diffing in to the Crossman M4-177

found a few things I would like opinions on,

First here is the exhaust hole in the piston stock....

Here is the exhaust hole in the valve, the rubber o ring's ID matched the ID of the hole in the barrel support (shown above)

http://i4.photobucket.com/albums/y14...7/DSC06450.jpg

I remove the o ring and find this curious metal washer between the o ring and the valve exhaust port

http://i4.photobucket.com/albums/y14...7/DSC06453.jpg

The actual hole in the valve is a lot bigger withut that washer. any particular reason it is there? My limited knowledge of airguns tells me this is robbing the rifle of power. If so do I just remove it, or does the washer have some function...and thus I would need to leave the washer, drilling out the center of the washer to match the hole in the valve.

Last I find this curious hole, just below where the valve stem sticks out of the valve....what is it for....it this to vent pressure and "de tune" the rifle?

http://i4.photobucket.com/albums/y14...7/DSC06454.jpg


EDIT subject should read M4-117 not M$-117

"Washer" will restrict the flow...also spaces out the seal....a dremel might be your friend here.

Bleed hole in valve is common on newer manufactured Crosman pumpers. A google search for plugging bleed hole in a Crosman might turn up a result or two.

Al

well I made a new washer out of a nylon washer I had....it eas a bit to big, but I sanded it down. Now all I need to do is sand it a bit thinner (same width as the original)

http://i4.photobucket.com/albums/y14...7/DSC06455.jpg

Fits real good :)

http://i4.photobucket.com/albums/y14...7/DSC06456.jpg

I would check the height of the seal stack. Ideally the breach sockets into the hole in the valve. If your stack is too high you'll have trouble getting everything back together and there is a good chance the seal will blowout on the exposed edge.

everything is back together with the new washer (washer size same in thickness and O.D. as original)

I thought the breech would socket into the hole in the valve as well, however, upon inspecting the stock o-ring..there is no way the o rings I.D. will fit around the O.D. of the breach.

the breach just sits in top of the gasket (sandwich fit). This is one of the reasons I want to be sure the new nylon washer was the same thickness. I actually left it a BIT thicker as to get more pressure in the "sandwich" between the o-ring and the breach.

Sorry about the confusion. I meant a sandwich stack but with the lug on the breach just entering the hole on the valve so that the entire stack is captured within the confines of the hole

In your first picture it looks like the oring is just proud of the valve and thus the lug is sitting above the socket hole.

In my experience of rebuilding crosman rifles of this type the lug normally just enters the socket....However, it may not be so in this version

well, the stock washer may just have to go back in. I do not have a "how-fast-a-ma-jig", but WOW the M4-117 is running HOT

All I have to go by is impact signatures in my targets from before and after mod, and the sound the round makes when it hits the target. Noticeable change.

I may have to put the washer back in as this "configuration" of rifle would be restricted if shooting over 500fps due to its appearance.

Super pleased with the rifle tho, accuracy is real nice and with no kick at all it is real easy to shoot like you know what you know how to ;)

Thanks for the pics!
I agree this is a great lil carbine for plinking in the backyard. I do want to mention that this rifle would NOT be restricted if made to go over 500fps as it is not a handgun. its a ten pump airgun lol

It is, by the CFC's determination, a "Restricted" product (due to it's appearance)- you can certainly take it up with them, but let's not start telling people things that could get them in serious legal trouble. The AR-15 is not a 'handgun' either- but it's also "Restricted", as are many assault-rifle appearing products.

yeah, fair enough, my bad.

Guess its so nonsensical that it gets me mad is all...

JUST GOT OFF THE PHONE with a RCMP Firearms tech.

"Absolutely not, the crosman m4-117 modded to go over 500fps would be a NON-restricted Firearm"
The logic here is any firearm that resembles an AR doesn't become restricted because of design features that make it LOOK like one. It would have to be built as an operating AR-15, gas line, etc...

BAM

Achmell

I understand that you are very keen on the subject of the M4-177.

But posting the same thing in three threads is spamming and that's not appreciated by anyone.

Further......"I talked to this guy on the phone" means nothing in court.

This is published....reference here http://www.rcmp-grc.gc.ca/cfp-pcaf/f...me_air-eng.htm

Quote:

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High-powered air rifles are generally classified as non-restricted firearms. However, the classification depends on the exact design of the air gun. Air rifles manufactured to resemble an assault rifle could be non-restricted, restricted or prohibited depending on the exact model imitated. High-powered air rifles would also be prohibited firearms if fully automatic or if they have a sawed-off barrel. They could also be restricted firearms if they have a folding stock that reduces the overall length to less than 660mm.

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I apologize for the spamming, did not mean to.

But I called the Canadian Firearms Program, talked to an RCMP Gun tech in Ottawa, and discussed this air gun, as well as many .22's out there that resemble, but do not operate as an AR-15 does.

I am aware of that passage you quoted. I talked to the people who make/enforce our firearm laws and they informed me that the M4-117 if modded to go over 500fps, would NOT be considered a Restricted rifle. Because it is a simple plastic shell surrounding a multi-pump air rifle.

Yes I am very keen on this subject, i encourage everyone to do whatever they wish with this information. Go ahead and call the CFP yourselves if you want.

Again, sorry for the spamming, guess i got a little excited.:icon_redface:

Getting 'excited' doesn't get anyone anywhere terribly quickly or efficiently.

I verified earlier today with the CFC that there was quite a bit of confusion on the M4-177 when it was coming to market- many people within the RCMP wanted to call it "Restricted" and initially it was- then someone decided to do a detailed analysis and it was apparently re-determined to be "non-restricted". Perhaps a bit more consistency would help avoid such confusion for everyone in future.

The thing to keep in mind in Canada is that until something is challenged in a court, the Legislated holder of an enforcement policy can make up the regulations for enforcement any way they like. Just stating something- i.e. "that isn't illegal" or what-not, is fairly irrelevant unless you want to be the one to spend time in court.

I see,
yeah we live in a ass-backwards country as far as gun control goes. Just look at how any AR-15 .22 is restricted, yet colt and ruger have tactical .22's that do the exact same thing, yet are non restricted...

Getting back to the heart of this thread,
Ive also removed that washer, haven't replaced it with anything and am pleased with the seemingly increased performance in my airgun.

What you need is a flat-top piston kit: http://scopesandammo.com/storefront/...ston-kit-p-383

Put the washer back in and actually haven't noticed a change. Didn't even need to sight it in again, I'm shooting from 35 meters and still hitting cans.

Quote:

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Originally Posted by achmell

Put the washer back in and actually haven't noticed a change. Didn't even need to sight it in again, I'm shooting from 35 meters and still hitting cans.

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does not make sense. That washer restricts flow big time. Mine lost lots of "punch" when I put it back in.

Well either way I had to return the airgun to Canadian Tire as the stock broke off. Got the replacement M4-177 and upon initial breakdown, noticed there is NO washer restricting airflow between compression chamber and breech. I taken the comp. chamber apart too, and it looks like they've modified it to reduce the pressure to the breech. So it looks like i have an "Un-modifiable" M4-177. Must be a "second generation" m4-177

Everything is modifiable, one way or another.

http://scopesandammo.com/storefront/...ston-kit-p-383