Frangible damaging commercial steel?

[Erick Gelhaus]

(Feel free to move this is its in the wrong place)

Damage to steel from frangible? This is commercially built, not something from Uncle Elmer’s machine shop. We’ve have had it for several years.

Can’t recall having seen anything like this when we shot .40SW. We switched to 9mm in mid-2014. This type of damage has only appeared within the last few months.

Those who might shoot rifles with frangible rounds in there deny that they are doing it.

We just completed a yearly perishable skills training cycle where the plate rack was used weekly, shot by most every deputy in the Office. (Yes, I know, there are people mashing the crap out of their triggers … we’re working on that)

The ammunition is Speer Lawman’s frangible round, 100gr, which we chronographed at 1300fps. That is 50fps faster than our old .40SW frangible loads.

If it isn’t visible in the pictures, we are getting cuts, dents in the steel that match the shape & depth of the projectiles. There is an edge hit that is a complete penetration of the steel. The dents are deep enough that you can feel and see them on the backside of the steel. Distance has been as short as 7 yards but 10 yards is common.

Thoughts on what is causing this? MP-5s with frangible?

[Hambo]

The only time I've seen that is with steel that was shot to shit, or when it's been shot with something it's not rated for.

[Jay Cunningham]

Frangible 5.56mm will in fact leave pin prick dimples in even the hardest steel. We're talking inside 25 yards here.

[Luke]

I've got many a round on steel with 9mm 115 grain JHP moving st 1500FPS.. never seen any damage in the slightest. Unless you've witnessed the damage I'd bet good money somebody's shooting their rifle at it.

[EricP]

This is the same plate rack. All the damage has been from rifle rounds.

[GuanoLoco]

"Commercial Steel" doen't mean squat. AR400 steel or AR500 steel?

[Redhat]

OP, Do you guys use a metal bullet trap type backstop? If so, is it being damaged as well?

[GuanoLoco]

Also, if you are getting dents in the back of your steel plates, they are either soft or really thin or something...

AR500 in 3/8"+ should be fine with any pistol, open gun, or pistol caliber carbine velocities (I am thinking to 1600 fps or so).

If you aren't using at least 3/8" AR500 then you need to really manage pistol velocities and maybe even mass.

[Erick Gelhaus]

A couple of the photos show the backstop / impact area. It is shredded tire rubber. For reasons not worth diving into here, this is a frangible only range - no live ammo is supposed to be there.

We haven't had issues shooting that with frangible previously. Up until 2014, it saw a pretty decent amount of .40 and .45ACP and then limited amounts of 9mm & .38Spl. Now it almost exclusively sees 9mm.

The rack was made by a reputable company. I have a name in mind but until I hear confirmation back, I'll stick with it's comercially built, from a reputable company, not Uncle Elmer's machine shop.

The plates aen't showing anything beyond very minimal dimpling, very minimal.

Luke, EricP - thank you.

[Erick Gelhaus]

This is the same plate rack. All the damage has been from rifle rounds.

I really appreciate you posting that information and photo. Damn near the exact same damage on a near identical, if not identical, rack.

My thought has been rifle at too close distances coupled with guys forgetting their off-sets. However, the instructors on SWAT keep denying that any of their guys have shot the plate rack with their 416s. I'd wondered if the increased bbl length and resultant MV of a MP-5 could do that but EricP's picture suggests they are not the source of the issue.