M4 Reliability Issues

[Trojan]

I'm having a few reliability and consistency issues with my M4, but other than that has been great after the recent upgrade. I am waiting on my compression parts to come to finish the upgrade, new CH, nozzle,new bucking.

The gun sometimes dry fires with a full mag, if i angle the gun down and cycle it it will begin shooting again, I think it's misfeeding somehow but I don't exactly know how it is. I'm waiting on a new set of front pins so the upper could simply be moving forward and creating problems, will update to see if it is fixed with new pin.

Another issue I have is the gun is curves left and right. How can I tell if my bucking is worn, I think that is the problem because the bucking looks roughed up and a bit torn.

Also I would like to know how improving compression will help the gun, I understand the FPS variation will be more consistent - but what does this mean for real world performance? Will my groupings be much tighter?

Ideally once I've finished the compression upgrades I really would just like the gun to shoot straight and as far out as 50m (a realistic goal?).

Upgrades done to it:

SHS 15 Steel Teeth Piston

Lonex A2

Shimmed

AoE'd

Sorbo

Radiused

16 AWG Silver Plated

Non AB Mosfet

SHS Pom Piston Head

ka v2 gb

Madbull TBB 6.03

will be installing:

lonex CH (sorbo it)

m140 shs

lonex m4 air nozzle

lonex 70deg bucking

do you think with the right hop tuning i could get good groups at 50m? what are the goals i should aim for?

im using bulldog .2gb BBs to test but if all goes well once I run out of these .2s ill purchase .36~ (something above .3 from a good brand that i can manage to get cheap). is the issue the BB quality (they arent as good as my blaster .25s lol), and is that the cause of the bullet curve (UK is windy, .2gs arent good in wind, would explain)

 

[straffham]

Once you've fitted the other new parts it will probably cure the poor grouping, sounds like your hop rubber is probably past it. A well set up AEG hop should get to 50m no problem, although wind is always going to be a factor to some degree. You may be better using 0.29/0.3 BBS, in my own guns I've found 0.36 only worked really well in 470-500fps set ups, but certainly wouldn't use cheap 0.2s even to test it tbh.

Has your sector gear got a tappet plate delaying chip fitted? If not this could be the cause of your misfires if the air nozzle is returning too quickly to chamber a BB.

 

[straffham]

Consistent compression is one factor in improving grouping along with using quality ammo and a decent hop rubber, and of course allowing for wind. I've never tried "sealing" the cylinder and cyl head with any sort of sealant and would be wary of doing so. There will always be small amounts of movement in these components caused by vibration and the sealant will just become ineffective with use. With the quality components you're using you should be looking for a shot to shot variation of no more than around 7 or 8 fps at 400fps, and hopefully less with good ammo.

 

[Trojan]

Hi man,

thanks for that... very informative

also since the UK is very windy could I get 50m on windy days and about 70m on non windy days, once i finish upgrading everything? Yes it has a delayer chip installed.

A problem I found was that my bbs have to be pushed into the hop unit, it gets stuck before it can enter the hop unit correctly and if i push it with a rod it will work. Any thoughts?

What bbs do you personally use for .36g?

 

[RR01]

Feeding issues sounds like your mag and the hop feed tube are not exactly in line, so that the BBs are feeding at a slight angle and getting stuck. Alternatively it could be your mag spring isn't pushing the BBs hard enough.

Unless you are going to use the M4 as a semi only DMR there are very few sites that will let you shoot full auto above 370 FPS, so any BB weight above 0.3 will be a waste of money. For around the 350 mark 0.25s are plenty heavy enough.

 

[straffham]

What bbs do you personally use for .36g?

I am still using Madbull 0.36s I purchased a couple of years back. I take it you're looking at around 400fps to use as a DMR from the spring you list? Its a heavy and slow BB to use at that power, and may not get to 50m let alone 70. Try asking around at your site if you can test different weights and brands of BB and see what works once its all working as it should.

As for the feeding issue, is the hop unit nice and tight against the gearbox?

 

[straffham]

Could be the hop rubber is too thick/tight in your hop unit causing the end that holds the BB to exert too much pressure. BB should push through FAIRLY easily with a rod, if it takes too much effort to push through that sounds like the problem. Try removing the inner barrel, refit the hop rubber onto it, apply a little silicon grease to the OUTSIDE of the hop rubber and refit into the hop unit. It SHOULD slide in smoothly, if not then you need to rethink your hop unit/rubber combo.

 

[straffham]

M140 should give you around 400 - 420fps, you'd need a 160 or 170 to get 500fps on 0.2s and tbh your gearbox would probably break pretty quick as V2 boxes aren't known for their ability to handle massive power.

Use 36s in my Tanaka K98 which doesn't see a lot of use atm lol.

 

[Trojan]

It's a reinforced GB that's been radiused and sorbod so there's probably less chance of any fault.. Still it's airsoft so anything can happen

Second hand v2s are about £15 so if I do get into any problems they're not too expensive to replace.

How do you remove the C clip, I haven't changed bucking in a long time and my clip is being stubborn so I don't want to damage it.

When my upgrades come should I swap out my spring only when I get the new 0.36s?

Will using .2s in a 420ish fps setup have any negatives to it?

I'll provably just bulk buy guarder 0.36 from Taiwan gun. Each £5 for 1K, 10k at £50 plus £10 postage so it's not too much of a rip off

 

[jcheeseright]

For BB weight I tend to go with whatever will give me 280-320fps actual muzzle velocity, so with a 500fps gun if expect that to be in the .40 ish region.

Anything faster than 330ish and wind resistance (which increases logarithmically with projectile velocity) takes effect much more quickly, sapping your BB's energy and reducing your overall range rather than increasing it.