Breach Block Inspection & General Maintenance after 1 Year (>4,000 pellets)

Recently tore down the breach block for preventative maintenance and inspection after over 4,000 pellets over the last year.

This is on a generation two 22 gauge with free floating hammer configuration. The hammer and spring configuration may differ if yours is a different generation or caliber. My spring does NOT travel all the way forward during firing. It stops against the breach block and the hammer flies forward free of the spring. Mine also has a DIY hammer spring damper and Delrin spring guide. I believe the 25 gauge and 22 gauge from generation 3 onward, omit the spring guide completely. Instead, the rear of the hammer has a short circular hub onto which the spring engages. The spring travels with the hammer all the way to the valve pin on later generation guns. The design change reduced the incidence of things hanging up and varying strike force.

Since writing this, I have changed to the newer generation style hammer and spring. The newer hammer and spring configuration is quieter because no spring guide slaps against the breach block.

The newer hammer and spring configuration are also needed to use a degassing tool provide for Vulcans that do not have a degassing valve on their firing valve assemblies. The spring guide configuration would interfere with the degassing tool.

Inspection today was largely pleasing.

There were a couple wear points and loosening bolts after a year of use. All were easily addressed. Some wear areas may be worth addressing early to reduce ongoing wear. I had already switched nearly the entire breach block to Dri-slide way back at the beginning when I noticed that the factory oil was not preventing wear of the brass elements, especially the pellet probe.

To enable inspection and cleaning, I completely removed the hammer and pellet probes. That let me inspect them and the barrels in which they ride. The barrels surfaces were cleaned then re-lubricated with a thin coat of Dri-slide. (moly dry lube)

Hammer, pellet probe, spring, spring guide were all cleaned, polished if needed and lubricated lightly wth dry slide. All parts were allowed to dry completely before reassembly.

1. When the gun was new, it had a factory brass spring guide. That was spalling as it impacted with the breach block with each shot. Replaced that brass guide with a Delrin guide nearly a year ago. No further wear material has accumulated in the hammer spring chamber.

2. Pellet probe body was factory lubricated with oil. The entire barrel housing of the pellet probe had been awash with lots of brass swarf. None was seen at this time despite thousands of cocking actions. The key was switching to Dri-slide instead of oil. Removing and inspecting the entire pellet probe revealed some minor wear, but nothing severe. There were no visible brass rubbings inside the guide barrel.

3. Clip holding the cocking plate and part of the trigger mechanism had loosened out about 0.5 mm. The clip is easily pressed back into position provided you provide counter pressure on opposite end of pin.

4. Bolts for cocking extensions of hammer and pellet probe were slightly loose.

5. There was significant notching of the pellet probe cocking extension. That part suffers high pressure wear and slides against the cocking plate. Examination of the cocking plate mating surface revealed surpassing roughness where it engages the round cocking extension. Some was nearly as rough as a file. I wish I had checked that when the gun was new. On the other hand, it was amazing that 4,000 cocking cycles had not cut further into the pellet probe’s cocking extension.

To reduce future wear, I completely removed the cocking plate. Took just a few minutes to smooth & polished its engagement edge surfaces to near mirror finish with a fine Dremel sanding drum and pollishing wheels. I also polished the worn portions of the round cocking extension. During reassembly, the cocking extension was rotated to present a fresh surface to the cocking plate. Just smooth the surfaces, don’t remove too much metal.

I think it worthwhile to check the smoothness of a new gun’s cocking plate engagement surfaces and smooth them before they can wear into the cocking extensions.

6. Hammer had very minor scratching. Engagement point of hammer with sear was minimally marked. After repolishing with flitz, the hammer was smooth, shiny and the minor marking at the sear engagement was gone. Basically, the sear isn’t wearing out its contact point on the hammer.
Don’t be confused by my hammer’s silver appearance. The hammer was originally black. I polished it to full shiny silver when gun was new.

7. Since the cocking rod was already out, I polished it to mirror smoothness.

8. Cocking rod is connected to pellet probe via two bolts. Those were slightly loose. It is best to have the probe advanced forward into the barrel when tightening its two bolts. Otherwise, alignment may be slightly off. I would advance the pellet probe with both bolts loose and then successively tighten each much like tightening scope ring bolts.

9. New foam dampers made from earplugs were installed for the hammer spring and cocking return spring. The old ones were actually still in good shape.

Overall, I am very pleased with how little wear has occurred. None of nasty, brass wear happening early in the guns’s life (when the pellet probe was factory oil lubricated) has recurred. The only point of major wear was due to roughness of the cocking plate’s edge (especially near its hooked end). That is easily fixed and worth checking even on a new gun.

The only unexpected change over time was slight loosing of the pin clips. When those are loose, the cocking lever has more lateral wobble. There is a thin washer between the cocking plate and breach block. When the pin clip is pressed in properly, the cocking lever remains largely out of contact with the breach block surface.

Dri-slide has done an incredible job for reducing wear of the brass pellet probe. No amount of lube could have prevented the rough edge surfaces of the cocking plate from causing wear. Mine had portions nearly as rough as a file. I’m pretty sure, things will wear more slowly now that the mating surfaces are smooth.

I used a tiny amount of moly grease along the high pressure contact edges of the cocking plate. Everything else is just Dri-slide lubricated.

BTW, the slight silvery appearance near the bolt holes is some residual anti-seize