Indication of overpressure?

After reading that Ultramax ammunition is often loaded too hot and has caused many AR rifle blow-ups (I found this out after purchasing 100 rounds), I did a little experiment to test ballistics against another brand to see what would happen, and see if there was any truth to the claims.

I packed an empty tuna can with 29 soup can lids so that there is 30 layers of metal for the bullet to pass through (29 lids, plus the can bottom itself). I used a 55 grain Federal FMJ and an Ultramax 55 grain FMJ, and fired one shot of each at the target. Take a look at these pictures and notice the difference between the exit holes. The bigger and nastier hole is from the Ultramax. The second can is similar and was placed behind the first can for the Ultramax shot, showing that even after passing through the thick metal 30 layers deep, it still had plenty of punch left in it.

Is there an indication here of a much higher pressure loading with the Ultramax? Remember, both rounds were 55 grain FMJ, so I believe the results of both shots should have been pretty similar. But I'd like to hear what you guys think. As it is now, I'm wondering if this ammo is safe to shoot.

I understand that you are stoked after shooting tuna cans.

My question is, if the ammunition was reported as being "loaded too hot and has caused many AR rifle blow-ups", why did you fire it? I would think of returning it to place of purchase or if that could not be done, breaking it down for components.

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I forgot to mention that Ultramax is "remanufactured" or reloaded ammo, supposedly from once fired brass. I didn't know that it was reportedly loaded too hot until after I bought it and shot some. I had gone to several stores and ammo prices were just unbelievably high. The last store I went to had prices of $1 per round and higher, except for the Ultramax. I hadn't even heard of it until then. I asked a salesman about it and he said that it's remanufactured by Federal, although I don't see that written anywhere on the box.

When I did my little test and saw the difference, I looked up reviews online and there was quite a few reports where peoples' opinions were very low, reports of blow-ups and so forth. Some even reported taking the ammo apart and finding that the wrong kind of powder was used, or too much of it. So, being a little concerned, I thought coming here and asking about it would be a good idea. I'd like to know if others here have used it and how much, and what experiences they've had. Any blowups or other problems?

As for returning the ammo, the store doesn't allow any returns. As for breaking it down for components--I'm not a reloader, so I'd have no use for components.

Could you link us to some instances?

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https://www.youtube.com/watch?v=ptP4CffMgG4 Youtube notice

From this link: http://www.ar15.com/forums/t_3_16/292040_Ammunition_review___Ultramax.html
“At our local range we have seen several issues and no longer allow it for class use. Twice I have seen squibs with the handgun ammo, and once with a .223, that required us to pound the bullets out with a cleaning rod. At this time I can't recall the make and model of the firearms.
On top of that Ultramax ammo was responsible for a kaboom in James Yeager’s personal rifle. He lent out his custom built SLR15 to one of his students not knowing that he was using Ultramax ammo. The student needed to borrow the rifle due to a stuck case in his own rifle (also Ultramax).
Ultramax did take responsibility and settle up with him. But I still can’t bring myself to use it or recommend it to anyone.”

Also from same link: “I have used this ammo many times. Not the best accuracy wise but hey, its cheap and I dont feel that it is underpowered like wolf. As mentioned earlier, you definetly have to inspect all of the rounds before shooting. I have had a few peculiar cartridges (flat spots, shallow seating) where I was puzzled that they made them through QC.”

http://www.thefirearmblog.com/blog/2012/09/24/rock-river-arms-kaboom/ Rifle blow up

http://www.ar15.com/archive/topic.html?b=5&f=20&t=129187 Blown case

It isn't TTBOMK.

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I don't know what that means, even though I looked at the link you posted to Ultramax's site.

External ballistics tell you absolutely nothing of internal ballistics.

The only way to determine overpressure without testing equipment is to pay attention to the fired case, particularly the primer. If the case extracts with difficulty or shows signs of stretching, or if the primer is flattened, cratered or pierced, then you may have an over-pressure condition.

Unfortunately, though, differences in the brass, the primer and the gun itself will yield different results, so you certainly can have an over-pressure round that does not exhibit these signs (smooth, tight, uniform chamber, thick brass, hard primer cup, tight bolt lock-up), and you can also have an in-spec round that does (sloppy, uneven, rough chamber, thin/soft/worn out brass, thin/soft primers, excessive cartridge headspace, firing pin that protrudes excessively).

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Fortunately, I haven't seen any of those signs.
As for the danger of the rifle getting "blown up", do I have less of a chance of that even if using a .223 round that is loaded too hot if my chambering is 5.56? I'm thinking (and hoping) that if it can handle 5.56, then it can handle a "too hot" .223.

That's a lot of soup.

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Actually, none of the lids were from soup cans (a generic term). They're from Beeferoni, Spinach and tuna.

I like to use assemblies of lids like that because it helps to determine the penetration of rounds. It really surprised me how deep .223 penetrates! It surprises me even more that people are always saying that an AR is good for home defense because the rounds are easily stopped by building materials in the home, and won't go through as many walls. I think 30 layers of metal, plus the second can is thicker than sheetrock.

All that shooting a stack of soup lids shows is terminal performance on soup can lids and isn't applicable to any other media.

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But it's metal! Metal is certainly more able to stop a bullet than anything else, especially when it's 30 layers thick. When I do this test with a 9mm, it barely makes it through. Sometimes it doesn't. But .223 is the only one that ever went through with so much energy left over that it went through half of another can.

Also the Hitler quote in your sig is bogus.

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Yeah, I looked it up once and heard it was questionable whether it was authentic or not. I changed it now so that it's more believable.

The miniscule increase in chamber volume of a 5.56 vs. .223 will not mitigate an overpressure .223 round.

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So I guess that won't give me much more margin for error.