JavaScript is disabled
Our website requires JavaScript to function properly. For a better experience, please enable JavaScript in your browser settings before proceeding.
Messages
11,542
Reactions
20,375
Considering getting a full auto steel BB gun from umarex (does not use battery) but I want to disable the blowback portion to save co2 gas and reduce noise. So I'm tying to research it to see if it can be done before I buy.

Does anyone know how to disable the blowback/bolt or have any links to how they work? If I can see how they function then I can probably make a guess as to how to disable the blowback part of it (if it can be done so that gun still functions I mean).

Thanks for any info. or leads to info! Cheers!
 
Why? Is it so you can do both stealthy stuff and have fun when you want?

Most have a reciprocating bolt mechanism and a similar hammer to a real gun. Once the hammer strikes the bolt it is usually hitting a spring loaded valve. That releases gas that shoots the bb out and the bolt reward to pick up another bb from the mag.

Im pretty sure you could rig up something to keep the bolt forward so the gas doesn't make the bolt go rearward.
 
I can't help you with the blowback, but I have the Crosman DPMS SBR and it is absolutely addictive.

1634410707889.png
 
Why? Is it so you can do both stealthy stuff and have fun when you want?

Most have a reciprocating bolt mechanism and a similar hammer to a real gun. Once the hammer strikes the bolt it is usually hitting a spring loaded valve. That releases gas that shoots the bb out and the bolt reward to pick up another bb from the mag.

Im pretty sure you could rig up something to keep the bolt forward so the gas doesn't make the bolt go rearward.
Yea trying to see if it can be backyard friendly. I found out u can use a 14M left hand thread female to 1/2x28 male adapter so that u can mount standard .22 suppressors. So that's a big chunk of noise reduction but I assume the action of the bolt plus gas coming out of the breech area when it cycles will also be very noisy (only guessing, cuz I have never shot one).

If that's right about it functioning like a regular semi auto gun (action picks up another round and cocks hammer) then it prob won't work for me cuz like u say u can block the bolt so it doesn't cycle, but then u have a single shot gun. For me this toy would be full-auto or go home ha ha cuz I have the silent single shot pellet gun type gun covered. Full auto is the only reason for getting one for me. Thx for the info and it's much appreciated. Would love to hear any one else experiences or ideas or links to info also if anybody has any knowledge or links. Thx!

Edit: I just had a thought that if it functions like a regular semi auto then perhaps a person could try to quiet down the action (wouldn't stop gas noise out the action though but that gas-derived noise may be so minor that it's a non issue -I don't know). I know this place claims great success in quieting down the ruger 10/22 so maybe similar mods to what they use could be an option. ?

 
Just adding a note regarding noise of the action that just came to mind: For a s&w 15-22 (powder burner, not airgun) shooting subsonic .22 rounds the action alone with no round fired is about 113 db measured to mil specs with proper meter, spacing etc. The gun (not just the the action) when fired with either a good suppressor or an integral suppressor is about 114db. So that is only about 1 db difference meaning for that particular gun most all (possibly all) the noise from the action when fired and cycling a new round is due to the action working, not due to gas escaping at the breach. Here are mrgunsandgear's test numbers fwiw and my testing has shown about the same. Also tone of action working is higher pitched metallic tone and gunshot (out of a suppressor I mean) is lower pitch non-metallic tone. It's funny but tone makes a difference in how "jarring" we perceive the sound IMO. Perhaps none of this correlates to co2 though I don't know, just passing along what I have seen/tested.

I would love to figure out how to quiet down 15-22 action just for the fun of it to see if it makes whole thing seem quieter. One thing I did notice is the all metal hk416 .22 is a fair bit louder than the polymer 15-22 using the same ammo and conditions. It must be due to the mostly-all-polymer 15-22 soaking up some of the noises of the action etc.
59FD73ED-10CB-4180-96A8-08743B0D4A94.jpeg
129B7976-F500-4B90-84F6-82E048361E54.jpeg
 
Last Edited:
Ordered one of the umarex mp40s cuz sportsman's guide has them for $133 after $20 coupon (fwiw the coupon is shown in "great deals" subforum). As I understand it from research it fires from an open bolt which is cool. Sounds like it is mostly metal except for the areas that were brown "Bakelite" on the original are now brown modern plastic. Apparently will shoot the 52 round mag with one trigger pull. Safe, semi, full are the safety switch options. Claims 465 fps but having shot a lot of co2 power drops off the more rapid shots u take due to decreasing temp from co2 gas.

Here are some pics of real mp40 from the 1940's (top photo) vs the weathered airgun version (middle photo) vs the non-weathered version (bottom photo) fwiw. Note that the lack of removable muzzle tip and no reinforcing ribs on mag well of the original 1940's version are due to that being an early model. Later versions had muzzle tip and ribs like the airgun does. My understanding is that the "weathered" version is no longer made but I suppose a guy could use some steel wool and oil to age it.
74A55F68-D8C1-42DC-9133-F3181167F7CE.jpeg
D87A1889-44B2-4636-81C7-4E843C4E46CA.png
 
Last Edited:
Most of these have a hammer that strikes a power valve. That valve is what releases a pulse of co2. The hammer is cycled by the blowback. If you wanted, you could manually hold the bolt closed for each shot, and then rack the slide to set the hammer and load another round.
 

Upcoming Events

Tillamook Gun & Knife Show
Tillamook, OR
"The Original" Kalispell Gun Show
Kalispell, MT
Teen Rifle 1 Class
Springfield, OR
Kids Firearm Safety 2 Class
Springfield, OR

New Resource Reviews

New Classified Ads

Back Top