GBB Pistol barrel length testing

[8bitninja]

I did some experimenting with barrel lengths and BB weights since I had them lying around. This is NOT a scientific test and there are MANY uncontrolled variables so please take this with a grain of salt and only in a broad sense. If anything, it makes for some amusing lunchtime reading for you.

I have two WE pistols which came with longer barrels (190mm, 215mm) to allow them for import. One is clearly brass and the other is a smooth chrome finish but I suspect it's just a rough steel inner. I do not know the inner diameter nor anything else other than the length. This is an uncontrolled variable.

The test platform is the WE G27 STOCK pistol. I forgot what the stock inner barrel is but it's quite short... probably around 75mm?

I've posted the targets shot at 20ft range in a crouched stabilized position. This is an uncontrolled variable. The numbers correspond to the BB weight (brand Elite Force), barrel length, and median FPS. The targets are not sized to any standard so only compare them against each other. The longer barrels are NOT stabilized inside the silencer tube. This is an uncontrolled variable.

THE SETUP:



STOCK BARREL:



MEDIUM BARREL:



LONG BARREL:




------


After my testing, I decided to let my Marui G26 with a short 6.02 barrel have a go for my own comparison purposes...

[8bitninja]

Draw whatever conclusions you will from this. I spent the time to do this for myself so I thought I'd share. Again, this is a very unscientific test.

[ThunderCactus]

Barrel length makes no difference to accuracy. Only quality matters.
Bb weight and hopup are the two biggest factors in accuracy, followed by muzzle energy and barrel quality.

[8bitninja]

Originally Posted by ThunderCactus

Barrel length makes no difference to accuracy. Only quality matters.
Bb weight and hopup are the two biggest factors in accuracy, followed by muzzle energy and barrel quality.

Thanks, I'm learning... and also that a decent hop up rubber is the most effective investment one can make.

Having said that, can you speculate on why the grouping from the short stock barrel to the mid barrel grouping is so different? Again, this is at 20-25ft only. I mean it could be that the stock shortly barrel is just terribly finished?

Without knowing any better, I'm just going to quote the "What a longer barrel WILL do for an AEG is give you a tighter grouping at longer ranges" from the "Why do I need to upgrade (or not) - with explanations!" sticky. Granted, it notes AEG but in this instance/range I guess it could apply to GBB?

[ThunderCactus]

The difference is more likely due to the changed weight of the pistol affecting your handling of it.
Honestly at 25ft, groupings really don't mean anything at all, and if you're not using a gun vise, ESPECIALLY on a pistol, then the groupings are highly subject to your own personal skill.

AEG's, GBB's, GBBR's, HPA, spring, etc, they all have the exact same shot potential.
What matters to the BB is the pressure of the substance being used to center it in the barrel, and the consistency of that.
A .30g BB being shot at 1.6j from any of the above type of gun has the exact same potential for shot performance.
The BB doesn't care WHAT medium is being used to propel it; air, propane, CO2, nitrogen, compressed farts, they all do the same thing.

Barrel length doesn't matter because a) the hopup is applied at the very start of the BB's travel, and b) the rate at which the BB becomes centered in the barrel is proportional to the initial gas pressure generated.
What that means, is a gas pistol with a 5" barrel shooting 1j is going to perform the same as say an MP5K with a 5" barrel shooting 1j on a ported cylinder.

Okay so now range and accuracy have nothing to do with barrel length, since once the BB is centered in the barrel, it is centered, and no extra amount of barrel will ever make it any MORE centered than it already is. Depending on your initial pressure it could be centered in the first half inch, or the first 4 inches.

Barrel bore has nothing to do with range or accuracy either. Since the BB never actually touches the barrel wall, it just rides a cushion of compressed air down the barrel. So the size of the bore doesn't matter as long as the BB is still riding the air cushion.

When we talk about accuracy at range.....
Your gun is dead accurate to 160ft, like we're talking groupings the size of a quarter, but it has trouble hitting a volkswagon beetle at 240ft. Now think about this really thoroughly; do you think the accuracy loss between 160 and 240ft has to do with your barrel? Or do you think it has something to do with the BB and the hopup?
Factually, your barrel only makes your gun accurate within the first 50ft or so. Beyond that, hopup and BB weight take over.
Because the BB quite literally flies itself to target (the magnus effect turns it into a little wing), it's weight and the stability of it's backspin are what make up the bulk of your accuracy at long range. The rest of it is how rigid your barrel group is, fps consistency, air bubbles in the BB, various outside factors. But the majority of the performance is dictated by BB weight and backspin.

Simply put:
-If your BBs fly straight, then flay out wildly in random directions, you need to use heavier ammo
-If your BBs fly straight, drop gently, but the flight path varies slightly left to right, you need better BBs or more likely a better hop rubber. Sometimes this can be caused by the slack in all your parts (like the inner barrel being loose in the outer barrel, etc)
-If you get better range with a .25 than you do with a .28, you need a better hop rubber that puts more backspin on the BB
-as a rule of thumb, to select BB weight, keep increasing the weight of the BB until you start losing range. So if you run .30s, then gain range on .32s, then lose range on .36s, then you should use .32s, or upgrade your hopup to use .36s

[8bitninja]

Originally Posted by ThunderCactus

The difference is more likely due to the changed weight of the pistol affecting your handling of it.
Honestly at 25ft, groupings really don't mean anything at all, and if you're not using a gun vise, ESPECIALLY on a pistol, then the groupings are highly subject to your own personal skill.

That's the thing... the groupings vary enough to almost rule out the individual skill bit. I didn't stabilize the silencer any more than I did without it so the vast increase in accuracy is an interesting find in my uncontrolled experiment. I do hear the lack of controls makes some results suspect. I'm leaning towards the stock barrel is rubbish... though the "free" extended barrels can't be that much better so the only variable left is length. Again, in a very broad sweep of considerations.

Originally Posted by ThunderCactus

Barrel length doesn't matter because a) the hopup is applied at the very start of the BB's travel, and b) the rate at which the BB becomes centered in the barrel is proportional to the initial gas pressure generated.
What that means, is a gas pistol with a 5" barrel shooting 1j is going to perform the same as say an MP5K with a 5" barrel shooting 1j on a ported cylinder.

So would the WE G26 barrel be so short that adding any length of barrel allows for the air to stabilize the BB further... or something like that? The alternative theory is that the extra 80-100mm is the difference between a tighter and loose grouping. That is, if I step back 200mm would I see the same spread using a longer barrel? I need to try. Of course, the spectacular groupings using the TM G27 and short 6.02 is astonishing for me when compared.

Originally Posted by ThunderCactus

Okay so now range and accuracy have nothing to do with barrel length, since once the BB is centered in the barrel, it is centered, and no extra amount of barrel will ever make it any MORE centered than it already is. Depending on your initial pressure it could be centered in the first half inch, or the first 4 inches.

Barrel bore has nothing to do with range or accuracy either. Since the BB never actually touches the barrel wall, it just rides a cushion of compressed air down the barrel. So the size of the bore doesn't matter as long as the BB is still riding the air cushion.

I remember in my travels the debates (or fact?) where a moderate quality tightbore will allow for greater accuracy at short distances, sacrificing long range. Just a general comment.

Originally Posted by ThunderCactus

When we talk about accuracy at range.....
Your gun is dead accurate to 160ft, like we're talking groupings the size of a quarter, but it has trouble hitting a volkswagon beetle at 240ft. Now think about this really thoroughly; do you think the accuracy loss between 160 and 240ft has to do with your barrel? Or do you think it has something to do with the BB and the hopup?
Factually, your barrel only makes your gun accurate within the first 50ft or so. Beyond that, hopup and BB weight take over.
Because the BB quite literally flies itself to target (the magnus effect turns it into a little wing), it's weight and the stability of it's backspin are what make up the bulk of your accuracy at long range. The rest of it is how rigid your barrel group is, fps consistency, air bubbles in the BB, various outside factors. But the majority of the performance is dictated by BB weight and backspin.

This, I already subscribe to and understand :smile:

Originally Posted by ThunderCactus

Simply put:
-If your BBs fly straight, then flay out wildly in random directions, you need to use heavier ammo
-If your BBs fly straight, drop gently, but the flight path varies slightly left to right, you need better BBs or more likely a better hop rubber. Sometimes this can be caused by the slack in all your parts (like the inner barrel being loose in the outer barrel, etc)
-If you get better range with a .25 than you do with a .28, you need a better hop rubber that puts more backspin on the BB
-as a rule of thumb, to select BB weight, keep increasing the weight of the BB until you start losing range. So if you run .30s, then gain range on .32s, then lose range on .36s, then you should use .32s, or upgrade your hopup to use .36s

Thanks for the summary. This is how I came to my other thread about velocity... I am all for shooting 0.28 if it increases potential accuracy. The TM rubber should be ok to start with 0.28 but only testing will tell. However, at some point the other inefficiencies some into play and you need better valves, seals, longer barrel (?) to ensure the BB is propelled at a reasonable (?) speed.

[ThunderCactus]

Take a read through the "how airsoft guns really work - the physics" thread in the noob section, lots of good in depth explanations in there

a higher quality barrel will increase groupings at all ranges, assuming your stock barrel was of poor quality to start.
There no "it does X, but sacrifices X", it simply improves accuracy across the board.

Range is absolutely entirely 100% determined by BB weight, hopup, and muzzle energy. weight and hopup having the greatest effect.
For example; a gun shooting 1.4j and one shooting 2j, both shooting .30s with the same hop rubber, the 2j gun will get maybe an extra 10-15ft of range.
But if the 2j gun is shooting .36s, it could gain 30-50ft

I'll say it again:
Range has absolutely nothing to do with your barrel, and everything to do with your BB weight, hopup, and muzzle energy.


Where this misconception takes root is when idiots upgrade their barrel and hop rubber at the same time. So they go from a 300mm stock barrel with a crappy stock CA hop rubber, to an Rhopped 509mm prometheus 6.03, and then they attribute all their gains in accuracy and range to the barrel, particularly the length of the barrel, instead of the hop rubber which is what's actually improving their range and accuracy.

[8bitninja]

Thanks, I'll read that thread. I have no misconceptions about range. The first few articles I read already ingrained that. I'll be doing some more unscientific testing for my benefit at 50ft. I drew an early conclusion of "assuming your stock barrel was of poor quality to start" as it's the only plausible explanation for my limited knowledge.

I missed a word in my reply. What I meant to say was... "I remember in my travels the debates (or fact?) where a moderate quality tightbore will allow for greater accuracy at short distances, sacrificing long range accuracy.

[Drakker]

You should try installing the barrel and hop-up rubber from your Marui G26 in your WE G27 and see if there is still a difference in accuracy. My guess is that you are using the stock WE hop-up rubber, which is absolute crap. Also, hop-up rubbers don't like oil, especially the stock WE rubbers, you might want to clean it thoroughly with dish soap and try again.

On the KJW G27 (and G23) the outer barrel has a lot of play in the slide, which seriously affects accuracy. If the WE has the same kind of play, it might explain part of the poorer accuracy versus the Marui G26.

[8bitninja]

Thanks mate it's not so much a comparo of the TM vs WE, but you definitely have a point and I agree from stock, the WE is leagues behind the TM for the rubber. I'm not going to swap the rubber it's beyond my unscientific test scope. What intrigued me was the barrel to barrel test of just the WE itself. I'm very happy with the way the TM G26 is running, only wish it can run a little faster (BB that is) towards the target. Though getting that result is an extreme case of diminishing returns from upgraded valves, etc.

In the meantime, I'm "running" the WE G27 with the longest barrel and silencer. It's just a "fun gun" which I wasn't even supposed to get, it was an accident hence a second class citizen to the TM G27.

What I will do is thoroughly clean the WE rubber and see how that affects things in a broad sense. Thanks for the tip.

[ThunderCactus]

aftermarket hop rubbers are generally much better
but pistols looooooove heavy ammo as well

[8bitninja]

Originally Posted by ThunderCactus

aftermarket hop rubbers are generally much better
but pistols looooooove heavy ammo as well

So bear with me for a moment. The TM rubber is pretty good out of the box. I would go a heavier weight (past 0.25) in this case, why?

Let's say I do go 0.28, the FPS would be lower and the hop up may struggle. So I upgrade the hop up but now I need more gas to propel the sucker. So I need to upgrade the mag valve, knocker, perhaps hammer, etc. What I'm suggesting above would be a very incremental return on effort, is that right? Assuming engagement distance of no more than 60ft.

[lurkingknight]

the stock rubber can lift .32s no problem.

[e-luder]

Sounds to me like you want the best of both worlds.
Either that or you don't really know what you want your gun to do.

If you're so desperate on getting a higher FPS, why don't you just invest in a CO2 mag or something?

If you want your distance to shoot past it's limits, use your rifle or something similar to your pistol (like an SMG) that's designed to carry heavier bb's.

I'm leaning towards the stock barrel is rubbish... though the "free" extended barrels can't be that much better so the only variable left is length.

This is not true. The other variable is you. The only real way to absolutely attain identical results is to use a gun grip like TC suggested. Otherwise, regardless of how "solid" you think your technique is, evidence shows that at some point that variable has changed. And the factual evidence of this is your results...

A high output blowoff valve is not as beneficial as you think it would be. They are only as good as the temperature the mag is operating in. Thus, if your magazine drops in temperature (which it will), that blowoff valve becomes basically moot. The kicker is that because of it's perpetuancy to let more propellant out of the mag, it will speed up the cooling of your magazine. What will happen is that you will get the FPS output that you desire for the first three of four shots then it will eventually normalize and drop your FPS values to norms (or a bit higher).

A pistol is a viable primary but i think it's a poor choice. Unless the game your participating requires you to use it ( like say IPSC type settings ), then there really is no need to bust it out.

You'll come to realize this fact the more you stick with airsoft and more the experience you gain....

[8bitninja]

Originally Posted by lurkingknight

the stock rubber can lift .32s no problem.

I need a BB sampler pack...