Let me ask you a question...would you use a slow powder in a short barrel? Most of the common powders are middle toward the slow end of powder burn rate charts.
Pistols use fast burning powders...WHY? Because they have short barrels and to get the most out of your powder charge, you want the last few grains at or near the muzzle.
I hunt out of trucks, blind and stalking through the woods all the time with 26" barrels. It's never cost me a shot nor given any reason to break out a saw to cut it in half.
As a mater of fact, UPS is delivering me a new 26" 6.5x284 varmint contour barrel tomorrow!
Interesting - you clearly illustrate your preferences for longer barrels, and trot out some anecdotes from your personal experience.
Yet, I am still waiting for your citation which backs up your claim that a 12 in. barrel is "burning the bulk of your powder charge in the air outside the muzzle."
I understand you have an opinion to which you are entitled. I do not agree, however, that you can float that opinion as fact without the supporting data.
If it's true that we are here to help others, then what exactly are the others here for?
02-28-2019, 06:58 PM (This post was last modified: 02-28-2019, 07:06 PM by LRRPF52.)
Powder conversion with most of the propellants we use in 6.5 Grendel is almost 100% complete within the first 1.5-3" usually, depending on the propellant/projectile combo.
"Unburnt" gets confused with "mostly-converted" powder that has already been burned and released its potential energy within the first few inches of the chamber, but leaves tiny residual particulates that are still very hot. We also get soot residue inside the spent case, which reloaders are generally familiar with.
If considerable unburnt powder was making it to the gas port, imagine what would be happening in your gas system.
Pressure and heat are greatest at peak chamber pressure, which is when the projectile has barely moved. Some adhere to the static projectile argument with it retained by the neck still, while the Army Research Lab shows primer-induced projectile jump into the lands, but still in contact with the neck.
Either way, those places are where the powder conversion happens. The potential chemical energy of the propellant compound is converted into an energetic gas wave when the primer detonates and ignites it, which continues to propagate for tiny fractions of a second after powder conversion. This is why barrel length adds velocity relative to the time the wave dwells in the bore up until a point where it doesn't, which is dependent on propellant volume, bore volume, propellant burn rate, projectile weight, and other factors. Even in the case of long barrels or insufficient propellant, the inertia imparted to the bullet is enough to get it to exit, with the rare cases of squibs where only the primer or unusually low propellant volume was detonated, leaving the projectile in the barrel.
This is why we have tested load data for specific rifle cartridges and projectile weights, because some powders don't convert well at all for the bore volume and projectile weight, and some convert too fast to the point of exceeding peak pressure set by SAAMI. For example, you wouldn't use really slow-burning propellants in 6.5 Grendel, like the kinds we use in large case volume magnums with larger bores.
The flash you see at the muzzle is the result of the converted gas wave once it hits open atmosphere with more oxygen present to feed the exiting hot gas, not unburnt powder continuing the conversion process. You will often have small particulate matter exiting the muzzle left over from the process, as well as jacket material from the bullet. At night, you will normally see sparks along with muzzle flash from a lot of guns. The residual particulate matter from the propellant is still extremely hot, so when you do see fiery little specs from short barrels at night, that's what you are witnessing.
To have unburnt powder flowing into your gas system would be really bad.
I would also point out that if you're on a phone, it may create the typo, "handy capping" when someone is trying to say, "handicap".
Of course, "handy capping" could be a serendipitous happy accident that gains traction as a convenient way of executing suckahs in the ghetto with a G-Lock fo-tay.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
As to the practicality of short barrels in 6.5 Grendel, it helps to look at .30-30 Winchester performance as a commonly-known and accepted hunting cartridge that is responsible for a lot of dead dear over the last 124 years and compare them within common hunting distances.
An 11.5" or 12" Grendel will have more energy at 400yds than a 20" barrel .30-30 Winchester has at 200yds, and excellent penetration, expansion, and weight retention with common hunting bullets.
It has plenty of killing power within 200yds, easily exceeding the longer barreled AK and SKS shooting the exact same bullet weights.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
LRRPF52 Wrote:Powder conversion with most of the propellants we use in 6.5 Grendel is almost 100% complete within the first 1.5-3" usually, depending on the propellant/projectile combo.
".
Thank you for the well composed reply. Scientifically, however, i am unfortunately in doubt on this claim.
Are there any white papers or other published research supporting it?
Respectdully, I don't think this claim is correct, but standing by
Jerry M. Wrote: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....
Here is the OP. He does not ask for the "best" but does ask about "optimal". Either way, both terms are judgment calls. As for the Ky long-rifle guys, you need 30" or better and Hawken 54 cal at least... Anyway, '52's (and others) answer that anything from 12-18" will suit the OP, keeping in mind his other reqts he added, 1-6x28 scope, 300 yds or less, suppressor et al... gives him plenty of room to make his own assessment. Maybe he wants the 20" or 26"... maybe he wants the 12 (or in my case the 12.5) b/c with suppressed it is just sweet to carry around.
Heck Op build 2! a 12-12.5 and a 16-20 (again your choice). Double your pleasure, double your fun. Nobody said you can only have 1.
I've owned and shot a 30-30 as I'm sure many on here have. And the Grrr is just must nicer to aim, shoot and watch your bullseyes -- better distance handling too....
CaptC if you want to stick with the 26" er's that's fine with me, should leave more Grendel stuff on the shelf for when I want it. But I don't really care either way.
"Down the floor, out the door, Go Brandon Go!!!!!"
Ok...will again require you go take some one other than me having an opinion.
These guys I look at them like I do fly fisherman...
Can you catch a marlin on a fly rod? Your damn right you can, but at least they would admit a 80 or 130 wide would be better!
The long range pistol guys like there hand guns but readily admit to the negative aspects of the shorter barrel when using rifle cartridges. For the time being, let's stay with that thought. Rifle chambered pistols...
I had both 30 Herrett and 357 Herrett...after shooting a few animals with the a 14" barreled 30...I got rid of them. I had one Contender frame and both uppers. But the performance was so poor with 125gr Nosler BT's penciling through. I had enough of chasing wounded animals around.
Most bolt pistols have 15" barrels and many use up to 17". So it's not really the same as this group of Grendel pistol followers/promoters.
If....IF....I ever have to have a short barreled...AR platform...hunting weapon, I'm going to pick something was designed to be a AR pistol...300 Black Out!
LRRPF52 Wrote:As to the practicality of short barrels in 6.5 Grendel, it helps to look at .30-30 Winchester performance as a commonly-known and accepted hunting cartridge that is responsible for a lot of dead dear over the last 124 years and compare them within common hunting distances.
An 11.5" or 12" Grendel will have more energy at 400yds than a 20" barrel .30-30 Winchester has at 200yds, and excellent penetration, expansion, and weight retention with common hunting bullets.
It has plenty of killing power within 200yds, easily exceeding the longer barreled AK and SKS shooting the exact same bullet weights.
CaptnC Wrote:If....IF....I ever have to have a short barreled...AR platform...hunting weapon, I'm going to pick something was designed to be a AR pistol...300 Black Out!
For someone who posts about not handy capping themselves............
A 6.5g pistol/sbr out performs a 300bo in every category except subsonic. Your "opinions" are no longer worth reading or replying to.
Umm, the grendel outperforms the 300 blackout with bullet weights and barrel lengths being equal. Who cares about the design purpose, chainsaws were designed to cut bone but mine all work really well on wood.
LRRPF52 Wrote:As to the practicality of short barrels in 6.5 Grendel, it helps to look at .30-30 Winchester performance as a commonly-known and accepted hunting cartridge that is responsible for a lot of dead dear over the last 124 years and compare them within common hunting distances.
An 11.5" or 12" Grendel will have more energy at 400yds than a 20" barrel .30-30 Winchester has at 200yds, and excellent penetration, expansion, and weight retention with common hunting bullets.
It has plenty of killing power within 200yds, easily exceeding the longer barreled AK and SKS shooting the exact same bullet weights.
I think this post sums it all up. This round is all around the best caliber for the ar platform.
It has better performance than a very widely used hunting round out of a much more compact package and it probably has way less drop to have to mess with too. I haven't shot a 30-30 in a while but I remember bullet drop quickly becomes an issue as well. A quick google search tells me that a grendel shot out of a 14.5" barrel drops 10" at 300 yrs, 28.7" at 400, and 57" at 500. While a 30-30 drops 26" at 300, and 64" at 400. That's more than double at all distances. Aim at the top of the head at 400 yds with a grendel and you still hit them a little above the belly button . A 30-30 at the same distance MIGHT hit their foot or shin if they aren't a garden gnome.
CaptnC-
I don't know what this has to do with the pistols you are talking about, those are obviously very gutless and underpowered rounds when compared to the grendel. The grendel is obviously a much better round. And the only reason to go 300blk would be to have an ultra quiet suppressed gun imo.
On something that LR posted about powder burn. I fully agree the peak pressure does occur in the first 1.5 to 3 inches of bullet travel. There are a few things causing this to happen.
Powder burns most rapidly while under pressure and the higher the pressure the faster it burns.
The bullet goes from rest to in motion and has to over come being a static object, crimp if it is crimped and neck tension from the brass case. Then it meats possibly its most resistance the rifling where it is forced into the barrel and pressure engrave the rifling into the bullet.
That is a lot going on in a small fraction of a second The bullet still has pressure being applied to the base the full length of the barrel but after 3 or so inches the powder has expended almost all its energy in the for of very hot gases and as the bullet travels the chamber containing the gas is increasing rapidly as the bullet moves and the further it travels the larger the chamber is.
After the bullet has been engraved by the rifling it is just friction of moving down the barrel it is now sized to and picks speed up rapidly and pressure drops off rapidly but the bullet is still gaining momentum as long as the pressure behind the bullet is greater than the friction of the bullet in the bore the bullet will still be gaining speed which is why longer barrels produce higher velocities than shorter barrels in a short barrel there is less time under pressure because it does not have to ravel as far.
One thing about shorter barrels is they is more muzzle blast from one due to the gases being under higher pressure upon exit of the barrel than long barrels where the pressure has more time to reduce further as the bullet travels down the barrel.
Ever wonder why barrels wear out at the throat where it is not protected by brass, your hottest burning gases during firing the gun are located there under peak pressure while the bullet is being engraved. hottest gases and highest chamber pressure are exposed to the barrel at that location.
No I am not a ballistic engineer but actually wanted to be at one time. Just did not take that route but I am an engineer and long time reloader for rifle, handgun and shotgun powder consumption wise cartridges from 32 acp to 50 BMG.
CaptnC Wrote:lazyengineer...only problem with 1000fpe at 300yds is you 800fpe below the threshold bullet manufacturer design their bullets.
Ok...it doesn't really look like many are using the "pair" nor their "brain"...this is stoked by ego! The "tacticool effect".
Ok...let's try using the brain for a minute seeing how no one went and read my link.
What is the keys to long range shooting? Plain and simple...ES and SD...how do we achieve those two? First you want efficient powder burn, that is timed with barrel harmonics.
Your not going to get that by burning the bulk of your powder charge in the air outside the muzzle. If your velocity is all over the map you will string your shots vertically and the BC of your bullet changes as the slows down. So some shots will drift more than other with the exact same hold!
Let's be honest, why was rifle cartridges built with short barrel...law enforcement and military entry teams. Where a 50yds shot is a long shot and most are point blank ranges.
The 30 BlackOut craze I guess started this, but it is basically a pistol cartridge that they make a little than necessary barrels for. I wish I could find the thread where a man was trying hit a 500 or 600 yards steel. He said he never could hit it. He was either beyond or short. His thoughts were the bullet path was mostly vertical. And the BO was really not designed to be a long range shooter originally.
So it looks like we have three groups in the Grendel crowd, those with a pair, those who really do use their brain (these two are actually the same guys) and the tacticool gang!
OUT!
Capt c you discredited your point going on these rants.
As many have agreed with you that a longer barrel give the 6.5 grendel better speed and performance at longer range. HOWEVER,
The op put stipulations on his question, under 300 yards and with a 1.5-6 scope. And specifically states intention of close quarter deer and pig hunting. If the question was what was the optimum barrel length for the 6.5 grendel that is a different discussion.
Stating you or your buddy get 6.5 creedmore speed with a longer barrel, is just as misleading as all the guys you call out using 12.5 barrels for long range 300 + yards quarter inch groups. Even worse in the fact that your comments can lead to others pushing the grendel beyond safe pressures.
Throwing in false bravado, that you don't have a pair if you can't carry 4" of barrel weight, discredits you the most. By that logic we should all carry 50 BMG's.
There are other reasons we choose the platforms and calibers we do.
Please take a breath, and set the ego aside for a moment, longer barrel grendel's have a place but that wasn't the question asked.
LRRPF52 Wrote:As to the practicality of short barrels in 6.5 Grendel, it helps to look at .30-30 Winchester performance as a commonly-known and accepted hunting cartridge that is responsible for a lot of dead dear over the last 124 years and compare them within common hunting distances.
An 11.5" or 12" Grendel will have more energy at 400yds than a 20" barrel .30-30 Winchester has at 200yds, and excellent penetration, expansion, and weight retention with common hunting bullets.
It has plenty of killing power within 200yds, easily exceeding the longer barreled AK and SKS shooting the exact same bullet weights.
My take on this topic is that bullets are either accelerating or decelerating, which means they are never at constant velocity. Bullets accelerate down a barrel until friction overcomes the decreasing pressure of burning powder, then they decelerate. In 223's and 308's that's about the 30" mark. In a 300Blackout it's the 16" mark due to the relatively large volume of the 30cal barrel relative to the small amount of powder burnt. The Blackout was never designed to be a 'pistol' or 'SBR', those are simply arbitrary lengths and requirements placed on firearm owners by the US authorities. The Blackout was designed to be both a supersonic and subsonic calibre for the AR15 platform and 16" just happens to be the point where acceleration ends and deceleration starts. Given the Blackout is such an average supersonic performer most 300BLK advocates concentrate on its subsonic capability, which is unique and reasonable. With subsonic you don't need 16" of Blackout barrel. It's actually easier to keep bullets subsonic but still with enough pressure to cycle to the action if you use a shorter barrel. That's why Blackout AR's tend to be short.
Back to accelerating and decelerating...The time/velocity curve is an inverted 'U'-shaped curve. This means acceleration is greatest at the start and lessens to a peak then the opposite occurs as friction and gravity take over. Rather than have the most efficient length of barrel, 30" we choose shorter barrels for weight and practicality. That means we are deliberately handy capping ourselves in velocity. But given velocity gains and losses are marginal towards the peak of the curve then the practical aspects of a compact rifle end up more important. In that scenario the bullet accelerates to the muzzle and decelerates from that point on.
Quickload displays time/pressure and distance/pressure curves for various scenarios. I am attaching a Blackout to show how you get negligible gains in velocity after about 12" of barrel. Plus QL predicts how much powder is burnt for various barrel lengths and how much muzzle pressure (which is synonymous with sound). The shorter the barrel the more likely there will be unburnt powder out the muzzle. If not all powder is burnt then there will be flames and sound and less consistent muzzle velocities. QL is great for doing what-if's with powder and barrel lengths.
Barrel length/Pressure/Velocity curve for a 30" Blackout barrel. Note that after 12" you get almost no incremental benefit from a longer barrel.
[ATTACH=CONFIG]13794[/ATTACH]
Footnote: I have hunted with both Blackout and Grendel. My experience is that in supersonic hunting the Blackout is almost a basket case compared to the far superior Grendel. I have never tried making the Grendel subsonic so I can only imagine the heavier Blackout would be superior, and with less problems getting the action to cycle. Subsonic Blackout hunting is like shooting animals with an accurate .45 handgun - same weight and velocity of bullet. They die slowly and this means for the same weight and size of rifle you are handy capping yourself. Subsonic hunting is more akin to bow hunting than rifle shooting.
My take on this topic is that bullets are either accelerating or decelerating, which means they are never at constant velocity. Bullets accelerate down a barrel until friction overcomes the decreasing pressure of burning powder, then they decelerate. In 223's and 308's that's about the 30" mark. In a 300Blackout it's the 16" mark due to the relatively large volume of the 30cal barrel relative to the small amount of powder burnt. The Blackout was never designed to be a 'pistol' or 'SBR', those are simply arbitrary lengths and requirements placed on firearm owners by the US authorities. The Blackout was designed to be both a supersonic and subsonic calibre for the AR15 platform and 16" just happens to be the point where there is no reasonable benefit from having a longer barrel. Given the Blackout is such an average supersonic performer most 300BLK advocates concentrate on its subsonic capability, which is unique and reasonable. With subsonic you don't need 16" of Blackout barrel. It's actually easier to keep bullets subsonic but still with enough pressure to cycle to the action if you use a shorter barrel. That's why Blackout AR's tend to be short.
Back to accelerating and decelerating...The time/velocity curve is an inverted 'U'-shaped curve. This means acceleration is greatest at the start and lessens to a peak then the opposite occurs as friction and gravity take over. Rather than have the most efficient length of barrel, 30" we choose shorter barrels for weight and practicality. That means we are deliberately handy capping ourselves in velocity. But given velocity gains and losses are marginal towards the peak of the curve then the practical aspects of a compact rifle end up more important. In that scenario the bullet accelerates to the muzzle and decelerates from that point on.
Quickload displays time/pressure and distance/pressure curves for various scenarios. I am attaching a Blackout to show how you get negligible gains in velocity after about 12" of barrel. Plus QL predicts how much powder is burnt for various barrel lengths and how much muzzle pressure (which is synonymous with sound). The shorter the barrel the more likely there will be unburnt powder out the muzzle. If not all powder is burnt then there will be flames and sound and less consistent muzzle velocities. QL is great for doing what-if's with powder and barrel lengths.
Barrel length/Pressure/Velocity curve for a 30" Blackout barrel. Note that after 12" you get almost no incremental benefit from a longer barrel.
[ATTACH=CONFIG]13794[/ATTACH]
Footnote: I have hunted with both Blackout and Grendel. My experience is that in supersonic hunting the Blackout is almost a basket case compared to the far superior Grendel. I have never tried making the Grendel subsonic so I can only imagine the heavier Blackout would be superior, and with less problems getting the action to cycle. Subsonic Blackout hunting is like shooting animals with an accurate .45 handgun - same weight and velocity of bullet. They die slowly and this means for the same weight and size of rifle you are handy capping yourself. Subsonic hunting is more akin to bow hunting than rifle shooting.
03-01-2019, 02:35 AM (This post was last modified: 03-01-2019, 06:10 AM by lazyengineer.)
LRRPF52 Wrote:Powder conversion with most of the propellants we use in 6.5 Grendel is almost 100% complete within the first 1.5-3" usually, depending on the propellant/projectile combo.
"Unburnt" gets confused with "mostly-converted" powder that has already been burned and released its potential energy within the first few inches of the chamber, but leaves tiny residual particulates that are still very hot. We also get soot residue inside the spent case, which reloaders are generally familiar with.
If considerable unburnt powder was making it to the gas port, imagine what would be happening in your gas system.
.
Quote:QuickLOAD also gives you a lot more perspective concerning the trajectory of your projectile, FPS, amount of powder burned and what percentage of powder should be burned within the barrel. Have you ever shot a round and then see unburned powder coming out of your barrel? Well, this software can tell you within a fair margin of accuracy if a load should burn all of the powder or if some (or a lot) will be left unburnt.
Nor does the American Chemical Society https://www.borlik.org/wp-content/upload...Bullet.pdf
They aren't detecting soot in residue from handgun discharges in these analysis - they are detecting nitrates. That's gunpowder.
Nor does the premise really make any logical sense, since why bother tuning burn-speed, if it's all burned in the first 3" anyway? I would just be reloading with the "slowest" gunpowder I could physically stuff into the case, if that were so.
As to still-burning kernels entering the gas system, I do agree relatively little mass of powder is left by that point. But I do think that indeed there is some potentially still burning powder entering the gas system. I don't think that's a problem at all: it's rated for heat and pressure, and the port remains open to the barrel (i.e. it cannot exceed the pressure of the barrel).
![[Image: e8989256-057e-44d5-8e96-c693fa28076e_zpsywuwizij.jpg]](http://i1085.photobucket.com/albums/j422/LRRPF52/65%20Grendel%20Reloading/e8989256-057e-44d5-8e96-c693fa28076e_zpsywuwizij.jpg)
. Subsonic hunting is more akin to bow hunting than rifle shooting.