1377 flat top setup questions

1377 flat top setup questions

Joined: January 5th, 2011, 2:32 am

January 17th, 2011, 2:47 am #1



Hi all,

I was wondering if I installed a flat top setup and stronger hammer spring and guide into a crosman 1377, without changing anything else, how many pumps would it take to get 650- 700 fps? I want to use the pistol for more reliable pest control and want at least these velocities in .177 cal.

Ifrit
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Joined: April 1st, 2009, 3:18 am

January 17th, 2011, 5:53 am #2

...can be found using the search function here. Really too many to mention...

For your idea, I would go with a slightly less stiff valve spring and leave the striker spring stock and, yes, restrict the valve volume a bit. This way you can build the pressure needed to zip a pellet without having to pump the thing 20 times.

The specs you state can be got. The 1377 valve volume is already a bit big for the pistol's barrel volume. I have restricted the volume in mine. Some disagree with this method, but has worked quite fine for me. Currently have no 1377 pistols, but have a carbine. Currently building a 1377 single stroke for target shooting 10-20 meters.

Now, if you decide to put a .22 cal barrel on it I'd leave the valve volume alone, but mess with the springs as mentioned.

"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."

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Joined: December 13th, 2010, 12:25 pm

January 17th, 2011, 12:22 pm #3


Hi all,

I was wondering if I installed a flat top setup and stronger hammer spring and guide into a crosman 1377, without changing anything else, how many pumps would it take to get 650- 700 fps? I want to use the pistol for more reliable pest control and want at least these velocities in .177 cal.

Ifrit
Stone stock it is rated at higher FPS than my little 66 and my late father-in-law used to kill rabbits & squirrels with the 66. I'm thinking of getting one to plink with.
Jerry
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Joined: April 1st, 2009, 3:18 am

January 17th, 2011, 4:20 pm #4

...HB series are priced far apart. The 1377 sells for around 50 bucks and has plastic funiture, the HB sells for around 125, wood furniture. If Wal*Mart is selling HB's for 50 bucks - where!? I'll send you cash to get me one!



"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."

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Joined: December 13th, 2010, 12:25 pm

January 17th, 2011, 5:58 pm #5

I'm not sure the model #, but wal-mart had the plastic stocked one for $49.99 recently.
Jerry
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Joined: January 4th, 2010, 4:13 am

January 17th, 2011, 7:39 pm #6


Hi all,

I was wondering if I installed a flat top setup and stronger hammer spring and guide into a crosman 1377, without changing anything else, how many pumps would it take to get 650- 700 fps? I want to use the pistol for more reliable pest control and want at least these velocities in .177 cal.

Ifrit
Before you start modding your 1377 take plenty of time to do searches of this forum
for pros and cons of each new modification. An excellent example would be the flat top
piston mod, as I understand it when you do this as well as flattening the end of the valve
more pumps are required, and more maintenance on your part.
The first mods I made on mine was the valve porting, replacing the plastic grips with wood
adding a steel breech, longer barrel and tubular stocks. I did replace the pistons, but with
homemade ridgid kynar plastic ones using the factory seals, as they are readily available and
cheap. What I believe to be the most important mods have to do with accuracy, the trigger
group and barrel recrown when needed, The Steel breech allows for a scope or better sights.

A BIG THANK YOU TO ALL THE GUYS HERE for the information and guidance freely given
I hope that I grow up to be able to pay some of this forward to some of the new airgunners.

The gun below started out as a stock 1377 but is now .22, 14" barrel w/valve ported, poly tube
mod, ridgid piston, my tubular stock w/ walnut fore and aft. Crosman steel breech, homemade trigger
w/honed sear and hammer, modified springs, and homemade safety.
Also without the Leapers 4X scope the iron rear sight works well with the factory front.
Shoots best with 11 pumps using JSB exacts.



I BRAKE FOR BISCUITS
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Joined: February 22nd, 2007, 1:37 am

January 17th, 2011, 9:11 pm #7

I'm not sure the model #, but wal-mart had the plastic stocked one for $49.99 recently.
Jerry
has the 1377 with steel breech and brass bolt, plastic grips and shooting 600-625 ft per second... it is 54$ before tax.
i just had a 1377 given to me with grip missing and in much need of TLC!!
ordered carbine stock new valve and cup for it... later it will get FT piston and valve and 16in barrel..
Larry

plink, plink, plink!!!
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Joined: February 22nd, 2007, 1:37 am

January 17th, 2011, 9:11 pm #8

I'm not sure the model #, but wal-mart had the plastic stocked one for $49.99 recently.
Jerry
Re: walmart.......
Last edited by twoblularry on January 17th, 2011, 9:12 pm, edited 1 time in total.
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Joined: February 22nd, 2007, 1:37 am

January 17th, 2011, 9:13 pm #9

has the 1377 with steel breech and brass bolt, plastic grips and shooting 600-625 ft per second... it is 54$ before tax.
i just had a 1377 given to me with grip missing and in much need of TLC!!
ordered carbine stock new valve and cup for it... later it will get FT piston and valve and 16in barrel..
Larry

plink, plink, plink!!!
plink, plink, plink!!!
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Joined: April 1st, 2009, 3:18 am

January 17th, 2011, 9:17 pm #10

has the 1377 with steel breech and brass bolt, plastic grips and shooting 600-625 ft per second... it is 54$ before tax.
i just had a 1377 given to me with grip missing and in much need of TLC!!
ordered carbine stock new valve and cup for it... later it will get FT piston and valve and 16in barrel..
Larry

plink, plink, plink!!!
...the 1377 has had a plastric breech for many years now. You can always stick a steel breech on it.

"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."

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