6.5 Grendel barrel Length?????

[kmon]

Thanks for the reply. I've been casually researching this some tonight, and there is indeed an interesting phenomenae, where once the pressure falls, the burn rate falls precipitously as well. Which makes sense, since high density (i.e. high pressure) and hot (i.e. high pressure; PV=nRT) gas will transfer heat more agressively into the powder to cause it to burn faster. And vice versa, and if the pressure gets low enough, it essentially quenches the burn. Fascinating science.

Here, I'm just tagging these here for future read, which perhaps dive into the topic more:

https://apps.dtic.mil/dtic/tr/fulltext/u2/462060.pdf

https://apps.dtic.mil/dtic/tr/fulltext/u2/676246.pdf

I tried to explain in a short form what myself and some other engineers had a discussion about a few years ago on internal ballistics powder burn and pressure in an earlier post in this thread. Powder burns most efficiently under heat and pressure, a simple example of this pour out a measure of powder that you are using in your Grendel onto dry concrete or steel and light it with a match. Watch how long it takes t to burn in the open air. Then think about how fast it burns when in an enclosed environment such as the brass in the chamber of a rifle.

this video is not bad on going over powder burn in the chamber

https://www.youtube.com/watch?v=AqMzUsTTFnA

Ever notice how on light weight barrels very shortly after the chamber they start getting smaller in diameter, that is safely possible because the pressures in that location have dropped to the point less material is required to contain the internal pressure.

LR interesting example with the powder burns on the hands. In the case of the revolver heavy roll crimps are used to hold the bullet in place longer for better ignition and burn of the powder before the bullet starts to move and the bullet in most cases is still being engraved by the rifling when the base of the bullet is at the barrel cylinder gap under high pressure. The larger the barrel cylinder gap the more gas and flames escape there. Ever not get a good crimp on a revolver reload? If you have that you will have more unburnt powder show up or at least more partially burnt powder.

[Mad Charlie]

I salute you for the quality of your contributions to this thread. That is a magnificent piece of useful information!

I agree completely, I am always glad to see his comments. No "hero worship" here, but his information pretty well matches what I have learned over the years, and adds to my storehouse, so to speak.

I am not an engineer, or a ballistician, or even that great of a shooter, and higher math over trig locks my brain. But I have 44 years of hand loading for rifles, pistols, and shotguns under my belt, with much studying and research along the way. I have been called "meticulous", a lifetime of carving metal with machine tools will do that to you.

I look for informative opinions and conversation, not ego trips and "my balls are bigger than your balls" crap. There is always something to learn from different approaches to achieving goals.

[Matt.Cross]

I am not an engineer, or a ballistician, or even that great of a shooter, and higher math over trig locks my brain. But I have 44 years of hand loading for rifles, pistols, and shotguns under my belt, with much studying and research along the way. I have been called "meticulous", a lifetime of carving metal with machine tools will do that to you.

Always nice to meet a fellow machinist! What industry?

[Sinclair]

Klem, I apologize for misspelling your name. Senior moments are a regular occurrence these days. And I could not think of the correct word instead of detonation to save my soul. Many of the guys I competed with back in the day worked in the ballistics lab. There were weekly discussions of the ideal barrel length, perfect powder/wad column, etc. and I listened intently. As I get older, I realize just how much I have learned by Listening.


lazyengineer, my favorite color is yellow and my favorite flower is the sunflower, last night an old man smiled for awhile. Thank you for that.

[Mad Charlie]

Always nice to meet a fellow machinist! What industry?

I apprenticed in a moldmaking shop in 1974, about the time I got into handloading. So it's been tool and die, moldmaking, job shops and production. I hate moldmaking. The last job before retirement was making prototype crossbow parts for Xtreme Research/ Patriot Crossbows. I have made a lot of different parts, from crossbow parts to business card slitters. All on manual machines, I can't spell CNC.

You know how it is, the boss shows you a funny paper, you make the part. I still have a lathe, Bridgeport, and surface grinder, primitive I know, but I still make things. Sometimes it's less expensive to buy than make, but there are lots of times in my life that off the shelf wont do what I want. There's a part hiding in every chunk of material.

[Matt.Cross]

I apprenticed in a moldmaking shop in 1974, about the time I got into handloading. So it's been tool and die, moldmaking, job shops and production. I hate moldmaking. The last job before retirement was making prototype crossbow parts for Xtreme Research/ Patriot Crossbows. I have made a lot of different parts, from crossbow parts to business card slitters. All on manual machines, I can't spell CNC.

You know how it is, the boss shows you a funny paper, you make the part. I still have a lathe, Bridgeport, and surface grinder, primitive I know, but I still make things. Sometimes it's less expensive to buy than make, but there are lots of times in my life that off the shelf wont do what I want. There's a part hiding in every chunk of material.

That's very cool! I don't have anything in the way of personal shop equipment, nothing more than the customary hand tools and measurement implements anyways, but I'll get there one of these days.

[cupp260]

I'm looking at putting a 6.5 Grendel together for deer/pig hunting here in Missouri and a few southern states and was wondering what is the optimal barrel length. No shots past 300yards. I do shoot suppressed at times. 1-6X28 is my scope of choice due to close shooting done here in Missouri. I welcome all the hunters suggestions. Thank you, Jerry....

I recently finished my 6.5 Grendel with 18" barrel and really like it. This is my first Grendel and I built it for hog hunting. It is a hog slayer!! To see more about my Grendel projects visit https://theolddeerhunters.com/65-grendel-rifle/

[Jeepster18_88]

As you can see from the previous comments, they vary and there are a lot of my way is the only way opinions on this forum, regardless of the subject. I'll throw my opinion out there but take it as just that because everyone else has made very valid points for their personal preference.

I like the feel and balance of a 16-18" barrel. Anything longer adds velocity but it also adds weight and hog hunting for me means a lot of walking so I prefer a little less weight. I also get into thick brush where I am literally feet away from very aggressive hogs and the longer barrel is more difficult to move quickly on a charging boar due to catching on vines and limbs. I also hunt from blinds sometimes and the longer barrels are more difficult to move around without bumping something. There's many reasons not to go overboard with barrel length IMO.

Going to the opposite end of the spectrum, there are many reasons not to go to the extreme on the short side. First, I don't use hearing protection when I hunt because I can be dangerously close and need every advantage I can get to helping my awareness of what's around me. The short barrels are incredibly loud and I never know that only a few inches of barrel could increase the blast and concussion until I shot one of the AR pistols. It only took one shot from one to let me know that I didn't like them. As others pointed out, you lose velocity and that is THE most important part of individual bullet performance. There's high BC bullets that help there, but that in itself is limiting options. Hunting from a blind, especially a box stand, the shorter barrels are closer under the roof and that magnifies the sound too. Obviously, adding a can to this would change things and if you go suppressed, it's a viable option for you. It literally takes away every issue that I have with the exception of velocity.

I think 16-18" is a better option for hunters like myself for the weight reduction, noise reduction, and added velocity without becoming heavy and cumbersome. If a can was added to this, it would obviously change that.

I find a lot of opinions on here interesting, and there's a lot of lurkers that don't comment much but really have good information if you can get them to share. I don't think like a lot of people here do and that's ok. Most want maximum velocity which means slow powder, I don't. I don't want added muzzle blast and flash to get a few fps more or single digit SD. It's not necessary for less than 300 shots. You won't find many people that would even consider fast powders as an option.

I probably have an unpopular opinion on bullet energy too and I mention this because someone has compared it to a 44 mag energy. This measurement imo is thrown around way to broadly and 1200lbs of energy out of a 223 doesn't perform like 1200lbs out of a 7.62x39. There's absolutely no comparison in performance on game tissue. To further demonstrate, compare a 22 hornet with a 45 Colt. The Hornet shoots flatter and faster, but the weaker 45 Colt will kill game much bigger than it's energy number suggests. IMO, it's a valid measurement but it's often used in the wrong context and causes misleading information. Game laws and recommendations are based on the number frequently but it doesn't really make sense across different calibers.

I started off using a 5.56 AR and was really disappointed with the performance. I moved to a 7.62x39 and completely fell in love with the AR and I prefer to use it when deer and hog hunting over every gun that I own. For everything under 200 yards, nothing I have kills them any better. I bought the Grendel to stretch that performance out to 300 yards without adding weight or recoil because I still need the fast follow up shots and quick handling. In my limited experience with the Grendel, it's more difficult in finding cheap accurate barrels, cheap accurate ammo, and solid "one size fits all" loads. But I have no doubt that it'll do exactly what I want it to do once everything comes together. I have already bought my second one and am currently shopping around for the parts for number 3. Welcome to the addiction.

[Redraider]

to the OP,

To me this all boils down to do you want a rifle or a pistol, if it is rifle the 16" will do all you need. If you want a pistol, the 12.5" will work. If you want an extra $200 SBR ....................

Redraider

[Stolivar]

Here we go again!

Seems mentioned 300yds...I have a 18" and 20" and both will delivered more foot pound of energy on target at any range compared to a 12.5 barrel.

My latest build is also going to have a can on it as soon as it gets out of jail. My shots will be limited to nothing over 15yds yards. Also because I am running a shorter barrel I elected to go with 7.62X39. I will also be hand loading it above AK pressures, but I will stay inside AR platform pressures.

That means my 0.310, 123gr SST will be running closer to 2500fps, not the usual 2100fps like most factory ammo is loaded to.

What seems like a normal thing to do on this site is not shared on other boards.

I'm getting a link for you....

Still nowhere close to the power of the 6.5 in a 12.5 Barrell. You fall below 1000 ft # after 175 yards where the same barrel in a Grendel after 275 yds

Steve

[seraph1bk]

12" for maneuverability and handling
16+" for increased "lethality"

Here's a brief oversimplified explanation regarding terminal ballistics that takes into account energy, and momentum:
- Shot placement is king - you want to poke holes in important things. CNS/Circulatory System/Major Organs
- Bullets make different sized holes via bullet expansion/yaw/fragmentation/cavitation
- Bullets traveling > 2200 FPS: A large portion of the temporary cavity becomes a permanent cavity. Higher kinetic energy means bigger temporary cavity which means a greater chance of hitting something important.
- Bullets traveling < 2200 FPS: kinetic energy largely absorbed by the elasticity of tissue. Permanent cavity is only generated by how big the bullet can expand or how far it travels after yawing/fragmenting. Higher momentum is important here as the further you penetrate, the greater the chance of hitting something important.

You'll have to be more deliberate with your shot placement if you're rocking a short barrel. You'll have to figure out how far you can reach out to before dropping below 2200fps and below the expansion threshold of the bullet. (~1800fps for sst, ~1300fps for ABLR)

[se3388]

Nothing wrong with a 16 inch, with that being said all my 6.5 Grendels all wear 18 or 20 inch barrels.

Steve.........

[CaptnC]

Nothing wrong with a 16 inch, with that being said all my 6.5 Grendels all wear 18 or 20 inch barrels.

Steve.........

Steve,
I've noticed a bunch of these guys are from the blue states of the N.E. USA they must be snowed in most of the time and can not get out to the gym. I'm almost 60yo (Sept) and I can carry a 24 or even bull barreled 26" all day without issue!

I'm really like'n my 24" SS 6.5 Grendel. You can really get some horse power out of this little guy with a longer barrel!

[Forgottenben]

That’s why the military runs 14.5 or sf runs into the 10.3. Bunch of softies.
If I wanted a 20-24” I’d go creedmoor. If I want an agile little gun I’ll go Grendel

[NugginFutz]

Steve,
I've noticed a bunch of these guys are from the blue states of the N.E. USA they must be snowed in most of the time and can not get out to the gym. I'm almost 60yo (Sept) and I can carry a 24 or even bull barreled 26" all day without issue!

I'm really like'n my 24" SS 6.5 Grendel. You can really get some horse power out of this little guy with a longer barrel!

Accusing people whose tastes run toward the light and maneuverable of being soft and out of shape will win you no friends, cc. Why not stick to stating your own preference and leave the comparative contempt out of the post?

[Randy99CL]

Accusing people whose tastes run toward the light and maneuverable of being soft and out of shape will win you no friends, cc. Why not stick to stating your own preference and leave the comparative contempt out of the post?

Where is the like button?

[CaptnC]

That’s why the military runs 14.5 or sf runs into the 10.3. Bunch of softies.
If I wanted a 20-24” I’d go creedmoor. If I want an agile little gun I’ll go Grendel

Our heroes in the military are using those rifles for what they were designed for close quarters combat...you damn sure sure don't want to be swinging a 20"+ barrel around in a small room clearing targets!

Plus my comments at least get people to read my post and maybe some will see a 12.5 Grendel is not really as practical as many here think it is.

Have you noticed there are not many people making barrels shorter than 16" and most are over 16". Someone sold Faxon on the idea and they seen the opportunity to sell a few barrel regardless of the logic behind it.

I have yet to see a 224 V. in anyone's barrel 12.5", you find very few as short as 16" the vast majority that I have found are over 18".

On the Long Range Hunting Online Magazine Forum, they have a Grenel barrel length thread pop up once in a while. So far nearly no one has suggested the need for anything shorter that 18".

My 24" looks rather odd sitting on the firing line because of the barrel length. But it serves a purpose and I will only be using it for a range rifle shooting steel at longer ranges. It might make a varmint hunt or two. I have my 20" for the bulk of my AR hunting.

[Labrat198]

Have you noticed there are not many people making barrels shorter than 16" and most are over 16". Someone sold Faxon on the idea and they seen the opportunity to sell a few barrel regardless of the logic behind it.

I have a feeling this has more to do with government regulations than anything else.

[A5BLASTER]

Our heroes in the military are using those rifles for what they were designed for close quarters combat...you damn sure sure don't want to be swinging a 20"+ barrel around in a small room clearing targets!

Plus my comments at least get people to read my post and maybe some will see a 12.5 Grendel is not really as practical as many here think it is.

Have you noticed there are not many people making barrels shorter than 16" and most are over 16". Someone sold Faxon on the idea and they seen the opportunity to sell a few barrel regardless of the logic behind it.

I have yet to see a 224 V. in anyone's barrel 12.5", you find very few as short as 16" the vast majority that I have found are over 18".

On the Long Range Hunting Online Magazine Forum, they have a Grenel barrel length thread pop up once in a while. So far nearly no one has suggested the need for anything shorter that 18".

My 24" looks rather odd sitting on the firing line because of the barrel length. But it serves a purpose and I will only be using it for a range rifle shooting steel at longer ranges. It might make a varmint hunt or two. I have my 20" for the bulk of my AR hunting.

Yep a 12 or 12.5 or even 11 inch grendel barrel is so unwanted there is only one company making them. Ohhh wait there is like 4 or more company's making them and almost every custom shop makes them too.

As well as AA who has had a 11 inch barrel for years and years.

We get it you don't want it, that's fine in of itself. For the rest of us we will keep killing this with less then 18 inch barrels.

As far as the 224v comment, meh it's a 22 if I want to shoot a 22 I have a Henry lever action.

[Bigs28]

On the Long Range Hunting Online Magazine Forum,

Ive never seen anyone claim they long range hunt with a 12" grendel. Then again "long range" is different for different people. My 12" grendel will kill out to 300 yards. Everywhere i hunt is thick woods with a maximum 150-200 yard view but mostly less then 100 yards so a 12" grendel is perfect.

Odin, alexander arms, psa, faxon all sell short barrels on their site. Maybe faxon owns them all.

It's clear that your way is the only right way and everyone else is stupid, a wuss, or now living in a blue state so their is no point in even attempting to educate you on anything.