Chronograph and Elite mods, 28 days later...

So it's been awful dead here.

I guess all the action has moved over to NM&R as of late, but I do know this place still exists and I am still a member. I'm not sure what the plans are for this place or if this post should be placed here given the NM&R deal, so if you want to move it or me over, that's OK. Unfortunately, I wasn't able to post much of anything back in the day due to being busy and having a distinct lack of new mods or any other nerf-related material, so sorry to Darthrambo for not being the contributor I should have at the time.


Anyway... now to business.

First of all, this is the latest addition to my nerf gear, a Chrony F1 chronograph.

Some of you may be familiar with chronos from seeing them used in Jerm's and SGnerf's blog posts in the past, but for those of you who are not, a chronograph is an instrument for measuring the velocity of projectiles.

Most nerfers are familiar with the old standby method for quantifying the velocity or energy of darts, the range test - but truth be told, ranges as a measure of gun performance are inaccurate, imprecise, and lacking in repeatability. It's a relic of the 1990s subject to way too many extraneous variables and not suited to the level of effort, practicality and thought put into nerf nowadays especially on the war side of things. You look at any other hobby involving the shooting of something (aside from soakers and laser tag, for obvious reasons) and you will find that velocity measurements and chronos are the standard.

The last straw was that ranges weren't working for me and trying to get usable results just made me mad more than anything. Especially for anything that shoots streamlines, ranges are totally useless - and even for war guns that shoot stefans, about all I could get was "Yeah, it shot that dart real fast and it went a long way." It's not enough resolution to get any real idea of small changes.

Then there is the matter of actually finding some suitable area to shoot darts for a range test, and then interminably recording distances and picking up darts. If I had to thoroughly test out 7 builds of something (like I did recently) by range, I would be out all day and my data still wouldn't be that great.

Enter the chrono.

120.5fps Elite dart shot. Not too unusual, NSE Retaliator with OMW spring

It's a massive difference. Using a chrono is convenient, instant and highly accurate. Without it, I would have not bothered giving any attention to the matter I address below, because first of all the streamline-shooting guns would foul up my data, and second, it would be too much of a pain and I would rather just wing it, forget the science, forget the last bit of performance, forget that nagging feeling that my primary is suddenly shooting cold and something major might be wrong, and go shoot zombies anyway.

Casual testing of a few HVZ guns with Jkfyeung from the forums

If you mod seriously or are at all interested in tuning guns of any variety, I highly recommend you get yourself a chronograph. IMO, they should be one of those tools that every good builder has, right alongside the Dremel and drill press. They aren't too expensive, either - check Walmart!

OK, now to the second part of this post, which concerns the NSE Rampage/Retaliator and their air restrictors whose removal is the subject of myths - specifically, that the AR has "no" effect on performance with either a stock spring or upgrade springs such as OMW and SGnerf's options.

I decided to put this to the test in the interest of making it clearer for the many members of my squad who have recently acquired these direct-plunger CS guns and want to mod them (there is a group buy of springs in progress as we speak). Along with that, one of my own upgrades for these was put to the test.

You may remember the strange-looking bolt in that Retaliator in my "new author" post. That was a sort of homebrew Massacre style "tightbore" bolt fabricated from CPVC, called the Thunderbolt or T-bolt. Here's a closer look:

Assembled to Retal bolt carrier and fitted with O-ring

It's fairly self-explanatory what it was intended to do: give better barrel fit and more efficiency. It has a full 2.5" of perfect spring fit, unlike a loose stock barrel, and anyone who has rebarreled anything or used a Massacre kit can attest to the seeming infallibility of the old NIC approach to designing a springer barrel. Loose is bad, right? There's no way perfectly fitting CPVC could do anything but help... or so I thought.

So anyway, a bunch of builds of Retaliator and some Rampage got chrono'd with both 1.3g Streamlines and 1.0g Elite darts. 

Here is all the data.

As to the AR, the myth of "no effect" on performance is soundly busted. The AR does, both with stock springs and upgrades, exactly what you would expect an AR does - loses you 3 to 8 fps, which is not as small as it sounds when you are shooting stock 70 with elite darts; removing it is around a 10% improvement in the case of stock spring and elite darts - in range testing terms, the vague "5-10 feet" that AR removals always claim. So, this is exactly what is expected for an AR removal on an average Nerf product. Nothing is different here.

On the flip side, these shoot very well stock, so whether that small improvement is worth it to you is the real question. Past guns that shoot 45-50fps stock may have been really hurting for power; these, not so much. There is something missing from the data, and that is the Rampage's AR-removed tests which I have no opportunity to do right now - but tentatively, the Rampage's AR is much more aggressive, and you should have a lot more to gain from removing it than on a Retaliator.

Now for the REALLY interesting side effect of this testing: that Thunderbolt? Well, it bumped velocity slightly with a stock spring in an unpublished test (though only a few fps over a simple AR-removed stock bolt) but LOST me performance with the OMW spring, as the data illustrates. Believe me, that is NOT a fluke. There were more shots that verified the data, and the bolt was tested with multiple guns and checked for perfect sealing to the PT and proper pushback distance and all was spot on. The simple fact is, these guns (in complete opposition to everything we know about springers) DO NOT LIKE even mildly tight barrels! A Massacre bolt for one of these, which would be near identical to my stab at barrel upgrades if it was designed according to OMW's past successes at rebarreling the old reverse-plunger guns, would be near useless!

Do not do this. It's not worth it, and if you swap springs, it's harmful. Just remove your AR and enjoy the performance.

So, why this seemingly nonsensical behavior? My hypothesis is that the extremely low plunger mass of these guns, which is a major factor in their efficiency (120fps/1.0 with only 5 kg of spring load!) is to blame. Light plungers mean rapid acceleration and a higher rate of air flow into the barrel. If you are familiar with airguns, you know that most like looser barrel fits for maximum efficiency - their rapid pressure rise means tight barrels to build pressure are only a waste of energy on friction and the necessarily higher wasted pressure at the muzzle. Most springers, on the other hand, require tight barrels because the inefficiency of the slower pressure rise with a loose barrel outweighs the effects of the tight barrel's friction loss. That barrier essentially means that most springers are inherently inefficient devices compared to an airgun with a high-performance, fast-opening valve, and these Elites seem to be the first springers ever to tackle that - they seem to flow more like airguns than springers, especially with upgraded springs.

So, in short, don't rebarrel your Elite guns! Unless it's a longer barrel length such as a stefan-accepting breech, it will not get you anywhere. I know it seems wrong that an OMW spring with i.e. some brass shoved into the bolt won't pick up performance, but that's just what it is.