Crosman 1701/1720

[fderry]

I bought a Crosman 1701 about a month ago because I wanted a good PCP .177 pistol. The 1720 is no longer available but was my first choice. I live at 7126 ft altitude and co2/springer pistols are limited in the usability (velocity) at my altitude.

My preference is a regulated PCP so I realized that I was going to have to convert my 1701 to a 1720 if I wanted a decent shot count when I added a Huma regulator. Long story short I now have a 1720 (with the help of Crosman parts personnel) with a Huma regulator! A little costly to do it this way but after 3 months looking for a 1720 and not finding one this was the option I took.

I have a P-Rod that was my first PCP. I have modified the P-Rod over time, so I had an idea of the modifications I was going to initially do to the 1701/1720.

I knew I was going to open the TP but was not sure what size would be best so I went with a 0.080” TP as a starting size. My research indicates a TP of 0.087” to 0.092” may be the sweat spot so I also have ordered some drills that will step me between these sizes.

So far, I have tested the stock 1701 configuration, the 1701 configuration with 1720 12” LW barrel, the 1701 configuration with 0.080” TP/1720 12” LW barrel and 1720 regulated configuration with 0.080” TP. I did not do any hammer/TP tuning for these tests because I knew I was moving to a 1720 regulated configuration. This where I am today:

1701 converted to 1720 with larger TP, larger air reservoir (stock 1720) & Huma regulator
Pellet = 8.48gr QYS
Air reservoir = stock 1720 (larger air reservoir)
Barrel = 1720 LW (12”)
TP = 0.080” (increased from stock 1701 TP)
Huma regulator set at approximately 1740psi (120 bar)
Hammer stroke - stock 1701 (3 ½ turn up (CW) from full CCW)
Hammer spring - stock 1701 (1 ¼ turn up (CW) from full CCW)
Moderator = TKO
Starting fill pressure 3000psi
Ending fill pressure 1400psi

Shot 1 – 10​	Shot 11 – 20​	Shot 21 – 30​	Shot 31 – 40​
703​	701​	701​	701​
709​	702​	705​	697​
701​	702​	704​	694​
703​	704​	707​	689​
701​	705​	702​	684​
701​	707​	705​	677​
699​	705​	706​	675​
704​	705​	705​	670​
706​	702​	705​	​
705​	703​	701​	​

1701/1720 current configuration
Crosman 1701 converted to 1720
Huma Regulator
TP = 0.080”
Alchemy Airwerks Stainless Steel 2 Stage Trigger
TKO Moderator
DonnyFL moderator adapter
Steven Corcoran Forearm & Grip
Optisan CP 3-12x32P Scope
UTG Accushot Scope Rings

 

[iAMzehTOASTY1]

Beautiful setup!!!

 

[beerthief]

very nice , i have heard good things about that pistol

 

[Felinis]

Yes springers suck at that altitude. But CO2 guns excel at altitude:

Shooting at altitude | Blog | Pyramyd AIR

by B.B. Pelletier I recently spoke to a disgruntled airgunner about how he hated spring-piston guns. He was fed up with them! They never lived up to their advertising. In the course of the conversation he happened to mention that he lives at 10,400 ft. altitude. Problem solved!Of course his...

www.pyramydair.com

 

[fderry]

Yes springers suck at that altitude. But CO2 guns excel at altitude:

Shooting at altitude | Blog | Pyramyd AIR

by B.B. Pelletier I recently spoke to a disgruntled airgunner about how he hated spring-piston guns. He was fed up with them! They never lived up to their advertising. In the course of the conversation he happened to mention that he lives at 10,400 ft. altitude. Problem solved!Of course his...

www.pyramydair.com

Where I live the best shooting weather is in the Fall when the temperatures are in the high 40s to low 60s. Co2 doesn't really like those temperatures. I played with co2 from 2003 to about 2009. I even got into bulk fill in custom Crosmans and QB78s. Still have some nice guns I converted back to co2 cartridge fill but don't shoot them very often.

 

[fderry]

I have been tuning with QYS 8.48gr pellets and when I got a good tune with the chrony I started accuracy testing at 30 yards. Very disappointed with accuracy – looked like I was shooting a shotgun! Paused for a few days and as weather got better, tried 3 other pellets of similar weight. The FX & AA 8.4gr and the H&N 8.64gr. The FX and AA loaded smoothly but the H&N had a lot of drag when loading. I have some JSB 8.4gr pellets on order. Looks like I will concentrate on the JSB manufactured pellets (FX, AA and JSB) as the best 8.xx gr pellet for my 1720. Also need more practice to tighten up my groups. Here is the data I have so far:

Configuration:
Full 1720 conversion
Alchemy Airwerks Stainless Steel 2 Stage Trigger
0.080” TP
Huma Regulator set at 1740psi (120bar)
Hammer Spring at 3.25 turns CW from CCW
Hammer Stroke at 3.0 turns CW from full CCW
Steven Corcoran grip and forearm
DonnyFL moderator adapter
No Moderator
Optisan CP 3-12x32P Scope
UTG Accushot Scope Rings

Starting fill 3000psi
Pistol gauge at 1740psi (regulator set pressure) for 30 test shots

Distance to target 30 yards

Altitude 7126ft
Temp *53
Barometer 23.34 inHg
Wind average 2.6 mph

FX 8.4gr
Shot count: 10
Low: 740
Hi: 742
Avg: 741
Spread: 2
STD Dev: 1.0

AA 8.4gr
Shot count: 10
Low: 740
Hi: 742
Avg: 741
Spread: 2
STD Dev: 1.1

H&N 8.64gr
Shot count: 10
Low: 731
Hi: 738
Avg: 735
Spread: 7
STD Dev: 2.4

 

[Simplemann]

Them are some nice numbers very little change in 40 shots. And that is some good shooting one big hole

 

[fderry]

Did some testing of JSB 10.34gr pellets without changing any tuning parameters other than adding the moderator back on the pistol. Not sure if I’m going for more velocity or which pellet I want to use with this pistol. The 8.4gr pellet tune I have now is consistent in ES and SD, plus fairly accurate. The JSB 10.34gr pellets are accurate with the current 8.4 tune so I think the next step is to optimize a JSB 10.34 tune. Same 8.4gr tune gives 10.24fpe for 8.4gr and 10.74fpe for 10.34gr pellets.

Configuration:
0.080” TP
Huma Regulator set at 1740psi (120bar)
Hammer Spring at 3.25 turns CW from full CCW
Hammer Stroke at 3.0 turns CW from full CCW
DonnyFL moderator adapter
TKO Moderator

Starting fill 3000psi
Pistol gauge at 1740psi (regulator set pressure) for 30 test shots

Distance to target 30 yards
Altitude 7126ft
Temp n/a
Barometer n/a
Wind average n/a

JSB 10.34gr
Shot count: 30
Low: 677
Hi: 691
Avg: 684
Spread: 14
STD Dev: 3.9

 

[bf1956]

Added red dot, got it dialed in and put the caps back on. Now to plink away...first up no poop.fly of some sort.

 

[boscoebrea]

shooting my 1701P and1720 today,28yards.Both have a Burris 7x scope mounted....easy 1/2" groups some 3/8" the pistols are rested, this is typical accuracy for them, they are stock other than grips and trigger shoes; use JSB Match8.02gr. ;Sometimes the RWS R10Match 8.2 can do better,um both are wadcutter about the same weight.
These pistols are more accurate the most rifles at that range,the thing is getting the right sight picture useing pistol scope,it's not easy, but after some practice not real hard either.... Pistols are harder to shoot only because of that .....when they are rested...for me more fun to.

 

[Gwelo]

Very good choice, although I may be a bit biased . Lets see some pics of how you have them set up. Targets too!!

Looks like a great time to show off my 1701P and 1720T! I shoot both at 10M and 25 yards since that's all I have to work with right now. Agree they are very accurate. The 1720T prefers AA 10.3 and the 1701P seems to like MeisterK 7.0 and JSB Match 7.33 but both shoot most everything pretty well.

The 1720T wears a Steve Corcoran stock and scope for benchrest and Tom West stock and red dot for offhand. The 1701P has a RB grips and a red dot.

 

[airgunner53]

Very good choice, although I may be a bit biased . Lets see some pics of how you have them set up. Targets too!!

Looks like a great time to show off my 1701P and 1720T! I shoot both at 10M and 25 yards since that's all I have to work with right now. Agree they are very accurate. The 1720T prefers AA 10.3 and the 1701P seems to like MeisterK 7.0 and JSB Match 7.33 but both shoot most everything pretty well.

The 1720T wears a Steve Corcoran stock and scope for benchrest and Tom West stock and red dot for offhand. The 1701P has a RB grips and a red dot.
View attachment 573435
View attachment 573436

WOW! good looking pair. Love that 1720, wish I bought one. for now its the 1701p for me.