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

...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."

This may be cover else where. I tried to search & couldn't find it. You mention converting to .22. Can you use parts from a 2240 or 2260 to convert to .22? If I get over to Wally World today I'll check on thst pistol they have.
Jerry

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

...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."

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!!!

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."

..seems like yesterday to us grey beards..

Must be a Local Sale?

I see Amazon has New 1377's for $49

Mario

What's this,Phil?

Mario

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

If I convert My 13XX w/ Steel Breech,FT Piston & Valve(Modded),Poly Port and
24" .22 Barrel How Many Pumps would I need for 625+ Velocity with 14.3 Cr HP's?

Mario

but you would definitely need a chrony to be sure, the set up of piston to valve face is
a big factor here as I understand it the closer to the valve face the piston travels, the
less pumps required. I not using the flat top pistons right now.
I have played with the valve to piston face distance and I want the piston cup to be kissing
the valve.

I BRAKE FOR BISCUITS

n/t

Although the fps numbers that you would like from a flat top piston are a little high you should get an average of 627 fps see http://crosmanairgunmods.blogspot.com/search?q=flat+top+piston+mod for numbers, date Wed June 23 2010). I bought my brass adjustable flat top piston with valve mods fromhttp://accustomparts.com Alejandro is a great guy to do business with and lots of questions are answered on his website. I am very pleased with my 1377 mods he has done for me including a 14" barrel, crowned and machined lead in with poly tube transfer port mods.

Joe

I did the same mods plus a valve from Mtn Air and a 14" barrel I can get 750fps with 15 pumps.

With the mods mentioned here, I get an average of 581 fps with 13 pumps on my 1322. Everything you do to your gun will factor in the final fps, from valve to barrel length.

1322 w/14" .22 cal barrel, custom valve, brass piston: (~581 fps)
[IMG][/IMG]

also;

1325 w/22" .25 cal barrel, full hot rod valve mod, brass piston, and power adjuster: (~565 fps)
[IMG][/IMG]

Have fun!

where did you get the stock for if? If you don't mind sharing?
emails OK
THANKS

I BRAKE FOR BISCUITS

Hi James,

The stock if from Muzzle Mack. I picked it up about a year ago. I think Joe is going back into stock production this spring. The grip and forearm are from RB Grips.

Have fun,

Kevin

Did you build it from scratch? I Like the Carbon Fiber Shroud w/ brass front end!

I ddn't think the 13XX's Had Power adjusters How does it work?

Mario

Hi Mario,

I started with a stock 1377 and built from there with parts purchased from the numerous artists out there. Roy @ Mountian Air played the largest role in parts for this gun. That's one of Roy's .25 cal top end sets with RJ Long Breech. Roy also made the shroud and "yes" a power adjuster which may or may not play a role in fps... It works just like a normal power adjuster to compress the hammer spring. I figured the more air that's released from that bored out valve the better.

It's a fun and very accurate gun and has no problem with most medium sized pests...

Thanks,

Kevin

I had asked Roy about getting one of his top end sets to Do My own 1325. at the time
he had some .25 L/W barrels Ordered from Germany & had put my name in book to send. I already have the basic 13XX a FT Valve & Piston I got on ebay I have the Poly tube for Transfer port and a 1399 Stock... and a Long breech. He now has some barrels & I have an AS2250Xt I want done Like his Model 13 but in .25

I'm Just waiting on word from him to open up shop again at new Address. I was gonna get his Model8
(1325)with a, 18-1/2" Barrel in Walnut...but it'll have to be put on back burner ,on Low...lol!

Mario

P.S. Never saw a Power adjuster on a Pumper before,what's it's purpose and where does it go?

My guess is where you used to cock the first Variant 1377 am I correct? I'd Like to get one of those for My 1377(Phase 1)

Just get a Benjamin 392 and do a lot less modding. Sorry. Couldn't resist.



I plink, therefore I am.

That's a nice looking Bengi! Does not look modded at all...

With the flat top valve and piston and lighter valve spring I was able to get about 630 fps on 14 pumps.....700 fps will probably require some kind of valve work like Phil suggested.