Ammo Test: Prime Time/Dart Zone Nitroshot (full length) Dart - NO GO/Incompatible with tightbore pro flywheelers

This is a somewhat recent dart from PT/DZ as part of the "Nitroshot" blaster line.

Interestingly - this clearly isn't the thematically purple foamed Green Tip Sureshot that would have been expected for a flywheel-optimized, full-caliber tipped, long, dart to go with the new line.

Nor is it, the same thing as the factory SHORT Nitroshot dart (which is a Max tip with a bambooed foam), But Long (and not bambooed would be most appropriate). That would also have been just as logical.

Why the hell it isn't EITHER ONE of these two things, I don't know; and as we will find out the hard way, it would have been infinitely preferable for it to be either of those options.

 

Mass as supplied:

1.06g

1.06g

1.09g

1.08g

1.08g

 

Unconfined foam OD (basic foam quality sanity-check): minimum 12.73mm, maximum 12.95mm - K

 

A qualitative glue test immediately pegs these as having overall weak tip bonding as delivered. The glue is a rubberized solvent based cement type, and the application is good and gets coverage on that foam/tip end face contact area that I am always a stickler about being unbonded on cheap darts and causing issues, but the combination of a sorry weak glue product that feels like rubber-cement with the very short core on this tip results in an easily decapitated assembly. Similar to the blue tip Sureshot.

So before we get to, trying to (um;) chrono and group test these, it's apt to discuss the tip construction. 

This is a Streamline/Elite/Voberry style design, where the energy absorber is a hollow dome, molded as an open-ended rubber cup and glued to a "squib" (Hasterminology, from a press release in 2012 about the Elite) which has the tip core and forms the seating portion of the tip.

Interestingly, this incorporates a feature theorycrafted in the dark ages of superstock back when there was still a persisting myth about the vent hole in the side of Elite and Streamline domes causing asymmetric drag and hence veering (spoiler alert: it got proven negligible with CFD, the problems of those darts were all mass distribution) - Venting the hollow dome tip through a hollow tip core and down the inside of the foam. Gee, did the trolls from the HvZ Forums grow up to work for Prime Time?? --Eh, it's not a bad idea, but it would have ...interesting ramifications of tip swell on firing when used in a barrel (this type of dart is often used in stock style, pushback breech springers as well as flywheelers).

The squib is higher durometer than the dome, but it is not rigid. It is no harder than the higher duro batches of waffle tips are in their entirety for instance. There have been a lot of remarks about a "stiff disc" in this tip causing issues with flywheelability and comparisons to those disc-sandwich style tips (X-Shot Excels and so on) for a superficial resemblance and feel; well, in fact it's neither that stiff nor is it a disc. It's just an exposed little edge of the squib portion, at the step that the dome registers on.

The dome incorporates a couple design features to maximize its mass and move the mass distribution forward without also maximizing its stiffness. The front wall has an isolated very thickened section; the OD is near cylindrical with a sharp front edge (wadcutter); the walls which produce most of the deformability taper up in thickness toward the front. All good principle.

 

And now on the note of good principle, it's time for things to go horribly south.

These are some examples of the carnage extracted from the malfunctioned test victim T19 after particularly unsuccessful attempts to fire these.

 

Note that these particular darts were from a number that were reglued and retested, and one on the left is one of several fitted with a different foam for what it's worth, but to NO avail whatsoever. 

No actual chrono data and no dispersion data was collected. Out of a mag of chrono shots, I recorded 178, 190, 152, 150 and 159 fps from "successful" shots, with the balance being squibs, shots which exited in a downright sideways attitude with very little energy, and shots which farted out and landed on the ground a foot away. Stability/dispersion outcomes from the few successful shots were highly promising, however.

So; from these vaporized tails and backed up by the other less dramatic squibs, sideways exit shots and extreme energy loss shots, what we have going on here is a nasty case of self-locking/self-wedging tip contact with ballistic path geometry. Given the nature and dimensions of the tip, the culprit is almost certainly the dome swelling in OD as it compresses axially - inertially upon firing, or upon incidental bore wall contact where the dome is "dragged" a little - it squishes, thus causing the sidewall to bulge outward, causing even more adverse contact and more compression, thus more swelling and more friction and so on. The 14mm control bore in the Hy-Con cage being the obvious trouble site where the very cylindrical and very full-caliber dome readily wedges and gets stuck. Stream/lites don't have this issue, but it's obvious why; their domes are tapered on the OD and shorter.

This is clearly one of the worst and most abject failure outcomes I have had evaluating a dart in 16 years of nerfing. A full-caliber tip with this characteristic of significantly expanding radially under compression takes tightly constrained flywheelers off the board, or more correctly takes this dart off the board for credible hobby grade flywheeling. For that matter it is probably liable to be a malfunction and degraded internal ballistics contributor in all sorts of things, even open bore cages and low performance BIB breech springers, because any kind of brush up against oncoming or sideswiping geometry nearby could result in some degree of grabby action. More than anything I don't see what this dart tip and its return to the generally obsolete multipart hollow dome construction is intended to achieve, particularly against Sureshot green tip, Sureshot blue tip, or the Max tip used on the short "version of this dart" all of which were prior existing products already in production. Or what/who the hell this product is actually meant for. It's probably the least barrel-compatible "streamline" tip ever, and the Sureshots are both far more flywheelable.

Worse yet, is that green tip Sureshot seems to have gone out of production DUE TO or been SUPERCEDED BY this product, according to some UPC-reuse observations at least.

Do better, DZ. You really dropped the ball on this one.