Tutorial how to build great DMR SR25 sniper rifle

[b.samriey]

Well beside my SR25 review i got many questions from people on how to build extremely accurate AEG DMR SR25 sniper rifle.
Also for our welcome guest desire Mathias from Vienna i start this topic.
I will try to make it short as much as i can but if there is something need to be clarified do not hesitate to ask your questions.
There is a few things you need to know before being a sniper especially when you based your skill on science and good knowledge to start from the top.
Where you aim is where the bullet should hit... If only it were that simple!
Once you fire the bb there is several components and challenge waiting for you:
A.Wind speed.
B.Gravity & drag.
C.FPS limit (rule and regulations).
D.Internal & external and terminal ballistics and understanding how your gun performing.
So to take down all these challenge and provide a great shot from the insight to the bullet's trajectory we will start from the power source till the barrel.

1.You need 11.1v lipo battery with low discharge such as 20c or 15c or even 10c because the sniper rifle doesn't required high discharge (much you have low discharge much you have consistent shot) and i will explain this point to you later.
2. HS Motor high torque long AXIS D-hole DJ0005 nvt
3. SR25 gear set
4. SHS piston - 19 steel teeth weigh 35g or even heaver piston is better much you got heaver piston much you got joule creep and your bb's will travel at higher energy and long range. When you throw the ball in your hand "volleyball" it is not the same energy when you kick it in your foot (at the same speed) also we need your piston travel slow to give time to the bb get out of the barrel to avoid any air suck back issue, because you're about to use tight long barrel.
5. Modify 6mm steel bushing.
6. You can keep the Stock trigger system with low resistance gearbox wiring.
7. SHS steel shims.
8. SHS Aluminium red color SR25 / AR10 series air nozzle
9. Keep the stock bearing mounted spring (is the best).
10. Bore up ICS aluminum cylinder head & piston head (oversize) this is a bore up set for long barrel type such as (510 to 530mm barrels and more) but you need smoothly hammer the piston head to make it fit inside the chrome bore-up cylinder.
Make the cylinder head and the cylinder swim in silicone oil and then smoothly hammer around the cylinder head to make it fit inside the cylinder (be careful of damaging the nozzle, it will take while like 5~6 minute to make fit perfectly). The benefit from this cylinder head it's silent design reduces sound and pressure to the gearbox plus it's double O-rings to improve amazing air seal with bearings piston head for high performance.
11.Keep the stock chrome bore-up cylinder as i mentioned above.
12.MODIFY Accurate Metal Hop Up Chamber for M16/M4 Series here you have to remove the stock pressure arms from the stock hop-up unit and install it in the new Modify hop-up unit. Carefully remove the pin by flat thin screw drive and also use the stock pressure arm gear as i show it to you in the picture.
Because MODIFY use toothed pressure arms and this will not allow you to adjust your hop-up enough (as a sniper rifle) the full turn adjustment of MODIFY hop-up unit is a half way turn of any regular hop-up unit. So there is no way you must replace it with the stock pressure arm and gear.

13. Prometheus 6.03mm EG Barrel 509mm
14. Maple Leaf Macarone Flathop Bucking 70° with Nub
Here you need to do some spell with Teflon tape:
After installing the Maple Leaf bucking in the barrel (carefully and tightly) wrap Teflon tape around the bucking edge at lest 8 wraps no less to make your hop-up unit press on the bucking edge and suppress any air leak may caused by high air pressure come from the giant piston. Also use the Teflon tape instead the brass inner barrel spacer this will gives you more accurate shots (make sure there is no Teflon tape parts out can inhibits the inner barrel clip) every thing must site correctly with zero losses, if you note there is a little losses in your inner barrel clip then check it out and re-sit it again till you reach %100 no losses.
*I use G&G GR-25 Midcap Magazine 120rnds
*G&G Bio BBs 2000 x 0,33g
*My scope is 3.5-10x50 from taiwangun.com
Now with this setup you will be able to any target from 75~80 meter, before i had problem barely i can reach 70 meter but i fix it with the Maple Leaf Nub.
When you done from the upgrade project i will start with you on zeroing your sight with your barrel (because this is just another story).
Good luck!

 

[Guest]

Pls don't tell me you got that 60 euro SHS motor? For that price you could have gotten a Tienly motor, gunfire overpriced that hard. Also why do you need a 11.1? Just a higher torque (22 TPA vs 16 TPA (SHS motor)) motor and a high C 7.4V should work fine too, maybe not as snappy trigger as with a 11.1 but should still work fine. Also no mosfet, no improved trigger response? Don't you need the 2 sec delay or does the field allow 450 FPS semi without delay? And did you correct AOE on the silenced pistonhead or is that impossible?

The rest I absolutely a good write up about DMR builds. What is your opinion of the modify steel bushings, need some for a DSG build in the near future.


BTW you might wanna try out the new truhop bucking en nub, initial testing show very good results in consistency and grouping, especially for higher FPS builds.

 

[Guest]

Pls don't tell me you got that 60 euro SHS motor? For that price you could have gotten a Tienly motor, gunfire overpriced that hard. Also why do you need a 11.1? Just a higher torque (22 TPA vs 16 TPA (SHS motor)) motor and a high C 7.4V should work fine too, maybe not as snappy trigger as with a 11.1 but should still work fine. Also no mosfet, no improved trigger response?

The 22 TPA expensive every where even in U.S, England and Europe union, but the 16TPA about 31 euro everywhere. No need to improve the trigger response or use mosfet anymore because the 11.1v battery took their place and doing his job for lower cost and higher performance (that's why i didn't recommend the 7.4v).

Don't you need the 2 sec delay or does the field allow 450 FPS semi without delay? And did you correct AOE on the silenced pistonhead or is that impossible?

450 FPS allowed for DMR's. The AoE already corrected by ICS piston head over size
Check here the same thing , so no AoE needed.

The rest I absolutely a good write up about DMR builds. What is your opinion of the modify steel bushings, need some for a DSG build in the near future.

Yet i have no issue to mention with the modify steel bushings so i can't tell if it's neet any further improvement but you can note from the video how my gun became more quiet (while the camcorder mic was very close from the gearbox).
https://www.youtube.com/watch?v=TR3vFkGCyqE

BTW you might wanna try out the new truhop bucking en nub, initial testing show very good results in consistency and grouping, especially for higher FPS builds.

I'll give it try in the future, but yet i have some bucking picked them mistakenly so i won't spend some more cash somewhere. but thanks for reference to it!

 

[Guest]

Well have fun with your trigger contacts (wile they last)...
Also other affordable High torque motors with different numbers of tpa do exist(mainly asian web stores).

22tpa is slower than 16tpa, pair a 22tpa with a 7.4v and its even slower.

Pair a relative low tpa motor with a strong spring, an 11.1v heck even a 7.4v and fire it on semi all day and you will burn your trigger contacts, fast. Should have gotten a mosfet with that extra bit of money you had left from the build.

Editdisclaimer: if this sounds angry it's nothing personal it's late and i don't feel to great but it's the truth.)

 

[Guest]

The 22 TPA expensive every where even in U.S, England and Europe union, but the 16TPA about 31 euro everywhere. No need to improve the trigger response or use mosfet anymore because the 11.1v battery took their place and doing his job for lower cost and higher performance (that's why i didn't recommend the 7.4v).

The SHS HT motor is not a 22 TPA, I said that before too but it is not, it is a 16 TPA motor and also very overpriced on all those websites: http://www.airsoftpeak.com/order-high-torque-motor-black-long-type-p-12303.html, also a ZCI HT 22 TPA motor is not that expensive: http://www.ak2m4.co.uk/internal-parts/motors-parts/zci-motor-high-torque-long.

22tpa is slower than 16tpa, pair a 22tpa with a 7.4v and its even slower.

Yeah but was more of a sort that the 22 TPA can pull the stronger spring with more ease so you have less stress, but still putting a 22 TPA on a DMR build might be better then the 16 TPA, offcourse all depends on the setup that is used.

Pair a relative low tpa motor with a strong spring, an 11.1v heck even a 7.4v and fire it on semi all day and you will burn your trigger contacts, fast. Should have gotten a mosfet with that extra bit of money you had left from the build.

Editdisclaimer: if this sounds angry it's nothing personal it's late and i don't feel to great but it's the truth.)

Absolutely agree, without a mosfet and using a 11.1V Lipo will burn the trigger contacts in a very short time. Especially on a build that requires more amperage from the battery to pull the spring and especially with a less torque motor (16 TPA).

 

[Guest]

@Ties nothing personal man, it's science and knowledge anyone bring better solutions or good ideas are welcome!
I'm able to offer INFINITY CNC U-45000, long axle motor or even more but this type of motor will not help to build AEG Sniper this kind of motor will make it just regular M16/M4 shooting semi automatic in short-mid range. All pro sniper from airsoftsniperforum.com recommended this SHS motor for SR25 , and as i mentioned above you need high energy + high speed gears with slow motor and heavy piston to achieve consistent shot. G&G and G&P some of the top brands in the markets and they have pretty good engineering airsoft guns history none of them use high speed motor in their GR25 or SR25, take look to the G&G GR25 SPR, Upgraded on unit13shop.eu also has slow Hi-torque motor 16000rpm.This mean all agreed that the long consistent shot can be achieved through slow movement to your piston.
But all together SHS high torque motor DJ0005 is really strong and good motor and equivalent to Action Army infinity motors if not even better, 130 spring is not that much strong so the SHS motor is perfect for this setup.

@Rebelattack it's just the same prices if you collect it right.
From airsoftpeak i have to pay tax and duties like what happened with my Trijicon ACOG 4x32 so at the end $38.99 price of motor "means 36,-euro" + tax and duties 25 euro = 61 euro , from UK £26 means 32 euro + 4,50 euro = 36,50 euro for average brand..
Regarding to the TPA motor there is widespread controversy whether the the SHS HT is 22 TPA or 16. But if you ask me i feel most likely 16 TPA and not 22.
gunfire.pl mostly misleads their customers by less information and not clear answered through customer service plus they are overprices as you said, i'm not going to shop from them anymore also for some other reasons..
About the mosfet, i use 7.4v lipo in my M4 without fuse or even mosfet i had no problem at all and before that i was using 11.1v, so is that really important part?
The mosfet not even expensive it's just about €13.50 on unit13shop GATE NanoSSR Mosfet but honestly i haven't seen any problem with power system on my KWA or the SR25, but if you give me good reason to get one, then i will.

 

[Guest]

OOOOH i get it now you might be confusing TPA(turnes per armature) with RPM(revolutions per minute)!
The higher TPA motors have a lower RPM. An SHS with with 16TPA has an higher RPM than say a 22TPA JG blue.

I'll repeat myself then: Pair a relative low tpa motor(witch you have) with a strong (anything above an M110 i'll consider strong) spring, an 11.1v heck even a 7.4v and FIRE IT ON SEMI ALL DAY and you will burn your trigger contacts, fast.
Firing it on semi is the biggest factor here.

 

[Guest]

@Rebelattack it's just the same prices if you collect it right.
From airsoftpeak i have to pay tax and duties like what happened with my Trijicon ACOG 4x32 so at the end $38.99 price of motor "means 36,-euro" + tax and duties 25 euro = 61 euro , from UK £26 means 32 euro + 4,50 euro = 36,50 euro for average brand..
Regarding to the TPA motor there is widespread controversy whether the the SHS HT is 22 TPA or 16. But if you ask me i feel most likely 16 TPA and not 22.
gunfire.pl mostly misleads their customers by less information and not clear answered through customer service plus they are overprices as you said, i'm not going to shop from them anymore also for some other reasons..
About the mosfet, i use 7.4v lipo in my M4 without fuse or even mosfet i had no problem at all and before that i was using 11.1v, so is that really important part?
The mosfet not even expensive it's just about €13.50 on unit13shop GATE NanoSSR Mosfet but honestly i haven't seen any problem with power system on my KWA or the SR25, but if you give me good reason to get one, then i will.

I have ordered about 7 times from airsoftpeak now and I never payed any taxes so I only payed 30 dollars the time I ordered one (was a discount then) and never had any extra cost. Lol btw ZCI motors are not average XD, people use those in DSG builds and high speed airsoft builds because they are very good motors XD. Price doesn't say everything in airsoft you should know that .

The problem with the SHS HT motors was that they actually were 22 TPA a long time ago but nowadays they aren't anymore that what was confusing me when I searched on the internet.

Yeah a basic mosfet that purely is there for trigger contact protection is not expensive. What I am gonna say next is mostly repeating what @Ties said. A 7.4 V isn't gonna damage your trigger contacts as fast on a 360 FPS build as the motor doesn't pull as much amperage from the battery because it needs less to pull the spring, eventually you will still wear down the trigger contacts but not as fast as with a higher stress build or with a higher voltage battery. With a 11.1V you already put more voltage over it to start with plus in your DMR build you are also pulling a much stronger spring which results in more power drawn from the battery by the motor to pull the spring. Then you also need to shoot semi the whole day because it is a DMR and you even increase the effect further due to that you constantly engage and disengage your trigger contacts resulting in constant creations of drawn arcs across the trigger contacts. Eventually this arcing will destroy your trigger contacts and they might not work anymore, which means you need to scrape of the black residue that is left and hope they will work again. To prevent this you are better off installing a cheap mosfet, heck you can even make one for like 7 euro's if you really want to cheap out. Plus the mosfet gives the added benefit that you get a much faster trigger response then you can ever achieve without one.

Another way to reduce the current drawn from the battery for each shot is a higher torque motor, it has a lower RPM (Higher TPA), but you won't see this in the trigger response, only in automatic fire but you can't use that anyway.

Lol if you want ultimate torque either get the ASG Ultimate Infinity U-18000 RPM (28 TPA) or build yourself a frankentorque (32 TPA) motor and it will pull any spring with a breeze, but be slow as shit.

 

[Guest]

I have ordered about 7 times from airsoftpeak now and I never payed any taxes

Strange!
Just me or someone ales each time bring something from outside the EU borders i have to pay tax and duties, even for the smaller things!

Lol btw ZCI motors are not average XD, people use those in DSG builds and high speed airsoft builds because they are very good motors XD. Price doesn't say everything in airsoft you should know that .

No doubt the price doesn't reflect the quality but the SHS motors has good reputation and more reliable and people feel confident with it, the ZCI motors looks unknown (at lest to me) and even if some people use it in DSG builds that's doesn't mean can fit this setup (as i said before all the pro users on airsoftsniperforum.com) recommend the SHS motors, So I could not adventure and make a decision by myself and pick another one..
On internet you may find thousand of brands and types but which one of these will fit perfectly your setup? when i post my first question here on upgrade Internals assist i didn't got any suggestion about the motor even by you, and @Ties advice me to keep the stock one. Therefore the SHS HT motor is the best option as many people use it and tried before.

Yeah a basic mosfet that purely is there for trigger contact protection is not expensive. What I am gonna say next is mostly repeating what @Ties said. A 7.4 V isn't gonna damage your trigger contacts as fast on a 360 FPS build as the motor doesn't pull as much amperage from the battery because it needs less to pull the spring, eventually you will still wear down the trigger contacts but not as fast as with a higher stress build or with a higher voltage battery. With a 11.1V you already put more voltage over it to start with plus in your DMR build you are also pulling a much stronger spring which results in more power drawn from the battery by the motor to pull the spring. Then you also need to shoot semi the whole day because it is a DMR and you even increase the effect further due to that you constantly engage and disengage your trigger contacts resulting in constant creations of drawn arcs across the trigger contacts. Eventually this arcing will destroy your trigger contacts and they might not work anymore, which means you need to scrape of the black residue that is left and hope they will work again. To prevent this you are better off installing a cheap mosfet, heck you can even make one for like 7 euro's if you really want to cheap out. Plus the mosfet gives the added benefit that you get a much faster trigger response then you can ever achieve without one.

Another way to reduce the current drawn from the battery for each shot is a higher torque motor, it has a lower RPM (Higher TPA), but you won't see this in the trigger response, only in automatic fire but you can't use that anyway.

Lol if you want ultimate torque either get the ASG Ultimate Infinity U-18000 RPM (28 TPA) or build yourself a frankentorque (32 TPA) motor and it will pull any spring with a breeze, but be slow as shit.

I will get one from unit13shop to my sr25 and give it try

 

[Guest]

Strange!
Just me or someone ales each time bring something from outside the EU borders i have to pay tax and duties, even for the smaller things!

Oh only with airsoftpeak I never had any extra tax or duties charged, but on my order from japan I had some, but airsoftpeak kinda cheats the system as they put a low value for your orders package and when it is only small airsoft parts I think they assume it is the correct value.

No doubt the price doesn't reflect the quality but the SHS motors has good reputation and more reliable and people feel confident with it, the ZCI motors looks unknown (at lest to me) and even if some people use it in DSG builds that's doesn't mean can fit this setup (as i said before all the pro users on airsoftsniperforum.com) recommend the SHS motors, So I could not adventure and make a decision by myself and pick another one..
On internet you may find thousand of brands and types but which one of these will fit perfectly your setup? when i post my first question here on upgrade Internals assist i didn't got any suggestion about the motor even by you, and @Ties advice me to keep the stock one. Therefore the SHS HT motor is the best option as many people use it and tried before.

True SHS motors have a good reputation and it is no way bad but neither does an unkown brand has to be bad. Well some what High speed airsoft and High fps builds are relatable as they both require quite a strong motor to pull a heavy spring as fast as possible and with high efficiency. Again the SHS is fine but for example if you would have gone for a 13:1 gear set instead of the SR25 one then a 22 TPA motor would be more favorable then a 16 TPA one, you would lose some RPS but it would be more efficient and a bit more responsive. With the normal gear ratio of the SR25 gears then a 16 TPA is more then fine. We also indeed never talked about the motor except saying one time that if the stock was a JG Blue (22 TPA) motor then that is a fine motor. Again in the end this is still good .

I will get one from unit13shop to my sr25 and give it try

Haha good to hear, let me know if you get a noticeable difference .