NPXL1500 GRT III Trigger, Lube, and Piston self tune guide - my experience
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NPXL1500 GRT III Trigger, Lube, and Piston self tune guide - my experience
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Topic: NPXL1500 GRT III Trigger, Lube, and Piston self tune guide - my experience (Read 1391 times))
LordDrow
Shooter
Posts: 27
yes
Real Name: Richard
NPXL1500 GRT III Trigger, Lube, and Piston self tune guide - my experience
«
on:
July 15, 2016, 12:14:33 PM »
First thing I would like to say is Thank you to:
- Shakey Sarge
- Old Cops
- Roadworthy
- Jay
- RWS_53
- Stickoff
- Cathy Curtis over at Charlie Da Tuna
- Sorry if I forgot you, there were several people with good comments and replies. So thank you all.[/li]
I decided to dive into the world of adult airguns and wanted a project so I can learn as I go.
Bought a NPXl1500 on sale and from what I read, this gun needs some help to tame the “beast”. So I went ahead knowing I was going to learn as I go and hit some bumps, and boy did I.
During my research I discovered most of the old posts for the NPXL have gone stagnant and a lot of the pictures are no longer available, so I would like to put together an updated NPXL self tune guide.
Learn from my mistakes:
1) Do each mod one by one and make sure they work before going to the next mod. This is not what I did and made it difficult to troubleshoot issues later. I should know better !
a. Pay attentions to all the warnings. Do not over lube, Do not take your hand off the barrel when cocking in case it does not catch, Do not adjust the first stage screw until you are sure you need to, Do not remove any other pins other than the fat pin, and did I mention not to over lube?
2) You DO NOT NEED a Spring Compressor for any of this.
3) At one point, I was not sure if it was “cocked” or not, it clicked when I broke the barrel, but it turns out.. it did not engage the piston so it was never under pressure or cocked. This diagram explained that to me.
a.
http://www.arld1.com/
Mod 1:
Brass Washers
These are items #22 on the parts break out.
https://support.crosman.com/hc/en-us/articles/203544960-BT1500WNP-Owner-s-Manual-EVP-2010-Present-
- I went to ACE and got 5/16th washers.
- Put them on a 5/16 bolt
- Put a nut half way down
- You need something to take up the slack or space between the washer and the bolt, it’s a little loose and if not centered your washer grinding could be off.
* I used plumbers tape. Very thin in width, but thick in depth see pics.
- Put washer over the plumbers tape.
- Put a second nut on
- Tighten both nuts and squeeze the washer in place.
- Put the other end of the bolt into a Drill.
- Take a file and secure it.
* I used my vice.
- Spin that bad boy up and grind away on the file.
- Grind and test until right and they pop into place.
- Add some grease ( I used GP205)
- Put gun back together
Mod 2:
Replace Piston Seal
Good write up here on how to get the piston seal put in place without damaging it.
http://www.gatewaytoairguns.org/GTA/index.php/topic,715.msg4889.html#msg4889
There are several videos and write ups on how to take it apart.
Tips:
When putting all back together and it will all go back.
The sear needs to be on the OUTSIDE of the chamber. It sits on a little crossbar and the trigger pack slides back in. This through me for a loop. I repeat the sear does not go in the chamber, but sits compressed on the OUTSIDE. See pic.
MOD 3:
Lube
I was not sure what and where to lube and was un able to find anything to show me where.
Did some research and reached out to Shakey Sarge and he was kind enough to put up with my newbieness and helped me out. He suggested I use Dupont Krytox GPL204 or GPL205. Sent some pictures to help me out. Thank you again!
Lube the area’s shown below
MOD 4:
GRT III Trigger
Follow these instructions and the troubleshooting guide which I had to do.
http://charliedatuna.com/pdfs/GRT%20III%20Trigger.pdf
http://charliedatuna.com/airgun_docs/Benji-Titan%20Hair%20trigger%20fix.pdf
Issues I had:
Lost the 1st stage screw – Don’t ask. BTW Cathy is awesome, she sent me a second trigger as a replacement. Thank you very much. Also incase you need to know the default setting for the 1st stage trigger screw is about this (see pic). It will at least get you in the ball park.
• Trigger would not fire – I ran into the known issue discussed here
o I will add a picture later, sorry I did not get one.
o I really had to grind the space to make this work and I had to use the test method which disengages the bear trap so be careful.
o I used this dremmel attachment and it went pretty quickly
I hope someone else finds this helpful and again thank you for all that helped me through this project. There are some great people here.
Results:
Shooting 10.5gr Crossman Mags .177
* Before the mods: Averaged 930 FPS
* After the mods: Averaged 970 FPS
For $20.00 (includes shipping) I can order the .22 barrel from Crossman and move up in caliber. Might be what I need to do, its easier to find heavier pellets in that size vs.. . 177. Plus more FPE in the end.
Take care
«
Last Edit: July 15, 2016, 04:12:46 PM by LordDrow
»
Logged
Eastern WA
Regards,
LordDrow
Benjamin NPXL 1500 - Stock at this time
Old Corps
GTA Senior Contributor
Posts: 2063
yes
Real Name: Ed
Re: NPXL1500 GRT III Trigger, Lube, and Piston self tune guide - my experience
«
Reply #1 on:
July 17, 2016, 12:19:10 PM »
Thanks for the great post Rich, I'm sure it'll be helpful to others!
Ed
Logged
Montrose,MI.
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USAFANG6799
"Keep your air dry"
GTA Senior Contributor
Posts: 2560
yes
Real Name: Matt
Re: NPXL1500 GRT III Trigger, Lube, and Piston self tune guide - my experience
«
Reply #2 on:
July 17, 2016, 07:29:16 PM »
I did a self tune on my Benjamin NP1 XL including a GTR III Trigger. I wish I would have had this as a guide. I muddled through it and the results were a much more civilized shooting rifle.
However I hope not to do it again even though it would be easier the second time around.
Many thanks for the write up!
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NPXL1500 GRT III Trigger, Lube, and Piston self tune guide - my experience