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Old meets new

September 8 2011 at 7:53 AM
  (Login Mac-1)
Crosman Forum Member
from IP address 69.234.25.56

 
The early 760/140/130 piston required a puller to get apart, cup replaced and the assembly was pressed back together. The force required gave you a good ooportunity to destroy the washer being pulled and fail to get the parts to separate. Pushing them back together was tricky to do without bending the aluminum piston at the threads.
The seals available for this have been getting softer and softer and it has resulted in the 140/1400 guns not intaking a full gulp of atmosphere each stroke. The last available factory seal did the same thing so I had to look at a solution for the new and old guns that gave the economies of scale worth manufacturing parts for.
The solution was make a a substiture piston head that has an oring groove in it. You replace the Alloy washer, brass retainer and the cup with the part I make leaving the Felt and then fiting a 90 durometer urethane oring to the groove in the head. A factory piston needs to be shortened a bit to be the correct length after fitting the head.
This piston will fit the modern guns once the valve is cut flat and I will be making copies of the early 760 piston rod in alloy and we will eventually supply the complete assembly with metal guide, jam nut and oringed piston head with all the aluminum parts anodized black.
The guide and piston rods will be a direct copy of the Crosman 760 early design which fit the 1377 as they share the same valve and piston layout.
The only part of the piston that won't be metal is the replaceable head so any damage to the head can be quickly swapped for a fresh part. It presses onto the piston with considerably less force than the factory brass part so piston bending should be a non-issue.
The New Mac1 Piston herad comes with two 90 duormeter orings and is $12 per kit. $8 for piston heads only. Parts rebuild kits for the 760, 130/1300 and 1400/140 will be $25 including the new piston head and one oring. Extra orings are $2 each.
I've delivered a dozen new style piston heads now and the silence is good evidence they are doing the business.
I'll let everyone klnow when the parts are available to make up complete assemblies. All 1377 reworks and new guns can now opt for a Flat head piston for a $22 upcharge when doing the Mac1 1322 long barrels that are so popular.
Now the 1377 converted to .22 with 18" will be putting out over 625 with average weight ammo at 12 strokes.
With Power prep, accuracy prep, flat top piston, XT steel breech, long barrel, Gen II brake and gun included the 1322 runs $242 with plastic grips and $269 with Shoulder stock & grips. It is one of the most popular things I do and everyone calls to tell me how accurate they are with a lot of guys telling me this is the most accurate pistol they own.

[linked image]

"NO GUNS WOULD BE A RIOT"

Later

Tim

Mac1 Airgun



 
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Anonymous
(Login 1377needshelp)
Crosman Forum Member
206.55.179.109

Re: Old meets new

September 8 2011, 1:51 PM 

thanks for posting this
i use the early 760/140/130 piston in all my 1377's old and new
this is a welcome change
are they available on your site???

 
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(Login Mac-1)
Crosman Forum Member
69.234.25.56

When I get the store up...

September 8 2011, 2:51 PM 

...and running again it will be available. The Stopre is non-fuctional currently.

[linked image]

"NO GUNS WOULD BE A RIOT"

Later

Tim

Mac1 Airgun



 
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airgunandy
(Login airgunandy)
Crosman Forum Member
206.208.93.60

Re: Old meets new

September 8 2011, 1:55 PM 

Will this new piston design work in a Crosman 101 or 102?

I plink, therefore I am.

 
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(Login Mac-1)
Crosman Forum Member
69.234.25.56

The type like the 1400 yes

September 8 2011, 2:50 PM 

Any of the type that pull apart like the S&W will work. Can't use it on a version that has the cup captured between threaded pieces but a coupler will need to be made to join the male threads of the piston with the shortened and rethreaded factory rod.

[linked image]

"NO GUNS WOULD BE A RIOT"

Later

Tim

Mac1 Airgun



 
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