[Guest]

Ok well I have an m4 dmr, and my brother has an ak47. They preform similar to each other but the ak47 has more range at lower fps. Here is the parts list:

I am only listing barrel assembly parts, fps, and both results are with matrix .3g

M4 dmr:
1.prommy 550mm 6.03 barrel(barrel spacers added)
2.prommy soft bucking
3.white h nub(glued to hopup arm)
4.metal no name hopup chamber (gears for hopup selected for the least amount of play, and o-ring between chamber and the gearbox, and hopup arm shimmed)
5.perfect compression on a matrix m125

AK47:
1.stock g&g barrel
2.prommy soft bucking
3.stock metal chamber
4. white h nub(glued down)
5.perfect compression

So I think that the more stable ak47 hopup is the reason the ak preforms better at lower fps, so give your input. Am I missing something about why this is so? Also is there any way my m4 could be more accurate that you guys can think of?

Also if there is any grammar issues let me know and ill fix it

 

[Cheese Man]

You need a shorter barrel on the M4. 550 is REALLY long for an AEG. Most that I have seen work best at around 450 or so. The stock length for the barrel is usually best. Ideally, you perform some calculations to determine what the optimum length should be, in the ratio of Cylinder:barrel::1.25:1, or something along those lines.

 

[Guest]

Well I am using a full cylinder. I get what your saying but alot of people say that a 509mm is the longest you should go and a 550mm is only 41mm longer.

 

[metallicafatcat]

It's actually 1.7:1. If you didn't change your cylinder your going to deal with underbalancing issues and will face "suck back" which is really a myth.

 

[Cheese Man]

^Really? Okay, I just didn't know exactly.

By the way, 41 mm makes a world of difference. My spotter had a 600 mm Inner barrel in his DMR, we put in a 650 (50 mm longer) and his range went from about 130 feet to over 230 feet. Remember, though, he had a PSG-1 cylinder in his gun. With yours, about a 509 is the best it is going to get in terms of barrel length. A nice prommy or madbull V2 6.03...

 

[metallicafatcat]

I'm calling bullshit, there's no way you gained an addition 100' o range with the addition of 50mm. It's nearly physically impossible to get that kind of distance gained with such a little adition of barrel length.

 

[hoggie]

I'm calling bullshit, there's no way you gained an addition 100' o range with the addition of 50mm. It's nearly physically impossible to get that kind of distance gained with such a little adition of barrel length.

Eh, maybe he wasn't getting the full extent of his compression, or it wasn't the right fit of the barrel. Some variables may have happened when he switched the barrel. It *could*, like I said could happen. Switching barrels may have caused him to align the bucking etc. better aswell.

 

[metallicafatcat]

It could as you said, but there would have to be so much wrong with the system that it would be impossible to not detect it unless your a monkey.

 

[dulas]

I will suggest you try a little lighter BBs, the more heavy the BBs so you want more air from the cylinder, so the 17:1 changes according to weight use

Try to 0.28 or 0.29

Also wash the BBs.

 

[Guest]

Well I am a bit confused because of the off topic posts, but when I used .3 compared to .25 i got significantly greater range. Also my full cylinder should be fine for my 550mm barrel right? I also got same ranges as the ak47 when i removed the internal mound in the bucking but it ripped really quick which got replaced. I will tinker with the hopup later but actually there is a black h nub in the ak47 but isnt the white one better? I will also try a really crappy 450ish barrel i have spare to see if the range improves, and when I washed my bb's I only got greater affect from the hopup (required less to lift the bb).

Just retested both guns and there is not a difference in range. So my new question is how do you guys think i can get more range? Accuracy is phenomenal in my m4.

 

[bobgengeskahn]

Let me know what kind of change you get when you change barrels. I am in the middle of a project on my new DMR (SL9) that I picked up. I swapped over a 6.03 x 550?mm inner barrel from my old DMR and am a little dissapointed in the range.

The set up before was on a G36:
Stock cylinder with the hole plugged (decent compression for a psudo full cylinder effect)
JBU piston/piston head - metal
Bravo Helical high Torque gears
Bravo Cylinder head
Guarder Infinite torque motor
Modified stock tappet plate
Modify nozzle
Metal spring guide with bearings

Stock Hop up
Guarder black bucking
Prommy 6.03x550mm polished barrel
Teflon mods
Stock nub


The SL9 after I broke down both guns and turned the G36c back to a C:

CA Bore up full cylinder (atleast I think its a bore up, I had to replace my O-Ring to get compression)
JBU piston/piston head - metal
Bravo Helical high Torque gears
CA Cylinder Head
Guarder Infinite torque motor
Stock Tappet plate
CA nozzle
Metal spring guide with bearings

Stock Hop up
Guarder black bucking
Prommy 6.03x550mm polished barrel
Teflon mods
Stock nub

The first time I fired the compression was all messed up and BBs were dropping at 20 - 80 ft. Replaced the Oring with a 15/16 OD and the seal is fine now. I test fired after doing this instal and the range is consistant, but is far shorter than what I expected, and shorter than it was previously in the G36c with the same spring. The SL9 is shooting decently hard with 0.3s, but the range just isn't there for some reason; its only goin about 150'-200'.

TL;DR: Did some internal swaps and lost range with nearly identical setups save the cylinder. Wondering if a shorter barrel is what I need too...

 

[metallicafatcat]

Possible with the longer barrel and the incredibly overweight piston your losing range.

 

[bobgengeskahn]

I was running the same piston, head and barrel in my last set up and I was easily getting an additional 30-50' out of it, I may try cutting up the piston to lighten it up, but its just so damn pretty with the removable metal teeth and all. The only new parts in the air system were the cylinder and the cylinder head, but the seals are all good, so I'm confsued.

I've contemplated getting a shorter barrel anyway, just because the 550 is too long for the stock outer barrel, but I'm debating how much shorter since I've never used a full cylinder before....

 

[Guest]

Well to begin the sl8 is not boreup kit (I have one). Though I need to measure range it seems I have the same issue with my guns. They do not seem to get over what looks like 200ft with what others have used with greater affect. The barrel length didnt affect the range after recomparing the ak47 and my m4. So can someone answer why we cant get over about 200ft? Also my piston is really light.

 

[bobgengeskahn]

Oh ok, I wasn't sure. The stock O-Ring on my piston head that worked in the stock cylinder on my G36 wasn't sealing on the SL9 so I assumed it was bigger. Although the guy I got it from had it upgraded, so I have no idea what is/was in there. Doesn't matter either way though since I have seal now

I am tempted to just get a new spring and see what that does so I have a known spring weight in there and work it from that angle...