My New .177 Crosman 1377 Pistol - Chronied - Results

[bltefft]

I went outside a moment ago and shoot two 12-shot strings from my brand new .177 Crosman 1377 air pistol through my Caldwell Precision Chronograph.

I pumped the pistol once, shot it, then pumped it twice and shot it, pumped it three times and shot it, etc. I did this routine all the way to 12 pumps (even though the instructions say don't go past 10 pumps - I was curious, hope my curiosity won't "kill the cat").

Here's what I got. Except for 4 pumps, seemed to me like it shot faster as time went by - maybe it heated up as I pumped it.

 

[bandg]

Interesting, but surprising to me. I believe they recommend a maximum number of pumps for a stock pistol, which I thought was 8. Maybe 10. But you are not only gaining more velocity from 8-10 (and beyond) but still gaining that velocity in relatively large steps. It is a DECREASING gain with higher pumps but still gaining velocity. I could see this with a modified pistol but it surprises me for a stock version.

Both my Crosman pistols (1377 and 1322) are modded with flat top pistons/valves as well as ported internal on the valve and both will still completely dump the air charge only to a point. Up to a certain number of pumps, you can recock and fire and only hear the hammer fall-no retained air causing an audible pop. Beyond that number of pumps, if you do the same you will dump a bit of retained air "pop". I would have thought a stock pistol would do that at about the recommened limit for pumps. I wonder if your pistol is "average" or maybe yours is functioning a bit "above the norm"? In any event, good results and good to have posted.

 

[bltefft]

Interesting, but surprising to me. I believe they recommend a maximum number of pumps for a stock pistol, which I thought was 8. Maybe 10. But you are not only gaining more velocity from 8-10 (and beyond) but still gaining that velocity in relatively large steps. It is a DECREASING gain with higher pumps but still gaining velocity. I could see this with a modified pistol but it surprises me for a stock version.

Both my Crosman pistols (1377 and 1322) are modded with flat top pistons/valves as well as ported internal on the valve and both will still completely dump the air charge only to a point. Up to a certain number of pumps, you can recock and fire and only hear the hammer fall-no retained air causing an audible pop. Beyond that number of pumps, if you do the same you will dump a bit of retained air "pop". I would have thought a stock pistol would do that at about the recommened limit for pumps. I wonder if your pistol is "average" or maybe yours is functioning a bit "above the norm"? In any event, good results and good to have posted.

Thanks for your input. I had no idea what to expect from this new pistol. Because I couldn't decide what to get between a 1377 and a 1322 I bought both. The 1322 arrived today. I'm going run the same test on it, probably tomorrow.

 

[DARKHORSE1967]

I thought it was a 13xx converted to a PCP 

 

[Archdesigner03]

That's really low velocity for 1377. My stock 1322 is 480fps with cphp at 10 pumps and 520fps at 12 pumps. A lot of 1377 owners complain about the pistol under performing per manufacturer specs while 1322 owners report it meets or exceeds the advertised velocity. 

 

[bltefft]

That's really low velocity for 1377. My stock 1322 is 480fps with cphp at 10 pumps and 520fps at 12 pumps. A lot of 1377 owners complain about the pistol under performing per manufacturer specs while 1322 owners report it meets or exceeds the advertised velocity.

I screwed up. I think you were you looking at the average of the # of pumps I was doing. And now that I think about it, the average of 399.9 fps makes no sense at all, don't even know why I posted it.

Bottom line - With my new 1377,

10 pumps gave me a highest velocity of 495 fps, producing 5.70 FPE. I was shooting a .177 Crosman Premier Ultra Mag 10.5 gr pellet (actually, it weighed 10.48 gr).

12 pumps gave me a velocity of 521 fps, producing 6.32 FPE, shooting the same kind of pellet.



Oh, and with my new 1322, 10 pumps gave me 478 fps shooting a .22 JSB Match Jumbo Diabolo 15.89 gr pellet (actually, it weighed 15.92 gr). 478 fps gives me 8.08 fpe.

12 pumps gave me 493 fps shooting the same pellet. 493 fps gives me 8.59 fpe.

 

[1Sprayanimal1]

Mine is crazy accurate but shoots 3” high at 20 yards. I’ve exhausted my adjustments. I contacted Crosman and there reply was ok and sent me a new gun. Also said keep the old one for parts. 

 

[1Sprayanimal1]

Sounds like transfer port size issue.