18 & 24 inch .177 barrel with F/T P&V .... fpe/fpe guesstimate ???

[DBOdude]

thinking about getting a .177 barrel for my DBO ...... it has a AC Customs flat top piston and valve , the valve has had the exhaust port angled , the stem has been turned to improve flow and it's been faced/flat topped and i'm using the stock transfer port . i was wondering what folks using a similar set up with the 18 or 24 inch barrel are getting with 5 , 10 and 15 pumps ? please tell what pellet/weight you used too .

i want to try .177 because of the wider variety of inexpensive pellets in .177 . i'll be doing %99.999 plinking and paper target shooting .... although i'm sure a .177 at 700 fpe will handle squirrels , rabbits and birds at the modest range i'd feel comfortable shooting them . i know the guns and their mods will vary a bit in actual performance so i'm wanting to get a ball park figure for playing with chairgun .

thanks

[JMJinNC]

I have roughly the same setup with a .177, 24" shrouded barrel, Mellon ft/fv, ported & profiled valve internals, stock TP, extended probe.

I'm getting 9-10 fpe with JSB exacts and exact heavies @ 10 pumps.

Favorite are the exacts, shooting 705fps at the muzzle.

At 4 pumps, exacts shoot 500fps for 10m target speeds.

Hope that helps.

JMJ

[DBOdude]

thats very helpful  500 fps @ 4 pumps is very nice . going by this thread ...
http://www.network54.com/Forum/275684/thread/1318040664/1377+to+1322+upgrade,+my+results.++Need+stronger+hammer+spring-
thats about what my stock DBO did with just a 24 inch .22 barrel added does with 10 pumps . 
9-10 fpe with just 10 pumps means there's a few more FPE available if i want/need them on occasion .
ya just gotta love the versatility pumping allows  and with zero recoil 

[Hung2]

Pardon me, what is a TP? I have seen it mentioned often.

[crossliner]

Transfer port.

[Cwlongshot]

Here is mine. It has the FTP&V ported a little in the valve, stock port, ext probe, and 17'' barrel. It gets 9-12 FPE with up to 20 pumps. (usually only pump to 15-17 if I feel full power is needed)

Here is 13g pellets @ 17 pumps:



Here is 9.3g @ 17pumps:



Here is 11g at 12 pumps:



Here is 7.2g @ 14 pumps:



Here is 7.2g @ 20 pumps:



Here is 13.6g @ 17 pumps:



Here is 11g @ 4 pumps:



JMJ,
I would love to add that cheek piece to mine! LOOK GREAT!! How did you make it or was it bought?  HELP PLEASE!

CW

[JMJinNC]

Thanks. I made the cheek rest. A search on this forum for "JMJ" and "cheek rest" should turn up the details.

JMJ

[crossliner]

Mr. JMJINNC is a genius he gave me autocad drawings for the 1377 barrel band/pivot plug so I had one made in ss via cnc machine..Here is the proof  Ain't she cute 

[Noah]

Cwlongshot - awesome report! Good on you!! 

I have a 1377 built by Roy at Mountain Air (with all the goodies inside and out) and if I remember correctly, with a 19" barrel I am/was getting 700ish fps with 7.9 pellets with 12 pumps. Accurate as hell, too.

I have a choice 24" Mellon barrel I am going to put on either the above-mentioned 1377 or perhaps another Mountain Air 1750 waiting to get some attention. More to come.

Have a great one and take care,

Noah

[Hung2]

What would be the optimal barrel length for a pumper? As a pistol, I would like it not more than 12" or it would become awkward to handle. A 17-18" barrel would be ok for a carbine with a shoulder stock. Is there more efficiency to be had between 12" and 17"? Thanks,

[Noah]

What would be the optimal barrel length for a pumper? As a pistol, I would like it not more than 12" or it would become awkward to handle. A 17-18" barrel would be ok for a carbine with a shoulder stock. Is there more efficiency to be had between 12" and 17"? Thanks,

True that on a pistol having a longer than 12" barrel does become sort of awkward, but I just sit around the range resting the gun(s) on sand bags while paper punching, so, mobility is not a huge concern for me.

I am most likely wrong, but I sort of remember the rule of each inch of a barrel should produce around 10 additional fps. 

[Hung2]

Darn, I just chopped my 2289 barrel down to 11.5". This is the most appealing length to me as a pistol. My be I should have left it at say 12.5".

[DBOdude]

thanks for the additional replies folks 

some mighty fine lookin guns too 

[onebaddj]

nice rigs!