Tuning My First Attempt at Tuning

[Zut]

So a few weeks ago I posted a target at 25yds with my HW77 .177 cal. and was sort of disappointed with my effort. I got out the chrony and the gun was way low on power. Built a spring vise, pulled out a broken spring and ordered a Maccari spring and a Vorkek seal. Put it together a few days ago and have been testing it.

I am really pleased with the accuracy so far. Here are two targets, the first one at 25 yards with 10 shots on each bull, and the other at 18yds today with 5 shots each. Wind was blowing to hard to go out to 25 so I moved behind the house and shot at 18yds. waiting between wind gusts.

Chrono results were a bit strange, Temperature has been pretty hot, about 80 to 90 degrees during the chrono testing.

I tested the gun after the first 20 shots and initial results were perfect.
H&N FTT's 8.64 10 shots averaged 860fps at 14.19fpe

Tested again the next afternoon after about 150 shots with temps around 85 degrees.
H&N FTT's 8.64 10 shots averaged 835fps at 13.38fpe

Tested this morning with a cool unfired gun at about 75 degrees
H&N FTT's 8.64 10 shots averaged 840fps at 13.54fpe

I was expecting the Vortek seal to break in and give me a bump in power. Not the case.

This was my first attempt at tuning and I might have gotten a small bit of ARH moly paste in front of the seal. I was having a heck of a time getting the trigger block screwed in and I pulled the piston apart to check if I had a washer in the end of the piston. I didn't so without thinking, I put the piston back in the cylinder without wiping down the walls to remove any moly. I manned up and got the thing back together. Spring vise absolutely necessary in my case.

Also I used very little tar on the spring, and I can hear the faintest spring buzz.

Long story short, the gun is bloody shooting great. I may tear it apart in a day or so to see if I have some moly in the front of the seal and add a bit of tar to the spring.

Cheers
Z

 

[Shuggoth]

I would just run several hundred pellets through it and see how it's doing. That will give time to blow out the lube and size the seal a bit.

 

[Moog]

I went the same route with my HW95. Maccari spring and Vortek piston seal. I've been very satisfied with the results.
I don't see what is strange. Your getting good velocities and nice accuracy. Those velocities seem normal for an HW77. The deviation in velocities is probably the new seal and spring breaking in. As far as a little moly paste on the piston seal, I wouldn't worry about it.
I would take Shuggoth's advice and shoot it for awhile and then check it again.

 

[MartyMcFly]

Your results make sense to me. As the spring took a set the power reduced slightly however, the piston seal probably began to wear in and along with the reduced thermal expansion at 75 degrees friction was reduced and it brought the power up a little. Assuming that the spring is done settling you may see the power go up a little more in moderate temperatures as the seal wears in even more.

-Marty

 

[maxtrouble]

Nice results! As long as the shot cycle is smooth and the rifle doesn't have too much buzz everything sounds great. Accuracy is right there as expected. Now get some soup cans and sling some lead! Reactive targets are fun.

 

[Hateful McNasty]

Your results make sense to me. As the spring took a set the power reduced slightly however, the piston seal probably began to wear in and along with the reduced thermal expansion at 75 degrees friction was reduced and it brought the power up a little. Assuming that the spring is done settling you may see the power go up a little more in moderate temperatures as the seal wears in even more.

-Marty

I like to pre set the spring also i think if you ask arh you can get ine he has preset. The 95 hornet for $5 more i think is listed as a preset .. also i feel makes the guide push in easier..

 

[Feinwerk]

Congratulations on your rebuild, looks like it's doing great. Extra atta boys for building your own spring compressor jig, very satisfying - nice going .
You may have had some minor dieseling during your first few strings and then the velocity started to settle down. I think that is the nature of the ARH moly paste. You can't help having some of the grease carrier of the paste from coating the cylinder walls from vibration and shot cycles and I think that contributes to minor dieseling. You want it to be there so that the piston seal can burnish the moly into the metal. You can usually tell if you're getting minor dieseling by sighting through the bore immediately after a shot (on breakbarrels) and seeing a brown haze inside even if you don't hear anything special. And of course you can smell it at the muzzle for underlever types.

If the spring is not scragged (pre-compressed), as someone else pointed out, it may be forming itself as well as the piston seal.

Shoot it and enjoy it. If you did not fit the piston seal, you may or may not consider checking its fit the next time you break it down but I wouldn't tear it apart just for that right now until you get a few tins of pellets through it and enjoy the good accuracy you're getting now.

Feinwerk

 

[Hateful McNasty]

A guy feel a bit more to accomplishment or pride doing his own.. then as / if you play with your tune job to fine tune it a little more or better to hit a goal fos or best for a certain pellet its nothing but added experance .

 

[Sqwirl57]

I'll third pre-setting the spring. Its easy to do and helps speed up the break in period for the spring. I've found ARH springs benefit more from this than the Vortek ones do and ARH specifically recommends it somewhere on his website. You just need a threaded rod that will fit the piston guide, a couple washers and two nuts. I like to tighten the spring down about 3/4 compressed and let it sit for 4hrs.

As far as the piston seal goes, that will usually take a tin or so, so be patient with it. They do not always size down all the way though so you may need to manually re-size them. Either way your gun looks to be shooting great so job well done man!

 

[Hateful McNasty]

I'll third pre-setting the spring. Its easy to do and helps speed up the break in period for the spring. I've found ARH springs benefit more from this than the Vortek ones do and ARH specifically recommends it somewhere on his website. You just need a threaded rod that will fit the piston guide, a couple washers and two nuts. I like to tighten the spring down about 3/4 compressed and let it sit for 4hrs.

View attachment 378150

As far as the piston seal goes, that will usually take a tin or so, so be patient with it. They do not always size down all the way though so you may need to manually re-size them. Either way your gun looks to be shooting great so job well done man!

I see you also added the guide in .. i found that being easier to get it pushed in durring the setting ..

Then with a set sprung you got less spring length to fight in the compressor during install ..

I put a undet spring in once and it slipped and shot out parts . Luckily the safety spring landed in a easy to find spot ..uhggg..

 

[Sqwirl57]

I see you also added the guide in .. i found that being easier to get it pushed in durring the setting ..

Then with a set sprung you got less spring length to fight in the compressor during install ..

I put a undet spring in once and it slipped and shot out parts . Luckily the safety spring landed in a easy to find spot ..uhggg..

Yes it shrunk down a decent bit and makes the install much simpler because I'm dumb and refuse to make a compressor

 

[Zut]

Thanks for all the good suggestions from the group here. That is what makes shooting these guns fun, lots of other folks to compare notes with.

I was comparing the velocity of the tune to the gun when I first bought it. The stock spring and seal was shooting 876fps and 14.73fpe. This setup is a bit less then the new numbers. I was thinking the Vorteck seal would give me a bit higher output. It's not a big deal that's for sure. It is shooting much better then with the borked spring.

I do think minor dieseling may have been the reason for the initial higher chrono readings. I did notice a odor that I figured was burnt moly.

"I love the smell of burnt moly in the morning" LOL

Z

 

[Hateful McNasty]

Well i never used the vortec seals yet but when i get a spring and seal from arh I add extra seals in . sometimes i mix the offered sizes/ types he has so i can try different sizings or in case of a oops i got extra on hand handy .. to try another fit to maybe better a tune cause you can take more off but you cant add back on one ..lol

 

[fishing43]

So a few weeks ago I posted a target at 25yds with my HW77 .177 cal. and was sort of disappointed with my effort. I got out the chrony and the gun was way low on power. Built a spring vise, pulled out a broken spring and ordered a Maccari spring and a Vorkek seal. Put it together a few days ago and have been testing it.

I am really pleased with the accuracy so far. Here are two targets, the first one at 25 yards with 10 shots on each bull, and the other at 18yds today with 5 shots each. Wind was blowing to hard to go out to 25 so I moved behind the house and shot at 18yds. waiting between wind gusts.

View attachment 378087

View attachment 378088



Chrono results were a bit strange, Temperature has been pretty hot, about 80 to 90 degrees during the chrono testing.

I tested the gun after the first 20 shots and initial results were perfect.
H&N FTT's 8.64 10 shots averaged 860fps at 14.19fpe

Tested again the next afternoon after about 150 shots with temps around 85 degrees.
H&N FTT's 8.64 10 shots averaged 835fps at 13.38fpe

Tested this morning with a cool unfired gun at about 75 degrees
H&N FTT's 8.64 10 shots averaged 840fps at 13.54fpe

I was expecting the Vortek seal to break in and give me a bump in power. Not the case.

This was my first attempt at tuning and I might have gotten a small bit of ARH moly paste in front of the seal. I was having a heck of a time getting the trigger block screwed in and I pulled the piston apart to check if I had a washer in the end of the piston. I didn't so without thinking, I put the piston back in the cylinder without wiping down the walls to remove any moly. I manned up and got the thing back together. Spring vise absolutely necessary in my case.

Also I used very little tar on the spring, and I can hear the faintest spring buzz.

Long story short, the gun is bloody shooting great. I may tear it apart in a day or so to see if I have some moly in the front of the seal and add a bit of tar to the spring.

Cheers
Z

Picture of your spring vice please

 

[Zut]

Picture of your spring vice please

I need to do a little modification and then I'll take a pic for ya
Z

 

[Zut]

Picture of your spring vice please

A few pics of the spring vise you asked for with an HW35 being disassembled. I used an 8" C-clamp from Lowe's and cut the end off of the clamp with an angle grinder I used 1 1/4" and 3/4" plastic conduit clamps to hold the gun in place. I just butted the barrel up to a block screwed to the end of the vise. I used some scrap pieces of 3/4 plywood and offset the the C-clamp so I could clamp the assembly to a table.

I adjusted the height of the clamp so I could get my hand around the trigger block to make it easier to unscrew. The foam pad was packing from something we purchased. Stuff was perfect to protect the blueing.

 

[fishing43]

A few pics of the spring vise you asked for. I used an 8" C-clamp from Lowe's and cut the end off of the clamp with an angle grinder I used 1 1/4" and 3/4" plastic conduit clamps to hold the gun in place. I just butted the barrel up to a block screwed to the end of the vise. I used some scrap pieces of 3/4 plywood and offset the the C-clamp so I could clamp the assembly to a table.

I adjusted the height of the clamp so I could get my hand around the trigger block to make it easier to unscrew. The foam pad was packing from something we purchased. Stuff was perfect to protect the blueing.

View attachment 379404

View attachment 379405

View attachment 379410

View attachment 379412

Great job and I very much appreciate that took the time to post the photos

 

[Mycapt65]

Thanks for all the good suggestions from the group here. That is what makes shooting these guns fun, lots of other folks to compare notes with.

I was comparing the velocity of the tune to the gun when I first bought it. The stock spring and seal was shooting 876fps and 14.73fpe. This setup is a bit less then the new numbers. I was thinking the Vorteck seal would give me a bit higher output. It's not a big deal that's for sure. It is shooting much better then with the borked spring.

I do think minor dieseling may have been the reason for the initial higher chrono readings. I did notice a odor that I figured was burnt moly.

"I love the smell of burnt moly in the morning" LOL

Z

That gun was dieseling badly if it was making that much power. That's pretty common with new Weihrauchs the seem to come factory with cut seals and way too much lubrication.
The 35 in 177 should make about twelve FPE when properly put together.

 

[cjtamu]

That gun was dieseling badly if it was making that much power. That's pretty common with new Weihrauchs the seem to come factory with cut seals and way too much lubrication.
The 35 in 177 should make about twelve FPE when properly put together.

+1. Mine makes right at 13 FPE, with PCP-like consistency. I’m at 35’ elevation so I get a little power bump compared to most. If you’re in 12-13 FPE range with new setup that’s probably where it should be.

 

[Zut]

That gun was dieseling badly if it was making that much power. That's pretty common with new Weihrauchs the seem to come factory with cut seals and way too much lubrication.
The 35 in 177 should make about twelve FPE when properly put together.

The gun I tuned in the first part of this post was an HW77K. It may have been burning a bit of moly on the first chrono test though.

I just posted some pics of my HW35 on the spring vise. Just to show the vise. The chrono numbers are from the HW77, not from the HW35.

Z