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Hi, I just got the Krytac spr rifle and I want to make it a DMR. I know I need to put in a rhop or flat hop and to stabilize the barrel and everything but I am wondering what parts I need to get like barrels, springs, and hop up nubs. Also, how would I make a flat hop and stabilize the barrel? What are some other modifications to extend the range and accuracy?

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There is a major difference between a DMR and a gun with above average range. If this is your first gun build, you will not be able to make what most would consider a DMR.


To answer your question. I like PDI inner barrels but they can ber very expensive if you order from the US so I suggest ordering from XFire in Japan. If you don't want to do that (which you probably don't) then go with a Madbull V2 or a ZCI barrel, they are the best bang for your buck (don't get caught up in tighter is better, 6.03 are good but I prefer 6.05 - 6.08). As for springs I don't know too much but someone here will pop in for that. If you R-Hop, you will use the M-Nub. Flat hop packings can be purchased or modified from an existing packing and I suggest watching a youtube video on how to do it. Barrel stabilization can be done by wrapping blue tape around the inner barrel until it does not wobble in the outer barrel.

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Do your mods in little steps. Try the flat hop first with .28g bbs. You may be surprised in the range you get and not need to do any more.


If this is your ONLY gun. Definitely take it in small steps. I see way to many kids/new players with tricked out "upgraded" guns implode on themselves after one round of play.

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One round? That's assuming it goes back together.


But yeah, make sure you learn about each part thoroughly and don't play with it until its done. I was building a gun for a friend and it was done but only on a plastic tooth piston. I put a MOSFET in and he was using 7.4v lipo so it was fine but he decided it would be a good idea to use an 11.1 and the piston stripped within a few minutes.


But really, work on the internals other than the gearbox first and don't try the R-Hop install yourself, but a pre made barrel or have someone do it for you as it is very easy to mess up.

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Speaking of barrels, what about bore lapping? I realize that gains realized from lapping are usually small when it's performed on higher-end barrels like PDI or Prommy--but how about when it's done on a cheaper, but still "reasonably good," barrel like the aforementioned ZCI? Is there a point in buying a Prommy barrel instead of getting a ZCI and putting in some time to lap it? How similar would the end results be for a lapped Prommy and ZCI side-by-side?


OP, start with some of the DIY mods listed here. The compression mods are especially important for long-range guns, as they help decrease shot-to-shot muzzle velocity variance. Start by testing the compression of your gun's airseal components and work from there.


Before you begin sinking money into your build, it'd also be a good idea to get familiar with how your gun works. Look up M4 takedown and V2 disassembly guides--be sure that you can take apart your gun and put it back together before you start throwing parts at it. That way, if you happen to break something, at least it'll be a stock part that you might replace anyway, rather than something you dropped X additional dollars on.

Edited by Cardboard Box

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It all depends..roll test it to check the straightness. Check the window cuts in all aspects of evenness...Some barrels can't be helped even with bore lapping.

If krytac barrels are anything like kwa barrels, Lap that "female dog" you will get beautiful results out of it.

You will NEED a new piston with metal teeth I recommend the SHS pistons.

SHS Aluminum Piston Head, use loctite when installing the Piston Head, stretch the o-ring and let it sit in silicone lube for a few days.

SHS Aluminum Cylinder head, add some Teflon tape when installing

O-ring nozzle, I like the SHS one but most are very similar

Stronger Spring, M140

neo magnet motor, 18tpa or 22tpa its your decision, 18 tpa will have a faster ROF but with less torque and efficiency.


For deciding what cylinder to use I need to know what barrel length and BB weight you want to use


Bucking route route

-maple leaf 75 degree bucking, remove the mound and the flat hop mods

-laylax bridge nub

try extending the hop up window and if needed extend the barrel window to fit the full size laylax nub without cutting the tabs off.




HS5 r-hop patch original


Your hop up is fine, no need to buy another one It wouldn't make a huge difference.


DIY stuff:

glue some foam to the front of your gearbox and the front of your body to reduce shock

use some tape to "candy cane" your barrel so that it fits perfectly snug inside the outer barrel

file down a little off the front of the tappet plate to allow the nozzle to rest at the front.

If you have nice mags file a little bit off of the tappet "flag" (triangle thing that engages the sector gear) to allow the nozzle more time to rest before the piston moves forward.

Edited by MrGearbox

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Ok. Anyone who suggest lapping your own barrel need to STOP right there.


First, this should be done by professional. No self proclaim garage scientist should be doing this.

Second, lapping should be done in ONE CONTINUOUS precise motion. Best performed by machine. Manually doing lapping with ANY stop motion, change in speed during the process WILL messed up the inner surface.

Third, there is no reason to do any lapping on brass barrel as the material is softer than steel. BBs firing thru will do Micro honing.


So please... I don't care what you read on internet or drinking the HS5 koolaid. Leave the lapping process to the machine.

Edited by Allizard

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Idk. so far I have gotten great results when lapping a brass barrel, there has certainly not been a decrease and normally my accuracy is improved. Then again I have only used the lower level kits on the brass barrels

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