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Benjamin Maurader with the full Hill kit

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Mason_0890

Mason_0890

Member
Jun 22, 2018
57
1
CA
So I installed the new Hill kit with valve / hammer / spring / regulator, ect. It was a pretty straight forward install and easier then I thought but, now that it's all together, it is crazy loud with the shroud. Can anyone shed any light on this? I would contact Tim, but due to where he is located I dont want to bother him right now. Every time I have spoken with him he has always been very helpful and polite. This isn't against him or his product, I'm sure it's just user error. Looking for other people with experience with this kit.
 
I have most of the same parts on mine. I had to tune it WAY down to get it to drop to ONLY 40 FPE with JSB 25.39 grain pellets. Step one would be to run it over a Chrony and tune from there. I have the lightest hammer spring available with the TSS, and it is literally just a couple threads from the bare minimum setting. At 40 FPE, it is quieter than factory stock.

My build.....

Huma Regulator for .25 caliber with integrated block for pressure gauge, adjusted to 1800 PSI (actual pressure, the knob on the regulator indicated a lower setting).
Hill valve, with optional very light 6 pound spring
Hill plastic transfer port, 0.187 internal diameter (ID).
Hill 25 gram hammer with lightest striker, pushed by the Twin Spring System (TSS) with lightest two springs available.
TSS, adjusted to minimum spring preload, with a very huge gap.
Barrel drilled 0.187 inch (deburred and polished the hole), to port match with the rest of the components (transfer port and valve).
Bolt, re-contoured to a spoon shape and narrowed at the transfer port (so the bolt blocks less of the transfer port hole)




 
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Your main adjustments will be regulator pressure, and hammer spring(s). If your regulator is much over 2200 PSI right now, consider starting at a lower regulated pressure. A loud PCP airgun, is frequently a sign of the valve staying open too long, and blowing air out the bore after the pellet has already left the bore. I would consider backing the hammer spring pressure a bit as well. But start with a chrony, see what you have right now, and then report back. We can guide you from there.

Give us a leg up, generation one or generation two, and what caliber is your Marauder.
 
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As others have said you really need to run it over a chronograph to see what its shooting at as well as tune it in.



I would imagine its just making a lot more power than before which is likely why the rifle is suddenly louder.


If you can't do that then for now I would do the following...



Reduce the hammer spring's pre-load until the sound is reduced to your liking and sight it in from there..If its at minimum pre-load and there is no further adjustment there then you need to if possible reduce the stroke length of the hammer by increasing the strikers length, not sure if hills hammer has that adjustment.



1900-2100 psi is fine, 2100 would be better suited for 50+ fpe tunes where as 1900~ would be better suited for 40 fpe tunes. I like 1960-2030 range (135-140 bar).




 
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How about a picture of the reshaped bolt? I'd really like to see it. I've been trying to get the speed up using only stock parts. I want to see what can be done without spending a large sum on aftermarket parts. So far I've opened the valve port, installed a lighter valve spring, replaced the TP with tubing, installed a heavier hammer spring, and a second hand Lane reg. Reshaping the bolt sounds like an intreging idea.
 
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Skip-in-WV,

Right now the bolt is in my Marauder, I will try to snap some pictures the next time I break it down. I generally tend to plan ahead and do all of my modifications at once, so most my airguns are only apart once in their lives (unless an O-Ring fails). It is well understood that the bolt probe partially blocks airflow from the transfer port at .25 caliber. If you are putting in a high flow valve with a larger outlet, and a larger transfer port, and a larger hole drilled into the barrel to port-match your transfer port... it only makes sense. For maximum efficiency/power, it is always wise to modify any point where the diameter changes. Special care needs to happen where the diameter changes AND the direction of airflow changes.
 
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1537199678_51689165b9fce3ee7e193.35741251_CE1D7BA0-40D8-46A5-8B6B-981F8D2E2702.jpeg
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As far as a custom bolt goes to allow more air thru the transfer port, contact Shorty on here or at GTA. I just ordered a new bolt then shipped it to him to have him mill it down. This is for my 25 cal synrod, and just this mod alone increased the FPS 15 FPS. The pics show my factory 25 cal bolt next to the new bolt, milled by Shorty. He did an awesome job. Why more folks don’t do this, I don’t know.



I have the Hill premium kit installed, and was able to achieve the 40/40 tune with an average of 860 FPS, an extreme spread of 14 FPS, using the H&N Barracuda extremes. You wanna silence that thing down? Get the Hill moderator along with his Peek striker. All I hear, no joke, is a PFFFFTTT at the shot, then a THWAAACCKKK! When it hits the metal trap filled with duct seal.
 
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I personallu use a gen 1 bolt in my gen 2 mrod. I gained the most fps even when compared to a milled down gen 2 bolt. (+ 5-10 more fps over milled down gen 2)

I do remove quite a bit of material from the gen 1 bolt to match my large ports (.225)



The primary difference between the two is the gen 2 bolt regardless of material removed causes an obstruction thats centered in the barrel for air flow. The gen 1 is more of a flow thru style that causes NO obstruction in the path of air flow whatsoever, the only downside is they cannot be swapped to lefty which doesn't matter to me :)



Below is a diagram showing the example of gen 1 vs gen 2 bolt flow path. Left is gen 2 right is gen 1. You can easily see which one will flow better/more efficiently with less turbulence.



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I personally use a gen 1 bolt in my gen 2 mrod. I gained the most fps even when compared to a milled down gen 2 bolt. (+ 5-10 more fps over milled down gen 2)

I do remove quite a bit of material from the gen 1 bolt to match my large ports (.225)



The primary difference between the two is the gen 2 bolt regardless of material removed causes an obstruction thats centered in the barrel for air flow. The gen 1 is more of a flow thru style that causes NO obstruction in the path of air flow whatsoever, the only downside is they cannot be swapped to lefty which doesn't matter to me :)



Below is a diagram showing the example of gen 1 vs gen 2 bolt flow path. Left is gen 2 right is gen 1. You can easily see which one will flow better/more efficiently with less turbulence.






 
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Mason, if you have the extra $$ towards modding your gun( I have to say this cause I know this PCP hobby gets expensive) look at Hill’s shorter barrel shroud/ moderator combo. He has it. It was cool looking at first when I put his moderator on the factory shroud, but after awhile cruising thrunthe house with the rifle slung on my shoulder I got tired of hitting the top of the door jambs if I forgot to crouch down. His shorter shroud/moderator combo was the ticket. You end up loosing two of your baffles. I contacted Tim if would affect that nice PFFFTTT! I had with the moderator and factory shroud, and his reply to me was “I’ll let you tell me if there’s a difference”.



no difference! Still quiet, and now I have a moderator close enough to the fill cap, but not too close where filling would be a problem. You can tell he did his homework on this one. Makes the Marauder look somewhat like a carbine.
 
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