Air Gun Home :: View topic - 'Soda straw' barrel lengths? (w/1077 modification notes)

AirGunEric · Site Admin

I'm having a frosting/liquid Co2 problem with a Crosman 1077. One of the possible solutions might be to install a longer barrel to give the Co2 more time and space to expand as it travels up the tube- hopefully also increasing muzzle output.

The 1077 'soda straw' barrel is approximately 20" long- does anyone know of longer barrels of this sort that I might be able to install (as well as find/manufacture a longer barrel shroud)? The longer the better- I can always cut something shorter as required.

AirGunEric · Site Admin

Well, after researching this and asking around, it turns out the 66, 766, 1077 and 2100/2200 all have 'soda straw' barrels which are 5/16" outer diameter. All of them are around 20" long.

Other Crosman guns with longer barrels- like the 2260 with a 24" barrel, are 7/16" outer diameter (and .22 caliber) and not technically of the 'soda straw' variety. They could be used as well, but would be more work to get everything set-up correctly for the finished product.

So- the easiest way I can attempt to put in a longer, 5/16" barrel in either .177 or .22 caliber is to use a barrel liner, which is typically used to repair rimfire guns, examples are:

http://www.e-gunparts.com/DisplayAd.asp?chrProductSKU=588180&chrSuperSKU=&MC=

http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=10974&title=.17+%26+.22+BARREL+LINER

There were some others I found online- but the prices were well over $100 per unit- whereas Brownells and E-Gunparts were well under $100 per unit.

I'm posting this so that anyone with a similar idea in the future has a reference on it.

StevieLaner7777 · Moderator

Hi AirGunEric!!

Doesn't the 1077 have and irregularly slanted barrel within the shrouding???

On my 1077 the rear end of the barrel is in contact with the lower part of the shrouding tube and the front end of the barrel is at the center of the shrouding tube at the muzzle of the rifle, Which gives it a slanted barrel angle!! I think the reason why Crosman have done this is to raise the trajectory of the pellet as this rifle lacks in power, This method prevents the scope from being adjusted to its max just to shoot a pellet with low power and therefore a low trajectory 30m downrange!

So wouldn't putting a longer barrel on inside the same diameter yet longer shrouding tube put strain onto the breech area of the rifle???

About the .22cal barrel:
A .22cal barrel on a 1077 would be very interesting to see how it preforms!! Personally though I think it would be a lot of extra work to change the magazine clip caliber, the valves and the internal mechanism as well!!! though I'm not saying that it's impossible, But if you ask me.. I'd think is best to stick with the same caliber to keep it simple! As you don't want to wreck the rifle by over doing it!!

Stevie Thumb Up!

AirGunEric · Site Admin

If I understand you correctly, you are right in that the sight/scope rail is not parallel with the barrel shroud- the rail points "upward" slightly as it travels towards the muzzle. I honestly can't remember if the barrel itself is centered in the shroud, or travels downward from the muzzle to the receiver- perhaps it does, thus the 'angled' rail- perhaps it is parallel with the barrel itself but not the shroud.

In any event- the plastic breech/receiver area is garbage. Now that I've had the gun apart 8 or 10 times- many of the screw holes are stripped/stripping and I've used a 24-hour epoxy to allow the screws to set and do their job. It is not the best quality plastic material, and it has no steel inserts in the screw holes to compensate for this. I don't think adding 4-6" of barrel length- with an appropriate new shroud or shroud extension would be too much strain- the barrel band ties the pieces together fairly well (it is steel) and then the stock reinforces everything. If the receiver were not held together this way- even "as from factory" the 1077 would fall apart in very short order due to the low quality plastic/resin.

As for converting to a .22 - it would be very interesting, but you are correct in that making a custom magazine and clip to hold .22 pellets would be problematic. The valve itself could probably remain the same, although expanding the exit hole on the spring-loaded front 'nose' that comes in contact with the rear of the pellet would probably be in order. About the only other internal change would be to shorten/tighten the hammer spring and/or put some weight on the hammer to hold the valve open longer to get more gas behind the pellet.

But anyways- for the moment I am going to stop working on the 1077- I've got it about as far as it will go without more radical modifications- i.e. custom valve, external expansion chamber (no way to fit one inside the gun it seems).

There is only one more thing I want to investigate- the difference in valve construction between the 'standard' valve and the 'de-tuned' valve- being able to compare the two of them would allow me to determine if either could be altered in such a way to get more Co2 through effectively (I have heard that the caplet to valve feed-tube on the de-tuned valve is set askew to restrict gas flow- if this is a method Crosman did use to de-tune, the opposite- i.e. a larger feed tube and orifice, might enhance the capabilities of the 'standard' valve)- I spoke with Crosman customer service earlier today about getting the other valve for comparison- but the C.Serv people don't know precisely how inventory is controlled- they couldn't confirm if they a) had the alternate valve available and b) if they could ship it. They will send me another valve- I just don't know which one yet- and apparently won't for at least a week ('backordered' on both apparently).

I finally (finally) decided to actually use an AirSource bottle on one of the 1077s today (I was always using 12g caplets) because of the number of times I had to disassemble/reassemble the gun with only a few test shots between each. Partially liquified Co2 was still spewing out the muzzle- but after taking a good 150 shots in total (it's handy having 12 magazines laying around and 3 clips to put them in!) I determined that some form of 'bulking' is the only way to use it- 12g caplets in the 1077 are a total waste of time to swap them out. So- I've decided that after the upcoming valve investigation, I need to 'bulk' the gun- the AirSource adapter and bottle are, in my opinion, way too heavy on the front end of the gun- if I could find a Cooper-T 1077 12g eliminator (if anyone has one- I'll pay good money for it) I would hook it up with a paintball tank attached to my waist- the adapter and hose couldn't possibly weigh more than the Crosman AS components. MaxZBulk has a 1077 adapter- but it too is bulky and looks heavy. If I could do this, due to the cost reduction and available volume, the Co2 spew from the muzzle would bother me much less- the gun would obviously still be wasting it instead of producing power with it- but whatever.

It's kinda sad really that the 1077 is so poorly constructed and has such crap quality control- being only one of a couple of repeater rifles (12-shot) it's great fun to be able to pop off 12 shots without reloading. This is the only reason I haven't taken my two 1077s and smashed them on the side of my garage!

StevieLaner7777 · Moderator

Hi AirGunEric

You Wrote:

AirGunEric · Site Admin

I hear what you are saying- and what I described is what the setup on one of my 1077s is like. Perhaps all any of this is, is further example of Crosman's lack of solid quality/standards control. If we think about it, it really doesn't matter how the barrel is position in relation to the shroud- the barrel is centered at the end of the shroud with the front sight piece- the barrel could curve around in a 'figure 8' and still shoot straight as long as the barrel end matches the sight positioning.

As for the Crosman AirSource unit, picture here attached to a resin (plastic) stock 1077:

It's hard to make out- but there is a shutoff knob/screw on the bottom to cut the Co2 off- but any Co2 still in the feed assembly and the gun itself will remain- about 6 shots with a reasonable power output's worth.

The valves- I have no idea where they come from- and I didn't bother asking the Crosman people- didn't seem too important- but China is probably as good a guess as anything.

The difference in power output between a "standard" 1077 and a "detuned" unit is that the standard has a stated Maximum velocity of 625fps, the detuned version a Maximum of 495fps. As I've found out, neither mean very much and either version of the gun could have an output as low as 350fps, and neither seem to come very close to their respective "maximum" outputs.