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PostPosted: Thu May 22, 2014 11:56 am 

Joined: Thu May 09, 2013 7:38 pm
Posts: 33
Hi guys!

I just got a under 495fps Crosman 1077 CO2 rifle (tsc flyer). Surprisingly accurate! So far my main issue is that the shot count is pretty low. Especially for a detuned rifle.

I'm getting about 3 decent magazines (36 shots), and then the velocity drops rapidly. I believe that's about the same one would expect from a full power rifle.

I noticed that a lot of CO2 is escaping through the magazine area. Pretty much with every shot I can feel it on my hand. The first few shots also produce a cloud of CO2 from the muzzle.

I'm wondering if the problem is just the seal behind the pellets or is there maybe too much CO2 released for the detuned valve assembly?

The first shots are in low 400 fps area (2-3 shots), then it stabilizes for a while in the 360-80 range, and then gradually drops. First magazine will have different POI than the second one. Third one is pretty much the same as the 2nd, and then the shots go low.
This is with 7.87gr pellets and 3-5s delay between shots. Ambient temperature of about 17 C.

I went through a bunch of threads about modding the 1077, but so far I didn't find one that would address this particular issue.

I'll appreciate your suggestions,

PostPosted: Thu May 22, 2014 12:43 pm 
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Joined: Tue Jun 03, 2008 5:46 pm
Posts: 2815
Location: Canada
Shot count seems about right from what I recall. The leak you feel during the shot cycle could be a couple things...

1) Barrel is in the forward position..(While I doubt this is the case, one never knows.)...this is for clearing jams at the magazine. Should be in the rear most position for shooting.

2) Can't remember the part number, but on the valve side of the magazine (in the rifle), there is a "nipple" of sorts. This commonly does not have an oring on it (even though it has a groove for one...010 IIRC). Gas pressure pushes this forward and against the magazine, sealing during the shot cycle. Adding the oring requires a complete tear down.

3) Magazines themselves are frequently an issue...if there is roughness on the flat side of the mag, use a piece of glass and some wet dry sand paper (600 or finer grit) to clean them up. Use soapy water to help prevent the paper from clogging. If there is gouging going on, look at the breech end of the barrel. Any roughness needs to be addressed...will require a complete tear down.

A good resource for 1077 users;



PostPosted: Thu May 22, 2014 1:34 pm 

Joined: Thu May 09, 2013 7:38 pm
Posts: 33
I'll look into the areas you mentioned. Thanks for the advice!

PostPosted: Sat May 24, 2014 5:16 pm 
Supporting Member 2009
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Joined: Sun Dec 24, 2006 12:37 am
Posts: 3468
Location: Out There
The 1077 is "detuned" in such a way that excess Co2 will escape from behind the spring-loaded detent prior to reaching the magazine- it really is the nature of the beast. The only "real" way to stop this is to reverse/not use the detuned version of the rifle- but then you would need a license to own/shoot it.


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