1701P Still Having Issues

[RetatCDude]

Well the pistol has been back from Crosman for a week now. About 500 pellets down the barrel. Shoots fine. They replaced the guage and did a pressure test when they had it. Note: I spoke to Crosman service this morning. They have a new vendor for their guages so they may not be marked Crosman or Benjamin. Anyway the guage when reading 3000psi, the guages on the pump and the scuba tank only read 2000. I have to go into the red to get an accurate 3000psi reading on the pump or scuba tank(s). Too, I suspect the hammer throw is adjusted to close to the internal valve (allowing air to escape) as, last night I aired up the pistol, fired two shots and the guage read empty. Crosman asked me to a bubble check which I will do this morning. I don't think it has a leak because I left 2200psi in the gun last night and 12 hours later it is still there. I also asked if she new how much air (cc) the gun held, she didn't know. The saga continues.

[bgmcgee]

Bummer.  Sorry to hear all the problems way to much money to have these issues.

[RetatCDude]

She suggested I could drive to the nearest repair center and they would fix it while I wait. Sure they will. They have nothing else to do.

[1377x]

usually a gauge change could be done on the spot. i had gauge issues myself the first time i told the service station he gave me a gauge and told me to bring the broke gauge in after i swapped them. call your local service station tell them what crosman said. maybe they will do the same
since its just a gauge swap it is possible they can do it on the spot

[RetatCDude]

If it IS the gauge, I have three in reserve. One I bought at a paintball store and two from McCarr. In fact the gauge Crosman put on my 1701P looks exactly like McCarr. I have the gun aired up now, to where it reads  3000psi on the scuba. It is at the far edge of the red zone on the pistol gauge. It has been at that location for two hours now. I can ASSume it is not leaking. Maybe because the tank only holds 45cc, I should not be using the scuba tank gauge. I am getting ready to chrono the gun from where it is now (right side of the red) and check the speeds all the way to 425 fps. Crosman advertises it at 450fps. 425fps is as low as I want to go for stable target work. I will be interested of the speed when the gun's gauge reads 3000psi. If it reads near 450fps, I will no longer use the scuba tank gauge.

[BDS]

Why struggle with under-rated gages?

4k psi gages are all over the place

[RetatCDude]

So I tested the pistol:


Chronograph Test
Crosman 1701P
Sep 12, 2013
7.9gr Crosman WC
PACT Professional Chronograph
2 feet in front of muzzle
Target at 10 yards for speed checking
Starting pressure 3000psi+, needle right side of red zone
After 25 shots the gauge read 3000psi

457.9
457.0
461.4
457.3
457.6
461.4
455.0
456.6
464.3
451.0
456.1
459.7
459.0
461.8
459.2
463.1
460.6
461.6
462.6
460.3
461.5
450.3
456.5
450.5
462.9
463.0
458.2
453.3
460.6
464.3
461.0
452.7
449.0
454.2
452.9
454.4
449.1
452.1
449.6
449.5
447.0
450.0
449.0
448.9
447.0
451.5
443.4
447.4
449.3
448.5
443.0
441.3
442.1
441.0
430.2
430.0
442.6
435.2
432.5
433.4
427.9
427.6
430.2
427.4
420.3
416.0
413.0
414.6
409.2
407.5
412.0
403.0
405.9
396.2
396.3

High: 464.3
Low: 396.2
SD: 10
ES 60.1
Avg: 445
The following target is labeled right to left:
1= shot 1-20
2= shot 21-40
3= shot 41-60
4= shot 61-75







If I use shot #26 (3000psi on the gun's gauge) through 75 (50 shots) the following are the numbers:
High: 464.3
Low: 396.2
SD: 19.3
Avg: 443.4

So, I will use the pistol's gauge not the one on the scuba tank!

Sorry about the long string, I tried to make columns.

[breakfastchef]

Decent number of shots on a fill with pretty good consistency. The gun comes out shooting flat, though, for the first 30 shots and then starts a linear decline in velocity. You may want to make some striker adjustments so the gun shoots a bell curve. Once you get the gentle rise to the peak velocity followed by a gentle decline, you can determine you sweet spot. For 10M shooting, I find velocities within 3%-4% of peak velocity to be fine.

[RetatCDude]

So maybe a small turn CW on the striker? Spring is ok?

[Fronzdan]

Not to hijack but Brian...where did you get those 4k gauges?  Same diameter, threads etc as the standard ones, right?  I think I want to try some I those out.

[breakfastchef]

So maybe a small turn CW on the striker? Spring is ok?

You can go as crazy as you want. If it shoots well for your needs, then no further adjustments are needed. If you want to fill several hours of time, you can go through a full setup for maximum efficiency, follow the procedure in this A-Team paper - http://ateam.alotspace.com/ateamh/A_Team_PCP_Tuning_Procedures.pdf


This is a link with very good information from PRod testing of fill pressure, hammer spring tension and striker adjustments.
http://www.network54.com/Forum/79537/message/1294258894/The+Benjamin+Marauder+Pistol+At+Various+Fills+%26amp%3B+Settings


Good video regarding the PRod tests above - [youtube]https://www.youtube.com/watch?v=IjtnIAiVxKc#]https://www.youtube.com/watch?v=IjtnIAiVxKc#[/url]


I am still trying to wrap my arms around these things hammer related. Keep us posted.

[RetatCDude]

I am aware of the A-Team settings. I used some of the info for my Marauders. I am not going to drill out the air port or anything like that though. Thanks.

Here is where you can get good gauges:
http://www.mcmaster.com/#atmospheric-pressure-gauges/=ohbvko

[tinker]

oops double post, sorrry!

Glen

[tinker]

Try 1/2 turn CW for the stroke, a little less hammer strike. Test again. You can the back off the hammer spring preload the same amount and test again until you get a nice bell curve.  It's going to take a lot of time as Larry said.  Or you can try the BStaley o-ring mod (http://www.network54.com/Forum/79537/message/1315440196/Poor+man%27s+M-Rod%2C+P-rod%2C+etc-+%26quot%3BRegulator%26quot%3B+explained+%28Long%29) and  tuning again.
  On my PRod and 2250B HPA I have the o-ring mod installed with good results.  The 2250B HPA has the complete PRod hammer system installed so I have both the same adjustments.
http://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,11264.0.html

Glen

[RetatCDude]

When bstaly starts messing with the 1701p I might consider it. My marauders shoot fine without that mod.