To pierce a plate or not to pierce a plate.......

[carpediem]

That is the question indeed.
I saw this video,

That got me wondering if, not including AP, a .308 could be necked down to use a projectile that would be moving sufficiently fast enough to pierce the plate as the 5.56 did. I believe he does the same demonstration with a 20" barreled AR.
Just something I was wondering about. If it is that bad to stop an armor wearing target, I would obviously just shoot for the soft parts.

 

[Podmonkey]

A tornado supposed to be able to pierce trees with pieces of straw. It just a matter of velocity.

 

[Marine Cpl]

What? Velocity? Who knew?

 

[Marine Cpl]

That settles it. 55 gr as intended.

 

[UltraT]

In another video I've seen, in slow motion it actually shows the bullet smashing into a cylinder shape and blowing apart while punching a circle out of the armor. In this video does he ever say if they're actually bullet pieces or pieces of the steel armor stuck in the gel?

 

[Podmonkey]

That settles it. 55 gr as intended.

That is a very narrow parameter by which to judge the worth of a projectile.
At 400 yards would you rather be slinging 55gr or 77gr.

 

[Marine Cpl]

That is a very narrow parameter by which to judgebthe worth of a projectile.
At 400 yards would you rather be slinging 55gr or 77gr.

Good point. However, I did qualify with the 55 gr in 1993 at 500 yards so I know it can hit. What it does at that range and what velocity it's going at is beyond me. I'll probably pin prick. Hell, the 77 will too.

 

[Podmonkey]

Good point. However, I did qualify with the 55 gr in 1993 at 500 yards so I know it can hit. What it does at that range and what velocity it's going at is beyond me. I'll probably pin prick. Hell, the 77 will too.

What is the holdover for 55gr at 500 yards? I imagine it is excessive.

 

[Marine Cpl]

What is the holdover for 55gr at 500 yards? I imagine it is excessive.

I don't know. All I know is that we had to set the rear sight to it from the 300 yard zero. It was probably 3 or 4 clicks. I can't remember on the charging handle.

 

[Marine Cpl]

Speer .223 55gr Gold Dot Law Enforcement Ammunition 20rds - 24446

 

[Marine Cpl]

In another video I've seen, in slow motion it actually shows the bullet smashing into a cylinder shape and blowing apart while punching a circle out of the armor. In this video does he ever say if they're actually bullet pieces or pieces of the steel armor stuck in the gel?

He didn't say.

 

[UltraT]

He didn't say.

I tried looking for the video I saw, but can't find it. So I'm not really sure if it actually 'pierces' it so much as blows a chunk out of it, but the end result seems like it's effective either way.

 

[Acer-m14]

30-06 resized to .270win , 130gr with max load is over 3000fps .. I would like to see how it would do on a plate at 50, 100, 200 yrds ..

 

[UltraT]

A .25-06 should also do nicely.

 

[Acer-m14]

level 3 plus and a level 3 ..

 

[Marine Cpl]

Pod. I found this chart. At 500 it drops a lot. I would imagine a 77 gr would drop even more.

 

[Marine Cpl]

level 3 plus and a level 3 ..

Interesting video.

 

[Acer-m14]

@Willjr75 i think he has a video on a ar500 plate above that 4 or something .. 20 to 30 shots of 223/556 before one made it thru ..

 

[Marine Cpl]

So the moral of the story? Shoot at the hips with a 55 gr.

 

[carpediem]

What about 7mm Magnum? At a point velocity cannot compensate for low mass. I have never seen a video of a test on plates with it.

 

[carpediem]

@meketrefe

 

[Podmonkey]

Pod. I found this chart. At 500 it drops a lot. I would imagine a 77 gr would drop even more.

View attachment 13743

I don't have any data handy, but given its successful use out to and beyond 600 yds in SPRs woukd indicate otherwise.
The 77gr bullet will leave the muzzle slower than the 55gr but the longer, sleeker profile combined with the extra inertia of mass it will deccelerate much less and be flatter. The Mk262 is a great round, nice target round too.

 

[@thewheels]

Pod. I found this chart. At 500 it drops a lot. I would imagine a 77 gr would drop even more.

View attachment 13743

Do you recall the barrel length for this chart? Or was it not listed? I'm unable to find this chart on Hornady's site to figure it out.

 

[Marine Cpl]

Do you recall the barrel length for this chart? Or was it not listed? I'm unable to find this chart on Hornady's site to figure it out.

No. I don't remember where I got it from. Pod is more than likely correct though about retaining velocity at distance.

 

[Podmonkey]

No. I don't remember where I got it from. Pod is more than likely correct though about retaining velocity at distance.

I may actually be wrong regarding trajectories within 600yds. @meketrefe help!

 

[Marine Cpl]

I may actually be wrong regarding trajectories within 600yds. @meketrefe help!

No you are right dude. Past 400 yards, the 77 gr pushes ahead.

 

[meketrefe]

No problem.

This is the trajectory of the MK262 using my own math in excel.

Ammo MK262 from black hills 77gr OTM
Firearm: 16" arp carbine.
Elevation: 555ft ASL
Temp: 20C
Wind est: 10mph Wind direction 90deg. full value.
Zero: 200 yards
G1: .362 (Between 3000 and 1700fps)
Adjusted retardation coefficient .30

 

[meketrefe]

This is the new one from Black hills using the TMK tips instead.

Ammo 5.56 black hills 77gr TMK
Firearm: 16" arp carbine.
Elevation: 555ft ASL
Temp: 20C
Wind est: 10mph Wind direction 90deg. full value.
Zero: 200 yards
G1: .415 (above 1700fps)
Adjusted retardation coefficient .30

 

[meketrefe]

The ballistics data from the online calculators is approximate.
This is actually tested with those uppers and with the corresponding correction factors.
I put the 200 yards zero as it is pretty standard for this type rifle/use.

This is the 55gr from Lake City NATO.

Ammo 5.56 M193 Lake City NATO.
Firearm: 16" DTI carbine.
Elevation: 555ft ASL
Temp: 20C
Wind est: 10mph Wind direction 90deg. full value.
Zero: 200 yards
G1: .240 (below 3000fps)
Adjusted retardation coefficient .30

 

[meketrefe]

Here you can see how they compare to other AR15 rounds.
I believe this might help see things more clearly but @Willjr75 and @Podmonkey, let me know if you learn anything from seen these views or it is too complicated ??