Need a second opinion - accurised AEG consistency problem

[RSM]

I was at an outdoor range today and was trying to set my scope to be able to engage a torso sized target at 65m and was experiancing problems with both consistency in elevation and windage dispite there being barely any wind, my AEG based set up is as follows (with relevance to consistency/etc)

 

PDI 6.01mm 520mm inner barrel with tape wraps to help snugness in 1 piece outer barrel, runs 30mm short of a silencer.

 

ICS M4 hop unit - drum type like in G36/G3/PSG/AUG

 

Guarder 70 degree hop rubber, worn in by running 2 highcaps past it. Has a white H hop outer

 

Guarder *sniper level* spring - fps variation is +/- 4fps

 

A majority of other parts have been changed from stock but aren't really relevant to the propulsion consistency

 

Ammunition is Xtreme .3s, I used their .28s in a Warrior 1 stock and could hit a torso all day with confidence at 50m with it when it was coming out the box at 480w/.2s, my AEG sniper runs a tad hotter than that hence the use of .3s. I believe the make the BBs to 5.96ish diameter whereas for example SGMs are 5.92mm - I'll elaborate on this later.

 

I've fitted an active braking mosfet to ensure the piston/tappet go through the same range of motion each time the gun is fire.

 

I just want some second opinions on what might be the problem - I've got some BBs screaming off up to the target fine, others swinging left and right, others plopping short and others flying over the frame I've set up.

 

Two things I've read that could be why I'm having the problems I am:

 

Too tight a barrel - There is possibly insufficient clearance between BB and barrel and because BBs have miniscule differences between them its causing unique cases of the BB's travel down the barrel being affected. The solution would be to use smaller ammo, or fit a looser bore barrel. Interestingly, I had more confidence in taking shots with my Warrior 1 stock with its 6.04/6.08mm (was never confirmed but these are the numbers floating about) barrel and I've seen a PSG upgraded with just metal bushings and a 200% spring hit things accurately at 60m

 

FPS variation leading to elevation differences at range - Read this in another topic and at first it made sense but then someone who does .22 target shooting told me that the maths for 1fps variation leading to a 12inch elevation difference at 70m were most likely wrong so I'd be surprised if this is the case.

 

[1-hit-1-kill]

has this been successful before? newly built system?

from my experience i've had some inconsistancies with guarder springs..

~ long tightbore's caused issues for me, im perfectly happy with my aps2 with a 340mm std barrel hitting people easily over 60m's.

~ shoot a bit more with the hop because i've always thought they take more than 2 mags to settle in.

~ try some SGM's out just to confirm its not bb problem.

~ cleaned? (obvious and silly but you know )

 

How far are you off by with the inconsistancies? if its miles off i would've thought theres issues if its slight miss i would've thought it might be bit of wind playing up aswell..

 

Unfortunatly upgrading isnt an exact science so i've given you what i would do if i had that problem, dont want to clutter your thread with foobar theories or statements. Hopefully someone more experienced will come along and help you out a bit more HTH anyway.

[Trasher]

Guarder *sniper level* spring - fps variation is +/- 4fps

Too high for a sniper rifle...

 

Ammunition is Xtreme .3s, I used their .28s in a Warrior 1 stock and could hit a torso all day with confidence at 50m

I can hit a 50m torso sized target all day with my stock, 300fps CA M4 CQB-R...

 

My tips:

 

- Test better BBs (.29 SGM), the longer the range, the more difference between BBs,

- Degrease the hopup/barrel with alcohol, use MINIMAL grease inside cylinder

- Experiment with different (more thicker) O-rings for the piston head

- Shoot 25m and 50m groups (<10cm at 25m, <20cm at 50m is your target number)

[1-hit-1-kill]

Edit: lol sorry cant get head on straight,

 

Yes +- 4fps is lots of difference in fps for a sniper rifle.. (thats 300-308fps ya?) typical guarger.......

[RSM]

Perhaps the variation is the problem - but I don't think that is something that can be dealt with without modifying the gun to precock PSG-1 style (the one I chrono'd had an FPS variation of .7fps) so its something to look into.

 

The barrel is clean, as is the hop rubbber, its going to be a fair while before I get a chance to get this out onto a range to tinker with though I'll bear those numbers in mind

 

And yeah, I have an M4 too that can effectively engage out to 50m which is a bit of a kick in the balls when you've built something that _should_ be able to hit a torso at 70m but gives a 2 foot spread at 60m.

 

While I'm here, what do snipers typically see through their scopes BB trajectory wise? Having shot through someones sniper they had set up to do 80m shots the BBs seem to just fly up and out of the scope before dropping back down - is this typical? When I used to use the L96 I had a slight rise over the horizontal lines of the crosshairs before dropping back down onto the target. Overhopping for range in snipers doesn't seem an incredibly precise way of going about things.

[1-hit-1-kill]

lol overkill..! i normally see perhaps a slight raise but not something out of view completely. if i wanted distance i would aim higher rather than have strong hop. (one time i shot someone well over 100m purely because he stood there in the open thinking "oh im far enough away,no-one can touch me", completely ignored me so i took pot shots aimed about 2-3ft above his head lol, that was classic! to see his expression on his face! )

 

Another thing, im familiar with MOSFET's but not familiar how the application works in an AEG, but im sure with a bit of tinkering you can have it set up much like the PSG1 where it does a pre-cock thing.

 

Get a systema/pdi spring and you'll have joy

[infected]

Another thing, im familiar with MOSFET's but not familiar how the application works in an AEG, but im sure with a bit of tinkering you can have it set up much like the PSG1 where it does a pre-cock thing.

 

Nope, can't be done with just a mosfet. You need something that can sense the position of the sector gear and something to handle the timing. So really you need a microcontroller for that.

 

Or, you can just modify the pin that hits your cut off lever and have a precocked setup like the PSG1. Much easier to do and much less expensive.

[RSM]

Used to have Systema in my M4 - 10fps variance - no thanks

 

Tried PDI - Generally wasn't impressed, consistency was comparable to the Guarders.

 

The reason for the mosfet is to simply eliminate overspin, so the system has to always start from at rest and with the tappet plate fully foward, so its putting the AEG in the same state a bolt action is after a shot is fired ie all parts forward, then on pulling the trigger the system is recocked, BB chambered and fired.

[AnotherJesus]

Typically, I'd blame the hop rubber. And I see no problem to in this case. You're talking colossal FPS for an AEG. I'd suggest you try a Systema rubber. Or if you can afford it, a KM RH75. I know it's a little fancy, but I also know they can cope with FPS up to and above 470fps. As tested through my friends PSG-1. I'm not to sure about the guarder 70 degree bucking, but I know the Guarder enhanced silicone hop bucking (the see through thing) was completely useless above 425 fps in an M4 I've been playing with. That was an old rubber though. So I might be wrong. Still, I'd consider the KM RH75 an upgrade anyway. They give great accuracy in my experience. Well worth a try.

 

As for the BB flight. I tend to slightly over hop mine. I get it to the point where the BB is flying strait and level. Then give it a nudge up. So it rises just a little way, towards the end of the flight. Giving it another 3m roughly.

 

Edit: On the FPS variation, do you have a bearing spring guide? They can make a big difference. As I found in my VSR. The spread dropped from 6fps total spread, to 1fps spread.

[RSM]

Tried Systema at an earlier range test in a less controlled environment and the spread was similar, perhaps it is a bedding in issue but I thought Systema's were even softer than Guarders?

 

I'll see if I can source the RH75 and perhaps the Prometheus Hard and see how it goes .

 

I have both a bearing spring guide and piston head, I might just have to throw a few more parts at it - just a bit of a nuisance that the budget as it were for this gun has run out for now.

 

 

[AnotherJesus]

For some reason my head is screaming no at the idea of a Prometheus hard bucking. Never had experience with them myself though. Has anyone here?

 

It's probably that I've heard one bad story about them along time ago. So I'm not gonna say you should pay any attention to me. Yet waiting for a third party, with first hand experience, is always a good idea.

[RSM]

Heh, to be honest I have heard the same, and I've also found a source for the KH75...do these things work with a H hop? I can't see why not seeing Bushman (I think) has the VSR version of KH55 in his VSR (which has a H hop applicator) and was getting shots out to 70m with it.

 

I am tempted to drop a Madbull/Prometheus 6.03 in the 450-500mm length range to see if a slightly looser bore and shorter barrel can help

[AnotherJesus]

I too have used the wide use KM RH55 in a VSR. It's worth noting though, that all hop chambers that can take that rubber, have a 2 prong system. So it would have been designed to be used that way. Not so in an AEG. But if it doesn't work, the rubber comes with it's own spacer anyway. Try it, find out.

[RSM]

Ah thats the thing, by using the Big Out H hops you effectively convert your hop application arm into a two point of contact thing (Sorry if that seems patronising).

 

Perhaps it is indeed a final bit of fettling thats needed to get this thing up to speed - and then my next project will be to build a moderately externally pimped VSR and we'll see just how much easier/cheaper it will have been compared to this

[1-hit-1-kill]

Nope, can't be done with just a mosfet. You need something that can sense the position of the sector gear and something to handle the timing. So really you need a microcontroller for that.

 

Or, you can just modify the pin that hits your cut off lever and have a precocked setup like the PSG1. Much easier to do and much less expensive.

 

i thought they did.. so mosfet litterally a fast on switch.. pfft.. how poo.. i've recently done a whole module how magical how mosfets can be so i thought that was being implemented into AEG's. I thought there was a magnetic sensor of some sort on the sector gear then mosfet to control release of spring etc.. suppose PIC's will be more versitial..!

 

 

 

 

Systema and pdi brand in general i feel very comfortable with generally.. as for barrels, if you have a shorter one, try it. 450mm would be sensible.

 

 

[Trasher]

bit of a kick in the balls when you've built something that _should_ be able to hit a torso at 70m but gives a 2 foot spread at 60m.

70m demands the best BBs money can buy, so don't expect good performance.

 

 

While I'm here, what do snipers typically see through their scopes BB trajectory wise?

Depends on the scope's FOV, magnification... I prefer to zero all my rifles to 50m (okay the Asahi is set to 75m) and compensate for longer shots. I don't like overhopping, it makes the trajectory less predictable (problem when shooting partial targets sticking out from cover, shooting through cover, shooting close range targets laying prone).

 

[RSM]

Its almost amusing how much you are pushing for the .29 SGMs, I understand they are very good but considering this is airsoft its not like I'm having to make a choice between Eley Tenex and Sport. While I'm not saying every BB is as good as another I find it hard to believe that SGMs are _that_ good, their light weight puts me off too, I would rather have a heavy BB and perhaps a max effective range of 60m with my sights set at 50m and be able to hear the BB hit the target rather than using a light BB that has lost so much energy by the time its got to 70m the person on the receiving end can't tell if it was a BB hit or a twig snapping.

 

By no means am I intending on causing offense, nor am I trying to fly in the face of your practical experiance, but having read a few accounts of people's rifles not liking SGMs or not happy with the impact recognition/wind susceptability due to the lighter weight and the fact SGMs seem to getting more and more inconsistent over time (read a batch test on gungineer which showed them increasingly failing the stated tolerance) I am finding it hard to accept them as the wonder BBs people make them out to be, nevertheless I'll probably end up buying a box of SGMs and some uncoated .34s and .43s and seeing what the rifle likes best.

[1-hit-1-kill]

my aps2 uses around 0.28/0.29 for most effective results for what i use. I push them because i've had good experience as possibly with others on here too.. £10 for 600 or whatever does seem v pricy but theres probably a reason for that... however i know my gun now and use G+P 0.28g's for similar but not perfect performance, fraction of the price, i can live with an rare occational miss. My/our point is is that its a very consistant good benchmark.

 

At the end of the day to get something Perfect you need to try everything regardless what people tell you, airsoft isnt a very scientific thing unfortuntaly and you need to find whats best suited for your specific set-up. We're just giving you pointers hopefully in the right direction, scientific tests (as nice and impressive as they seem) isnt worth as much as a good few guru people with 1st and experience giving advice imo. (im not a airsoft guru mind lol )

[RSM]

Totally agree, it might be a fair while before I get back to this thread with any conclusive information but the information has been useful so thanks for everything so far.

 

One last question - what is a good o-ring size to experiment with? I keep getting #14 cropping up in my head...

[infected]

a #14 is the stock replacement size from the hardware store. I've used them in my guns with no problems.

[Trasher]

Its almost amusing how much you are pushing for the .29 SGMs, I understand they are very good but considering this is airsoft its not like I'm having to make a choice between Eley Tenex and Sport. While I'm not saying every BB is as good as another I find it hard to believe that SGMs are _that_ good, their light weight puts me off too,

We push the SGM because some of us tested the available BBs extensively (chronoing, micrometering, shooting long range groups, bore test, etc). I tested more than 20 different BBs from .28 to .87 ... Like it or not, the SGM is the most consistent plastic BB available on the market at the moment... Weight means nothing if the BBs is crappy and inconsistent otherwise (like the Straight/Digicon .36s and .43s).

 

The uncoated Straight .36s can be very accurate IF they're hand picked and checked. Too bad they're discontinued now, like all other Straight/Digicons.

 

To simply put, SGMs pretty much beat anything else I tested up to 70 meters with 550-600fps rifles (different VSRs, Atoz SVD, Maruzen L96)... For very windy games, I use the aforementioned .36 Straight, but those BBs have a tendency to can ruin a perfectly set up shot with random flyers over 40-50 meters. With the .29, I get far more one shot kills.

 

The best "bulk BBs" I tested:

 

- Blaster Pro Invisible .28 (dark green)

- Guarder HPM .28 (white, plastic bottled)

[banjo]

<br />For some reason my head is screaming no at the idea of a Prometheus hard bucking. Never had experience with them myself though. Has anyone here?<br /><br />It's probably that I've heard one bad story about them along time ago. So I'm not gonna say you should pay any attention to me. Yet waiting for a third party, with first hand experience, is always a good idea.<br />

 

So what was the story? As I've just bought 1 (already had it before I started reading this thread) and would like to know if I've waisted me cash and to save me waisting me time aswell by fitting it.

[AnotherJesus]

Well, the story is, "poor accuracy ensued." Like I said, I don't know if it's a story or the truth. I don't even remember where I heard it.

[banjo]

I'll try it in my 350fps SOC16 first then before I give it a go in my higher powered M14. If there are any issues I will report back

[greg]

that the maths for 1fps variation leading to a 12inch elevation difference at 70m were most likely wrong so I'd be surprised if this is the case.

 

 

I have no idea about the maths, but I spent a (almost wind free) day firing at targets at various ranges to try & understand trajectory. Did about 2000 rounds through a vsr that day & my shoulder was buggered, but boy did I learn!

 

Firing through a chrono at targets over 60m I observed a very specific pattern, that +/-1fps variance did give roughly 1' elevation variance. This was with sgms at around 500fps; 499-501.

 

I have not tried this with guns that vary more, but I believe a 4 fps variation (around 500fps) will be responsible for elevation variation of at least a few feet at 70m. Depending on the set up & bb.

 

 

Greg.