[sherlock]

Okay first a brief into to this project, and my intended use.
This is not my primary (KA m1a1), I wanted to get a project gun to work on and learn more about fixing things up without f'ing up my primary and not being able to airsoft till I fix it.

Goals:
- First and foremost learn a heck of a lot about building/modifying airsoft guns
- Be able to consistently peg targets 100' and reach out to 200'? (perhaps to optimistic?) I understand that there is a lot of variation in airsoft and I don't expect to have a godlike sniper rifle by the time im done, just at least a decent DMR.
- Have fun! (I like tinkering)
Limitations:
- Budget no more than ~250 completed.
- 450 FPS .2 field limitations

Base Rifle:
Jg g36k
Why? I got it used shipped for 70$ came with the carry handle with scope (yes I know it's a poor scope but its somewhere to start on a budget). Also I heard v3 is a tougher gearbox and that JG is good at building robust gearboxes for their low price. I also seen teardowns of it and it seems rather simple for the most part unlike the SIG 556 that I really wanted to use.

Okay basically I intend on breaking this project into three sections. This also should create good performance intervals to reference, and allow it to be fielded now and then and play tested at various stages. This approach should also allow for easy purchase of parts as easier to grab a grouping of parts at a time, or break apart into free shipping blocks

Step 1 restore used gun, and basic modifications:
Being that the gun comes used and or is of a lesser brand there is a few key things that I think will need to be done.
- Strip down
- Shim the gears
- Steel bushings (if it comes with plastic)
- Silicon pad (not sorbo) the stock head (partially for practice
- Clean and re-lube
- Clean + polish barrel
- do some basic hopup work shimming, air seal, is it flat hop? Removing the nub on the rubber? Whatever that is called that
- 2c lipo, rewire, mosfet, deans
At the end of this step should have just a really well performing AEG, can still use it for field or whatever.

Step 2 Increasing range and accuracy:
- Replace the barrel
- Replace spring m125, m130 maybe?
- Bearing Piston
- Head
- Bearing guide
- O-ring nozzle
- Once again silicon on new parts (love that idea and thread)
- Use a better hopup rubber? Maybe r hop?
- Fixed semi auto
Here I am pretty much trying to add the necessary new parts to get to a higher FPS, range and tighten up the accuracy with better hopup and barrel. At this point I do not think a stock motor and gears are a problem they will not have the response desired but I think it should be workable or livable

Step 3 increase trigger response, and quietness, coolness:
- Dynamat the gearbox and shell where possible
- Replace motor with a high torque motor
- Use a high speed gear set (optional prev believed a high torque was needed)
- Use a 3c lipo pack
- Do any further tweaks to the hopup
- Replace carry rail, and add a "real" optic
Basically any improvements in this step are purely to make it more effective as far as trigger response etc. as well as more effective in field in regards to stealth and optics.

And there you have it! I will try and keep this thread updated with progress as well as keep this main post updated with any changes and my part list below. I do have a few questions though if anyone would be kind enough to help or share their thoughts on these or any part of my build layout.

Barrel length, I understand the effective length of a barrel is like 350-450mm ish from my understanding. The G36k barrel is ~350mm should I try and find a g36e grip and barrel? (not sure how long that is) or just affix a mock suppressor to get another 50-100mm out of it?

Barrel Diameter, so lots of debate here, I've been reading all over the place and am quite unsure on what to use and I believe it varies with length too? My initial thoughts and from what I have read is like a 6.03 or 6.04 for lets say a target barrel length around 400-450mm?

PASRTS LIST:
(is coming or any suggestions welcome too)

 

[BoesBoes]

Hey Sherlock, nice upgrade plans and steps!

If you want that 200'ft (or close to) definitely go for that r-hop so you can use them .30g .36g .40g bbs effectively.

In step 3 you have high torque gears on the list but the stock 18:1 gear ratio gives better response and if you want even better trigger response you could go for a high speed gear set like a 16:1. Yes your HT motor with the right battery will pull that M130

For the barrel, keep it between 350-400.

Have fun teching

 

[Reliku]

If trigger response is also on the list, a tightbore might be interesting. You don't need to make it long (400mm-ish will do?), but tightbores have an fps boost. While widebore barrels allow for more accuracy (theoretically), if the quality of the barrel is high the difference is minimal. With a 100% smooth bore the difference between a tight and widebore is actually zero (but such a barrel does not exist in real life).

A better airseal from the barrel allows you to use a weaker spring, it's easier on the internals + you get a better trigger response

I'd also recommend a good hopup chamber and maximizing airseal everywhere. That will also give you a fairly decent fps boost, you may even get to 420-430ish fps with the stock spring, which is fairly decent if your limit is 450.

Another item is balancing your cylinder:barrel ratio. A longer barrel will give you more fps and be more quiet (more efficient), but less joule creep. A shorter barrel will give you more power when you start putting heavier bb's in it. Look up the concept of cylinder:barrel ratios for a better understanding of it

Other than that, looking good! Boesboes already addressed some of the gearbox things, I'm not very good at that myself but I reckon he's right

If you have any more questions or anything, be sure to ask

 

[sherlock]

Hey Sherlock, nice upgrade plans and steps!

If you want that 200'ft (or close to) definitely go for that r-hop so you can use them .30g .36g .40g bbs effectively.

In step 3 you have high torque gears on the list but the stock 18:1 gear ratio gives better response and if you want even better trigger response you could go for a high speed gear set like a 16:1. Yes your HT motor with the right battery will pull that M130

For the barrel, keep it between 350-400.

Have fun teching

Thanks! exactly the sort of input I was after! so even the stock JG gears should be fine (shimmed properly that is)? Thats sweet! (means less out of pocket, ill drop it from my list) Ill just be sure to nab a high torque motor when upgrading spring

Ill try the Rhop think but TBH it kinda scare me because I have no clue wth I am doing there! Gears yeah they are all mechanical and have messed with similar things. but yeah i know its the key to a good dmr so will look there

If trigger response is also on the list, a tightbore might be interesting. You don't need to make it long (400mm-ish will do?), but tightbores have an fps boost. While widebore barrels allow for more accuracy (theoretically), if the quality of the barrel is high the difference is minimal. With a 100% smooth bore the difference between a tight and widebore is actually zero (but such a barrel does not exist in real life).

A better airseal from the barrel allows you to use a weaker spring, it's easier on the internals + you get a better trigger response

I'd also recommend a good hopup chamber and maximizing airseal everywhere. That will also give you a fairly decent fps boost, you may even get to 420-430ish fps with the stock spring, which is fairly decent if your limit is 450.

Another item is balancing your cylinder:barrel ratio. A longer barrel will give you more fps and be more quiet (more efficient), but less joule creep. A shorter barrel will give you more power when you start putting heavier bb's in it. Look up the concept of cylinder:barrel ratios for a better understanding of it

Other than that, looking good! Boesboes already addressed some of the gearbox things, I'm not very good at that myself but I reckon he's right

If you have any more questions or anything, be sure to ask

Thanks to you too, ill try and dig up some info on that. The whole tightbore vs loosebore thing sorta confuses me! I guess if anything I try for the most accurate scenario without being to hard on the internals? reasearch incoming

And conclusions from both of your inputs barrel length is pretty close without getting any upgrades personally i would like to push it just a bit longer but idk if they make short outer barrel extensions or just drop on a suppressor. Ill have to take a look at it and get some measurements too.

 

[Topper]

Thanks! exactly the sort of input I was after! so even the stock JG gears should be fine (shimmed properly that is)? Thats sweet! (means less out of pocket, ill drop it from my list) Ill just be sure to nab a high torque motor when upgrading spring
Brill armory sells JG Blue clones. That would be a wonderful motor.
Ill try the Rhop think but TBH it kinda scare me because I have no clue wth I am doing there! Gears yeah they are all mechanical and have messed with similar things. but yeah i know its the key to a good dmr so will look there
There are more r-hop guides than you think. Follow one and you should be fine. Your stock gears will be okay but not perfect. In other words, they'll work fine but you can do better .

Thanks to you too, ill try and dig up some info on that. The whole tightbore vs loosebore thing sorta confuses me! I guess if anything I try for the most accurate scenario without being to hard on the internals? reasearch incoming
6.05/6.08 is well regarded for long range accuracy, especially the PDI 6.08.

And conclusions from both of your inputs barrel length is pretty close without getting any upgrades personally i would like to push it just a bit longer but idk if they make short outer barrel extensions or just drop on a suppressor. Ill have to take a look at it and get some measurements too.

455mm is the best length, as it is almost exactly when the BB is stabilized. Any longer is unnecessary and shorter won't be as stable.

 

[Reliku]

455mm is the best length, as it is almost exactly when the BB is stabilized. Any longer is unnecessary and shorter won't be as stable.

That would depend on the cylinder volume, bore size, bb diameter, spring and bb weight as well

Matching cylinder:barrel volumes to your bb weight is what gives you the best performance, sadly it is not as simple as one length fits all :tup:

As for barrels, the wider PDI barrels are indeed the best, but keep in mind that the difference is marginal compared to a PDI 6.01 for example. The tightbore will give you a better trigger response for the same fps though because the spring can be weaker.

 

[1tonne]

455mm is the best length, as it is almost exactly when the BB is stabilized. Any longer is unnecessary and shorter won't be as stable.

As Reliku said. There is no fixed best length inner barrel. It all depends on the bb weight. The heavier the bb the more volume is needed to push out the bb. So a full cylinder with a 455mm barrel and a 0.45gm bb will not work that well as there is not enough air in the cylinder to push the bb out of the barrel fully.

 

[Topper]

As Reliku said. There is no fixed best length inner barrel. It all depends on the bb weight. The heavier the bb the more volume is needed to push out the bb. So a full cylinder with a 455mm barrel and a 0.45gm bb will not work that well as there is not enough air in the cylinder to push the bb out of the barrel fully.

But off topic, but you say a .45 BB wouldn't work. On a 455 MM with a type 0 using .43's, would I be "pushing it" so to speak or would I be too far/okay?

 

[vanevery]

As Reliku said. There is no fixed best length inner barrel. It all depends on the bb weight. The heavier the bb the more volume is needed to push out the bb. So a full cylinder with a 455mm barrel and a 0.45gm bb will not work that well as there is not enough air in the cylinder to push the bb out of the barrel fully.

But off topic, but you say a .45 BB wouldn't work. On a 455 MM with a type 0 using .43's, would I be "pushing it" so to speak or would I be too far/okay?

Not trying to get off topic.
Just want to address this point.

I have used the 455mm length barrel exclusively for max range and accuracy testing in my DMR's for two years now.
I test other barrels, but when its money time, I use the 455mm.
Typically I run a two DMR set-up.
One for field legal use capped at 450 fps measured w/ .25's.
One for high power/range only testing that has a power output much higher than 450fps.

The ammo I typically use is MadBull .43's.
I purchased several jars a couple years ago before the material filament was changed.
Before this, The MadBull .40 Tan was my go to ammo.

I can say to anyone who has a question on using a 455mm Inner Barrel, a Full/Type-O Cylinder, and ammo at least up to .43grams, that this set-up and ammo has no problem sending rounds as far as you want them to go, per your technical skills and at least 450fps.

To be clear, I am not debating that a shorter length barrel may prove to be better.
I am just making clear that the 455mm can do the job quite well, per the set-up stated and the ammo weight cited.

 

[1tonne]

It can work (depending on where your air nozzle stops) but once all the air has been expelled from the cylinder the bb is still in the inner barrel and is then just traveling on it's own momentum. The bb continues to move forward but instead of being pushed by air from behind it, it sucks in air from the bucking end of the inner barrel. The air is able to come in as the air nozzle has already moved backwards.

 

[sherlock]

That would depend on the cylinder volume, bore size, bb diameter, spring and bb weight as well

Matching cylinder:barrel volumes to your bb weight is what gives you the best performance, sadly it is not as simple as one length fits all :tup:

As for barrels, the wider PDI barrels are indeed the best, but keep in mind that the difference is marginal compared to a PDI 6.01 for example. The tightbore will give you a better trigger response for the same fps though because the spring can be weaker.

This is exceedingly interesting! I was aware of the cylinder volume to barrel volume problem (intend on measuring and doing some calculations) but was not aware how the bb weight played in???

Also while I'm thinking about it wouldn't the wider bore require significantly more air by some factor aside of volume for the amount of air that escapes past the bb?? (just mind hypothesizing remember I'm just a noob) also to while all this hypothesizing and barrel talk is exceedingly interesting looking up some of these barrels mentioned and holey course I understand that cost bits quality but is there some more middle road that is good without breaking the bank?

Also did question where does one buy airsoft gun parts? I know like evike but yeah idk I've seen alot of sketch about them. Don't mean to start anything with that statement either just wondering because everywhere else I looked would only seem to have one part and then shopping would stack up like mad.

Thanks again

 

[BoesBoes]

Reliku, stop implying 'tightbore = better trigger responce' because its confusing.
It only implies when your battery (and/or motor are)is to weak, say a 1800mAh 20c-40c lipo vs a 3200mAh 20c-40c lipo trying to pull a m140 on say 16:1 gears.

Vanevery, have you tested with shorter barrels all the way down to 300mm?

 

[Reliku]

Reliku, stop implying 'tightbore = better trigger responce' because its confusing.
It only implies when your battery (and/or motor are)is to weak, say a 1800mAh 20c-40c lipo vs a 3200mAh 20c-40c lipo trying to pull a m140 on say 16:1 gears.

Vanevery, have you tested with shorter barrels all the way down to 300mm?

Sorry

But it does help a little, and I just wanted to point out every difference, even if it's just marginal. Same reason I use a tightbore in my bolt action rifles, easier bolt pull :hehe:

Vanevery, there are several factors that come into play. Like 1tonne said, it could work just fine, but you can always have a better setup (you're not a true tech unless you keep thinking it can be better I'd say :hehe. Different bb's with different mass have different optimal cylinder:barrel ratios for maximum efficiency. The efficiency will never be 100%, but the goal (for maximum fps and quietness) is to get as close as possible. Heavier bb's have a higher optimal cylinder:barrel ratio while lighter bb's have a lower optimal ratio.

If your ratio is too low, your bb will start decellerating and possibly get its spin messed up, because there's not enough pressure behind it.

On the other hand, if your ratio is too high for the bb's mass, the bb will leave the barrel before it's maximum efficiency point, which means there's still more pressure behind the bb and you haven't used up all energy. That means you've got an inefficient setup (so you need a strong spring for low fps) and the gun will not be quiet (because of all the air escaping as soon as the bb leaves the barrel).

The goal is to have an optimal ratio. If your ratio is not optimal it'll still work generally, but it could be better

To make it more complex, it's actually not a cylinder:barrel volume ratio, but it's actually some complex cylinder-volume:barrel-length:barrel-bore:spring-power:bb-mass:airseal-percentage ratio. And I'm sure there are other things that come into play as well (theoretically) such as how much hop up is applied.

Either way, without going too far off topic here, the efficient barrel length depends on a lot of things. But if you don't get it right it's no disaster, because it'll still work. You'll just lose some efficiency, but you'll generally still be able to take long shots. :tup:

And I'd say 450-ish mm with a .4g on a full cylinder isn't that bad of a match, depending on the rest of your setup of course, but like I said, it'll work.

You'll never get a gun as efficient as it could be anyway. Too many things come into play for that...

To be clear, I am not debating that a shorter length barrel may prove to be better.
I am just making clear that the 455mm can do the job quite well, per the set-up stated and the ammo weight cited.

Fair point, but yes, the 455mm should do the job fine. I'm just implying it could always be better and offering some theory behind the phenomenon :tup:

Also while I'm thinking about it wouldn't the wider bore require significantly more air by some factor aside of volume for the amount of air that escapes past the bb?? (just mind hypothesizing remember I'm just a noob) also to while all this hypothesizing and barrel talk is exceedingly interesting looking up some of these barrels mentioned and holey course I understand that cost bits quality but is there some more middle road that is good without breaking the bank?

Yes, that's the downside of widebores, more air escapes so you need a bigger cylinder and more powerful spring for the same fps

As for a middle road, try madbull 6.03mm barrels. For about $40 you get a very decent barrel for as far as I've experienced

But off topic, but you say a .45 BB wouldn't work. On a 455 MM with a type 0 using .43's, would I be "pushing it" so to speak or would I be too far/okay?

You're probably fine, although I'd personally have picked a shorter barrel. But that's just me

 

[sherlock]

All very interesting. I do assume that my build will likely be filed with inefficiencies though I would like to try and minimize them I just know it will happen.


So I think to summarize my understanding of knowledge gleened here. Basically there are two camps or at least for me two possible configurations. Like a 6.03 tightbore Erich can lose accuracy at range to bouncing degrading the hop up at range. And the wide bore that had less bounce more even spin through barrel so greater accuracy or at least at range. However the wide bore seems to at least cost way more and can be harder on the gun at least I'd you maintain fps. I also assume each had their optimum length range and probably ammo weight.

So I guess my head is a bit spinning still... But I have a few thoughts that I would like opinions on. Specifically considering situations where budget is concerned

So on the whole what bore size to use I think maintaining the stock or barrel length I could afford to go wide bore ~350mm because I would not need to buy a suppressor or ag36e barrel/grip. Alternatively I could go with a cheaper tightbore 6.03 and extend the length with a suppressor etc with the barrel cost savings, or just go with the 350mm length and skip the grip of suppressor ask together?


I looked into the aforementioned mad I'll barrels for cost effectiveness and seen that they were aluminum??? Is it just me or does that seem like it will be g flimsy? Or are you talking about a different one.

Another thought I just had is on ammo? What wrought should one be using? Or field is bio only so yeah... I know some ppl there that use elite force.32 bios and turns out well? Will that be too light for such a dmr as I am constructing?

Once again thanks for all the inputs and discussion

 

[Reliku]

Madbull also makes steel barrels, called a "steel bull". It's what I have in my rifle right now. They're more durable and vibrate less than the aluminium barrels. I haven't fielded it yet but initial tests are very promising.

Read this as well, I just made it to prevent explaining the same thing all the time. Your barrel length depends on what cylinder and what bb's you're going to use

Cylinder:barrel ratios explained - Airsoft Sniper Forum

I'm also limited to bio bb's myself, and I currently use bioval .3g with pretty decent results. Many people use green devil, they're considered the best bio bb's you can get, but they're also expensive.

Valken makes .36g bio bb's, but they're hard to find.

G&G makes .33g bio bb's, I've used them as well. Good bb's, but grey, so hard to see.

HPA makes .4g bio bb's, they're tan, and by far the heaviest bios you can find. Worth considering

 

[sherlock]

I hope that gets stickied seems very informative! I feel my thoughts were about on the right track just not really sure scientifically why?

I guess it's more of hitting that efficient point and use the proper porting in the cylinder to match barrel length. In that regard I think... If I understand that post right using a decent heavy bb let's say like a .32 with proper porting on a tight bore 6.03 there is no real right answer to a barrel length just so long as its decent and you optimize it right?

 

[Reliku]

With .32g you should use about 2.3:1 as for a cylinder:barrel ratio on a 6.03mm barrel. Assuming your airseal is good.

What cylinder do you have? With a full cylinder 455mm is about right (about 2.3:1 ratio).

 

[Topper]

You're probably fine, although I'd personally have picked a shorter barrel. But that's just me

I haven't bought it yet, so I'll get a slightly shorter one.

 

[vanevery]

It can work (depending on where your air nozzle stops) but once all the air has been expelled from the cylinder the bb is still in the inner barrel and is then just traveling on it's own momentum. The bb continues to move forward but instead of being pushed by air from behind it, it sucks in air from the bucking end of the inner barrel. The air is able to come in as the air nozzle has already moved backwards.

I get what you are saying.
Not going to split hairs regarding vacuum effect.
I agree that the air ratio should be optimal.
Depending on the specific goals of the gun build, a slight over-voluming, or under-voluming can net the result intended, but this is trivial information related to this topic.
In short, I hear what you are saying and agree with you.

Sorry
Vanevery, there are several factors that come into play. Like 1tonne said, it could work just fine, but you can always have a better setup (you're not a true tech unless you keep thinking it can be better I'd say :hehe.

I agree completely with you on this point.
I also agree with most of your other points, if not all of them.
I am not debating anything here, just to be clear.

Either way, without going too far off topic here, the efficient barrel length depends on a lot of things. But if you don't get it right it's no disaster, because it'll still work. You'll just lose some efficiency, but you'll generally still be able to take long shots. :tup:

You'll never get a gun as efficient as it could be anyway. Too many things come into play for that...

Agree with this 100%.

Vanevery, have you tested with shorter barrels all the way down to 300mm?

In my DMRs, no.
I get back to my DMR's this month and testing shorter barrels is one of the primary objectives.
I may even test everything shortest to longest.
Something like:
161mm, 225mmm, 300mm, 363mm, 400mm, 425mm, 455mm.
I may not have the time to test that many barrels, but I will focus on shorter barrels.

 

[BoesBoes]

In my DMRs, no.
I get back to my DMR's this month and testing shorter barrels is one of the primary objectives.
I may even test everything shortest to longest.
Something like:
161mm, 225mmm, 300mm, 363mm, 400mm, 425mm, 455mm.
I may not have the time to test that many barrels, but I will focus on shorter barrels.

Looking forward to the results!