’t have a 24 inch barrel and huge glass for being a sniper’s rifle.

However, it does quite well at both distance and closer ranges objectives. Even though there were those who suggested I wouldn’t or couldn’t keep it under 8 or 9 pounds. After much research and waiting 2 years to carefully pick and choose the accessories for my lightweight designated JOT, that all around Jack of all trades AR, is now ready to go and comes in at only 7 lbs and 13 ounces. :)

It took 2 years to accomplish this, but I finally gotter done. :)

I have done a bunch of research on many other forums concerning the 6.5 Grendel and in possibly making it a subsonic round.

From what I have read and researched, subsonic Grendel and a properly functioning gas system in an AR don’t mix.

So I purchased a Ruger American Bolt Action Rifle. They had two models I was looking at, the ‘Predator’ model in 6.5 was a contoured 22” threaded parkerized barrel and receiver with an OD Green stock.

I chose the Ranch Rifle model which has what looks to be a 16.12” heavy threaded parkerized barrel and receiver with an FDE colored stock. The bolt had a cut out to work with all brands of AR-15 magazines. So, 5, 10, 20 or 30 round AR mags will work in this bolt action rifle. My kinda rifle. :)

My goal for this rifle, is to shoot suppressed with 123 grain slugs supersonic at distance out to 800 yards and also, my goal anyway, is to possibly see if I can load a 160 grain heavier slug, which will help slow it down along with the 16 inch barrel and match a powder to it where it’s moving only around 1000 fps?

This would be used only out to about 300 or 400 yards. I can already feel a response coming from someone who says, just get a .300 Blackout!

While I get the fact that the 300 BO is designed for this and the 6.5 Grendel isn’t. If a successful round could be found or made, I could see where it’s ballistic coefficients could be had at greater distances with better accuracy considering the Grendel’s boat tail bullet compared to the short distances of the blunt bulldog shape of the BO. The Blackouts knockdown comes from it’s 220 grain anvil of a slug. But it’s best coefficients are pressed after 200 yds?

I’m looking to do that same 200 yds and maybe a bit further with a 160 grain boat tail suppressed subsonic Grendel. It’s knock down at range, would basically be like a 147 gr 9mm at 25 yds but it will be a 6.5 Grendel at 300 yds instead?

What do y’all think? Am I crazy? :)

Here is a pic of the rifle

755E73F7-43BD-4C66-B62D-C031683CCC4B.jpeg
 
I honestly have not dealt with suppressors, but I am thinking supersonic suppress is a pipe dream. You still have the sonic crack and probably to even get the 123 gr pill supersonic, you will have a very large amount of gas to deal with in a suppressor. Just my thoughts. I have several Grendels, 3 different forms of AR, one a short carbine two large bench/target types, one of those being gas piston operated which I like. I also have a nice little CZ 527 in Grendel, I think the heaviest bullet I have tried has been 129 or 130 gr, kinda got away from reloading and need to get back to doing some of that. The longest range I have access to is 250 yards and even with a 100 yard zero, no problem hitting a small gong at 250. My thinking is if the 300 Blackout can do it with heavy, long for caliber bullets the Grendel should be able to do so, Some of those heavier 6.5 boat tail spitzers look more like guided missles than bullets. I really do not need them, the only other 6.5 caliber I play with is the 6.5x55 in some old Swedish Mausers, so really no need at the ranges I shoot,
 

Ad Astra

The Instigator
🤔 It's complicated. The AR Grendel not taking regular mags was the deal breaker for me and I went BO. Love the round, no regrets.

But I do shoot and load a wonderful 6.5 round, in amazing well-built military rifles.... 6.5x50sr Arisaka.

Grendel has a lot to like. Should be a wonderful project to really wind it out! Congrats on the new rifle.


AA
 

OkieStubble

The Men Who Sniff at Goats
I honestly have not dealt with suppressors, but I am thinking supersonic suppress is a pipe dream. You still have the sonic crack and probably to even get the 123 gr pill supersonic, you will have a very large amount of gas to deal with in a suppressor. Just my thoughts. I have several Grendels, 3 different forms of AR, one a short carbine two large bench/target types, one of those being gas piston operated which I like. I also have a nice little CZ 527 in Grendel, I think the heaviest bullet I have tried has been 129 or 130 gr, kinda got away from reloading and need to get back to doing some of that. The longest range I have access to is 250 yards and even with a 100 yard zero, no problem hitting a small gong at 250. My thinking is if the 300 Blackout can do it with heavy, long for caliber bullets the Grendel should be able to do so, Some of those heavier 6.5 boat tail spitzers look more like guided missles than bullets. I really do not need them, the only other 6.5 caliber I play with is the 6.5x55 in some old Swedish Mausers, so really no need at the ranges I shoot,

Great post Jeff! You are absolutely right about the sonic crack even when suppressing at supersonic speeds. My thoughts on it is this. When shooting supersonic at distance, out to 800 yards or so, while the suppressor muffles the bang of the rifle quite well, it’s still not an easy job to locate the shooter, from the crack of the round breaking the sound barrier, unless the shooter shoots from the same location more than once.

A person is more likely to change positions at ranges of 800 yards then they are at say, 200 yds? So at ranges of 300 or less, the stealth of subsonic ammunition would be more useful.

This is why I chose the 18 inch barrel over a 22” inch barrel. At longer ranges, a 4 or 6 inch suppressor will help enhance the velocity of a shorter barrel with longer ranges.

And in thr the same token, a shorter barrel and heavier slug, will help slow it down when reloading slower powders for subsonic loads.

My main concern in this would be the 6.5 Grendel is a pretty good sized cartridge. When trying to reload for subsonic, if the powder doesn’t fill up at least 80% of the case, when that case goes horizontal in the chamber and is fired, the risk of over flashing gasses could happen which could cause a catastrophic failure of the chamber.

So, definitely lots to think about and research. I was hoping I would run into some folks in this thread who might have some experience with the Grendel round and reloading it. :)
 

nortac

"Can't Raise an Eyebrow"
While I have a 6.5 Grendel and have the dies for it, I have yet to reload for it. I built my AR upper with an adjustable gas block to address the potential issues of shooting subsonic. The upper I built has a heavy barrel for bench/prone shooting, I would like to build another lightweight upper in that caliber for my lightweight carbine. I would love to have a 6.5 G bolt action rifle. I wish I had got one of the CZ's in that caliber. I look forward to hearing @OkieStubble 's experience with the Ruger. If you haven't already, check out the 6.5Grendel forum.
 

nortac

"Can't Raise an Eyebrow"
@OkieStubble , for subsonic loads, you use a different powder for subsonic loads than for regular loads. Trailboss is often used for subsonics, very bulky powder, not sure if that is the one to use with 6.5 G though.
 

nortac

"Can't Raise an Eyebrow"
While I get the fact that the 300 BO is designed for this and the 6.5 Grendel isn’t. If a successful round could be found or made, I could see where it’s ballistic coefficients could be had at greater distances with better accuracy considering the Grendel’s boat tail bullet compared to the short distances of the blunt bulldog shape of the BO. The Blackouts knockdown comes from it’s 220 grain anvil of a slug. But it’s best coefficients are pressed after 200 yds?

@OkieStubble , I believe I read in one of Bryan Litzs's books that flat based projectiles are actually more accurate at subsonic velocity than boat tails. I think the whole drag coefficient issue changes at subsonic velocities, but I can't recall the details. I think that is why bullets for the .300 BO have flat bases.
 

OkieStubble

The Men Who Sniff at Goats
While I have a 6.5 Grendel and have the dies for it, I have yet to reload for it. I built my AR upper with an adjustable gas block to address the potential issues of shooting subsonic. The upper I built has a heavy barrel for bench/prone shooting, I would like to build another lightweight upper in that caliber for my lightweight carbine. I would love to have a 6.5 G bolt action rifle. I wish I had got one of the CZ's in that caliber. I look forward to hearing @OkieStubble 's experience with the Ruger. If you haven't already, check out the 6.5Grendel forum.

Yeah, I probably should have spent a bit more money and went the CZ route, because by the time I finish dressing up this cheap little Ruger which cost me $600 and some change after taxes, I will have spent CZ money.

It’s just my interest wasn’t about spending money on something that was already set up to punch small little holes on top of each other, but to create and build something that will eventually do this.

The three choices I originally looked at, was the Ruger American Predator and Ranch, Savage’s cheap little Axis rifle that the Ruger competes for sales with and Howa’s mini action rifle.

I really liked the way Howa’s looked and their little short action, but I didn’t want traditional mounted tapped scope rings and while it doesn’t weigh much, it was the heaviest of the three.

Everyone knows Savage’s cheap rifles have great accurate barrels and pretty nice adjustable triggers. I love my model 110 in .270.

But I looked high & low for an Axis II model in Grendel and couldn’t find it. Lots of Creedmore, but no Grendel.

Watching YouTube videos, I was astonished by all of the inherent accuracy from Ruger’s little American. And while the barrel is supposed to be free float, The stock design and fit on mine is touching that barrel all over the place, so the stock will be the first thing to go. :)

But for the price, it’s really light and very accurate from that small bull barrel.
 
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OkieStubble

The Men Who Sniff at Goats
@OkieStubble , for subsonic loads, you use a different powder for subsonic loads than for regular loads. Trailboss is often used for subsonics, very bulky powder, not sure if that is the one to use with 6.5 G though.

Trail boss is the powder from what I have read and researched. But those convo’s are about Grendel and AR’s?

Maybe I will have more options with a Bolt?
 

OkieStubble

The Men Who Sniff at Goats
@OkieStubble , I believe I read in one of Bryan Litzs's books that flat based projectiles are actually more accurate at subsonic velocity than boat tails. I think the whole drag coefficient issue changes at subsonic velocities, but I can't recall the details. I think that is why bullets for the .300 BO have flat bases.

I was just reading about this last night. :)

I have read just a couple of things from people talking about Grendel stability and possibly tumbling when it gets down to 1,000 fps, but again, this is all coming from people who aren’t actually reloading Grendel or are talking about gas operated rifles, so it’s still all in the realm of hearsay, or fable. I haven’t seen a single thing from someone actually saying,

“I tried it and it didn’t work.” :)
 

nortac

"Can't Raise an Eyebrow"
If you found some cast 160 gr bullet with a flat base, intended for use in a 6.5 Swede or Arisaka, that might work. Again subsonic loads aren’t for long range, so tumbling may not even be an issue.
 

OkieStubble

The Men Who Sniff at Goats
If you found some cast 160 gr bullet with a flat base, intended for use in a 6.5 Swede or Arisaka, that might work. Again subsonic loads aren’t for long range, so tumbling may not even be an issue.

I’ve read 160 Hornady round nose works well.

Just think if I can get this little bolt to shoot supersonic at long range with 123’s and short to mid range with suppressed subsonic 160’s?

;)
 
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OkieStubble

The Men Who Sniff at Goats
If you found some cast 160 gr bullet with a flat base, intended for use in a 6.5 Swede or Arisaka, that might work. Again subsonic loads aren’t for long range, so tumbling may not even be an issu

I was reading a thread the other day where someone successfully loaded 160’s and used them in a bolt and chrono’d it at 1050? I remember him saying the bullet was Hornady 160’s but I can’t remember the powder and grains? I can’t find that link again, dammit…
 

nortac

"Can't Raise an Eyebrow"
That sounds like the ticket. In general, long range shooters want to keep their bullets supersonic all the way to the target because of the instability that occurs when just about any bullet becomes unstable as it crosses the transonic range. Likewise, you don’t want to use super sonic .22LR ammo to shoot long distance because of the instability crossing the transonic barrier. Rather lob a slow.22 with accuracy that an erratic.22 with more velocity.
 
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