The amazing R-hop test project!

[ThunderCactus]

So I've been doing a lot of reading on other forums about this, and whenever someone bashes it, says it's not all it's cracked up to be, or says there's no gain, I'm not convinced they understand the physics behind the mod, or have proper test conditions.

So firstly, one HUGE misconception is that it makes a ridiculously huge difference in range and accuracy.
This is not false, but tends to be over exaggerated.
Why?
Well most often, someone has a STOCK gun, and upgrades it immediately to an R-hop. Obviously you're going to see a huge improvement.
But when you go from something already really good, like a firefly or PDI-W, then the gains aren't quite so drastic. Then we're talking about 5-10s of feet difference as opposed to an extra 120ft.

Second, applied hop
On an AEG, you don't have nearly as much initial pressure to drive that BB past the hop rubber with a lot of force. I haven't seen an AEG yet that doesn't jam before it gets to it's max hop setting. And the more hop you apply, the more force is lost trying to force the BB past the rubber, resulting in FPS losses. With heavy rounds and low FPS, you typically can't apply enough hop to a round to get it to fly straight.
There's a lot of complications comparing AEG performance to GBBR performance on heavy rounds, so I'll explain it in more common terms;
Most 300fps GBB pistols do REALLY well on .30s, whereas a 330fps AEG typically does not. If a low fps AEG and GBB pistol have the same muzzle velocity when shooting a .30(that means they're both shooting around 220fps on the chrono or whatever it comes out to), the pistol tends to achieve a flatter trajectory, and the AEG tends to jam from over-hop before you can get it shooting to it's max range.

So that's complicated stuff I'm not confident about with out testing.
How am I gonna prove that crap out?

WELL, what all that means is that the Rhop should allow you to use heavier rounds on AEG's that you normally wouldn't be able to use.
So as far as proving the rubber, it's pretty straight forward, so here's what I'm gonna do (and I'd LOVE to have some other gunsmiths test this out as well!)

Get a low FPS gun 300-330fps, start shooting with a high quality hop rubber, then install an Rhop and re-test
-Test with the .25g BB they would typically run at that FPS
-Then with .30s, which often fall short on low FPS platforms
-Then with .36s, which most definitely will jam anything under 350 before it will fly straight

THEN, repeat that test with a more common 380-400fps AEG
-Test with .28s as they would commonly run
-Then with .36s, that should still do alright
-Then with .43s which should outline a clear difference between the two!

EDIT: Also needs to be compared between longer and shorter barrels. Ideally testing with the same gun. Practically, I would accept a graph of results from various longer and shorter barreled guns.

Now the reason I'm upgrading the same AEG for both is to ensure the internals play no part on the test, since the mod only affects the hop/barrel end of things.

So, what we SHOULD see is the R-hop being same or slightly better with the common weight of BB, and then perform better with heavier ammo.

So of course not being a physicist myself, what I put forth could be totally ass backwards, but that's what the practical test is for. Once we get some factual results, we can figure out the science from that. If nothing else, this will prove if the R-hop is really a better rubber, or just being puffed up by people who just don't know any better.

We're building a measured range at two of our Mb fields this year (that's the pan anyway), so I'll have measured results. (Gonna do my PTW as well since google maps tells me I'm shooting stupid far)

So for any gunsmiths interested in partaking, make sure the mechbox is getting a REALLY good seal before testing. We want the AEG's to be in peak performance condition BEFORE getting the R-hop.
Measure out the distance you're shooting and please use a spotter to verify where they land.
I'm sure we'd all appreciate having detailed performance results on this

Also it's the end of march and we've still got a good 2ft of snow here in Mb, so it could take us a while to set up for this =/

I've currently got an R-hop in my G&P 249 at the moment, and preliminary testing looks good, but not mind-blowing (testing at 380 with .28s). Getting good range and accuracy, but certainly not an extra 60ft, maybe 20-30.

Buddy o mine has the same G&P, so I'm gonna borrow his barrel to quick swap between R-hop and standard rubber to do some real time comparison if I ever manage to get my ass out to a game sometime soon lol

[Rabbit]

Finally! I look forward to the results.

[sab567]

I'm trying the same with my AEG setup (G&G SR-25, with the stock brass barrel and with a 6.01x650mm too).
I'will use 2 differents hop up rubber (a stock one and a A+ rubber) with 0.25, 0.30 and 0.36g bbs for every setup.
I'will test the accuracy and range
So i'll post the result here when it's done.

[Stealth]

In my mind the only way to do proper range test is as follows:

1. Indoor range of 300ft.
2. A gun vice bolted to a really heavy table.
3. M16 platform for easy barrel and lower receiver swaps. Do a 300fps and a 400fps and throw in a 500fps - why not?
4. Identical barrels (prommy because they are well QCed and consistent)
5. Identical hop up units
6. Firing tests in semi-automatic and full-automatic;

For each hop up rubber you want to test, you build a barrel-hop up unit combo.

I can do #3,4,5 but have no access to #1 and 2.

If you want to go even more scientific, do n=3, meaning 3 Rhop barrels, 3 PDI, etc.

Given a choice I would want to do the following - rhop, PDI, flat hop, regular mound sleeves

John

[Troy T. Moore]

Originally Posted by ThunderCactus

Also it's the end of march and we've still got a good 2ft of snow here in Mb, so it could take us a while to set up for this =/

We have 3.5 feet here in central Saskatchewan!

Looking forward to the results as well.

[Kos-Mos]

Well, count me in.
I have a G36 that is currently stock, but works great.
I also have a L96 clone that is getting upped. With a PDI hop-up chamber it uses AEG barrels, so that will give a hint in that direction too.

And I should be able to setup a range if we get access to the MALL again...

[Stealth]

Your original hypothesis isn't too far from what I've observed. While the R-hop IS more consistent, it doesn't achieve a crazy WTFBBQ increase in accuracy and consistency when you're lifting .28g and lighter ammo, given you already had a "baller" setup before (talking about something like a Madbull or Prometheus 6.03 with a PDI rubber and a good hop unit)

Where it really shines is its ability to lift the heavier ammo without jamming via the longer contact patch, more gradual application of backspin and dwell time of the BB in the chamber. And by using heavier ammo, you WILL see an increase in accuracy and consistency just by nature of using the heavier ammo.

[ThunderCactus]

Stealth, agreed on all points!
300ft indoor range would be ideal, but outdoors will have to suffice.
Quick swapping identical barrel assemblies will make it easy to compare results in field, but taking the gun back and upgrading it to R-hop should produce the same test accuracy since you're using all the same parts you did before minus the mod. It just requires two tests.

The gun vice is an excellent point, I'll have to brace the gun against the side of my truck box or something while shooting to make sure there's no human element to inaccuracy!

At 500fps I'm worried there either won't be enough grip over the short patch, or the results will be too close without using some pricey extra heavy ammo.
At SOME point you do need to switch to an ER-hop, although I'd like to know what that point is, and how long the ER hop actually needs to be, I don't want to deal with that yet. At least not until we understand exactly what the R-hop actually does.

One argument I read was that the amount of time the BB is in contact with the hop patch is insignificant since the number is so small. I dismissed is as ignorant assumption since the man clearly did not grasp the scale of forces involved. Any way you look at it, the hop patch is DOUBLE the contact area. And if the BB goes from being in contact for .5ms to 1ms, that's still double the contact time. It obviously has to be doing something lol

Hunterseeker armories theorizes that it also reduces bounce in the barrel, allowing the BB to stabilize quicker. If that's true then we should also be able to shrink the ideal barrel length from 420 down to whatever. I've heard as low as 247 for AEGs, but in practice the magic number seems to be between 380 and 430mm. Between using heavier ammo and less bounce, perhaps that number could very well shrink to 247?

And I guess we'll find out if BB's really do have ideal relative velocities. It's been my experience that every weight of ammo like to sit around 320-350fps to get it's ideal flight stability. So now with the ability to add more hop to heavier ammo at lower speeds, maybe we'll find destabilization points where the BB just isn't going fast enough to maintain a straight path. Or that once the ideal backspin is reached FPS then equals range? Like if a 310fps gun can only send a .30 to 180ft without having that bump in the flightpath, and a 380fps gun can send it out to 260ft before having the hop hump.

It's exciting to work through this now, it's like the missing link of airsoft science!

Also we need a standard report model;
Make/model of AEG
barrel length
ROF
Brand of ammo used
test conditions (indoors, slight wind, etc)
distance verified by (tape measure, measuring wheel, rangefinder, shot at metal can, shot my buddy, videotaped on receiving end)

Standard hop ____ type rubber
fps on zero hop
fps at ideal hop
distance and spread with ____g BB
distance and spread with ____g BB
distance and spread with ____g BB

R or IR-hop
fps on zero hop
fps at ideal hop
distance and spread with ____g BB
distance and spread with ____g BB
distance and spread with ____g BB

[Stealth]

You'll need to watch out for weather variances if you're testing on different days.

Another aspect that I'm interested in is the trajectory of the BB.

At what range does the BB start to arc upwards and then come back down to your original firing plane? I suspect with rubbers like PDI with a shorter point of contact you're going to see it arcing upward earlier than Rhop.

Sigh... How much I would give to have an indoor 300ft range...

[lurkingknight]

with each setup, take a range reading at 50 ft, 100 ft and 150 ft from there you can extrapolate the cone of fire and calculate the grouping size relatively accurately imo. If you need to make a shot beyond 150ft, you'll have a lot more to worry about than hopup accuracy, and imo it's pretty uncommon to engage at that range effectively.

I have done a non scientific test between a madbull 6.03 using a pdi W hold and an IR hop with mnub.

Power is power, you can't get more than what is there in a 400fps setup, so you aren't going to see magical range increases, and in my test, I didn't. What I did see was flatter trajactory at higher hopup settings, where a standard setup you would see a pronounced hump in the flight, with Rhop it was much flatter throughout the range. Only at the more extreme settings you would see a more pronounced hump in flight.

Grouping sizes did shrink, and it was definitely a lot more consistent with fewer fliers, but without actually doing it indoors with paper, I can't give you a measurement.

I was using .25s and .28s up until the rhop install, now .28 is the lightest I use, going up to .32s

Also, there's a lot of skewed data, people install R-hops immediately on the gun without addressing air seal problems... R-hop is something you do when your fps variance has been reduced to <5fps from shot to shot. It's normally not the first mod one does to a gun, more like the last mod... but before dsg of course. :P

[ThunderCactus]

Although I totally agree that what you get from 400fps is what you get, we just don't know what we can get from 400fps. Maybe we do, but we just haven't proved it yet.
6 years ago, the maximum range of an airsoft gun in manitoba was like 80ft. Since then the numbers constantly been going up. Amos' VSR-10 and my VSR-10 seemed to top the scales with their impressive distance, but now it seems there might be a few guns shooting even further than those.

So now, what we get at "400fps" and using .28s, there's obviously a set maximum performance we can achieve where you just can't get that BB to fly any straighter, or further, until it runs out of momentum. And THAT point we may have reached with hop-modded PTWs and tweaked VSR-10s. We generally know what a .28g BB is capable of.
But we're changing a big variable, at the same "400fps" it may be possible to use heavier ammo. So the relative velocity drops, but the range may very well increase. Or we may have the same range and much better accuracy due to the heavier ammo.

Now before we start using high speed cameras, let's just stick to simple methods
flattest trajectory possible
maximum range
Accuracy noted, I wouldn't be too anal about it. Man sized target, torso, would have trouble hitting a school bus, etc

Accuracy can only be compared against same weight ammo. So you have to test .28s against .28s. If we find the R-hops can handle much heavier .36s with ease, then of course we can state what kind of accuracy you're getting, but you can't make it a case for accuracy since the heavier ammo is the likely cause of it. We have to be careful how we go about wording the results.

For example;
Say the Rhop and standard hop have the same accuracy on a .28
But the Rhop allows you to run .36s, which may drastically improve grouping at range
You can't say the Rhop is more accurate, but you can say that a .36 is more accurate than a .28

But if the Rhop is more accurate on .28s like you said, then we can say it's a more accurate hop.


It's nice to see some positive results already though!

[MaciekA]

Reducing the number of variables in this experiment is key. Down to using the same buckings. Tricky stuff. I agree with Stealth ... an indoor range is going to be really important for gathering data.

[ThunderCactus]

Well, if you're looking to test a minimal amount of guns, by yourself, in the most accurate way possible, then yes.
I'm hoping there will be enough of us plotting enough data to give everyone an average figure.
I'm more interested in accomplishing this as a group, because it gives our findings significantly more clout. And most importantly, since it requires personal technical skill, we'll also be able to weed out those who are potentially not installing them correctly.

"Somebody does an elaborate analysis of R-hops across 10 guns and fails it miserably, and we only find out later that this person has no manual dexterity what so ever and messed up all the installs" lol

[MaciekA]

The scientist in me says you need to do this lab style.

The pragmatist says we'll learn something even if it's a windy day.

[wind_comm]

Originally Posted by ThunderCactus

this person has no manual dexterity what so ever

in all seriousness,
would any local indoor field owners like to chime in? it would help quite a bit to know if there's a: any facilities big enough, b: anybody willing to support this.