Spring gun tuning: Part 1
Spring gun tuning: Part 2 – Building a mainspring compressor
Spring gun tuning: Part 3 – Mainspring compressor continued
Spring gun tuning: Part 4 – Let’s disassemble a gun!
Spring gun tuning: Part 5 – Powerplant disassembly

by B.B. Pelletier

Now, the pivot bolt can be unscrewed from the left side of the compression/mainspring tube.

The pivot bolt has been removed from the left side of the compression/mainspring tube. The large washer sitting on the base block next to the bolt hole is one of two thrust washers that fit between the base block and the sides of the compression/mainspring tube. They allow the base block to pivot freely without galling the compression/mainspring tube.
Pay attention here!
Notice the large thrust washer laying on the base block. It is very thin, but it allows the base block to pivot without scraping against the compression/mainspring tube. You can see where it wore some of the finish from the base block around the pivot bolt hole. Lubricating these washers (there is another one on the other side of the base block) with a heavy-duty lube is very important to a smooth cocking cycle. Also, lubricate the pivot bolt, itself, for the same reason. I use a moly-impregnated grease, because molybdenum disulfide particles bond with the steel and continue to lubricate the region for a long time. Moly is one of the slickest substances known.

Notice that the cocking link is riveted to the base block. It never needs to come off unless there’s a problem. As of this moment, the cocking link is still attached to the piston by a sliding link. It is quite easy to now separate the barrel cocking link from the sliding link by just moving the barrel away from the compression/mainspring tube.

The cocking link has been separated from the sliding link in the piston. The sliding link is seen at 7 o’clock to the center of this photo.
How to get the piston out
You can see an enlargement in the cocking slot under the cocking link in the picture. The sliding link can be slid up to this enlargement and drop free of the gun, making the piston free to come out. The piston will require some coaxing, because it is really tight in the compression/mainspring tube. Use a screwdriver blade through the cocking slot to gently shove the piston to the rear of the tube.

The edges around the cocking slot are razor-sharp, and I am not exaggerating. Working around the slot to remove the piston, you can easily slice your fingers. Please be careful. Also, the piston has a cocking slot in it that’s nearly as sharp. Handle these parts as though they were knives.

The powerplant consists of the piston, mainspring and spring guide. The end cap is aligned with the spring guide exactly as it was inside the gun (look at the picture of the end cap when it came loose from the mainspring tube).
This disassembly took about 30 minutes. The first time you do it with a brand new R1 should take 2 hours. Other spring guns are not as easy to disassemble and will take longer. I’ll stop here today. I will return in a few days to discuss the other ways guns come apart. I want to do a few other reports before then so we don’t bore anybody.