[Big Bird]

7.5" barrel?

Totally different animal than a proper length barrel (for 5.56)

What's the velocity from a 14.5 or 16" barrel? 2400 fps?

 

[Warp]

What's the velocity from a 14.5 or 16" barrel? 2400 fps?

Velocity of what?

XM193 out of a standard 16" barrel should be in the area of 3,000-3,100 FPS, minimum

 

[faawrenchbndr]

XM193 Velocity

3165 fps out of a 20" barrel, subtract 25-50 fps per inch of barrel lost. So somewhere between 2900-3065 fps from a 16" barrel.

http://www.federalpremium.com/resources/xm193.aspx

 

[Warp]

What velocity will XM193 give out of a 7.5"? 2,300? 2,400?

 

[faawrenchbndr]

Forget how to do math?

Should be about 2700 fps.....or there about.

 

[Warp]

Forget how to do math?

Should be about 2700 fps.....or there about.

It isn't a simple linear equation in the real world. If it was you could take the 20" and 3165 that you posted...subtract 19" of barrel at the high end of 50 fps per inch (19x50)...3165-950= 2,215 FPS out of a 1" barrel. Do you think that's what would happen?

You won't get 2,700 FPS out of a 7.5" barrel. Not even close.

 

[dkf]

Thank you Truckin' Joe. That certainly helps prove my argument. :thumbsup:

Not really. Comparing a 16" barrel to 7.5" barrel to "prove your point" is like comparing a turnip to a watermelon.

The real question is why are you pushing your XM193 so hard when it has absolutely nothing to do with what the OP was asking about. You tend to lose your beans when people do this in other threads. But if you do it then it is all ok.....

With XM193 out of a 7.5" barrel you are looking at velocities between 2300-2400 fps which is well below the reliable fragmentation velocity.

 

[Warp]

With XM193 out of a 7.5" barrel you are looking at velocities between 2300-2400 fps which is well below the reliable fragmentation velocity.

Precisely.

 

[Truckin' Joe]

I've been looking for a ballistic gel test of the BH .77gr OTM with a 16" but can't find one. I'm curious to see the results from 21' with the BH ammo myself.

 

[dkf]

I've been looking for a ballistic gel test of the BH .77gr OTM with a 16" but can't find one. I'm curious to see the results from 21' with the BH ammo myself.

Available Youtube videos can be lacking sometimes. Tnoutdoors tested the OTM but he did so at longer distances. The liks I posted in post #9 show some ballistics result. The Hornady links show some velocity data from different barrel lengths along with some gels.

 

[Big Bird]

Velocity of what?

XM193 out of a standard 16" barrel should be in the area of 3,000-3,100 FPS, minimum

No, sorry..I meant 77 gr ammo.

In the vid the author says the 77 gr averaged in the low 2,000 FPS out of his SBR and I was wondering what you can expect with 77 grain ammo in a 14.5 or 16 in carbine.

 

[faawrenchbndr]

It isn't a simple linear equation in the real world. If it was you could take the 20" and 3165 that you posted...subtract 19" of barrel at the high end of 50 fps per inch (19x50)...3165-950= 2,215 FPS out of a 1" barrel. Do you think that's what would happen?

You won't get 2,700 FPS out of a 7.5" barrel. Not even close.

Well.........the average velocity for and AVERAGE of barrels is 25-50 FPS. That gives us an AVERAGE of 37.5 FPS.

Do the math with that data. Using 50 FPS across the board is retarded and you are smart enough to know that! Use your head and quit trying to simply *** with the numbers to show a result that proves your petty argument!


Better yet.....get off your arse and shoot through a Crono

 

[Warp]

What velocity will XM193 give out of a 7.5"? 2,300? 2,400?

Forget how to do math?

Should be about 2700 fps.....or there about.

You will not get 2,700 FPS out of a 7.5" barrel.

You are wrong.

Well.........the average velocity for and AVERAGE of barrels is 25-50 FPS. That gives us an AVERAGE of 37.5 FPS.

Do the math with that data. Using 50 FPS across the board is retarded and you are smart enough to know that! Use your head and quit trying to simply *** with the numbers to show a result that proves your petty argument!

You will not get 2,700 FPS out of a 7.5" barrel.

You are wrong.

With XM193 out of a 7.5" barrel you are looking at velocities between 2300-2400 fps which is well below the reliable fragmentation velocity.

This guy gets it, and is correct.

 

[faawrenchbndr]

*** it.........Not getting sucked into this

 

[jrs93accord]

Doing the math based on video and the percentage of velocity loss (10%) from a 20" to a 16" barrel using XM193, a 7.5" would deliver around 2475 FPS. A 14.5" barrel would deliver around 2937 FPS. Like I said, this is based on a 10% drop for every 4" of barrel length.

The results from the top video show that at 20' from a 7.5" barrel, the XM193 ammo will frangment and produce a devasting cavity as well. The 77gr did not do nearly as well from the same barrel.

 

[dkf]

Doing the math based on video and the percentage of velocity loss (10%) from a 20" to a 16" barrel using XM193, a 7.5" would deliver around 2475 FPS. A 14.5" barrel would deliver around 2937 FPS. Like I said, this is based on a 10% drop for every 4" of barrel length.

The results from the top video show that at 20' from a 7.5" barrel, the XM193 ammo will frangment and produce a devasting cavity as well. The 77gr did not do nearly as well from the same barrel.

The video posted of the XM193 is from a 16" barrel not 7.5" barrel. The OTM from a 7.5" barrel. Might want to read the descriptions of the videos.

Actual chrono numbers of XM193 out of a 7.5" barrel is 2300-2400fps depending on barrel.

 

[dkf]

No, sorry..I meant 77 gr ammo.

In the vid the author says the 77 gr averaged in the low 2,000 FPS out of his SBR and I was wondering what you can expect with 77 grain ammo in a 14.5 or 16 in carbine.

Velocities from 16" in the article.

http://www.ar15.com/ammo/project/Ballistic_Gel_Experiments/BTAmmoLabsTest6/Test6.htm

 

[GlockViking]

To answer your question, both manufacturers have good reputations. You’ll be fine with either one.
My HD load is Gold Dot or one of the other 64g SP loadings. I keep about 200 rounds of defensive ammo at the house. If I need to deal with some end of the world scenario I have plenty of FMJ.
Some bullets are better than others but there are no magic ones. It’s all about shot placement.

Roger that on the shot placement...hitting what one aims at is crucial.

Thanks also for the tip on the GD. I am just trying to increase my odds by making the best round selection.

 

[jrs93accord]

The video posted of the XM193 is from a 16" barrel not 7.5" barrel. The OTM from a 7.5" barrel. Might want to read the descriptions of the videos.

Actual chrono numbers of XM193 out of a 7.5" barrel is 2300-2400fps depending on barrel.

Okay. My mistake. None the less, it still shows the impact the 5.56mm 55gr. round has. Even the 77gr. round out of the 7.5" barrel still went completely through the gelatin without any fragmentation. I am not an expert on ballististics by any means, but one would think that the same round traveling at a higher velocity from a 14.5" to 16" barrel would penetrate and travel even further after exiting the gelatin at 20'. There could be more cavitation as well, but I would still wonder about the fragmentation ability at that range. For myself, I will trust the 55gr. because I know what it can do, not because of what I saw in a video.

 

[dkf]

Okay. My mistake. None the less, it still shows the impact the 5.56mm 55gr. round has. Even the 77gr. round out of the 7.5" barrel still went completely through the gelatin without any fragmentation. I am not an expert on ballististics by any means, but one would think that the same round traveling at a higher velocity from a 14.5" to 16" barrel would penetrate and travel even further after exiting the gelatin at 20'. There could be more cavitation as well, but I would still wonder about the fragmentation ability at that range. For myself, I will trust the 55gr. because I know what it can do, not because of what I saw in a video.

Look at the testing of the OTM rounds I posted in post #9. Your assumptions are wrong.

From a 7.5" barrel the OTM rounds are below their velocity window for expansion/fragmentation just like the XM193 is from the same barrel. It is why SBRs can be a complete different animal with terminal ballistics and currently available bullets designed for longer barrels.