Tuning .177 Weihrauch HW77K project - complete

In very early September, I purchased from AGN member Deepbass9, a very nice .177 Weihrauch with a beech stock. It had previously been tuned by another person, using a button compression tube and piston and Maccarelli spring kit (see image 1 - below). Dave A. was terrific to work with and the rifle arrived as advertised and in perfect condition.

I immediately put it to the test, with a variety of pellets, with the best performing pellet combination to be the Air Arms Diablo Field 8.4 grain. I was not at all happy with the results, particularly at 30 yards. (see image 2 - below). I immediately disassembled and inspected the rifle, and determined that the button compression tube and piston did not appear to have a tight enough tolerance. After consulting with my AGN on-line friends, I identified that a new factory manufactured compression tube and piston were available from Airgun Spares the UK. I ordered the set and it was delivered to my home in Indiana within less than a week - great service. I also ordered a Vortek PG3 HO kit - a kit that I have had terrific success with in various other of my spring rifles within my collection. It arrived in three days from the time of order.

While waiting on the parts, I hand polished every single component, and then did the same to the new compression tube and piston. Using Air Venturi's "tune-in-a-tube" lubricant, I reassembled the rifle using the new HO kit and components. I also changed the seals. The results can be seen by viewing image 3 - below, and by viewing the test table found at the link listed below. While the 18 yard groups were very good, I still was not content with the 30 yard groups, so I didn't even test performance at 50 yards.

The next step was to order a Vortek PG3 <12 ft lb kit. Upon receipt, the rifle was disassembled again, and the replacement spring kit installed. Producing +/- 10.5 ft lbs, the 18 yard accuracy was very good, but I felt like I wanted a little more power to flatten the trajectory. I disassembled the rifle a third time, this time placing four 10MM stainless steel washers behind the spring as shims, with the rifle producing 11.62 fpe, and an SD of 2 FPS, across a 40 shot string (see image 4 - below). The accuracy at 30 yards was incredible shooting the AA 8.4s, and at 50 yards produced groups very acceptable with a springer, at least to me. The file found at the link below will show all test results, with all spring combinations, and various pellets, plus the resulting scope hold over card that now is attached to the rifle.

All in all, this was a very enjoyable experience and should provide thousands of dependable shots over a long period of time.

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View attachment Test results.10.19.20.1603109891.xlsx

1 - rifle image.1603109913.jpg
2 - .177 Weihrauch 77K Beech. AA DF 8.4 gr.Maccarrelli spring.1603109913.jpg
3 - Test Target.177 Weihrauch 77K Beech. AA DF 8.4 gr.Vortek PG3 HO.1603109914.jpg
4 - Final at 18 yards.1603109914.jpg
5 - Final at 30 yards.1603109915.jpg
6 - Final at 50 yards.1603109915.jpg

 
I'm glad you had fun with it, Dan. In all honesty, this was the 2nd spring gun I purchased having all PCPs until I had bought a Diana 430L. Well that little 430L was so darn accurate and fun out of the box that I wanted to get a "real" springer to see what that was like. When the 430L consistently outshot that HW77K I figured I got an apple of a Diana and a sour grape of a Weihrauch. And I also figured some people define accurate differently than I do. 👍🏻