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Barry McGee's Custom 2300

Cothrane stainless tube, left handed breech, power adjuster,
Lothar 10" barrel, H.P.A.sports co2 cap, Clague ldc,1701 trigger group,
Stace trigger, Rick Andres grips and a Mueller quick shot reflex sight.

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1377 MOD

January 29 2010 at 6:33 PM

Bentong  (Login Oragon2)
Crosman Forum Member
from IP address 24.129.98.4

Just finished modding my 1377. Installed metal breech, 18" barrel and flat top piston/valve. Before installing the FTP I was getting 607-597fps with 7.9CPHP 10pumps with Flat top piston/valve I was getting these with 7.9CPHP's
646fps @ 8 pumps
686fps @ 10 pumps
735.5fps @ 15 pumps with residual air
@20 pumps I was able to get 2 shots
1st 692fps
2nd 732fps
To get her to shoot all air in one shot, what tweak do I need to do. Do I lighten the valve spring or just get a stronger hammer spring or combination of both?

 
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AuthorReply
Anonymous
(Login 1377needshelp)
Crosman Forum Member
206.55.179.109

Re: 1377 MOD

January 29 2010, 8:41 PM 

from what i have read both need modding
use the search function type in 1377 hammer mod
you will get plenty of info such as what size spring to use where to get them
how long they should be
if you want to know recent mods use the date option in the search
the match option will give you random mod dates

 
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Anonymous
(Login Thejohnnyairgun)
Crosman Forum Member
66.32.194.109

Where did you get your valve and piston? n.t.

January 30 2010, 12:32 AM 


 
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Bentong
(Login Oragon2)
Crosman Forum Member
24.129.98.4

Try here

January 30 2010, 5:50 AM 

Got it from AC
http://accustomparts.com/13xxFlatTopPiston.aspx
and the valve was OEM that I just flatten (filed/sanded) and opened up the port and dremeled the corner. You can mail him your valve and he can turn it for free or add $5 for power mod with it.

 
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Pete
(Login petedrans)
Crosman Forum Member
74.75.236.245

Re: 1377 MOD

January 30 2010, 7:22 AM 

I put a lighter spring in my 1377 valve, getting a good dump of air. I started out with a harder/stiffer hammer spring, but ended up putting the stock spring back in. i did this because with the harder hammer spring effected trigger pressure as well as being much harder on the internals. The hammer was hitting so hard it was loosening grip screws and felt like it was much harder on the gun. Mine has a 14" .22 barrel and I am shooting 635fps on 15 pumps with superdomes (full dump)12.8ft/lbs. I also cut valve threads and ported valve (some say this only makes you have to pump it more to get up to pressure,true, but I use mine for hunting and like to pump it up for one powerful kill shot. I can think of maybe three times when a squirrel/starling/crow has let me get a follow up shot...chipmunks have been the only prey that will sit there frozen in their tracks) I could get a bigger dump with the hard hammer spring, but you'll find what you prefer once you start messing up the springs. oh yeah, flat top piston from airgunsmith.com as well.

Pete
[linked image]

 
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twhooper
(Login twhooper)
Crosman Forum Member
70.241.103.168

I agree the lighter valve spring...

January 30 2010, 10:31 AM 

is easier on the gun, and lets you dump more air. Seems more accurate as the trigger is lighter and gun doesn't thump as much when you shoot. If you get a flat top piston I recommend you install some sort of quick remove pump arm pivot pin. Several types have been posted here. I just happen to like the ones made by Charles Mellon.

Be Well... Tom
Think as though you LIFE depends on it...IT DOES!
"A fear of weapons is a sign of retarded sexual and emotional maturity." - Sigmund Freud

 
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Anonymous
(Login 1377needshelp)
Crosman Forum Member
206.55.179.109

try this

January 30 2010, 11:40 AM 

"Take a short socket head cap screw that is slightly larger diameter(the head) than the spring
and place it behind to spring to add preload."
some one here suggested this

 
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Bentong
(Login Oragon2)
Crosman Forum Member
24.129.98.4

Zero

January 30 2010, 1:14 PM 

air left now after 20 pumps. I replaced the valve spring with my scrap 2250 spring. Tried it at 20 and still some residual air left so I shimmed the hammer spring with 3 small washers and now it dumps all. When I try to pump it leaks the air through the barrel so I cock it first then pumps. If ever I have to go past 20, I'll just swap to a bit more softer valve spring to ease up the pumping exercise. Now I'm just waiting for the cocking pivot screw mod from Charlie and I'm good to go. Roll pin on the pivot is a PITA to stay put if I shoot a lot. Thanks to all the tips.

 
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Mike
(Login CarsonRatSniper)
Crosman Forum Member
71.93.75.154

My rig will dump 40+ pumps

January 31 2010, 9:28 PM 

Lighter valve spring & tapered Delrin stem. I used a 2200 Magnum spring with the stock hammer.

[IMG][linked image][/IMG]

[IMG][linked image][/IMG]


 
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Bentong
(Login Oragon2)
Crosman Forum Member
24.129.98.4

Whooze

February 1 2010, 6:41 AM 

that's fast! What pellet did you use? That's a lot of pumping.

 
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John
(Login Thejohnnyairgun)
Crosman Forum Member
66.32.211.20

please put a video on you tube.

February 3 2010, 8:28 AM 

Im sure all us 1377 owners want to see that in action. That gun is a urban legend beast, it looks fantastic also, keep up the good work.

 
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