JG SL8 DMR upgrade parts help. Somewhat of a quiet build.

[Asomodai]

Hello all. 

Following on from here. 







So far I have just a bog standard JG SL8, never fired in anger. I have replaced the top rail for the full length one with ironsights. I have 6 spare mags. 

I actually need to make a list of things that I need for this build. Pretty much all of the things I have upgraded before haven't included gearsets and motors. The idea is to spend a bunch of money on the off to build a relatively silent DMR that will last some time. So I would rather replace most of the internals in the first instance. It is a Version 3 gearbox. The SL8 is a glorified G36 and will take TM Spec G36 parts. 

What I am after: 

 - Something relatively quiet

 - Up to 450 FPS, preferably slightly below that to take into account environmental variations on the day. 

 - Made to last. 

 - Shortish trigger pull (Not hair trigger)

So far I have: 

 - Laylax/Prometheus 6.03 tightbore 509MM inner barrel. 

 - AirsoftPRO G36 Hop unit

 - AirsoftPRO Aluminium Air Nozzle

Which leaves me wanting the following

 - High torque Motor (Short type)

 - Decent gearset

 - Ball bearing String guide

 - Mosfet (Not fussed about programmable ones)

 - Spring

 - Compression parts (Piston/Cylinder/Head)

 - 7MM Bushings/bearings

 - Some form of bucking/nub. 

I am looking not to cheap out on this, but I do want parts which make sense from the least amount of diminishing returns aspect (IE, if I am paying decent money for the parts, I want to see/know why they are that expensive with a tangible benefit.) I am not looking to fit these myself, but will be handing over to my tech to do. I have seen bore up kits by guarder etc, but many people seem to say to keep away from them as they are substandard. 

With regards to the gearset, I would like a fairly decent trigger response, should I be looking at pairing up a high torque motor with a 13:1 Gear set? Or stick with a balance 16:1 set and make sure the motor has some real beef behind it? Any ideas on what a good combo would be?

With a barrel length of 509mm, would special consideration should i be taking into account with regards the compression parts?

Cheers ladies and gents!

View attachment 37049

 

[Iceni]

Are you wanting Quiet or Silent?

If you want quiet go with the standard aluminium silent head sets. If you want silent go with the plastic type piston heads. Those plastic ones significantly reduce noise.

Again with the cylinder if you want quiet go with the thinner bore up cylinder set, but if you want silent you want the thicker standard steel or brass walled cylinder, It'll hold in more noise. And transfer more to the shell rather than the air. The thinner bore up ones act like sound amplifiers.

Piston the same deal applies, Plastic is quieter. 1 or 2 steel teeth but keep as much plastic as possible. The only time this changes is if you are chewing up pistons and need the steel rack. Steel on steel is naturally noisy, even with a good thick grease. Plastic on steel isn't.

Barrel length 509 is standard for an AUG, I cut all mine back to about 450mm to increase the volume ratio. Even with a bore up running 509 is pushing those numbers. Do a full math evaluation of the volumes and head directly for a ratio of 3. Your going to be pushing that air harder and faster, so provided the barrel is of a decent quality length after 400mm is not going to make a difference. Having a shorter barrel and a suppressor will significantly alter the sound the gun makes. Using the suppressor just to hide the barrel won't.

Run oil-lite bronze, or stainless bushings. Bushings have no chatter, and make a quieter gearbox. Reducing noise.

Brass spring guide. A big solid lump. It'll act like a sound damper to the shell rather than a lightweight one that will transfer energy and therefore noise to the air.

For the gears and motor I have no idea. I don't run higher than 350fps in any gun. 

The ultimate goal for silence is to have the most solid gearbox you can make, with the most diverse selection of materials. The more materials you get in there the more the sound has to change tone and speed to escape the gearbox. A silent gearbox naturally runs hotter. A Lightweight approach just acts like a tuning fork, giving more opportunity for the sounds to directly escape. Your goal in all instances with silent is to contain that sound energy and spread it into the gun not the air.

The solid parts also have the effect of producing a lower tone sound. This is important as a lower tone travels further in the air, but it's also much harder to pinpoint by ear. A clack pulls your eyes right to the target, a low thump doesn't, and is easily drowned out when everyone else around you is clacking away.

 

[Asomodai]

Are you wanting Quiet or Silent?

If you want quiet go with the standard aluminium silent head sets. If you want silent go with the plastic type piston heads. Those plastic ones significantly reduce noise.

Again with the cylinder if you want quiet go with the thinner bore up cylinder set, but if you want silent you want the thicker standard steel or brass walled cylinder, It'll hold in more noise. And transfer more to the shell rather than the air. The thinner bore up ones act like sound amplifiers.

Piston the same deal applies, Plastic is quieter. 1 or 2 steel teeth but keep as much plastic as possible. The only time this changes is if you are chewing up pistons and need the steel rack. Steel on steel is naturally noisy, even with a good thick grease. Plastic on steel isn't.

Barrel length 509 is standard for an AUG, I cut all mine back to about 450mm to increase the volume ratio. Even with a bore up running 509 is pushing those numbers. Do a full math evaluation of the volumes and head directly for a ratio of 3. Your going to be pushing that air harder and faster, so provided the barrel is of a decent quality length after 400mm is not going to make a difference. Having a shorter barrel and a suppressor will significantly alter the sound the gun makes. Using the suppressor just to hide the barrel won't.

Run oil-lite bronze, or stainless bushings. Bushings have no chatter, and make a quieter gearbox. Reducing noise.

Brass spring guide. A big solid lump. It'll act like a sound damper to the shell rather than a lightweight one that will transfer energy and therefore noise to the air.

For the gears and motor I have no idea. I don't run higher than 350fps in any gun. 

The ultimate goal for silence is to have the most solid gearbox you can make, with the most diverse selection of materials. The more materials you get in there the more the sound has to change tone and speed to escape the gearbox. A silent gearbox naturally runs hotter. A Lightweight approach just acts like a tuning fork, giving more opportunity for the sounds to directly escape. Your goal in all instances with silent is to contain that sound energy and spread it into the gun not the air.

The solid parts also have the effect of producing a lower tone sound. This is important as a lower tone travels further in the air, but it's also much harder to pinpoint by ear. A clack pulls your eyes right to the target, a low thump doesn't, and is easily drowned out when everyone else around you is clacking away.

Some interesting points there. I guess I just want something that is quiet rather then silent. I would rather have reliability over silence. 

Presumably I will be able to use a shorter inner barrel with no problems? 

Do you have any specific brand spring guides, bushings and compression parts I should look at?

 

[Iceni]

If all you want is a quiet gun that is reliable at 400-425 fps stop spending money.

400fps is the USA standard. All standard parts will run at that. All you need to do to any gearbox is drop in an M130 spring, and you will bring the gun back up to the fps that your gun would have if it shipped to the usa.

The £4.50 cheap zci stainless bushings well shimmed will be fine (ak2m4).
Add a sorbo pad £2.50 ak2m4

A stock motor will pull an M130. A high speed might not, but your bog standards should.

You already have the upgraded hop unit and air nozzle. So just drop in a quality barrel and hop rubber and it should be good to go.
 

Presumably I will be able to use a shorter inner barrel with no problems? 

Some of the best sniper rifles use a short barrel. It's got nothing to do with the length, it's the quality of the finish, and the volume ratio that produce the most accuracy. Most snipers will aim to get a ratio over 2.5 heading out to 3. @Hangtight knows more about this as he did some math on it a while ago.

Basically is boils down to longer barrels not been all they have been touted as for AEG's. It's different for a sniper rifle as they have bigger cylinders. For an AEG however you only have a very limited amount of air you can push down a barrel. So you have to shorten the barrel length to compensate. Down to as low as 300mm. He'll advise 363mm for a sorbo AOE corrected piston for 0.28g bb's. And he's probably right, I just haven't manned up to going that short yet! I will at some point to see if it really does help.