Ssg24 Low FPS Problem

[AP77]

Hi all,

 

I recently bought an SSG24 and upon cleaning and a full inspection, I installed an M150 spring to get just below 500fps. The seal is excellent and the piston is not worn however, the chronograph only get just below 400fps (1.82Joules) with 0.25 BBs when the Novritsch website's chart read I should have circa 480fps (2.15joules) with 0.2 BBs. I realise from 0.25 to 0.2 would imply a higher fps but I doubt it would make for the almost 20% inscrease (?).

 

I checked the obvious and the barrel is not scratched and degreased / cleaned, so is the nozzle, brand new HopUp from Novritsch etc.

 

Is someone has any idea where I missed the obvious ?

[Adolf Hamster]

What weight are you normally using in-game?

[Piman]

How have you set the hop up?

[AP77]

9 hours ago, Adolf Hamster said:

What weight are you normally using in-game?

I will be using 0,43g -> I am a veteran but new to airsoft

fps are measured with 0.2g if I am not mistaking ? 

 

9 hours ago, Piman said:

How have you set the hop up?

at about 60mtr flat trajectory so about mid-range setting available -> are the measure done with minimum hop up for the fastest fps data ?

9 hours ago, Piman said:

How have you set the hop up?

 

at about 60mtr flat trajectory so about mid-range setting available -> are the measure done with minimum hop up for the fastest fps data ?

[Adolf Hamster]

2 minutes ago, AP77 said:

I will be using 0,43g -> I am a veteran but new to airsoft

fps are measured with 0.2g if I am not mistaking ? 

 

 

yes and no

 

there's a phenominon called joule creep that can apply to spring rifles if the piston is heavy enough, i'm not sure if out of the box the ssg24 is one of those rifles but it's worth using your game weight to chrono to be sure.

[Piman]

One of the key things to note is that springs are not an exact science. One makes M150 will be different to another and depending on the brand this can even vary within a brand (it is not unheard of that a spring can be miss labelled/packaged).

 

The key thing is to see how consistently it is shooting. This could indicate if the issue lies else where (key areas for fps will be air seal, hop & barrel). What sort of variation are you getting on the fps? How consistent are the shots? Ant the end of the day I would not worry about getting to within 1 fps of 500. Consistency and effective range is what is truly important. 

[Skara]

3 hours ago, Adolf Hamster said:

 

yes and no

 

there's a phenominon called joule creep that can apply to spring rifles if the piston is heavy enough, i'm not sure if out of the box the ssg24 is one of those rifles but it's worth using your game weight to chrono to be sure.

It is, the cylinder volume is similar to the VSR, which is known for being a creepy fuck  (my VSR gains 0.5J going from 0.2s to 0.4s)

@AP77I suggest chronoing in Joules with 0.43g or whatever bb weight you want to use and the hop set for that weight, just to make sure you don't run a hot gun

 

Having the hop on vs off does not exactly give the same results in every gun. Some will see a decrease of fps/J, others will have a boost.

[AP77]

1 hour ago, Piman said:

One of the key things to note is that springs are not an exact science. One makes M150 will be different to another and depending on the brand this can even vary within a brand (it is not unheard of that a spring can be miss labelled/packaged).

 

The key thing is to see how consistently it is shooting. This could indicate if the issue lies else where (key areas for fps will be air seal, hop & barrel). What sort of variation are you getting on the fps? How consistent are the shots? Ant the end of the day I would not worry about getting to within 1 fps of 500. Consistency and effective range is what is truly important. 

These are fair points you raised. As I am not sure what to expect for Airsoft,  I did some test (screen shot attached) with chrono results for .25 BBs in yellow and .43 in orange. Is a 50fps drop significant in Airsoft ? That’s a fair point about not worrying too much about being 1fps below the 500, I am just looking to stay around 450 which seems reasonable (?).

[Adolf Hamster]

So your getting 1.8j with 0.25's and 2.4j on 0.43's with the same spring if i'm reading that right.

 

2.4j sounds close enough for me, you work that out its equivalent to ~460fps on 0.2's.

 

Might be a little headroom there but at the same time being a bit under is no bad thing as it means you've got a safety margin to account for questionable site chrono's.

 

What is worth doing is chrono'ing a few shots to check the fps variation shot-shot, valid for any gun but especially a bolty your gonna want that number to be as low as possible.

[AP77]

45 minutes ago, Skara said:

It is, the cylinder volume is similar to the VSR, which is known for being a creepy fuck  (my VSR gains 0.5J going from 0.2s to 0.4s)

@AP77I suggest chronoing in Joules with 0.43g or whatever bb weight you want to use and the hop set for that weight, just to make sure you don't run a hot gun

 

Having the hop on vs off does not exactly give the same results in every gun. Some will see a decrease of fps/J, others will have a boost.

Thanks Skara, would this help if I make the piston lighter ...? 

11 minutes ago, Adolf Hamster said:

So your getting 1.8j with 0.25's and 2.4j on 0.43's with the same spring if i'm reading that right.

 

2.4j sounds close enough for me, you work that out its equivalent to ~460fps on 0.2's.

 

Might be a little headroom there but at the same time being a bit under is no bad thing as it means you've got a safety margin to account for questionable site chrono's.

 

What is worth doing is chrono'ing a few shots to check the fps variation shot-shot, valid for any gun but especially a bolty your gonna want that number to be as low as possible.

All noted thank you this is appreciated

[Shaydee]

36 minutes ago, Adolf Hamster said:

So your getting 1.8j with 0.25's and 2.4j on 0.43's with the same spring if i'm reading that right.

 

2.4j sounds close enough for me, you work that out its equivalent to ~460fps on 0.2's.

 

Might be a little headroom there but at the same time being a bit under is no bad thing as it means you've got a safety margin to account for questionable site chrono's.

 

What is worth doing is chrono'ing a few shots to check the fps variation shot-shot, valid for any gun but especially a bolty your gonna want that number to be as low as possible.

 

It's more like 507 FPS on 0.2s unless I'm misreading something. So dependent on OP's location that would be over the majority of British site limits by a small margin. 2.32 joules is the old 500fps on 0.2g limit.

 

I'll echo the sentiment with regards to recording the shot to shot consistency, this is the most important thing for a bolty. @AP77 spreadsheet screengrab you've posted only lists one number per line - is this an average or just one reading?

[Adolf Hamster]

12 minutes ago, Shaydee said:

 

It's more like 507 FPS on 0.2s unless I'm misreading something. So dependent on OP's location that would be over the majority of British site limits by a small margin. 2.32 joules is the old 500fps on 0.2g limit.

 

You are indeed correct, must have mistyped into the calculator. Tried again gives 508 on 0.2

[AP77]

27 minutes ago, Shaydee said:

 

It's more like 507 FPS on 0.2s unless I'm misreading something. So dependent on OP's location that would be over the majority of British site limits by a small margin. 2.32 joules is the old 500fps on 0.2g limit.

 

I'll echo the sentiment with regards to recording the shot to shot consistency, this is the most important thing for a bolty. @AP77 spreadsheet screengrab you've posted only lists one number per line - is this an average or just one reading?

This is an average. I did a shot per shot reading this morning (attached) and If I am not mistaking I am well above the 2.32joules thus will have to remove some of the spacers on the spring..

[Shaydee]

Should be able to tighten that consistency up a bit as well, a 15 fps spread isn't the worst I've seen but I'd expect more like 3-5 if everything is tip top. Also again, run the BB weight you intend to use through the chrono and measure the energy on that not on .25s . . . unless for some reason you're going to use .25?

[Adolf Hamster]

also worth noting that fps variation is gonna seem worse with lighter ammo.

 

15fps on a bolty doesn't sound right to me, i'd be wanting to see single digits on an aeg let alone something that's meant to be even higher precision.

[Skara]

1 hour ago, AP77 said:

Thanks Skara, would this help if I make the piston lighter ...? 

In my testing I have found that a lighter piston actually increases Joule Creep, at least it does on my build. A heavier piston only killed the energy output with 0.2s but the Joules on 0.4s stayed the same

 

Either way, 15 fps is roughly 3 m/s deviation, which per se isn't too bad but as a sniper you want all the consistency you can get to have repeatable shots.

Check each individual "step" in air seal:

• Piston head to cylinder;
• Cylinder to Cylinder head;
• Nozzle (on top of the cylinder head) to hop rubber lips;
• Hop rubber to barrel.

The first two are easy to check, with just the cylinder in the receiver (so everything else, stock, barrel removed) cock it, press your finger on the nozzle and pull the trigger, the piston head (where the o-ring sits) should travel just past the port and stop, being held back by the compressed air inside the "closed" portion of the cylinder. If it doesn't, there is a possible air leak around the piston head o-ring or the cylinder head.

Use proper lubricant and not PTFE, please.

 

Nozzle to hop rubber lips: gun upside down, place a piece of tissue paper where the bb feed hole is and fire a shot, if it flies away it means that there's air escaping from the rubber's feed lips. Either replace the hop rubber or wrap (and then superglue) a small portion of heat shrink around the nozzle end.

 

Hop rubber to barrel: hardest to test, it's always good to wrap PTFE where the rubber overlaps the barrel. Some people wrap until the bottom channel of the barrel is covered (so say 3-4 centimetres from the end of the rubber). The hop chamber will compress the PTFE enhancing the seal, don't overdo it or you won't be able to close the chamber anymore.

 

Some hop rubbers, like the Maple Leaf MR-Hop, are known for not giving good air seal (GBB/VSR version only, the AEG version is super air tight), but in my experience with them the leak is so consistent that it becomes irrelevant.

 

Once you sort these things out the fps deviation will drop considerably and test the seal with the gun fully assembled (by doing test n.1 but with your finger over the inner barrel this time).

 

I've read of people getting less than 5 fps in deviation in some cases and it's pretty impressive tbf, given the shit tolerances of our toys..

[Adolf Hamster]

4 minutes ago, Skara said:

A heavier piston only killed the energy output with 0.2s but the Joules on 0.4s stayed the same

 

isnt that exactly joule creep?

 

the theory i have with the heavy piston thing is that the inertia of the piston prevents it travelling fast enough to get full velocity on lighter ammo.

 

it explains why you don't see it on aeg's as aeg piston weights tend to be lighter to prevent pme.

[Skara]

5 minutes ago, Adolf Hamster said:

isnt that exactly joule creep?

 

no that is deliberately cheating the chrono on those sites that only chrono on fps (or m/s) on 0.2s..

 

Joule Creep is about the (whoever has some education in science please don't read) process of energy transfer that happens inside our guns.

What happens is that there is only a very limited space (the barrel) in which the system can transfer its energy to the BB. A lighter BB will receive a higher "initial" amount of energy but it leaves the barrel so quickly the system doesn't transfer much energy, whereas a heavier BB that will stay in the barrel for longer will receive way more energy.

(you now have autism and won an extra chromosome, but don't blame me, I warned you)

 

At least that's my understanding of JC

 

[Adolf Hamster]

5 minutes ago, Skara said:

no that is deliberately cheating the chrono on those sites that only chrono on fps (or m/s) on 0.2s..

 

Joule Creep is about the (whoever has some education in science please don't read) process of energy transfer that happens inside our guns.

What happens is that there is only a very limited space (the barrel) in which the system can transfer its energy to the BB. A lighter BB will receive a higher "initial" amount of energy but it leaves the barrel so quickly the system doesn't transfer much energy, whereas a heavier BB that will stay in the barrel for longer will receive way more energy.

(you now have autism and won an extra chromosome, but don't blame me, I warned you)

 

At least that's my understanding of JC

 

 

yeah that's my meaning having a higher energy output with a heavier weight is what is meant by joule creep.

 

it can be used to cheat chrono for sure, although generally it's an accidental side effect of how our pews work (insofar as how it applies to constant pressure systems such as gas/hpa).

 

i'm not sure what advantage a heavier piston has in a bolty aside from intentionally creating joule creep, maybe it's a noise thing with a heavy thud being preferable to a light slap when the piston hits end of travel?

[AP77]

10 hours ago, Shaydee said:

Should be able to tighten that consistency up a bit as well, a 15 fps spread isn't the worst I've seen but I'd expect more like 3-5 if everything is tip top. Also again, run the BB weight you intend to use through the chrono and measure the energy on that not on .25s . . . unless for some reason you're going to use .25?

it was only to get closer to what I thought would be the site testing with the .2 BBs

10 hours ago, Skara said:

In my testing I have found that a lighter piston actually increases Joule Creep, at least it does on my build. A heavier piston only killed the energy output with 0.2s but the Joules on 0.4s stayed the same

 

Either way, 15 fps is roughly 3 m/s deviation, which per se isn't too bad but as a sniper you want all the consistency you can get to have repeatable shots.

Check each individual "step" in air seal:

• Piston head to cylinder;
• Cylinder to Cylinder head;
• Nozzle (on top of the cylinder head) to hop rubber lips;
• Hop rubber to barrel.

The first two are easy to check, with just the cylinder in the receiver (so everything else, stock, barrel removed) cock it, press your finger on the nozzle and pull the trigger, the piston head (where the o-ring sits) should travel just past the port and stop, being held back by the compressed air inside the "closed" portion of the cylinder. If it doesn't, there is a possible air leak around the piston head o-ring or the cylinder head.

Use proper lubricant and not PTFE, please.

 

Nozzle to hop rubber lips: gun upside down, place a piece of tissue paper where the bb feed hole is and fire a shot, if it flies away it means that there's air escaping from the rubber's feed lips. Either replace the hop rubber or wrap (and then superglue) a small portion of heat shrink around the nozzle end.

 

Hop rubber to barrel: hardest to test, it's always good to wrap PTFE where the rubber overlaps the barrel. Some people wrap until the bottom channel of the barrel is covered (so say 3-4 centimetres from the end of the rubber). The hop chamber will compress the PTFE enhancing the seal, don't overdo it or you won't be able to close the chamber anymore.

 

Some hop rubbers, like the Maple Leaf MR-Hop, are known for not giving good air seal (GBB/VSR version only, the AEG version is super air tight), but in my experience with them the leak is so consistent that it becomes irrelevant.

 

Once you sort these things out the fps deviation will drop considerably and test the seal with the gun fully assembled (by doing test n.1 but with your finger over the inner barrel this time).

 

I've read of people getting less than 5 fps in deviation in some cases and it's pretty impressive tbf, given the shit tolerances of our toys..

Thanks for the tips :

Piston head to cylinder test : the piston was held by the pressure very well / did not travel all the way down and even after 15s there is a considerable amount of pressure left in the cylinder = PASS
Nozzle to hop rubber lips test : the tissue did not moved at all = PASS

After the above I did a shot-to-shot comparison with 0.43 BBs and found 5.8fps difference over 5 shots which seems not bad considering the comments above (?) therefore I did not do the other tests, although I did fire with a finger at the end of the inner barrel and had the same result as the first test above (the cylinder held pressure) thus a PASS ! 

Many thanks to all of you for your help with this, this is greatly appreciated