|
Centerfire Rifles - Semiautomatic or Gas Operated Centerfire rifles, carbines and other gas operated rifles. |
|
Thread Tools | Display Modes |
#1
|
||||
|
||||
AR Ballistic Comparisons
The common opinion online is that the 6.8SPC is better in the shorter ranges but then the 6.5mm Grendel takes over after 300 yards. I ran the ballistics for both rounds assuming a 16in barrel and using the Hornady 120grish SST hunting rounds. Looking at the results it seems that the Grendel actually takes over at the barrel not at 300 yards. The Hornady HITS score shows the Grendel is more effective as a deer rifle at all measured ranges not just after 300 yards. Notice that the Grendel has a 100 point HITS advantage already at 100 yards. Once again you have to beware of "experts" on forums and forum folklore in general.
http://www.hornady.com/hits/calculator http://www.hornady.com/hits
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) Last edited by Xcountryrider; 07-09-2013 at 11:29 AM.. |
#2
|
||||
|
||||
They are two different cartridges with two different purposes. They just happen to have some overlap. And I hate to say it, but your chart is old. The SPEC II 6.8 goes a bit faster than that. You are comparing apples to really old oranges. With the SPEC II information, the 6.8 holds its own until a bit farther out. Also, remember that the 6.8 wasn't designed to be a long range (for an AR platform) cartridge. It was designed to give a better punch than 5.56 out to 300 yards when fired from a shorter barrel. It does that quite well. The fact that it can't always beat a round that was designed for longer range shooting at longer ranges shouldn't be a surprise. The fact that it does hold even as long as it does, with a smaller case and powder charge, is just one of those serendipitous accidents.
-Mb
__________________
|
#3
|
||||
|
||||
That data is over the counter 6.8SPC 120 SST rounds and is up to date. Buy a box Hornady 120gr SST and fire it out of a SPC II upper and you get these or very close to these results. Did you miss my point the grendel beats it AT SHORTER RANGES not just long range. When using it for a hunting application.
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) Last edited by Xcountryrider; 07-05-2013 at 3:03 PM.. |
#4
|
||||
|
||||
(sigh) Grendelites. They are as bad as the 10mm zealots when you mention 40 S&W. Okay, I am backing away from the thread s-l-o-w-l-y. I am not making any sudden moves. Please feel free to go rock quietly in the corner with your rifle. And just keep telling yourself that it is better.
-Mb
__________________
|
#5
|
||||
|
||||
I think what throws people off is that the 6.8SPC is larger caliber and has a larger muzzle velocity which makes people assume its better for hunting. The secret of the 6.5mm is the remarkably higher ballistic coefficient (BC). The Grendel maintains its velocity and penetrates deeper on impact. The short stubby 6.8SPC sheds velocity and energy quickly and does less damage on impact. Hence the lower HITS scores. Give the 6.8SPC a couple hundred more FPS at muzzle and the 6.5 Grendel still has a higher HITS score at muzzle. Once the argument moves away from old history and real data is used it become clear which one makes a better hunting rifle. If you disagree show us your data.
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) Last edited by Xcountryrider; 07-05-2013 at 3:12 PM.. |
#6
|
||||
|
||||
Neither are great due to the price. I'll start to care when I can get them at walmart and big5 for .40 cents a round consistently. While we are at it .338 Lapua is better. Oh, wait that's 5$ a round.
|
#7
|
||||
|
||||
Nothing is going for 40 cents a round thats a decent hunting bullet. The 223 hunting rounds cost just as much or close to the Grendel rounds. You can't get them at Walmart or Big 5 but this thing called the internet is pretty cool.
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) |
#8
|
||||
|
||||
Good luck centerfire folks, Xcountryrider was banned from the Hunting sub-forum.
__________________
|
#9
|
||||
|
||||
O RLY?
Quote:
Although I bet you are right that the old ammo out of a new spec II upper behaves just like the old spec ammo. I'd be willing to bet that if you fired .223 out of a 5.56 upper you don't get the performance of 5.56. I've even heard that a .357 magnum firing 38 special is surprisingly anemic for a .357. Sorry I don't have a spread sheet with HITS scores to back it up.
__________________
"don't be that guy"... |
#10
|
||||
|
||||
Quote:
Sent from my MB860 using Tapatalk 2
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) |
#12
|
||||
|
||||
I would remind you that those velocitys are from different length barrels . The grendel is 24" and the 6.8 spc is out of a 16" barrel . If you put the 6.8 in a 24" barrel it will be about the same maybe a bit better then the grendel . The 6.8spc will crush the grendel if you shoot the grendel out of a 16" barrel .I have the grendel losing 40fps per inch for 8 inchs putting it at 2260fps. I know you were trying to compare apples to apples but I think you missed that part .
6.8 spc look just below the bullet . It has the barrel length http://www.hornady.com/store/6.8mm-SPC-120-GR-SST/ now look at the 6.5 grendel http://www.hornady.com/store/6.5-Grendel-123-gr-SST/
__________________
Tolerate allow the existence, occurrence, or practice of (something that one does not necessarily like or agree with) without interference. Anyone else find it sad that those who preach tolerance CAN'T allow the existence, occurrence, or practice of (something that they do not necessarily like or agree with) without interference. I write almost everything in a jovial manner regardless of content . If that's not how you took it please try again Last edited by Metal God; 07-05-2013 at 5:31 PM.. |
#13
|
||||
|
||||
Both data is from 16in barrels in my chart. Notice my numbers for the grendel are not from a 24 in barrel.
Sent from my MB860 using Tapatalk 2
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) Last edited by Xcountryrider; 07-05-2013 at 5:18 PM.. |
#14
|
||||
|
||||
Quote:
Sent from my MB860 using Tapatalk 2
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) |
#15
|
||||
|
||||
I had been doing some editting on my post but in short I get 2260fps out of the grendel with a 16" barrel .Your are going to lose at least 30fps per inch and I used 40
__________________
Tolerate allow the existence, occurrence, or practice of (something that one does not necessarily like or agree with) without interference. Anyone else find it sad that those who preach tolerance CAN'T allow the existence, occurrence, or practice of (something that they do not necessarily like or agree with) without interference. I write almost everything in a jovial manner regardless of content . If that's not how you took it please try again |
#16
|
||||
|
||||
Quote:
Sent from my MB860 using Tapatalk 2
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) |
#17
|
||||
|
||||
How much do we have to pay to send him back to you?
__________________
|
#18
|
||||
|
||||
lol - the fail is strong in this thread...
Quote:
140-grain (9.1 g) Berger VLD; 2,401 ft/s (732 m/s) - Silver State Armory (SSA) factory load, HITS score of 877 at the muzzle out of a 16 inch barrel (see http://en.wikipedia.org/wiki/6.8_mm_...A0mm.29_barrel ) Like I said before, if you load to the old spec, you are right, they are almost the same. If you continue to ignore the new spec, regardless of the published data, you can still pretend you are right. Does your Grendle upper come with a membership to the flat earth society? Or are you just trolling?
__________________
"don't be that guy"... |
#19
|
|||
|
|||
Quote:
|
#20
|
||||
|
||||
Quote:
It also comes with a remote control that turns the wind off, lowers all the grass and bushes so he can see game at 600yds, and finally, it comes with an invisibility cloak which makes him invisible to the game...
__________________
Randall Rausch AR work: www.ar15barrels.com Bolt actions: www.700barrels.com Foreign Semi Autos: www.akbarrels.com Barrel, sight and trigger work on most pistols and shotguns. Most work performed while-you-wait, evening and saturday appointments available. |
#21
|
||||
|
||||
Quote:
__________________
Tolerate allow the existence, occurrence, or practice of (something that one does not necessarily like or agree with) without interference. Anyone else find it sad that those who preach tolerance CAN'T allow the existence, occurrence, or practice of (something that they do not necessarily like or agree with) without interference. I write almost everything in a jovial manner regardless of content . If that's not how you took it please try again |
#22
|
||||
|
||||
Quote:
You have to have specific cartridge/bullet/load/barrel info to compare different barrel lengths. For example, you lose less FPS per inch between 24" and 22" than you do between 18" and 16". It's drastically different actually.
__________________
Randall Rausch AR work: www.ar15barrels.com Bolt actions: www.700barrels.com Foreign Semi Autos: www.akbarrels.com Barrel, sight and trigger work on most pistols and shotguns. Most work performed while-you-wait, evening and saturday appointments available. |
#23
|
||||
|
||||
I dont dispute that but when you hack off 8 inches of any barrel your going to lose a bunch . I do know you will lose much more then the 150fps that was figured in the OP comparisons . I would add it was my understanding that we were talking in general term based on the OP comparisons to factory loads that we all know will be different with every rifle used .
__________________
Tolerate allow the existence, occurrence, or practice of (something that one does not necessarily like or agree with) without interference. Anyone else find it sad that those who preach tolerance CAN'T allow the existence, occurrence, or practice of (something that they do not necessarily like or agree with) without interference. I write almost everything in a jovial manner regardless of content . If that's not how you took it please try again Last edited by Metal God; 07-05-2013 at 8:05 PM.. |
#25
|
||||
|
||||
Quote:
There is a big difference in Ballistic Coefficients (BC's) between the two which could give somewhat similar results to the SST comparison. The Grendel 140gr Berger VLD has a whooping .612 BC while the 6.8 SPC Berger 140gr VLD has a someone more modest BC of .487 which is on the high end for the 6.8SPC. In other words the 6.8SPC 140gr Berger will come out of the barrel faster but it will quickly loose velocity and energy in comparison to the much higher BC of the Grendel. The Grendel will take over at some point. How many yards out does that turn over take place? I don't know. I know out of a 24in barrel its coming out at 2315FPS with a HITS score of 930 but i don't know for a 16in barrel. I also know you can't just subtract so many FPS for each barrel inch. It no worky that way as a earlier poster tried to do. It needs to be measured with a chronometer. I have a box that will get loaded at some point this fall but not yet. I ordered Redding dies the first requirement to load the VLD's so we shall see. 6.5mm BC = 0.612 6.8mm BC = 0.487
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) Last edited by Xcountryrider; 07-05-2013 at 9:10 PM.. |
#26
|
||||
|
||||
i only know one thing about this debate, JP makes a 6.5 and not a 6.8
that's all i need to know, until john paul makes a wacky video explaining why. |
#27
|
||||
|
||||
Quote:
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) |
#28
|
||||
|
||||
Another ballistic comparison this time 120gr to 120gr.
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) |
#29
|
||||
|
||||
Something is wrong with your data if you have the same weight bullets starting at about the same speed in the 6.5grenade and the 6.8spc.
The grenade case head is larger so can not run at as high of a pressure level. Also, the 6.5 bullet has less area to be pushed by the gas pressure. Given the 5,000psi operating difference and the bullet base diameter differences, you should see a velocity spread of at least 125fps between those two cartridges with the same 120gr bullet when both cartridges are loaded to their full potentials.
__________________
Randall Rausch AR work: www.ar15barrels.com Bolt actions: www.700barrels.com Foreign Semi Autos: www.akbarrels.com Barrel, sight and trigger work on most pistols and shotguns. Most work performed while-you-wait, evening and saturday appointments available. |
#30
|
||||
|
||||
Quote:
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) |
#31
|
||||
|
||||
Quote:
Given the same weight, the higher the velocity on target, the higher the energy.
__________________
Randall Rausch AR work: www.ar15barrels.com Bolt actions: www.700barrels.com Foreign Semi Autos: www.akbarrels.com Barrel, sight and trigger work on most pistols and shotguns. Most work performed while-you-wait, evening and saturday appointments available. |
#32
|
||||
|
||||
Dibs for my Sig
__________________
|
#33
|
||||
|
||||
Look at my first post and follow the links to Hornadys site to read up. All things being equal a 6.5 gets a higher HITS score than a 6.8SPC because the 6.8SPC does not cause as much damage to a game because of its short stubby shape and lower BC compared to a 6.5mm bullet. That said HITS does not factor in the TYPE of bullet so when doing comparisons you should use the same type of bullet to take out that variable.
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) Last edited by Xcountryrider; 07-05-2013 at 9:43 PM.. |
#34
|
||||
|
||||
Quote:
Arguing otherwise is silly. BC and bullet shape have everything to do with the bullet performance BEFORE the bullet arrives at the target.
__________________
Randall Rausch AR work: www.ar15barrels.com Bolt actions: www.700barrels.com Foreign Semi Autos: www.akbarrels.com Barrel, sight and trigger work on most pistols and shotguns. Most work performed while-you-wait, evening and saturday appointments available. |
#35
|
||||
|
||||
No not exactly bullet shape effects what happens when the bullet hits the target as well as what happens on the way to the target.
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) |
#36
|
||||
|
||||
Quote:
You can have a pointy match bullet punch a clean hole and not dump much energy into the target because it's not designed to expand and you can have a slow moving pistol bullet mushroom and put all of it's energy into the target and you would get better performance from the pistol bullet. Way too many factors to worry about when talking generalities...
__________________
Randall Rausch AR work: www.ar15barrels.com Bolt actions: www.700barrels.com Foreign Semi Autos: www.akbarrels.com Barrel, sight and trigger work on most pistols and shotguns. Most work performed while-you-wait, evening and saturday appointments available. |
#38
|
||||
|
||||
I have both 6.5grenade and 6.8spc.
I like to take my 6.5grenade remote controller with me hunting, but I use 308 cartridge in my rifle because both the 6.5grenade and the 6.8spc are anemic hunting cartridges best left to arguing between internet commandos...
__________________
Randall Rausch AR work: www.ar15barrels.com Bolt actions: www.700barrels.com Foreign Semi Autos: www.akbarrels.com Barrel, sight and trigger work on most pistols and shotguns. Most work performed while-you-wait, evening and saturday appointments available. |
#39
|
||||
|
||||
I was just getting antsy waiting to see what he had to "refute" what you were saying haha
__________________
|
#40
|
||||
|
||||
Quote:
Grendel Vs 200lb Texas Boar. Taken at 200 yards with Hornady 123gr SST Hunter was Cameron Woodall
__________________
Hunting with the Modern Sporting Rifle (AR-15/AR-10) Last edited by Xcountryrider; 07-05-2013 at 10:17 PM.. |
Thread Tools | |
Display Modes | |
|
|