Heat Damages AR 500 Targets

[Chilo]

I had some 1/2" AR 500 plate left over from a project and built a few targets with the scraps. The edges were cut with a plasma torch and they have taken several hits without much deformation. I was having a lot of trouble piercing the 1/2" plate with my plasma cutter without ruining the tips when I cut the mounting holes, so I used the oxy/acetylene torch instead. The mounting bolts were all grade 8 bolts and stand up to the impacts that I've thrown at them well.
As seen here, the area immediately around the mounting holes is much softer that the rest of the target.



.223 casing in the hole



Back of the target. You will notice the bulging in the angle iron used as the mount. Had the angle iron not been here, I suspect that the bullet would have punched a clean hole through the plate.



This target was at 230 yards. We were working up data for a friend's .270 WSM. He was shooting 140 grain Accubonds at 3200 fps. You can see two impacts near the center of the target. These left craters less than 1/16" deep. The one hole above the left mounting bolt is nearly all the way through. You can see the plug sticking out on the third picture, just above the bolt and nut.

These targets are angled down at about a 15* angle. They are also spring loaded to fall back and then stand back up after impacts. I haven't run the data, but the impacts look like .300 WM hits as far as energy goes. I sure wouldn't want to be a deer, antelope, elk, anything downrange of this guy.

You DIY guys, this can be done, but be careful about your targets and ricochets. This one got moved back to 350 yards, just to be safe(er).

Cheers

 

[JFComfort]

Re: Heat Damages AR 500 Targets

Thank you for sharing, we have noticed the steel is softer where it has been cut with a plasma cutter. The best way to do it is with a water jet but it will be a long time before any of us pick up one of those! lol

 

[Ratbert]

Re: Heat Damages AR 500 Targets

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JFComfort</div><div class="ubbcode-body">The best way to do it is with a water jet but it will be a long time before any of us pick up one of those! lol</div></div>

Nonsense, you just need the right friends/neighbors.

 

[Mister Ouchie]

Re: Heat Damages AR 500 Targets

I had read about that effect but it's interesting to see photos. Makes sense, anneals the metal. I wonder if you could just re-temper it.

Big Dog uses a water jet I think.

 

[shoot4fun]

Re: Heat Damages AR 500 Targets

Big Dog Steel is the best I have used by far. It has taken a beating, even large doses of 338LM and 300WM (and a hot 7MM08 at 200 yds) without any issues. Even his bolts are tough. I've hit one a few times and they held up great.
As for heating AR500, it just makes sense that, by the time you burn it enough to get a hole thru, the heat changes the temper and softens it up.

 

[Chilo]

Re: Heat Damages AR 500 Targets

Ratbert,

First you say that you've got a CNC in your garage, then this comment about the water jet...you're killing me here.

Seriously, this was a great use of a couple of pieces of scrap. I'll continue to shoot them because, well, why not?

I just thought the pictures were interesting.

 

[Ratbert]

Re: Heat Damages AR 500 Targets

Kyle and I got lucky and one of my neighbor's father owns a machine shop with a big ass waterjet. I help him out with his computers and he lets me steal spare time on it every now and then. It's great being able to draw pretty much anything we want and then just sit there and watch it trace it out on 3/8" armor plate like it was butter.

Word on shooting scrap, if you can get it cheap enough it's probably easier to replace swiss cheese steel than cut it so that it lasts a bit longer. The water jet really only helps us because we like to have consistently sized pieces when setting up match stages with multiple simultaneous shooters.

 

[phreakmode]

Re: Heat Damages AR 500 Targets

You will get crystaline structure changes when heat cutting Abrasion Resistant plate, it is exagerated some as impacts on edges have less area to absorb energy, even with water jet cuts edges will get damaged on higher velocity impacts.

 

[RoosterShooter]

Re: Heat Damages AR 500 Targets

+2 on what others have said.

You took the temper out of the metal when you cut it with a plasma cutter. Save those targets for lead-only or pistol targets.

You can do a few things next time.

#1 Drill the holes with a hard temper or tungsten bit (service available through most large machine shops)

#2 Do what I did. Affix the brackets on the back of the targets with <span style="font-weight: bold">Devcon Steel Putty</span>. It works as good as a weld, and you have a constant, flat surface that is undisturbed by a weaker metal bolt. I've been using mine for 6 years now, and they stay outside in the elements with no affect whatsoever.

 

[Chilo]

Re: Heat Damages AR 500 Targets

Rooster,

I've use Devcon for bedding a rifle, but not the steel putty. Thanks for the heads up. I've got a little bit of scrap left that I'll try it out on. I knew torching the holes would wreck the temper, but I did it anyway. Sometimes I'm like that.

 

[Big Dog Steel]

Re: Heat Damages AR 500 Targets

We offer a wide variety of waterjet cut AR500 steel targets. We also do custom work every week.

 

[RoosterShooter]

Re: Heat Damages AR 500 Targets

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Chilo</div><div class="ubbcode-body">Rooster,

I've use Devcon for bedding a rifle, but not the steel putty. Thanks for the heads up. I've got a little bit of scrap left that I'll try it out on. I knew torching the holes would wreck the temper, but I did it anyway. Sometimes I'm like that. </div></div>

Be sure to take both sides to be bonded down to bare metal. It's also best to use a very coarse sanding (80 grit or lower) on the bonding surfaces. Clean the area with brake cleaner or a strong degreaser to remove any dust. Let it sit for a full 24 hours before using it. It should work great for years to come.