Need help building DMR

[Luke-1418]

Hey guys, I'm not really "new" to airsoft but never really got into missing my guns internals... I'm running krytac Trident MK2 CRB, I am on extending the inner barrel through a suppressor for that extra length but need to know the internals I'd need? e.g. bucking, gears stuff like that, thanks alot :)

[BigStew]

Too vague a question with not enough information. what do you want to do? are you wanting a true DMR locked to semi with higher FPS? or do you just wat a bit more range. also you really don't want to start upgrading and go down the DMR route with out a back up gun. i would use the search function there are a lot of posts about DMRs read and figure out what you wat the gun to do.

[Rogerborg]

No need to over think it.  You already have a rotary hop, so just drop in a Maple Leaf rubber and you should be able to lift any BB that you can afford.  70 or 60 degree, I wouldn't go harder. Softer will wear faster, but changing hop rubbers is cheap and quick compared to just about anything else in airsoft.

 

Buy a heavier spring or springs, depending on your site's energy limits.  It's not an exact science, don't expect 140m / 459fps on a 0.2g out of an M140 spring, and be prepared to clip off a coil at a time and heat and flatten the end in order to tune the power.  Get a chrono, and understand whether you need to tune for Joules at the BB weight that you're using (good site), or for fps on 0.2g (bad site).

 

You can use an outer barrel extension rather than a silencer to hide a longer barrel, e.g. https://www.ak2m4.co.uk/external-parts/outer-barrels

 

But bear in mind that barrel quality beats barrel length.  I'm running an AOLS 455m, which to be honest is far longer than you need, it was just about willy waggling.  AOLS or ZCI are fine at the cheap end.

 

Internals, eh, leave 'em alone. Maybe a full cylinder if you need it, and a full steel rack on the piston - although stock CYMAs shoot at up to 1.5J using a plastic rack, there's no need to change it until and unless it strips.

 

If your motor struggles, I'd replace that rather than fiddling with the gears.  I like the Big Dragon M140 or M160 motors from Ali Express, you might as well buy honestly Chinese branded Chinese motors (or "mortors" as they say on the packaging ). 

 

Locking to semi is just a case of cutting a bit off the selector plate.  I'd suggest buying a spare one for that and keeping the stock one safely aside in case you want to go back to full auto.

 

 

Heaviest BBs that you can lift and afford, and don't expect instant magic from it, you'll have to tune and tweak it.  One handy thing about having a longer inner barrel hidden inside a suppressor or extension is that you can remove the outer and rotate the inner if you have consistent curve to one side from the barrel being slightly rotated.

[Mad-Al]

If you're going to DMR then make sure your gearbox is radiused and grab a well lock bracer to offset some of the extra strain you are putting the front of your gearbox under. 

Both of these things are cheap and easy to do and will increase the life of your gearbox.

Edited July 29, 2021 by Mad-Al

[Rogerborg]

1 hour ago, Mad-Al said:

a well lock bracer

 

Things I didn't know existed but now desperately need.  BAM, Ali Expressed.

 

Good shout on the radiusing as well.

 

 

[Lozart]

6 hours ago, Rogerborg said:

No need to over think it.  You already have a rotary hop, so just drop in a Maple Leaf rubber and you should be able to lift any BB that you can afford.  70 or 60 degree, I wouldn't go harder. Softer will wear faster, but changing hop rubbers is cheap and quick compared to just about anything else in airsoft.

 

Buy a heavier spring or springs, depending on your site's energy limits.  It's not an exact science, don't expect 140m / 459fps on a 0.2g out of an M140 spring, and be prepared to clip off a coil at a time and heat and flatten the end in order to tune the power.  Get a chrono, and understand whether you need to tune for Joules at the BB weight that you're using (good site), or for fps on 0.2g (bad site).

 

You can use an outer barrel extension rather than a silencer to hide a longer barrel, e.g. https://www.ak2m4.co.uk/external-parts/outer-barrels

 

But bear in mind that barrel quality beats barrel length.  I'm running an AOLS 455m, which to be honest is far longer than you need, it was just about willy waggling.  AOLS or ZCI are fine at the cheap end.

 

Internals, eh, leave 'em alone. Maybe a full cylinder if you need it, and a full steel rack on the piston - although stock CYMAs shoot at up to 1.5J using a plastic rack, there's no need to change it until and unless it strips.

 

If your motor struggles, I'd replace that rather than fiddling with the gears.  I like the Big Dragon M140 or M160 motors from Ali Express, you might as well buy honestly Chinese branded Chinese motors (or "mortors" as they say on the packaging ). 

 

Locking to semi is just a case of cutting a bit off the selector plate.  I'd suggest buying a spare one for that and keeping the stock one safely aside in case you want to go back to full auto.

 

 

Heaviest BBs that you can lift and afford, and don't expect instant magic from it, you'll have to tune and tweak it.  One handy thing about having a longer inner barrel hidden inside a suppressor or extension is that you can remove the outer and rotate the inner if you have consistent curve to one side from the barrel being slightly rotated.

 

With regards to the outer barrel vs silencer - depending on how long he wants to go that will look ridiculous without a matching handguard (the original inner barrel is only 280mm long). Personally I'd go for the new barrel and handguard but budget isn't the same for everyone.

 

As for the hop rubber, Maple Leaf is a good shout but the Krytac arm has a weird bit for holding the nub, don't think it'll work with the Omega nub he'd need. Still, £8 zci rotary and bob's your mothers live in lover.

[Impulse]

Potentially unpopular opinion, but have you considered HPA? V2 gearbox-based HPA engines are pretty common.

 

As long as you get used to the tank and line, or come up with a way to mount a small tank to the rifle, the performance really can't be beaten in my opinion. Yes, it's expensive to build. Yes, you have to carry a tank, but the stupidly good consistency as well as the silence are just too good to pass up. Also, you can tune it to the exact power you need. I've done the conversion to one of my VSRs and will be converting one of my m14s once I clear my debts because I'm a complete HPA convert at this point.

 

Outside of that, I'll echo the maple leaf rubber suggestions. I've got a ML macaron in my m14 and I can't fault it; it's otherwise a stock Cyma m14 shooting at 1J, but most people think it's some sort of 1.6J DMR with an MED because of how far it reaches out to and all I've done is shove a stainless steel prometheus barrel and a maple leaf macaron rubber in it.

[Rogerborg]

9 minutes ago, Lozart said:

With regards to the outer barrel vs silencer - depending on how long he wants to go that will look ridiculous without a matching handguard (the original inner barrel is only 280mm long). Personally I'd go for the new barrel and handguard but budget isn't the same for everyone.

 

It's very much an aesthetic thing. Some folk like big thicc silencers, but I reckon that just makes it look like, well, a carbine with a silencer.  I prefer some pokey-out length to make it clear that it's all barrel, baby.  Something like this.

 

 

 

 

Although I'm personally rocking a SA-E02 DMR with a short M933 style Fudd handguard and a 5" extension.  It would look horrible to a purist, but, well, that's one reason to do it.  

 

 

 

9 minutes ago, Lozart said:

 

As for the hop rubber, Maple Leaf is a good shout but the Krytac arm has a weird bit for holding the nub, don't think it'll work with the Omega nub he'd need. Still, £8 zci rotary and bob's your mothers live in lover.

 

Good shout, and holy heck, and AK2M4 actually has them in stock: https://www.ak2m4.co.uk/internal-parts/hop-up-chambers/zci-rotary-hopup-chamber-plastic-m4

 

Although I've never really been sold on the omega nubs anyway. I actually like the Specna Arms nub which is sort of omega, but front-to-back rather than side-to-side, in combination with a Maple Leaf macaron (if I remember correctly).