Sniper M4 project finished with 650mm barrel... Now a few questions!

[MasterGoa]

Thanks all for the advice!

The hop-up I have is a metal quality one. So the main issue
is the bucking. I will look into this.

As for the barrel, what is the breaking procedure?

Finally, can someone point me to a bore-up kit for the M4?

Regards!

MG

[Skruface]

You could also try a Big Out H-Hop hopup nub. At only $15, it's a cheap experiment:

http://www.airsoftparts.ca/store2/in...roducts_id=720

Also, you don't want an M4 bore up kit with that length of barrel - go with an M16A2 boreup set - same nozzle/cylinder head/piston head as the M4, but it will have an unported cylinder (which you need with that 650mm barrel).

Search any retailer (redwolf, WGC, WarIV, UNCo) for part #ZA-03-34 (New Bore Up Cylinder Set - Systema).

Also, Juggles at airsoftparts.ca carries the Modify bore-up kits for M16A2:
http://www.airsoftparts.ca/store2/in...roducts_id=682

ROF too high? It's a sniper rifle, it's not supposed to be FA! Get a Triggermaster MOSFET (http://www.airsoftcanada.com/showthr...trigger+master) programmed to semi-auto-only with a 3 second delay between shots. It will make your response time on the trigger pull almost non-existant. Then, make sure you get a battery with high discharge rate (I like LiPoly 11.1v myself) and you'll have virtually no lag from the time you touch the trigger until the shot is fired.

[Styrak]

Yeah, ported M4 cylinder with PSG+ length barrel = bad idea. Get a bore-up, or a LEAST a non-ported cylinder.

[m102404]

Nice rifle, but I'd mirror the comments of some others...lose the vert grip and light, put a nice bipod on it. Bigger scope (low powered but more substantial)! The JP kits come with the sling studs (2 on the long kit) and Harris type bipods lock straight on nicely.

I built a similar rifle over the winter, but it was too long for me. All of the below are just my own opinions...

I'd keep the 9.6v and retain the snappy trigger response. With a DMR/sniper like that...you really shouldn't be shooting full auto, right? But if you must...I'd keep the burst short.

A quick test if you have an extra shorter barrel and / or hopup unit...swap in a shorter barrel and screw on a shorter front barrel (the 18 or 20"). See if you get any weird dropper shots.

If you do all of your shooting on semi (which would be applicable on a DMR/sniper rifle like this), do you still get weird shots? or is it just on full auto? If it's on semi, you've got issues in your hopup or it's barrel drag. If it's only on full auto, it could be suck-back, barrel drag and/or the hopup.

Shoot with heavier BBs (i.e. 0.25/0.28/0.30) an see if the shot to shot flight paths don't settle down. Still doesn't address the 20ft droppers...but removes the inclusions in the 0.20bbs as an potential issue.

A bore up kit won't hurt anything and might be a good choice for a 650mm barrel. And it'll certainly ensure that there's enough air to completely push the BB out the barrel under force.

You didn't give a chrony reading, but for a 400fps rifle, you'd want a med-hard rubber (or else just replace the softer ones more frequently). A guarder enhanced (black) should hold up fine for a long time.

I'd ditch the guarder metal unit for a KA Enhanced hopup unit. On the last two Guarder units...I could not get the wheels to stay in position and they always seemed to back off easily. The last two KA units were very nice.

There is no break in procedure for an airsoft rifle. Swab it out if it get's dirty with a bit of pure silicone oil...patch dry-ish. Avoid soaking your hopup rubber with oil. A little bit (i.e. a drop or two in the loading nozzle) is fine, too much will just make a mess and may make the hopup rubber lips warp.

Contact Airsoftparts.ca...Jugglez will sort your out and he's top notch.

Best of luck, hope you get it resolved.

Tys

[Renegade)]

Originally Posted by Styrak

Yeah, ported M4 cylinder with PSG+ length barrel = bad idea. Get a bore-up, or a LEAST a non-ported cylinder.

As I stated earlier, I am using a 590mm PSG1 in my SPR with a ported reg M4 Cylinder and its shooting perfect. All I did was turn the port up, so that closing of the mech blocks some of the port to compensate. I thought of going to the non ported M16 one I have, but then I would probably suffer a bit when I go to my CQB mode which features a barrel not even stock M4 length, so I just left it at what works great for me.

[Amos]

Originally Posted by Renegade)

As I stated earlier, I am using a 590mm PSG1 in my SPR with a ported reg M4 Cylinder and its shooting perfect. All I did was turn the port up, so that closing of the mech blocks some of the port to compensate. I thought of going to the non ported M16 one I have, but then I would probably suffer a bit when I go to my CQB mode which features a barrel not even stock M4 length, so I just left it at what works great for me.

... Turning the port upwards wont really effect anything... It's still not air-tight and the piston wont start compressing until it gets past that point...

If you want to be REALLY cheap... I guess you could wrap your cylinder in teflon tape...

590 is less than 650. With 590 you can still use a stock fill cylinder and get decent results, but as you go longer it starts to get worse and worse.

[Styrak]

Originally Posted by Renegade)

As I stated earlier, I am using a 590mm PSG1 in my SPR with a ported reg M4 Cylinder and its shooting perfect. All I did was turn the port up, so that closing of the mech blocks some of the port to compensate. I thought of going to the non ported M16 one I have, but then I would probably suffer a bit when I go to my CQB mode which features a barrel not even stock M4 length, so I just left it at what works great for me.

A full cylinder won't have any ill effect in a short barrel besides maybe being a bit harder on the mechbox. A ported cylinder in a long barrel however will have problems.

[lord_sid]

If you are really worried about using a full cylinder with a short barrel, just get a sorbo pad. It will absorb most of the shock from the piston, prolonging the live of the mechbox.

As for the hopup bucking: If you want to try the Big Out H-Hop Bucking, you can also get the H-hop made by element. If you can find it, its around 5-6 bucks USD shipped. There are great reviews for H-hop bucking.

[Hectic]

You can only go to 460mm with a stock M4 cylinder (most brands) you can go to 580mm with an stock M16 cylinder

this may help you out as well also good for future mods

http://www.21stcenturyairsoft.com/cylinderguide.php


Good luck

Nice rifle by the way

[MasterGoa]

Thanks a lot guys!

Here are some findings based on what you guys suggested:

After a lot of reading, I have invested on an M16A2 bore up kit
from airsoftparts.ca which I ordered and shipped not two hours after!

I have observed my current bucking carefully and noticed that
it is MUCH harder than the Guarder I unfortunately destroyed.
I am actually thinking that the hop-up must be too tight to giver
proper back spin. I have two types of Madbull on the way and I
picked up all the ones Skaldfin has left so I can try various combinations
and figure out what is best.

I too noticed the hop-up setting not very tight so I put a drop
of shoe-goo under the main gear to it is very gummy and hard to turn.
This should prevent any loss of setting of the hop-up.

Finally, I will proceed to clean the barrel and start from scratch with
the new quality BB's coming.

Thanks for the comments about the rifle!

As for the scope, this is a 15 year old Japan made Tasco pro point
with a cross-hair red dot, not an illuminated cross hair. It has 0 parallax and
they are no longer made like this so it is staying put! The grip is moved back
and I will add a bipod since I have a couple of versa-pods lying around...

The flash light is optional of course...

Cheers!

MasterGoa

[MasterGoa]

Alright!

Well, I got most of my stuff today, so I will be upgrading
tomorrow.

I will keep you guys posted on my results.

But just as a reference, the cylinder was ported about halp way
which means that it was ported for a 363MM barrel.

At 650, I think I had no more air...

Cheers!

MG

[Amos]

... Ooh Madbull rubbers...

Big mistake.

You should invest in a RH75 or RH85 rubber by KMhead.

[MasterGoa]

Thanks for the info.

I have bought 5 kinds of buckings, so I am sure
I will find something that works.

MG

[CDN_Stalker]

Originally Posted by Amos

... Ooh Madbull rubbers...

Big mistake.

You should invest in a RH75 or RH85 rubber by KMhead.

I've bought a lot of Madbull hop up rubbers and have never had any good experiences with them, largely the problem of airleaks. Will always get much lower fps ratings than predicted (like a 390fps spring putting out only 300fps, if that) and checking everything. And leave it to the flashlight up the loading tube and looking down the barrel to see a gap of light shining into the barrel to show me the problem (this is with nozzle full forward). Changing the rubber to even a stock TM one fixes it every time. And this wasn't from just one gun, this is at least a half dozen guns I've installed the Madbull rubbers into.

I've been running the RH65 in my 500fps CA M24 the past year and really like it, it works well even if it's only rated up to 400fps.

[Mantelope]

Originally Posted by Styrak

A full cylinder won't have any ill effect in a short barrel besides maybe being a bit harder on the mechbox. A ported cylinder in a long barrel however will have problems.

Incorrect; it'll actually drop your expected FPS as well as introduce greater variance. Not quite as serious as the long barrel/short cylinder situation, but regardless, you need to match your cylinder and your barrel.