.30 cal Marauder

[rsterne]

I haven't had a Challenger, but CarsonRatSniper converted one to accept Disco parts, so he can answer that question.... Perhaps PM him to not Hijack the thread?....

Bob

[Tomg]

Thanks, I'll pm him.

T

[au hunter]

     Any up dates on this project???
FPS? FPE?  Groups?
enquiring minds need to know

[PakProtector]

Well...I can tell you that grumpy's rifle, built around that valve of Sean's runs nearly 160 FPE with 70 gr slugs for 13 shots to under 2k psi. My .224 shoots over 100 FPE with a similar( but slightly smaller ) valve. If the .22 didn't work so well, I'd likely build a .257 around that one. Sean's valve is a solid performer, and I have one( slightly bigger than grumpy's ) like it under construction for a .308.

Still hoping to hear about strever's rifle....

For youse considering an uber Marauder build, kicking open such a valve at pressures over ~2k6 requires more energy than can be reasonably applied with the limited hammer travel available in a stock marauder tube. The Gen1 sear is also built with some unforgiveable stress risers and I would not trust them with a really nutty spring...A7 tool steel to the rescue.
cheers,
Douglas

[rsterne]

That's using a 500cc, 250 bar bottle, right?.... so 3600 psi down to 2000?....

Bob

[michaelthomas]

I had made an inquiry about Marauders and the feasibility of putting in one of my electronic solenoid strikes, and Dick offered to send me a Marauder to experiment with.  (nice guy, eh?)

This is the gun he sent me. 

I have never seen a Marauder before, so it was kind of interesting to put this thing together.

I initially charged it to 3200 psi, and began to fiddle with the hammer spring setting.  I only had 3200 in both of my tanks, so that was the reason I chose that pressure.  I did a few 10 shot strings, and was able to get decent consistency (withing 5 fps) for 10 shots and left it like that to see what it would shoot like.  The velocity was about 815 with the 44.5 gr JSB's.  I had only one tin, so I didn't really want to blow through them all testing on the chrony.  I could get 850 out of it at that pressure, but it was rather wasteful.....so I settled for 815.

We took it out and set up a target at 75 yards.  The wind was ridiculous at 15-20 sustained and gusts near 30mph.  We shot it anyway.  Of the 3 scopes I had.....all were fixed 36 power bench scopes.  The only 11mm dovetail rings I had were too low to make use of the magazine, so we just single loaded.  We finally found the target with only a few clicks of elevation on the turret remaining.  Since we knew it would at least shoot 10 consistent shots.....we topped it off every 10.  Seemed like we were using around 300 psi or so for 10 shots.  The 25m benchrest targets we had have a 50mm box around each bull, and it was easy to stay in whatever box we chose.  I had one 4 shot group where all shots were touching making one somewhat elongated hole.  That was not, however, something that I would consider repeatable in those conditions.....more of a lucky group.  It will be interesting to see what it will do in calm conditions.

That was the day after Thanksgiving, and I have not shot it since.  I plan to get some more pellets so I can do some more testing in the near future.

Bob, the bottle is 500cc, and 250Bar max.

Mike

[rsterne]

Hmmmmmmmmm.... Seems like getting that 160 FPE was pretty costly on air.... 160 x 13 = 2080 FPE total.... 1600 psi drop (110 bar) x 500cc (30.5 CI = 3355 CI of air used.... that works out to only 0.62 FPE/CI....

On the other hand, 10 shots at 815 fps (65.6 FPE) is 656 FPE on 300 psi (20.7 bar) x 30.5 CI = 631 CI of air, which is 1.04 FPE/CI.... significantly better....

Bob

[gabi.nechita]

Hi Mike.
Do you think that is possible to use solenoid striker in 300-400FPE bigbore airgun?
If yes how big must be solenoid?

Thank you.

[michaelthomas]

Hi Mike.
Do you think that is possible to use solenoid striker in 300-400FPE bigbore airgun?
If yes how big must be solenoid?

Thank you.

To be honest, I don't know.  I'm not a big bore guy.....so I really don't know what kind of force it takes to get the valve necessary for that kind of power off the seat.

The solenoid and boost converter that I use will handle anything I need for benchrest on less than 60 volts.....as long as the valve is purpose built.  The valve on my 30 FPE open class bench gun flows as much air as the valve in this Marauder, but only takes about 1/3 of the power to open.  (roughly)

Mike

[grumpy]

Hmmmmmmmmm.... Seems like getting that 160 FPE was pretty costly on air.... 160 x 13 = 2080 FPE total.... 1600 psi drop (110 bar) x 500cc (30.5 CI = 3355 CI of air used.... that works out to only 0.62 FPE/CI....

Bob

It is Bob, but that was pretty much our starting point. We did next to no tuning of the gun othen then try for max power, within reason. There is much more power in this gun but we all know thats not always where the accuracy lies. It may end up being de-tuned a tad bit since 100 + yard accuracy is the primary goal.

[PakProtector]

The pressure drop was more like 2k5 to 1k8 psi over 13 shots Bob. Not enough hammer to open the big valve at higher pressure for any significant energy. Hence the long-travel mod I have underway.
cheers,
Douglas

[rsterne]

Interesting.... With only a 700 psi (48.3 bar) drop, that works out to 48.3 x 30.5 =  1473 CI and an efficiency of 1.41 FPE/CI.... That is wonderfully impressive at 160 FPE, you are to be congratulated....

I wonder why the efficiency at 3200 psi at a much lower FPE level (65 FPE) was so much lower.... Strange things going on there, for sure, the reverse of what could be expected....

Bob

[PakProtector]

Interesting.... With only a 700 psi (48.3 bar) drop, that works out to 48.3 x 30.5 =  1473 CI and an efficiency of 1.41 FPE/CI.... That is wonderfully impressive at 160 FPE, you are to be congratulated....

I wonder why the efficiency at 3200 psi at a much lower FPE level (65 FPE) was so much lower.... Strange things going on there, for sure, the reverse of what could be expected....

Bob

Just so we don't have to work too much dependent on my memory, I will see about a thorough string on Dave's this Sunday....but the big diff is the valve. One used to be a Crosman, and the other was never even shipped over New York.
cheers,
Douglas

[rsterne]

ahhhhhh.... thought it was the same gun, sorry....

Bob

[cjk]

I am anxiously waiting for a 30 cal marauder from Sean, complete with his valve and CF over the barrel.
With only a couple years shooting PCPs under my belt, this big bore will be a blast to learn on!

[PakProtector]

I am anxiously waiting for a 30 cal marauder from Sean, complete with his valve and CF over the barrel.
With only a couple years shooting PCPs under my belt, this big bore will be a blast to learn on!

Cool...both Dave's .30 and my .224 run one of Sean's valves. Very capable bits I think. Hoping to hear from him about a LW Poly .22 pellet barrel he's had for a while now...
cheers,
Douglas