Starting with a Blob target and some scrap lumber...
Improvise a frame to hold a sheet of printer paper (24# quality) a few inches in front of the target with a second sheet on the target face.
Pre-Test
Will the paper alone cause the blades to open? I tested this by dropping an arrow with a banded broadhead onto the frame laying on the ground, but it wasn't enough force to penetrate the paper (note the hole from the tip). So I tossed the arrow downward and it successfully penetrated the paper and proved that the blades would stay closed.
Test Items
Micro Suppressor 400 TD w/stock string
Stock Proflight arrow (250.5 gr) [Selected to maximize launch speed]
ProChrono Chronograph
Rocket Hammerhead Broadhead
Spitfire XXX Broadhead
Rocket Sidewinder Broadhead
Pill Bug 1/4" Medium neon elastics
Outers Varminter Rifle Rest
First up, one of my favorite broadheads, a new Rocket Hammerhead equipped with only the single stock black band.
We all know how this is going to end. The launch speed was in the neighborhood...
And the results were just as I expected. The single stock band is nowhere close to enough to keep these long blades closed on launch. I'm just happy I hit the paper at 20y.
You have to admit, that's a wicked looking cut.
Round 2.
In attempt to get in the right ballpark, I sent the Hammerhead a second time but dressed it up with two 1/4 medium dental elastics.
Its still smokin' them downrange...
Hmmm. That's still not enough? This looks peculiar. Notice that one of the blades was not like the others, almost like it's shorter or not fully open.
Well, that explains a few things. My 2" mechanical turned into a 1" mechanical when strapped with two dental bands. This is exactly what happened to the Hammerhead that I shot my 2nd 8pt with this past season, although 70fps slower. Granted that the Blob target is a tad firm and maybe the blades aren't as sharp on the second trip causing added drag. In either case, I wouldn't recommend launching them this hard and repeat trips are questionalble.
Round 3.
Lots of folks love Spitfire heads and I've killed a few deer with them myself. This trip will be a new Spitfire XXX 2" head in it's unbanded glory because according to the package, they don't need bands.

Let'er rip tater chip...
So much for being unbanded...
It took the punishment well and leaves a wicked hole.
Round 4.
Enough playing around. Adding a dental band to the Spitfire XXX and sending it again...
Still zinging...
Well, almost there. It appears that a single blade still managed to open before landing.
Round 5.
Next up is a used Rocket Sidewinder that met previous success. Its a 1.5" cut, so maybe the shorter blades will have a better chance of staying closed because there is less leverage. To cut to the chase, we'll start with it double banded.
Mini-Flamethrower...
Nope. Wide open the whole trip...
Round 6.
This time, the same Sidewinder but with a single 1/4" dental band doubled over to double the holding power.
All day...
Well, I'm guessing the jagged edges are because the blades aren't sharp. But they're open which is still a problem.
Round 7 (Final Round)
For this last trip, the same Sidewinder gets a single 1/4" elastic doubled over then slid close to the tip as possible. We're going to get to stay closed eventually.
Great speed to finish with...
Finally! We have made it to the target without opening in flight!
The surface of the target looked much the same, so that means the broadhead had very little entrance hole so the blades deployed mostly on the inside of the target. When the broadhead was removed, it looked like it had seen better days. Unlike the Hammerhead, the blades didn't shear. But, these don't appear to be far from it.
Conclusion: For the high powered bows, it appears that it would be wise to invest in higher quality broadheads. The brutal launch from a Micro 400TD will put the blade containment solution of any mechanical head to the ultimate test. It seems to me there will be two common scenarios for mechanical heads at this speed. Either your broadhead will open in flight, or the blades will be strapped down so tight that your entrance wounds will be small. If the blades are strapped down very hard, the force at impact could cause them to bend and/or break. I'll certainly be doing more broadhead testing with this bow before next season. Obviously what works well at slower speeds may not apply when the speed gets cranked up.
It appears that some fixed head testing may be a necessity which seems like a waste with all this power.