Marauder advice

[louigi600]

Hi Guys,
I have an old gen 1 Marauder (unsure if they current ones are still exactly the same) in .177, mostly unmodded. In fact the only things I did to it was to install a rubber de-ping and a the 3 oring stack (known as the poor man's regulator back then).
The rifle is set to shoot around 277 m/s (almost exactly 900 fps), the TP lock nut is completely out of the way (I'm using the striker adjuster and hammer spring pretension adjuster to regulate the power) but I am getting some horrific valve/hammer bounce that also translates to tons of wasted air.

This morning I installed a shorter but stiffer hammer spring, so that the hammer would not be pushing against the valve stem,  leaving the last few mm of free travel before hitting the valve stem. This did reduce the bounce, but I can still hear some. If I reduce the muzzle velocity to around 240 m/s the bounce does almost completely disappear but also the groups open up a lot (at least when shooting JSB KO mk2).

I really don't want to give up on the slugs because they do perform a lot better than pellets for longer ranges and for windy conditions.
Anyone got some advice on how to keep the speed up but reduce the bounce ?

[Frank in Fairfield]

When I had my Marauders I used four o-rings for about 3/8”.
I think I would re-assemble the TP adjustment screws, too.
After you put the four o-rings in the HS & HT adjustments are reversed from before the bStaley modification.
Good luck.
You make want to send for a regulator, too.

[louigi600]

Maybe the 3 orings I used have a thicker section, in any case they are enough to take 100% of the hamer strike if the striker is backed off enough ... I see no need to stack another one.
I have been considering a regulator and a barrel swap with some higher quality one but the thing is that I'd need to take away quite a lot of air volume to fit a regulator and some regulated plenum volume.
Huma makes all in one that has integrated plenum where the pressure gauge block is ... but that means you need to remove the gauge to take the regulator out for adjustments ... not a fan of that because of the tapered threads on the gauge fitting. Not sure I can carve out enough from the original gauge block to make an effective plenum for 26J.
Shooting directly from the regulator air flow would likely not be very effective.
But on the other hand, maybe once regulated with enough plenum, the bounce issue might not be there effectively compensating for whatever volume is lost from the high pressure volume.
Another option for my DIY bulpup is to rig up a regulated bottle under the pressure tube, then the original pressure tube would all be plenum ... regulators for cylinders are really cheap noways ... a reasonable one off ALI can be like 30 bucks ... would just need to figure out the pluming and some brackets to hold the bottle in place.
At that point I'll have enough plenum even for high power .30 cal.

[Motorhead]

SSG devise will do that you wish for 

[louigi600]

Not looking for a build but rather advice in which way to go.

[3crows]

SSG. Air Gun Revisions has a good and inexpensive drop in solution or make your own.

I will be surprised if you get slugs to shoot but perhaps the .177 is sufficiently different from the .25 that some do. All four of mine are scatter guns with the choked barrels, GM or Crosman.

[JPSAXNC]

You could go a little shorter on the hammer spring and use about 1/10 of an inch free play. Making any adjustment to the hammer strike will change the overall harmonics of the shot, affecting accuracy +or-. hth

[louigi600]

I will be surprised if you get slugs to shoot but perhaps the .177 is sufficiently different from the .25 that some do. All four of mine are scatter guns with the choked barrels, GM or Crosman.

Well I have gotten sub 3/4" five shot groups at 50 yards with JSB KO MK2, but that only works over a limited pressure range ... then I start getting a lot of drift from right to left. Ok it's not fantastic but it's good enough for pest control upto 50y and the slugs carry a lot more energy down range. Maybe a pressure regulator would assist in limiting the side drift.
But "dang" it my .22 P15 shoots regularly sub 3/4" at 50y over an entire usable pressure range (about 45 shots) without any hassle at all. Maybe I should get another P15 also for Italy.

You could go a little shorter on the hammer spring and use about 1/10 of an inch free play. Making any adjustment to the hammer strike will change the overall harmonics of the shot, affecting accuracy +or-. hth

Sounds a lot like what I described in my initial post:

This morning I installed a shorter but stiffer hammer spring, so that the hammer would not be pushing against the valve stem,  leaving the last few mm of free travel before hitting the valve stem. This did reduce the bounce, but I can still hear some. If I reduce the muzzle velocity to around 240 m/s the bounce does almost completely disappear but also the groups open up a lot (at least when shooting JSB KO mk2).

If I can get my hands on some PEEK I may try to make a custom valve with a 2mm shaft instead of the 1/8" original one along with a bushing for the valve assembly.

[JPSAXNC]

I reread your OP. I don't know if it matters to you, but the o-ring stack could be keeping your gun from self regulating, if the hammer can only compress the o-ring stack the same distance for every shot regardless of the reservoir pressure. So that the valve dwell and duration can't change to match the pressure.

[louigi600]

I reread your OP. I don't know if it matters to you, but the o-ring stack could be keeping your gun from self regulating, if the hammer can only compress the o-ring stack the same distance for every shot regardless of the reservoir pressure. So that the valve dwell and duration can't change to match the pressure.

I think that is something you need to come to terms with. My interpretation of the oring stack is that it was an easy way to regulate the power of an unregulated gun ... with some sacrifices. But the oring stack is not perfectly solid, it will give in slightly more as there is less of a fight from the valve but yes the self regulation is somewhat hindered to allow for easy power adjusting.

Maybe I'll do the external regulated bottle and then the original pressure cylinder becomes plenum.
Another option would be to sacrifice the pressure gauge for some supplementary external plenum and then a regulator could sit on the gauge block.
The thing is that unless I do it myself there are cheaper options on the marker for that same accuracy. I think I may have entered a loop here

[HunterWhite]

+1 on the AirGun Revisions SSG.
Mine works great.


Hunter

[louigi600]

To they have service also in europe ?

[HunterWhite]

I don’t think so. The he part that I suggested is “ out of stock” now.

[louigi600]

The he part that I suggested is “ out of stock” now.

Sorry I missed the part you were suggesting.

[Struckat]

SSG. Air Gun Revisions has a good and inexpensive drop in solution or make your own.

I will be surprised if you get slugs to shoot but perhaps the .177 is sufficiently different from the .25 that some do. All four of mine are scatter guns with the choked barrels, GM or Crosman.

The AR SSG is a wonderful thing.

[HunterWhite]

The website is:
AIRGUNREVISIONS.COM


The "parts" section has the SSG kit with a captive spring and a modified hammer, and modified hammer spring tension screw.

https://www.airgunrevisions.com/product/tines-ssg-hammer-kit-for-gen12-marauders/




Link below
https://www.airgunrevisions.com/product/tuned-ssg-hammer-kit-for-gen12-marauders/


Hunter

[3crows]

The three items that I am fond of from AGR are:

1) SSG, currently out of stock but he will make more. He used to have a lightweight version which I am also using.
2) Thumb rest, makes cocking easier than a side lever. And I have two M-Rod SL guns to compare to .
3) Hybrid custom air tube, reduces weight, improves balance. Cannot be used with a regulator due to different ID.

[louigi600]

I get an error if I try to post a reply with a quote from Hunter ... complains about spam.

tines-ssg-hammer-kit-for-gen12-marauders/[
Hunter

One of the links goes to an error page for  me. ... maybe it should be tuned-ssg-hammer-kit-for-gen12-marauders
instead of tines-ssg-hammer-kit-for-gen12-marauders
Anyway I definitely have a gen1 with 3 screw receiver block.

Not sure if that thing is going to solve my problems but it might further reduce hammer bounce.
I suspect I'm having a harmonics issue with poi drift over the different muzzle energies as the fill pressure goes down, but the odd thing is that the vertical poi drift is insignificant compared to the horizontal drift.
Can harmonics issues be so sensitive to muzzle energy to make a much bigger impact on lateral poi drift compared to the vertical poi drift for the different muzzle velocity ?
Any other suggestions at to what the cause may be ? 

[HunterWhite]

Davide, sorry for that typographical error.
Yes that product is used to reduce hammer bounce.




Hunter

[HunterWhite]

The website is:
AIRGUNREVISIONS.COM


The "parts" section has the SSG kit with a captive spring and a modified hammer, and modified hammer spring tension screw.

https://www.airgunrevisions.com/product/tuned-ssg-hammer-kit-for-gen12-marauders/




Link below
https://www.airgunrevisions.com/product/tuned-ssg-hammer-kit-for-gen12-marauders/


Hunter