One for the techs to ponder....

[Prisce]

So today over at AP in billericay I was using my TM Scar Recoil, completely stock, with ASG Blaster .25g BBs.

Chroned before the game got 295fps on the .25s, cushty.

During the warm up game, got spot checked, no worries I know I'm fine, put it up to the chrono, 327fps, dafuq, legal limit is 315fps on .25s.

Took it back to safe zone, completely perplexed, tried it on the other chrono, same result...hmmm, took the BBs out tried another bottle... Same result... Dafuq?

Changed mag, boom 295fps.

So The mag that was over is brand new, the one that is perfect is used slightly.

How on this crazy planet is this possible?

Everyone on site had no idea. I decided to empty the mag and give it a bit of a lube and put it into the magwell and remove it a few times to try and "rough it up", this worked.

But my limited knowledge of these toys we play with tells me that this should be impossible, there isn't that much of a seal between the mag and hop chamber is there?

 

[sp00n]

Probably the mag pressing on the hop may be improving the nozzle/hop seal

 

[Prisce]

But 32fps just on a mag seal? Really?

 

[jcheeseright]

The difference there is EXACTLY what would happen if the mag that shot 'over' had .20g BBs in.  1 joule both times. 

Double check that the magazine didnt have .20g in it, that's the most likely cause of this. 

 

[Samurai]

It is pressing the hopup into the gearbox more or less. This shouldn't happen.

 

[proffrink]

The difference there is EXACTLY what would happen if the mag that shot 'over' had .20g BBs in.  1 joule both times. 

Double check that the magazine didnt have .20g in it, that's the most likely cause of this. 

I thought it was the opposite. I.e. crono-ing at home with lighter BBs will result in Joule creep with lower-weight BBs, but this is the other way around :S

 

[Sitting Duck]

Seals blowing on one mag (old mag under site limit)

Perfect or non-blowing seals on other mag = over site limit

You are under the limit most likely coz the gun is a bit hot but poor seal drops the fps

Had a gun that was shooting 360fps with hardly any deviation at all

Took a piece of heatshrink - medium width (maybe 20mm/25mm wide used to insulate mosfet)

Punched a 9mm hole in it and stretched it over hop, fitted to M4 & chrono'd  - 342fps

Just enough to scrape under chrono 350fps limit

Another time I fitted a hop up to a gun and got say 240fps - wtf ???

another hop and similar barrel - 335fps

first hop isn't sealing - poor bucking lips or just incompatible hop or way it is all installed

Sounds bollox but ask anybody that  who fitted a nice pro-win hop unit then got crap feed issues

There is fine line of stuff working/not working that we all take for granted

On v2's you only got about a 7mm to 7.5mm nozzle "window"

Where this falls determines how perfect it feeds & seals

Just enough retraction to feed a bb just slipping in front of nozzle

Enough return that nozzle seals against bucking without blowing

The moment you change or alter any crap in the mix you run the risk of screwing with stuff

Perhaps - just perhaps your gun is bang on limit or just over if nozzle seals 101%

You old mag, the way the feed tube sat, or how slightly loose the mag allowed the seals to blow

New mag might be a smidge different and kept the seal better increasing the fps

Sounds like the new mag might have "worn in" a little so no biggy

but if not you could try a strip of velcro/duct tape in mag-well at rear or at rear of mag

This will effectively push the mag a whisker forward, which when it engages with hop

will ever so slightly pull the hop unit a hairline whisker forward too

This in turn will weaken the seal of nozzle to bucking lips  & under compression blowing to lose fps

This may sound complete bollox but is about the only real explanation

Your gun is very close - perhaps a smidge warm and some mag help the seals and others blow slightly

 

[jcheeseright]

I thought it was the opposite. I.e. crono-ing at home with lighter BBs will result in Joule creep with lower-weight BBs, but this is the other way around :S

Theres no joule creep occurring here. It's 1joule with both weights. 

327 on a .20 = 0.99j, 295 on a .25 = 0.99j.  

He's just mixed up his ammo, nothing to do with seals or mag pressure or any of that. 

Occams razor! 

 

[proffrink]

Ah, I see what you mean now.

 

[Prisce]

Theres no joule creep occurring here. It's 1joule with both weights. 

327 on a .20 = 0.99j, 295 on a .25 = 0.99j.  

He's just mixed up his ammo, nothing to do with seals or mag pressure or any of that. 

Occams razor! 

If this is the case then it is a dodgy batch of BBs.

1)The mag was new, no BBs through it.

2)I only took a brand new bottle of .25s with me.

I thought this on site, and did look at the bottle to see if there was a colour change in BBs to see if this had happened, but because there wasn't I ruled it out, I didn't believe a manufacturer as big as ASG would make that sorta mistake.

This is one of the reasons I asked. We went through all the motions on site, checking chronos, BBs, hop everything, the only thing that was different was indeed the magazine which is what lead me to believe it was the seal.

So do you reckon it was a bad batch of BBs?  If so I will contact ASG.

 

[Sitting Duck]

Took it back to safe zone, completely perplexed, tried it on the other chrono, same result...hmmm, took the BBs out tried another bottle... Same result... Dafuq?

Changed mag, boom 295fps.

Is why I liked the mention of mixed bb's BUT OP  said he tried ANOTHER BOTTLE but now says he only took a new bottle

Thing is before the site pi$$ed itself - they could have ejected half a dozen bb's from the suspect mag

Then speed loaded some KNOWN 0.20's in there like they do at Mall on certain bespoke mags/gbb mags etc...

Then chrono on their half a dozen known 0.20's to ensure the chrono is reading genuine 0.20's etc....

Admittedly it is the owners responsibility but the site "could have" performed this check with their 0.20's

Then they would have known for sure if gun was chrono-ing on 0.20's and for sure if it was hot etc....

Guess they can weigh bb's but f*ck that crap in a field or whatever and it isn't their job ffs

but empty mag say half a dozen bb's, speed load a few of site's 0.20's and all sorted

reducing errors or different chrono results

Do not for one minute think anybody was trying to cheat chrono or anything like that

But think site could have checked with their own 0.20's like the Mall does

 

[Prisce]

Yes, I took one bottle, friends let me try theirs from same make as one of my friends had issues with his sniper creeping also so had come back to safe zone with me.

I have noticed people get very pinnickity on here recently. I didn't want to write a novel with every step I took on the day, just wondered if there was something I and the site hadn't considered.

Also AP work on the weight your using during game to chrono with because of Joule Creep, it was only found out due to spot checking, and they knew it wasn't intentional as we go there almost all the time and have never been over before.

 

[jcheeseright]

Thing is there's no reasonable way a magazine can affect the air seal of a gun, once the BB has come off the top and the nozzle is forward the magazine just exists in the magwell. 

For a different magazine to cause a gun to shoot the exact amount more to give a reading that coincides perfectly with the difference between 0.20g and 0.25g is unrealstic in the extreme. If it were gas I'd absolutely be looking at the magazine but in an AEG, especially with the design of the hop up in a Marui SCAR (super rigid, perfect air seal out of the box). 

 

[Sitting Duck]

Yes, I took one bottle, friends let me try theirs from same make as one of my friends had issues with his sniper creeping also so had come back to safe zone with me.

I have noticed people get very pinnickity on here recently. I didn't want to write a novel with every step I took on the day, just wondered if there was something I and the site hadn't considered.

Also AP work on the weight your using during game to chrono with because of Joule Creep, it was only found out due to spot checking, and they knew it wasn't intentional as we go there almost all the time and have never been over before.

jcheeseright made a valid point as it could appear to correlate to a mix of 0.20's & 0.25's

I tried to explain what it could be and still maintain that lips can blow and fps drop etc....

Site could have used their 0.20's speed-loaded or hand loaded into both mags and we might know more

Never meant to have a go - stuff rarely gets told 101% accurately or so clearly it can never be misinterpreted

so I guess it was just one of those weird things that we are unlikely to get to the bottom of

 

[Sitting Duck]

Thing is there's no reasonable way a magazine can affect the air seal of a gun, once the BB has come off the top and the nozzle is forward the magazine just exists in the magwell. 

For a different magazine to cause a gun to shoot the exact amount more to give a reading that coincides perfectly with the difference between 0.20g and 0.25g is unrealstic in the extreme. If it were gas I'd absolutely be looking at the magazine but in an AEG, especially with the design of the hop up in a Marui SCAR (super rigid, perfect air seal out of the box). 

it is possible in the way mag #1 feeds great but another mag #2 doesn't feed well

the front of nozzle doesn't clear the mag #2 to just chamber a bb

but a bit tape in magwell fixes any wobble and pushes or aligns better so both mags feed better

Same principle "could" apply to a variation in fps between two mags sealing great/not so perfectly

End of the day - if the site had plopped their 020's into both mags the matter would have been clarified straight away

just 4 or 6 0.20's then chrono on both mags would have been a worthy consideration in clearing this matter up

Didn't say if was a scar H or L - could have just seen if a regular stagmag could have fitted or plopped 0.20's in there

 

[Prisce]

Apologies if I seemed blunt earlier, bad day.

I do appreciate all the input, it was the reason I started the thread. 

Im still not actually sure what caused the issue, I thought it was the mag seals, but I agree with @jcheeseright I don't think it's possible, and it's more likely the BBs.

Has anyone had issues with BBs being sold as one size and actually being another? Or mislabelled  bottles?

 

[stig]

Thing is there's no reasonable way a magazine can affect the air seal of a gun, once the BB has come off the top and the nozzle is forward the magazine just exists in the magwell. 

For a different magazine to cause a gun to shoot the exact amount more to give a reading that coincides perfectly with the difference between 0.20g and 0.25g is unrealstic in the extreme. If it were gas I'd absolutely be looking at the magazine but in an AEG, especially with the design of the hop up in a Marui SCAR (super rigid, perfect air seal out of the box). 

 Actually, there is. 

As the hop feed tube is usually floating, the mag can move it away from the nozzle when inserted. My Bolt does just this - to the order of about 2mm!

Manually feeding bbs gets you over 350fps  - with a mag in, that becomes 310! Adding o-rings to the front of the hop minimises this movement, but you need to be careful that the mag still feeds. By doing this I added another 15fps!

So yes - mags can make a difference.

 

[jcheeseright]

 Actually, there is. 

As the hop feed tube is usually floating, the mag can move it away from the nozzle when inserted. My Bolt does just this - to the order of about 2mm!

Manually feeding bbs gets you over 350fps  - with a mag in, that becomes 310! Adding o-rings to the front of the hop minimises this movement, but you need to be careful that the mag still feeds. By doing this I added another 15fps!

So yes - mags can make a difference.

Not in a TM SCAR where the hop unit is on rails. 

 

[stig]

Not in a TM SCAR where the hop unit is on rails. 

Apologies - I stand corrected. Hadn't realised you were specifically referring to the TM Scar.

That'll learn me

 

[Sitting Duck]

As I said - if the place had speedloaded a few 0.20's or a mag with known 0.20's

Then the matter could have been clarified very quickly

One thing that impressed me the most was the Mall's chrono methods

Mixed up bb's can/do happen, if they do then I guess keep for support gun, cqb pistol or just bin them

(not as if they are made from highly expensive material)