Most Compact Marauader!

[ackuric]

Here's a before and after pic showing how much more forward the rifle is held now, you can see by the scope positions. Drastic difference! Still need to wrap the new hand guard in carbon fiber vinyl.

[ackuric]

Ran a brief string at 40-41 FPE with 25.4's. Results were pleasant @ 1.88~ FPE/CI. Gun is operating very efficiently and quietly and I think the slight bit of drag on the prod sear really eliminates any hammer bounce especially when coupled with a SSG.

I used a 10 lb spring with very little preload and a 42 gram hammer to obtain the 850~ fps average. I'd say the prod trigger group is still reducing the fps around 70~ but I really can't complain with the results its giving

My custom valve really is impressing me, during the down time I tweaked a few things by increasing my plenum passage holes, making a new TP that blends the oblong passages from the valve to the barrel as they are opposing, and then went back to a gen l style bolt just because it out performs my gen ll that is turned down.

-Matt

[ackuric]

Tossed in my 11.5 lb spring with the 42 gr hammer, and sent some 33.9gr's flying off at 870 FPS avg...8 shots from 2500~ down to 2100~ = 1.4 FPE/CI~

That gives me 24 fairly powerful shots! Very thrilled, I used to see more around 1.2~ FPE/CI around this power level so things are definitely looking good! I bet with slugs/heavier pellets this tune would really shine!

Next I'll set my tune up for the 52-54 fpe range I like for the 33.9 gr

-Matt

[ackuric]

Couldn't get under 860 fps on the 11.5 lb spring so I put the 10 lb spring in with some preload, not much was needed to hit 835 fps average with the 33.9gr... Results were great, @ 52.5 FPE I am currently at 1.5~ FPE/CI

-Matt

[ackuric]

I wanted to check out the range of power I have on just the 7.5 lb hammer spring along with a 42gr hammer after my few modifications.

Under max preload its looking to be around 47 FPE, and under no preload I am getting about 18 FPE. All from just 7.5 lbs of hammer spring!

The range on the 10 lb spring is around 30-60 FPE.

So the only two springs I need (and luckily have) are 7.5 / 10 to obtain all my tunes.

This valve is simply AMAZING, with just a custom poppet and mild port work...a modification that costs around 20$, anyone could get these results! I would love to test it unregulated and push out some 43 gr's @ 80-85 FPE but I personally don't have a need for that power out of this rifle, but at least I know she can do it!

[oldpro]

Where are the shot strings?? Or are you taking small samples and using fuzzy logic to fill in the blanks?? I for one would love to see some of those actual strings i.e. The 72 shot string at 2.2 efficiency or your 50ft lb tune.

[ackuric]

Where are the shot strings?? Or are you taking small samples and using fuzzy logic to fill in the blanks?? I for one would love to see some of those actual strings i.e. The 72 shot string at 2.2 efficiency or your 50ft lb tune.

Been a bit busy, still tinkering and testing, my strings were ran over 400-500 psi to compile accurate data, which I believe has been deemed acceptable for running strings by the community. I've run a full 16 shot 60 FPE string, I have run 32 shot strings @ 22 fpe, and currently the longest 53 fpe string I recorded was only 8 shots, but the air usage was incredibly low and I don't see why anyone would argue 32 shots @ 53 fpe being possible. 8 shots used 350 psi (2500>2150 @ 840 fps / 33.9 gr = 1.55 FPE/CI). I don't consider that tune better than the 40 shots @ 50...thats 2,000 fpe versus 1700.

I tend not to post big long strings as it has become too competitive on the forums as to who can run the longest or most efficient. I can actually do more than 72 shots @ 22 FPE, just tested this weekend how well the tune did OFF the regulator and I achieved an amazing bell curve that went from 710~ fps up to 730 fps and back down for another 20~ shots. Quite surprising being that I am regulated @ 2k psi and have ports of .212" that I can still have a bell curve at a low fps tune when coming off reg, I never expected it...I know full complete strings tickle some peoples fancy but I have been doing a lot of accuracy testing on a new pellet which is more important to me than using around 100~ pellets to run a full string with my low power setting.

I tossed back in my 25 gram hammer, as my 42 gram hammer has ribs on it and was catching the prod sear during the cycle and you could feel it while cocking.

Now its much more butter smooth and my fps with the 19.91 gr went from 730 (last settings on 42 gr hammer) to 670 on the 25 gr hammer (no change in spring/preload). My fps should of dropped a bunch more if it was solely a hammer weight change, but the non-ribbed 25 gr hammer is causing much less friction and performing very well. Much quieter too I might add! I guessed 400-500 fps when I dry fired the rifle, took it over the chrony and it did 668 to my surprise...

My modified stock valve is not that special, sure it cracks open VERY easily and is VERY tune-able with just hammer spring, it operates quietly and efficiently...but I am pretty sure it wouldn't do nearly as well as it does without my plenum extension which reduces pressure drop across the valve during the shot cycle....which I believe your SS valve does better on its own without the extra volume to assist, I hope I have one of your valves in hand some day soon, until then I am just doing my best to keep myself entertained with my own valve.

-Matt

[FuzzyGrub]

Here's a before and after pic showing how much more forward the rifle is held now, you can see by the scope positions. Drastic difference! Still need to wrap the new hand guard in carbon fiber vinyl.

I was wondering why the scope is mounted that far back on the syn stocked gun???   With the typical scope relief of 3.5", it would seem it is way too far back.  On all my Gen II Mrods, the scope eyepiece ends before the steep rise to the to the adj comb.   I figure there has to be a reason, just not obvious to me.

[triggertreat]

Where are the shot strings?? Or are you taking small samples and using fuzzy logic to fill in the blanks?? I for one would love to see some of those actual strings i.e. The 72 shot string at 2.2 efficiency or your 50ft lb tune.

Been a bit busy, still tinkering and testing, my strings were ran over 400-500 psi to compile accurate data, which I believe has been deemed acceptable for running strings by the community. I've run a full 16 shot 60 FPE string, I have run 32 shot strings @ 22 fpe, and currently the longest 53 fpe string I recorded was only 8 shots, but the air usage was incredibly low and I don't see why anyone would argue 32 shots @ 53 fpe being possible. 8 shots used 350 psi (2500>2150 @ 840 fps / 33.9 gr = 1.55 FPE/CI). I don't consider that tune better than the 40 shots @ 50...thats 2,000 fpe versus 1700.

I tend not to post big long strings as it has become too competitive on the forums as to who can run the longest or most efficient. I can actually do more than 72 shots @ 22 FPE, just tested this weekend how well the tune did OFF the regulator and I achieved an amazing bell curve that went from 710~ fps up to 730 fps and back down for another 20~ shots. Quite surprising being that I am regulated @ 2k psi and have ports of .212" that I can still have a bell curve at a low fps tune when coming off reg, I never expected it...I know full complete strings tickle some peoples fancy but I have been doing a lot of accuracy testing on a new pellet which is more important to me than using around 100~ pellets to run a full string with my low power setting.

I tossed back in my 25 gram hammer, as my 42 gram hammer has ribs on it and was catching the prod sear during the cycle and you could feel it while cocking.

Now its much more butter smooth and my fps with the 19.91 gr went from 730 (last settings on 42 gr hammer) to 670 on the 25 gr hammer (no change in spring/preload). My fps should of dropped a bunch more if it was solely a hammer weight change, but the non-ribbed 25 gr hammer is causing much less friction and performing very well. Much quieter too I might add! I guessed 400-500 fps when I dry fired the rifle, took it over the chrony and it did 668 to my surprise...

My modified stock valve is not that special, sure it cracks open VERY easily and is VERY tune-able with just hammer spring, it operates quietly and efficiently...but I am pretty sure it wouldn't do nearly as well as it does without my plenum extension which reduces pressure drop across the valve during the shot cycle....which I believe your SS valve does better on its own without the extra volume to assist, I hope I have one of your valves in hand some day soon, until then I am just doing my best to keep myself entertained with my own valve.

-Matt

You might want to check your math.  I ran those numbers through the Lloyd Sikes efficiency calculator and come up with 1.34 FPE/cu in.  That's based on 215cc and with your extra plenum the efficiency would even be less.  Not bad though and nothing to be shy about.

[Nomadic Pirate]

Sorry man, but that foregrip sure is ugly,...I can think of several ways to make it look much, much nicer.

[mobilemail]

You are quite the craftsman! 

I just read through the thread and have a question about your C02 extension for the plenum space.   As I understand it, C02 is normally somewhere around 700-1100psi.  But regulator output is about twice that, triple that if the reg fails. Is there any concern with long-term fatigue or thread failure?  I only ask because I have never seen a C02 cartridge used like this...of course, there is a lot I haven't seen....

[ackuric]

Ordered some carbon fiber kydex (not real CF) and made a new stock. Also ordered 8mm OD / 4mm ID carbon fiber shaft/tubing from China that SHOULD work for my rods. 3-4 week wait on that shipment unfortunately, and I am not sure how they will hold up to being a sliding rod but I spent 10$ to find out. I still need to cut/mold the new stock some but couldn't help but want to show it off! I really wish I could do the pistol grips with the same material!



-Matt

[ackuric]

And here is the stock in its near final form! Very happy with the feel. This kydex stuff is amazing! Also my carbon fiber rods hit the States yesterday so I should have them within a week, very excited to try those out!

[UCChris]

Gotta agree with Pirate, that foregrip is blocky! I'm also skeptical of 1.2 efficiency at 60 fpe.

Other than the foregrip, gun looks good.

[ackuric]

Gotta agree with Pirate, that foregrip is blocky! I'm also skeptical of 1.2 efficiency at 60 fpe.

Other than the foregrip, gun looks good.

The foregrip is quite contoured in the current version. I wanted a nice flat bottom so the rifle can rest there easily. Its actually less blocky feeling than the stock OEM grip so by all means I am much happier My grip contours to the tube and leaves a .08" edge that is sanded down to more like .04"...where as the oem does not contour to the tube and has an edge of .240" prior to meeting with the tube which is very uncomfortable and not form fitting.

my grip:


oem grip:




The 60 FPE @ 1.2 FPE/CI tune is at a raised reg pressure of 2250 FWIW. (higher set points allow for potentially higher efficiency) 3 main factors in efficiency, barrel volume, plenum volume, and pressure. There are many others but those are the primaries, and increase in any of them can potentially increase efficiency...

-Matt

[UCChris]

You're getting 16 shots at 60 fpe, from 3000 down to 2250 psi, on a less than 215 cc cylinder?

[ackuric]

You're getting 16 shots at 60 fpe, from 3000 down to 2250 psi, on a less than 215 cc cylinder?

Close but no.

3200 PSI > 2200 PSI with 187 CC's of HPA volume (approximate) / 45 cc plenum which is 62.5 PSI per shot.

This is by no means  some amazing new grounds that can't be beat, toss in a 24" barrel with 80 cc of plenum see how it does for the same 1000 psi pressure range, likely much, much better.

-Matt

[UCChris]

You're getting 16 shots at 60 fpe, from 3000 down to 2250 psi, on a less than 215 cc cylinder?

Close but no.

3200 PSI > 2200 PSI with 187 CC's of HPA volume (approximate) / 45 cc plenum which is 62.5 PSI per shot.

This is by no means  some amazing new grounds that can't be beat, toss in a 24" barrel with 80 cc of plenum see how it does for the same 1000 psi pressure range, likely much, much better.

-Matt

What valve work have you done? Mind giving me port measurements? Spring weight? Stroke and hammer settings? Valve spring rate?

How are you getting 232 cc of air out of a 215 cc tube?

[ackuric]

You're getting 16 shots at 60 fpe, from 3000 down to 2250 psi, on a less than 215 cc cylinder?

Close but no.

3200 PSI > 2200 PSI with 187 CC's of HPA volume (approximate) / 45 cc plenum which is 62.5 PSI per shot.

This is by no means  some amazing new grounds that can't be beat, toss in a 24" barrel with 80 cc of plenum see how it does for the same 1000 psi pressure range, likely much, much better.

-Matt

What valve work have you done? Mind giving me port measurements? Spring weight? Stroke and hammer settings? Valve spring rate?

How are you getting 232 cc of air out of a 215 cc tube?

232 - 25 = 207. The 8 CC loss / difference is from swapping the stock gauge block with the lane regulator+plenum... I have a 25 cc plenum extension that is made from a 20 g co2 cartridge. Originally the lane regulator came with a 20 cc plenum, increasing my plenum from 20 to 45 cc's provides over half the pressure drop across the valve during the shot cycle which means better efficiency/higher power. Here is a pic of the modification I did to obtain 25 more cc's for plenum.



All the info you requested in regards to my valve work is in my signature..

hammer stroke is roughly .1" more than stock.
.212" exit porting (seat moved forward to achieve)
.255" spring retainer cap entry hole
.25" poppet
.04" valve stem
.2255" valve seat (seat moved forward to achieve)
.23" valve throat
5lb hammer spring
42 gram hammer (have a 25gr one I use as well)
7.5-11lb hammer spring used depending on my tune (11 lb spring at low preload hits 60 fpe with 42 gr hammer)


-Matt

[ackuric]

I sought out 4 months ago to attempt an aluminum air tube for the marauder, and as promised I delivered a finished product with the help of a forum members CNC skills. I have no need to fabricate information/ideas that are fantasy and not reality.

I sought out 6 months ago to attempt to reduce cocking force and make a valve that is easier to open than stock, I achieved that, and that number is simple. Here is how it works....

.34 OD / 3k PSI you see 272 lbs of force against the poppet, which causes it to decompress more on the seat which means its harder to unseat as well

.25 OD / 3k psi you see 147 lbs of force against poppet...which is a 45% drop in force holding the poppet closed, when coupled with less compression on the poppet during seating and an increased throw by reducing OAL length of poppet stem, you have a valve that is much easier to open than stock. I've provided all the details and information free for anyone to follow. Real life results were identical to what the math on paper says...

I did my valve mods for a whopping total of 10 cents as I have tested it with the stock poppet @ .25" and it does fine and is comparable to peek at these very low forces as it does not compress nearly the same @ 150~ lbs as it would at 300~...I tested peek, delrin and stock material in my valve and saw near 0 gains in fps from either material at these reduced forces. The peek poppet starts to leak at lower pressures, where as the stock poppet could be shot down to 500 psi if you wish. At 500 psi the pressure against a .25" poppet is only 29 lbs and that is including a 5 lb spring. Peek needs around 100~ lbs of force to seal well, from what I have learned...and would be better suited in valves with 150~+ lbs of force always against the poppet.

-Matt