1701
- Thread starter BWAGS
- Start date
Best thing to do is read the owners manual. It gives a good description on how to do it by accessing the rear hole in the back of the receiver with the proper allen wrench. If no manual, can always get one from Crosman or the internet
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I opened up my transfer port from .041 to .054 if I remember correctly. That gave a bump up to 600ish with 7.4 grain wadcutters. The 1720 port,. 068, was too hot for my purposes.
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Drill out the transfer port. Crosman PCP pistols are the easiest airguns to work on and/or soup up in history. From my testing-
.177 Crosman 1701P precharged pneumatic ten-meter/silhouette pistol
7.9gr JSB Express, 3000 PSI, 76 shot power-band 448 473 25 3 462/3.7
10.3 Exact, 2800 PSI, .075” transfer port, 15 shots 684 709 25 8 699/11.2
After doing a B-Staley tune
10.3 Exact, 2600 PSI, .075” transfer port, 22 shots 641 670 29 2.5 657/9.9
8.4 Exact, 2600 PSI, .075” transfer port, 18 shots 702 732 30 4 715/9.6
10.3 Exact, 2500 PSI, .075” TP, resealed, 20 shots 647 676 29 8.6 663/10.1
3/8/2018- 4 consecutive 5-shot groups with 10.3 gr. JSBs averaged .62” c-t-c at 35 yards w/6X.
8/1/2018- Five consecutive 5-shot groups with 10.3 gr. JSBs averaged .68” c-t-c at 35 yards w/6X
.177 Crosman 1701P precharged pneumatic ten-meter/silhouette pistol
7.9gr JSB Express, 3000 PSI, 76 shot power-band 448 473 25 3 462/3.7
10.3 Exact, 2800 PSI, .075” transfer port, 15 shots 684 709 25 8 699/11.2
After doing a B-Staley tune
10.3 Exact, 2600 PSI, .075” transfer port, 22 shots 641 670 29 2.5 657/9.9
8.4 Exact, 2600 PSI, .075” transfer port, 18 shots 702 732 30 4 715/9.6
10.3 Exact, 2500 PSI, .075” TP, resealed, 20 shots 647 676 29 8.6 663/10.1
3/8/2018- 4 consecutive 5-shot groups with 10.3 gr. JSBs averaged .62” c-t-c at 35 yards w/6X.
8/1/2018- Five consecutive 5-shot groups with 10.3 gr. JSBs averaged .68” c-t-c at 35 yards w/6X
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I read these figures yesterday and thought on them for a bit. A question for those who've posted regarding the larger transfer port. How much additional tuning did you have to do (if any) after installing a larger TP?
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Rcarlisle – I have just started down the road of tuning my new 1701. I can answer your question on if additional tuning is required if you increase the TP size. The answer is yes based on my initial testing of my new 1701. I can’t answer what has to be adjusted.
I have been playing with PCPs for about 6 years and am familiar with hammer spring, hammer weight, and regulator pressure adjustments. I am not familiar with tuning an unregulated PCP. Also, not sure how hammer length of travel comes into play. Hopefully somebody can help explain how to tune an unregulated PCP with an adjustable hammer length of travel.
I tested my 1701 in the out of box configuration. Then modified with 12” 1720 barrel, Hill 0.080 TP and TKO moderator. Large power gain but power curve looked bad. Realized I should only do one modification at a time (I know this but got ahead of myself). Went to current configuration of stock 1701 configuration (stock TP) with just the 12” 1720 barrel installed (no moderator). I have attached a MS Word document that is a log of where I’m at today. I was a bit surprised that the 1720 barrel didn’t add more power but happy with large, consistent power curve.
Weather has been typical of Spring time in the Rockies. Looking out my window at 2” of snow! Should be gone by tomorrow. Next step is to test accuracy at 10 yards tomorrow (weather permitting).
Based on what I have seen so far, I need to learn more about tuning a 1701 before playing with the TP size.
View attachment Crosman 1701P.docx
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Any time you change the power produced by a PCP you'll have to do some tuning if you want to maximize shot-count; no matter if the change is from transfer-port size or hammer-blow. I was able to tune my HOT-rodded 1701P with just it's hammer-blow adjustments.
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