[Livonia]

Been over ten years since I have fielded my Maruzen 96. Over the years I have always kept it operational, and shooting very well, back then .36's were considered heavy.
Over the last couple weeks I have dove back into figuring what I have missed out on, and modernized my rifle. A few friends and I have 40 acres surrounded by state land in upper Michigan we plan to use. As well attending some Michigan community hosted games. For this, I bought a Xcoretech mk3 chrono to see where my rifle is at. Back then the limit was 550fps with .20g. I always hovered at 530-540fps. Now I understand fields measure by Joules, which makes sense to me with heavier BBs. What is your field limit? Here it is "2.7j with whatever BB you use" according to a friend, but he uses an AEG.

I have done a lot of time consuming chrono testing between several springs, pistons, cylinder, cylinder heads, buckings, and hop chambers. The setup I found best consistent power is
-ActionArmy hop chamber
-MapleLeaf 80% MR hop bucking
-PDI black raven cylinder
-PDI cylinder head
-Custom made 22g piston (7mm Guide)
-AA M150 spring
-AngelCustom red piston cup
-PDI steel spring guide
-Prom 650mm 6.03 (yes I know its long)
I have another 13mm spring and piston setup that is 28g weight, using the same red cup it is 5fps lower, but same ~6 fps variance with .45g BBs.
Now hearing piston weight has great effect with heavier BBs, I tried stepping the 22g piston up to 30g, then 35g, then 40g, losing fps the whole time it got heavier. Also so much more mechanical whack in the cylinder, which will obviously ruin things easier. Could be because my barrel is so long? Quite interesting to me.

More interesting chrono results....
With the 22g piston, and M150 spring im varying 530-546fps with .20g BBs ~2.7J (i have maybe 250 rounds through the spring). I recall my rifle getting just at 500 with a laylax M150, and am reading an action army is the same thing, 470-500fps.
With .25s (ammo set to .25 on chrono) I am getting 519-526fps at ~3.2J.
With .45s (chrono only has .43g bb option) I am getting 420-426fps at ~3.6J.
Finally got out to test my new setups, using a range finder. I can shoot dead flat 75 yards with .40s, and with not a whole lot of lob hit 90 yards with decent accuracy. I didnt have time to dial it with the .45s, but they shoot very well.
Trajectory is so much more stable than what it was before, but im afraid its shooting quite hot Joule wise. I dont exactly know what im doing with the chrono measuring the .45s on a .43 setting, its obviously throwing it off a little.
I do have other weaker springs like a 15 year old OK 500 spring (actually shoots 520 with .20s) and the Novritsch M160 shoots 470 with .25, feels weak and has a lot of twang.

Now about my 650mm barrel, I understand it is several inches too long, but I do not think its hurting me. I have a 6.01 I tried that is 500mm, and the 650 6.03 performed much better. Cant say about chrono results because I didnt have one at the time. I do think I will try a shorter 6.03, because I never trusted 6.01s even twenty years ago when I first started. That will increase my cylinder/barrel ratio and theoretically the muzzle velocity, but may require a heavier piston to do its job. None of the science or theory existed when I played last.

Any comments concerns and help bringing me back up to speed are greatly appreciated.

 

[SiliconeSword]

I'd say just use what works for you.

The light piston thing sounds weird, but that's probably because your barrel is super long, and with heavy BBs that will probably throw stuff off.
I recommend that you buy some .45g or .48g and just stick with that weight and brand, and tune your gun to those BBs.
I'd do that by picking the spring that gets you the most power for the lightest pull, pair it with the piston that gives the most power, and get the barrel to whatever length gives you the most power.
Usually whatever setup gets the most power is the most efficient, and should probably be the most accurate in terms of purely mechanical stuff.

If the gun shoots pretty well though, I'd leave it alone, as you can take a great gun apart and put it back together and it will never be the same again, as is the way with airsoft.

 

[1tonne]

You do need to chrono with a shorter barrel and then see if you get better results (Try somewhere around 470-500mm). It is strange that you are getting more energy with the longer barrel with the heavier bb's. At 650mm long it is really tuned for 0.2gm bb's and not heavy weights. But each rifle can be different and I did find that even I had some different results that suprised me with this L96. It did seem to be able to take a longer barrel than the VSR even though it has less cylinder volume. This has always perplexed me. Maybe it is something to do with the longer cylinder and piston. -I am not sure.
Also, 6.01mm barrels are fine these days. Back years ago the bb's were not good quality and so the barrels will clog up and then jam. This day and age most bb's are good quality and so we no longer get clogging. I even use a 5.98mm and my barrels never clog and I would only clean them maybe once every 4 months. So get a 6.01mm and not the 6.03mm.

 

[Livonia]

You do need to chrono with a shorter barrel and then see if you get better results (Try somewhere around 470-500mm). It is strange that you are getting more energy with the longer barrel with the heavier bb's. At 650mm long it is really tuned for 0.2gm bb's and not heavy weights. But each rifle can be different and I did find that even I had some different results that suprised me with this L96. It did seem to be able to take a longer barrel than the VSR even though it has less cylinder volume. This has always perplexed me. Maybe it is something to do with the longer cylinder and piston. -I am not sure.
Also, 6.01mm barrels are fine these days. Back years ago the bb's were not good quality and so the barrels will clog up and then jam. This day and age most bb's are good quality and so we no longer get clogging. I even use a 5.98mm and my barrels never clog and I would only clean them maybe once every 4 months. So get a 6.01mm and not the 6.03mm.

What is the volume of the VSR cylinder? I measured 30.4cc (20mmx97mm) usable volume on my setup, and if i make a slightly shorter piston could achieve 20mmx100mm (31.41cc). A 500mm 6.01 barrel gives me a 2.14:1 ratio, a good bump up from my current 1.64:1. probably worth trying.

 

[1tonne]

The VSR is about 35.8cc.
Piston Travel Length: 90.2mm
Cylinder diameter: 22.5mm

More volume is always better and so if you can get it, then go for it.
For an L96, I found the best barrel length for a 0.4gm bb was 500mm. In a VSR, even though it has a bigger cylinder it was 470mm. Like I said, not sure why. Both of the rifles that I experimented on had 100% air seal.

 

[RonSwanson]

Type96 volume is 32.99cc or just round to 33 for math sake. I've got detailed cylinder measurements in my post history for the asg clone. Cylinder is thinner by 8% but longer by 10% than a vsr from memory.

 

[SiliconeSword]

One thing that you guys may not be measuring is how far the piston is back when cocked, as this will give you the actual used volume of your cylinder.
This can be done be cocking the gun, removing the cylinder head, measuring the depth, and subtracting the threads from the cylinder head, or you can fill it with water and struggle a lot.

Piston length will change things, but this is a more exact way than just measuring from the slot to the end.

As for the APS2 having the capability of handling longer barrels, I imagine it's because the air is released in a slower manner, and the lesser surface area on the cylinder head adding resistance will get you "more power per CC" so to speak.

 

[RonSwanson]

Also much shorter barrel should help somewhere between 430mm to 450mm is likely the sweat spot for heaviest weights (non ceramic). Been thinking about this and I'm wondering if due to your barrel being so long it's acting as a LRB almost as the BB ends up settling and riding along the top or bottom.
Action army and zci do good and cheap barrels in that length.

 

[Frohst]

Since you mentioned not knowing how to Chrono J when your Chrono didn't let you put the weight in...

Joules = 1/2 * mass * velocity^2.
Mass of bb in kg. Velocity of bb in m/s. No freedom units here.

So if your shooting .45g at 100m/s...
0.5*0.00045*100^2.

Assuming you can algebra, you can us the above to translate what your Chrono says your doing when you tell it 0.whatever and pew pew something else.

And you can guess pretty darn well what fps you'll get out of a diff weight bb. (±all those small efficiency factors, voluming sizing effects, etc that help make a rifle actually tuned and consistent on a specific weight ammo. But not really applicable to a lot of gas setups because of how much gas they dump vs a cylinder volume)

 

[1tonne]

Joules calculator
FPS/Joules Calculator – Asiaairsoft

 

[RonSwanson]

Airsoft ballistics app is also good for working out Joule's and checking equivalents on different weights

 

[Livonia]

Thank you all for your replies. I ended up figuring out how to program my chrono for my different bb weights.
I really should test more with a shorter barrel yet, but things are still interesting using the chrono properly.
Action army M150 (7mm guide) with 24g piston and 590mm 6.01
.20g=560fps/2.9J - .25g=530fps/3.27J - .36g=465fps/3.63j - .40g=450fps/3.7j - .45g=422fps/3.73j
Tried adding 8 grams of weight to the piston making it 32g, lost 12fps with .20g BB, 5fps with .25g, then made no change with heavier bbs.
With the 6.01 my fps consistency is tighter, varying 5.5fps with .40g BBs, where it is a 7.1fps variation with the 6.03. Both barrels shoot great, almost identically.

The Novritsch M160 (9mm Guide), with 28g piston, 590mm 6.01 is my only field legal setup. If I use .36g I can shim the spring up some to reach the 2.7j limit. This spring is softer, and about 35mm shorter than my other springs. Feels like a M120-130 from my experience.
.20g=525fps/2.5j - .25g=460fps/2.5j - .36g=390fps/2.54j - .40g=378fps/2.65j - .45g=346fps/2.3j.

I do a lot of high performance motorcycle engine building. With engines, the bore and stroke change the characteristics of performance. Same im sure it does with a spring and piston type rifle. There is probably a lot to be learned from comparing shorter stroke, larger bore like the VSR to the longer, skinner APS96.
I have a bruette for measuring engine compression ratios, which can be used for measuring down the cylinder head with the piston in the cocked position. This takes head volume into consideration too. I wonder if there is some kind of flow test that can be done? The idea seems to be, get the air out of the cylinder as quickly as possible, but I believe certain shape cylinders compliment certain length barrels. Also certain length springs have effect too regardless of tension. Still trying to find that recipe for my rifle. The M150 being 560fps with .20g shocks me, it doesnt feel like an overly stiff spring. Is this normal power for it? With a laylax M170 spring its 610fps.

I really appreciate all the help getting it back to spec!

 

[RonSwanson]

My current theory I posted I that the the longer nature of the l96 cylinder gives it more time to release the air over which means longer barrels work compared to a vsr. (Also less friction on piston but with grease don't think that plays too much in it).

 

[Masada]

It’s not about getting all the air out as quickly as possible, but getting it out in the same amount of time it takes your bb of choice to leave the barrel. Same concept in firearms. You want to burn as much powder as possible while the bullet is in the barrel for the most efficiency and fps.