Resurrection feedneck blowback

[minionPB]

I can't seem to shake the feedneck blowback in my (new to me) Empire Resurrection. Marker is stock except for the Inception hammer and spring that I just added. I searched here and elsewhere, and watched multiple videos on timing. Hammer lug is set as short as I can get it while still catching the sear consistently on recock.

Following Simon's videos, I first set the three-way timing fairly soon after hammer release. Then with the blowback issue, I lengthened the three-way as far as I could while still cycling the marker. This didn't help the blowback. Tried half-turns in between with no notable change. Also tried different LPR pressures with no effect on blowback.

Based on suggestions in other threads here, I replaced the bolt o-rings. I also tested with the LPR essentially turned off, held the bolt forward, and fired a ball. No blowback there, so I don't think air is escaping around the bolt. O-rings appear to span the feedneck properly.

So at the moment I'm out of ideas. Is there something I've overlooked, or anything else I might tweak?

[Trbo323]

You can play with the o ring size on the ressy bolt. Ignore what the manual says and go up one size on the rings that span the air passage. Sometimes that will work, sometimes it adds too much friction to the bolt

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[minionPB]

As far as I can determine I'm not losing air from around the bolt on hammer drop. But o-rings are cheap, so I'm willing to try.

[autococker04]

In my experience the second best way to deal with blowback is to leave an excessive gap between when the hammer drops and when any movement of the ram begins.

The best way is to use a rotor.

It sounds like you’ve already tried a variety of actuating positions. If holding the bolt forward and shooting eliminated the problem, your sled is probably too far back on the pump arm or your LPR is too low

[minionPB]

So far that gap is as big as I can make it without the marker failing to operate. I can certainly toss a force-fed hopper on it, if it turns out that a band-aid solution is the best available. Any other issues I should be aware of with that option?

[autococker04]

Nope, as long as it’s timed reasonably well it should work alright.

[minionPB]

Random thought: could the softer hammer spring result in the bolt being pushed back too soon, and thus losing air despite the timing? I'm using Inception hammer spring C, but I can switch to spring B or even A.

[autococker04]

It shouldn’t, it would be a really weird situation but if the hammer were bouncing enough on the valve maybe it could be opening and closing the valve a little bit while the bolt moves backwards, allowing air up where there are no orings. It would be a first for me, but I wouldn’t rule it out completely.