DPMS m4 upgrade path

[Janz99]

We just came back from a newb day at a local airsoft place and i have a few questions for you guys.

I have an m4 dpms and im noticing some inconsistancy's with it. I know its a very entry level gun, but i would like to start upgrading it slowly as i can afford to. Im not really interested in buying a whole new gun so that is not an option. I noticed on the chrono they had there, that the gun would vary on each shot fired. Anywhere from 408fps to 360 and anywhere inbetween.

I have the gun sighted in very well, but i am noticing that in auto mode, the BB's dont all shoot straight. One will go straight, then the next one might go to the left of the target then the next to the right. Im wondering if the inconsistant FPS could be causing this? And if so, what would cause the inconsistant fps rating?

Id like to try and get the gun shooting 380-400 fps with .28 bb's, and id like to get the gun shooting a little more accurate. Where is a good place to start upgrading this gun?

Ryan

[Crunchmeister]

Velocity-wise, your gun is perfect for outdoor gaming. Those JG M4s shoot 360-380 out of the box, which is perfect. 380-400 with .28 is equivalent to 450-473 with .2, and that's not game legal anywhere in Canada.

What you can do to improve your consistency is to installed a bearing spring guide and preferably a bearing piston head. That will give you more power consistency by removing torsion in your spring. And get yourself a new hopup rubber and a tightbore inner barrel. Those 2 will improve your accuracy significantly.

While you're in there, you should also replace those nylon bushings with metal ones, clean, reshim and regrease the mechbox.

[theguy]

380FPS will put you wayyy over the safe field limit for most fields. The general rule of thumb is 400FPS for AEGs Shooting 0.20G if your gun is doing close to that with 0.28s you will probably be close to 500 with 0.20s

Not only will you not be allowed to play with a gun that hot, you will destroy you mechbox pretty quickly.


EDIT: sorry crunch, did'nt see your post there

[Janz99]

I didnt realize there was that much of a differance in the velosity of the .28's compared to the .2's. Im shooting .2's right now, i just figured the .28's would help the gun possibly shoot straighter.

What does everyone normaly shoot, .2's? Can you guys recomend any online canadian based vendors that i can order the parts through?

How much will a tighter bore barrell help? I didnt get a chance to measure the stock barrell but i noticed online that they offer aftermarket barrells that are supposidly tighter then the factory one.

[Crunchmeister]

It's really not velocity you're measuring, it's muzzle energy. The heavier the BB, the more energy it carries travelling at the same velocity. A .2g BB @ 400 fps delivers 1.486J of energy, and that's the limit. A .28g BB at 400 fps delivers 2.081, which is significantly higher.

You can use heavier BBs such as .25 or .28 and they'll fly straighter, have better resistance to wind, better brush penetration, and increase your effective range. However, the tradeoff is that your BBs travel slower with heavier weights. A gun shooting 400 with .2 will be shooting 338 with .28.

But that's still not a bad tradeoff. 338 fps is still plenty of velocity. It's guns that shoot under 340 fps with .2 that should limit themselves to lighter .2 and .25, and it will reduce velocity to under 300 and hurt the gun's effective range.

A 6.04 or 6.03mm tightbore barrel will increase both your range and accuracy pretty significantly, as well as add some extra velocity (10-20 fps).

Check http://www.airsoftparts.ca/store2/index.php for parts/

[Janz99]

Thanks for the information, that helps a ton. Are all the tight bore barrels compatable with this particular gun? Is there any upgrades that should be done at the same time when switching to a tighter bore barrel?

Is the factory spring also playing a role in the inconsistancy?

Thanks again for the help guys!

Ryan

[Crunchmeister]

What generally causes power inconsistencies is the spring guide and piston head. As the spring is compressed, it twists a bit, and it may not twist the same amount each time. Adding a bearing spring guide and piston head elimintates this twising effect and gives more consistent results.

[Janz99]

What do you guys think of these manufacturers for the parts you recommended:

Bearing piston head:
http://www.airsoftparts.ca/store2/in...oducts_id=1316

Bearing spring guide:
http://www.airsoftparts.ca/store2/in...roducts_id=741

Bushings:
http://www.airsoftparts.ca/store2/in...roducts_id=525


I have a couple questions on the tight bore barrel and the hop up rubber. What is the factory length of the barrel on the m4's? I was thinking i might get a tight bore that is slightly longer if possible, an inch if they make it?

I also didnt see any separate rubbers for the hop up? I seen complete hop up units, but do i really need to upgrade the whole unit, or just the rubber?

[Crunchmeister]

Avoid bearing bushings. They're only good in low velocity setups. Get some solid metal bushings instead. I haven't used that Deepfire spring guide, but seems ok. I tend to lean towards Modify parts now. They've always seemed to work best for me. I have Modify spring guides in most of my guns.

I would get something other than a metal piston head. Get something plastic. That way, it don't impart your mechbox shell as hard. Metal piston heads wreck stock V2 mechboxes rather quickly.

[NoGear]

is ur m4 the clear soft version because i seen a dpms at a local surpluse saying it shoots 370 fps and on the box its shooting 0.12's hopefully u can clear this up

[Janz99]

Yes it is the m4 clear soft I'm not sure which one you were looking at, but im pretty sure mine said 460fps on the box with .12's. It came in at an average of 360-370 with .2's.

Thanks again crunch for all the help. Any recommendations on tight bore barrels? And is there anything i should be looking at upgrading with the barrel?

So after all these upgrades, will this push me over the 425fps limit we have here?

[Janz99]

I went ahead and ordered a few parts for the gun last week. Coming in the mail this week, should be:

-Modify, bearing spring guide
-Modify, polycarbonate bearing spring head
-Madbull tight bore barrel
-Modify s120 spring
-New hop up rubber

I opened up the gun before i ordered the parts to inspect everything and make sure something else didnt need to be replaced. The gun came with steel bushings already, so i neglected to order those.

My question is the spring really. I know its going to put the gun over our FPS limit here at local events, but for the most part, we play outdoors with friends and dont set any sort of fps limit for ourselves. Is the gear box going to be able to handle this strong of a spring, or should i leave the spring out for now untill i have upgraded other parts?

The point of these upgrades was to get the gun shooting more accurate and consistant. If the spring is going to hinder this, or be counter productive, then im just going to leave it out for now. Just looking for some opinions from guys who have used this spring/gun combo or something similar.

Thanks
Ryan

[ThunderCactus]

I don't think those gearboxes can handle even 350fps for half a season
Don't forget to buy a new air nozzle, it's EXTREMELY important!
Some stock air nozzles are crap and cause huge FPS losses which drastically affects performance.
When you buy gears, buy the same brand of bushings for those gears, you don't want to be mixing and matching different brands in your mechbox

Now the spring actually has almost nothing to do with your accuracy, the things that affect your accuracy are any of the parts that touch the air that's used to push the BB:
air nozzle, piston and cylinder head, cylinder, barrel, hopup rubber
As long as you have high quality parts, and have them installed properly, you'll get excellent range and accuracy at 300fps.
Having higher fps is good for long range engagement where people have time to move before the BB gets to them, punching through bush, resisting windage (since you can use heavier ammo), and generally getting people to become more aware that they're being shot lol

[Janz99]

We went to the noob day out in stonewall a few weeks ago, and the gun was shooting anywhere from 350-380fps depending on how it felt at that particular time . This was completly stock. Ive shot almost 10 000 rounds through it as it sits right now. The main reason i opted to get a new spring was because i was hopeing to shoot the same fps as i am right now, but using heavier ammo.

I really noticed at the noob day, using the .2's, i was very limited as to what i could shoot through (brush wise). I was also hopeing the heavier ammo would help with keeping the BB's alittle straighter during flight.

[ThunderCactus]

Well as was stated, FPS limits are based on joules of energy, not the actual speed of the BB.
Like common sense here, do you think we'd put a speed limit so people have a chance to dodge the BB or what? lol

Anyway the proper course of action would be to use .25s or .28s while shooting 400fps on .20's, just like the rest of us lol
You'll notice a huge difference in accuracy using heavier ammo
And furthermore, if your shooting 380 on .28s, thats about 450 on .2s, and that's definitely going to wreck your stock gun