Tuning Crosman DPMS SBR build

Some quick testing on the P1 this AM. Initial pressurize of mag had no leaks, but when inserted in the gun a small leak occurred. Tightened the PW fitting a little more, but could hear a small leak, still . Put a CO2 cart in, to make sure it wasn't a mag issue. It wasn't.

Put the compressed air assembly in a different mag and not leaking. Only shot another mags worth. A couple shot felt "slower" than the rest. Wondering if the check-valve is sticking? Pressure in the cart dropping significantly before it re-opens? I'll need to check if I have some non-spring type to test. Needs more investigation.

The little red slider bleed worked great. Slider Bleed

PS: At 900psi, and you disconnect, there is only a few shots before it runs out of air.

I did a few more mags on the P1. I still hear a "softer" shot every 5 or so shots. I wish the chrony would see the BB's so I could tell for sure.

Also shot 4 mags on the DPMS. No leaking and don't hear a "softer" shot. That could be because it has the air in the empty CO2, which is fed from the Ebay cart. There is an internal check-valve between them. Then the same spring loaded check valve on the input to the Ebay cart.

I do have a couple of plunger style check-valves, but there is no cavity to keep them from coming out. I'd have to make something that would reside within the fittings.

I might just remove the check-valve and see if the "softer" shots go away.

Well, a couple of hours ago, would have asked you, "How did you keep the plunger from falling out?". Turns out that the long stem plunger, used on Ninja bottle regs, will work in my pistol configuration. The 1" male coupler forms the base to stop the plunger.

I did shoot another 2 mags in P1 with the ninja style fill nipple. I still hear a few "softer" shots but with no chrony reading, can't really say that is a problem. I guess I should still do a no check-valve test. The check valve did work without any sealing issues.

I'm considering some changes to my tethered line. If I do, will post pictures.

On the DPMS, found a 4.25" braided hose and will see if that fits with the shorter swivel 90. If it does, it will allow for pulling the mag without loosening the dovetail adapter. After that, will consider this one done. If I run across a 9ci bottle sometime in the future, would grab that for better gun mounted option.

I did install a 0-1500psi gauge on the output.

I had hooked up the bleed/female foster (internal check-valve) with a male foster (no check valve), such that it could be easily tested and removed. It worked great at these pressures, so converting the tether line such that it can be removed for easier transport and storage. While the rest of line is rated for 3000psi working pressure, the the bleed/female foster is low pressure. No using this 24" line on filling pcps.



I'm considering putting an inline output gauge using a T, but leaning toward not.

I ended up using the gauge but getting rid of the large bleed that is not needed with the slider bleed. 

Nicely done, guys. My parts on ordered finally got here. I'll let you know how it goes with my connection. I ordered both nipples with and without a check valve. If it only gets 10-12 shots without a direct connection, I'll probably go without a check valve.

Also, I ordered the Tippmann Remote adapter kit, and it does not fit into the ebay dummy cartridge. I'll have to send it back. I'll post my final build part list when I get everything working on my pistol setup.

I did install the 4.25" braided line with a swivel 90. It does make it such that you can remove the mag without taking off the dovetail asa. You do have to futz with it some, though.





I'll probably run it mostly tethered. Would make switching to the P1 easy.

FWIW: The swivel 90's leaked at the male pipe threads. I use the thicker yellow gas pipe tape. With 3 wraps, still wouldn't seal. Threads might be undersized.

Went back to the old 90.



The check-valve on the pistol is nice, to be able to reload without loosing air. Harder to feed those BB's with line attached. I had to reconfigure my coat hanger mag slide holder to get around the new plumbing. I wish the P1 had a separate mag for BB's from the CO2

I went with a simple water bottle holder for the 13ci tank. It can store the tether line, too.







.

Hey Joey did you ever get vids of this thing in action????

This is a thing of beauty! A local gun shop just brought the crosman dpms down to 228 CAD.,...pretty close to pulling the trigger, pun intended

Hey Joey did you ever post a list of the parts you used? If not can you?

Also if it's not too much trouble I have no clue how to mod the qr mag can you offer me some guidance?

I've been following the thread watching for interesting mods to the Crosman line of CO2 Replica "M4" variants. I have 2 Panther DPMS SBR's in black, 1 MPW "Ultra Short BR" in Dark Earth, and my preferred of the bunch a Crosman CFAR1 in Dark Earth because it matches my real Colt AR-15/M4 I shoot in competition "Run n Gun" matches. We have a bunch of ex-Military that use the Crosman replica's and also the SIG Sauer models to practice for firearm Run n Gun, it's cheaper to practice and we can do it at homemade ranges closer to home. BB and Pellet guns used in our "practices" must be true replica's in size and weight and only hold a max of 30 rounds (BB or Pellet), you must then switch magazines to continue (for rifles) and no more than 16 rounds for pistols.

After follow this thread, I have to say I don't the reason for converting any of the Crosman AR/M-16/M4 replica's to PCP if you are going to using it for tactical practice! Why (?), the dual C02 25 rd magazine gives you a MINIMUM 150 to 160 shots! Reasons not to: (1) Increases the weight of the gun (more fittings, valves, gauges, hoses, etc), (2) more things to FAIL in the field (more fittings, valves, gauges, hoses, etc)., (3) it's clunky and cumbersome. (4) it looks Dumb, anything BUT a replica M4. (5) where is the benefit? (6) you can't increase the shooting pressure without blowing out expensive seals, we've tried and paid the price. But, to each his own, enjoy.

Here's my Crosman CFAR1 modded to literally be identical to my Colt AR/M4:
FMA 7.3in REAL "suppressor", 532nm wavelength Green Laser (300ft in broad daylight, 1000 ft night), Q4 Cree light, Magpul angle fore-grip, Magpul Flipup "Co-sights", Red/Green 4-type Reflex Sight, Ranger Armory M4 Tactical Stock, Pro-Mag Magazine protectors, attachments for both 2-point and 1-point Bungie Mil-spec Harnesses. Bolt, hammer and sear polished and trigger jobs.

Hello all.

Newbie to all this and just purchased a DPMS SBR

OP has gotten me motivated to do an HPA conversion 

I searched but cannot find any info on what needs to be done to mod the trigger assembly/weight as OP alludes to.

I typed out a PM to him but when I went to send it prevented me, alas I dont have enough posts lol.

So here's my first lol Thank you all

Cheers!

Doug

Hey "dg", your DPMS SBR is about to the be most expensive hobby in Airguns you never knew was coming ..... because there is so much you can do to "Mod" it. I have 2 DPMS SBR's, 1 CFAR1 (above post pictures) and a MPW Bushmaster, the DPMS were to cheaply "practice" for Run n Gun competition since 5.56 ammo costs have skyrocketted lately (I have a real Panther Arms SBR M4 and a Colt AR156A4 (M4) for that competition. I now actually prefer the Crosman CFAR1 over the DPMS since it uses the std MIl Spec collapsible stock and is upgradeable.

I VERY briefly considered the HPA conversion, but all in all I think it's a really dumb idea for reasons of mobility, weight and the excessive added cost/benefit for it. If you're going to sit at a bench and shoot like at a Carnival shooting game and not do fantasy combat in the field or urban situations, then go for it. But trust me, as a retired military in spl ops, when you gear-up with everything else, you'll wish you weren't also dragging around all that extra HPA crap. Besides, 150 to 175 shots with 2 CO2's in a mag that can only hold 25 BB's, what the h3ll more do you need??

Some Crosman AR15/M16 replica's are blessed with nice trigger action, while the next one on a shelf will have a crappy one. No one seems to have done a "How-to" video or article I've ever seen. Both of my 2nd generation DPMS SBR's came with smooth no stutter trigger actions, though nothing a smooth and short as my real Panther SBR. My CFAR1 is not as good, short but not smooth, so I polished all the trigger and sear mating surfaces with a polishing stone all gunsmiths have and use for "Trigger jobs". The trigger on my MPW Bushmaster is terrible, feels like it has 2-stages and too long. I bought it as a "Mfr Refurbished" direct from Crosman and it was an earlier 2019 made unit. I just got it a week ago and I'll be tearing it down and shorting and polishing the trigger and sear contact area and see how it goes. WIll look into a slightly lighter coil spring too.

I don't know if you know, but Crosman DOES NOT MAKE these. They have an exclusive contract with KWC of Taiwan to engineer and make these at the KWC Factory in Taiwan. No other company can sell any variation of these. KWC is a premier manufacturer of Air Rifles, been at it since the 1980's. They also make "Practice" weapons for military and police use around the world.

So the first thing you need to learn is how to tear down you DPMS SBR and maintain it. https://youtu.be/vavnA73Gehk  best video on the Crosman's on You Tube.

Thanks cobra!

Sorry I missed your post as I'm slowly learning my way around this forum.

You make great points, and informative, lol unfortunately I have already gone down that rabbit hole. I ordered up a 9 ci hpa tank, the hand pump, the slide check adapter, the 12g dummy with side port, 300 rd mag, etc the list goes on lol! Much of this stuff is so new to me and I'm kinda winging it as I go along. For example, I am perplexed about what I need to fill the hpa tank, the fittings to connect the tank to the hand pump. I'm hoping that the fittings all work nice together when I get the air tank. I think it is a Foster valve? I know, such newb quest lol

Also, when I realized that 45 degree picatinny rail add-ons exist I pretty much used up all remaining real estate haha.

Thanks for the link to the vid. and I will be looking forward to learning more about trigger work.

Cheers!