Tuning Crosman DPMS SBR build
- Thread starter Hatsan123
- Start date
As I have not yet tore into mine, please explain to this newjack what are these spacers you speak of?
Thanks to all helping out!
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You still have to determine how many spacer's you want to put so you will need to experiment
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Of you don't have confidence on disassembling Or you're scared you will f up the gin just stay at 850psi
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Ok thanks Gold
Great info!
Got the tank and line.
Been away from it and busy with other projects but gonna get back into it. All this knowledge is mint thanx pal
Great info!
Got the tank and line.
Been away from it and busy with other projects but gonna get back into it. All this knowledge is mint thanx pal
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FWIW: This measured 8.8lbs on my postal scale and 9lbs on the bathroom scale. QR mag full of BB's. I can put bottle in pocket and tether for lighter weight. Also, can remove QR and bottle and use the oem CO2 mag in just a few minutes. Only the mount at the bottom of the pistol grip remains.
If I was into realism and training, then would not do these mods. These are good for CO2 independence and those who want more power. BTW, those arcades were fun.
If I was into realism and training, then would not do these mods. These are good for CO2 independence and those who want more power. BTW, those arcades were fun.
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I don't recall any problems when i removed mine, outside of it having left hand threads. BTW, a "working" compensator didn't make it much quieter because the mechanical noise from the action is the main driver.
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Joey, you appear to have one of the few performance builds out there. Were you getting close to 1000 fps at 1100 psi? It looks like you went up to 1800 psi after your original post, so I am curious what the performance is like now. In your experience, would there be any benefit to shimming the hammer spring at the stock air pressure? I’m sure a lot of people would like to see any videos or pictures you can put together to show the change in performance.
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I would like to see the performance data, as well. My chrony doesn't like registering the small BB's.
I do know that the spring shimming or heavier spring is so the action works with the higher pressures. Doing it at the lower pressure will just cause problems.
In case anyone is looking for them, here are the schematics and parts list:
Also, crosman has a Black Friday/Cyber Monday deal coming to get $50 off a few of their full auto BB guns and 25% off everything else: BF DEAL
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FuzzyGrub,
Great post! I’ve seen references to the parts list, but this is the first time I have seen the diagram to go with it. Nice bonus with the discount code too!
I have read that shimming the hammer spring might become necessary at higher pressures to avoid valve lock, but I thought it may still help open the valve more at stock pressures. My paintball marker had a pretty significant change in velocity from just changing the preload on the hammer spring at the stock pressure. Unfortunately, I do not have a chronograph to see where the ideal adjustment might be.
Great post! I’ve seen references to the parts list, but this is the first time I have seen the diagram to go with it. Nice bonus with the discount code too!
I have read that shimming the hammer spring might become necessary at higher pressures to avoid valve lock, but I thought it may still help open the valve more at stock pressures. My paintball marker had a pretty significant change in velocity from just changing the preload on the hammer spring at the stock pressure. Unfortunately, I do not have a chronograph to see where the ideal adjustment might be.
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Typically, in a CO2 gun, a heavier spring would produce a small fps increase at the expense of allot more gas use. For these semi/full auto guns, the blowback needed for cocking the hammer is also in the mix.
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HPA seems like the way to go. I’d just like to see more information on what kind of results to expect before I order a bunch of stuff. I thought adding preload to the hammer spring might be something inexpensive to try while I consider my options.
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Don't let me hold you back from any experimentation.
I have been eyeing that A4P, but would have to add a rear stock Already have a QR mag and dummy co2 cartrage, and would use my existing tether.
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FWIW: you can get those same full autos right now, for a bigger discount of 40%. Use “EARLYBIRD” discount code.
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In case anyone is considering an extended barrel to try increasing fps, the barrel is a simple tube held in place by a rubber bushing at each end. I measured the OD as 0.2355”, so it is most likely specified as 6 mm. An extended barrel would just take finding another BB gun with a longer barrel that uses 6 mm OD, and then making a different bushing on the muzzle end. You could then cover the extension with some air soft accessory. The barrel is really only 9-5/8” long, so it seems like 16-18” would have more potential without looking bad.
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Hey I was wondering if you would send me the details on how you did this pls and pics of how you changed the trigger pretty much everything pls this is so awesome in my book your a badass thanks for sharing
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