.30 Marauder Test W/ Chrony and Target

[Rescue35]

How did it come to this? http://www.gatewaytoairguns.org/GTA/index.php/topic,35466.0.html

Target was at 30 yards for a point of referance. I was not shooting for groups. This test was to get a full string across the crony to see what she is doing with the internal mods. I did discover that my bolt is not completly sealing in the barrel as I get a slight puff of air with every shot.

.32 Roundball (.310) ~45 grains. Starting fill was 3100psi. Pressures listed below are after the shot using stock gauge.

 1: 638
 2: 667  3000psi
 3: 662
 4: 668
 5: 703
 6: 704
 7: 708
 8: 713  2,800psi
 9: 724
10: 722

11: 729
12: 741
13: 745
14: 752  2,600psi  56fpe
15: 747
16: 749
17: 747
18: 747  2,400psi
19: 743
20: 737

21: 728
22: 746  2,200psi  (I was a longer pause before this shot was fired)
23: 721
24: 717
25: 719
26: 710
27: 687  2,000psi (I was done with my test at this point but decided to make it an even 30)
28: 692
29: 701
30: 685  1,750psi

To test the crony I fired my .22 Mrod across it and the 18gr JSBs where getting me 870fps.



She was shooting a little low and left but fairly consistent. I had only bore sighted it prior to shooting. The little red sticker that was my aim point was obliterated.

This is how my shooting sesion went.
 

[PakProtector]

hey-Hey!!!,
That is absolutely outstanding. Thanks for the note on the valve sleeve in the 2563 valve, I was considering taking a pull at it... It looks like you've got 30 shots around 50 FPE, that is an absolutely outstanding 1500 FPE from a fill; very impressive. I'd consider a longer barrel; that efficiency will go up as velocity will increase on the same air usage...but yours is working well...don't tell me about the noise level just yet.
cheers,
Douglas

[melloroadman]

Looks like you have been busy . I did not see what the length of the barrel is . I am sure you will get it dialed in . Enjoy and keep the up dates coming .Marvin

[Rescue35]

The barrel is only 20".

Noise level is not bad at all. Of course I was in the woods. Although it is not as loud as my Dragon Slayer, when I fired the .22 Mrod it reminded me how quite it could be.

I will crank up the hammer spring preload and see how she does. I am even considering a heavier hammer.

I just received my molds for 93, 100, 113, and 220 grain .309-.311 projectiles. Along with the appropriate sizing die of course. Oh and the 220grain is for the 300 AAC Blackout dies that where in the box too, not the Mrod.

[rsterne]

14 shots within 4% ES on 600 psi from what I can see.... The average FPE would be about 55 x 14 = 770 FPE.... Air used was 600/14.5 = 41 bar x 13 CI = 538 CI.... Efficiency works out to 770/538 = 1.43 FPE.CI.... Sound pretty good for initial trials, and sounds like there is more power available....

Bob

[amb5500c]

Very cool indeed.
Richard

[kevinbrian]

Good heavens that is just flat out awesome!!!!!!!!!!!!!! Great job!!!!!!!!

[Rescue35]

Thanks Bob for running the math on it's efficency. Thanks to everyone else for there interest.

I will try to do some adjusting on it and get her back out there this week. I have a few more projectiles to try now too.



I will need more pure lead.

[melloroadman]

Nice . If you are using the pure as a base and then alloying I guess you need more . But pure lead being needed in AR is a myth . BHD does not use pure nor does Jerry . You will find that even a 6-8 bhn alloy will make your casting sessions much more enjoyable . Marvin

[Rescue35]

Thanks for the feedback Marvin. I know you are well experienced at casting your own. I have plenty of wheel weight lead too. I will cast up some of each and see if there is a difference.

[melloroadman]

You might try a 50-50 mix of pure and wheel weight lead as well . But the wheel weights should work well in that barrel . You get a better fill out with less culls with a alloy . It does not take much but it sure makes a difference in the bands and base .Marvin

[Rescue35]

So true. I've cast WW before and had good luck. Had good luck this afternoon too. I will work on getting them sized, weighed, and sorted to see what works so far. Unless I find a winner with these, the next batch I will try some 50% Pb / 50% WW.

I also picked up 100 more .32 roundballs. They work ok for getting her dialed in. Shooting 30 at a time was not expected and runs through them rather quick.

I will have more info later this week.

[tworr]

This is outstanding!! You may also try picking up some .345 round balls and swaging them down to .308 and see how they do. I swage both .345 and .320 for .50 and 60 grain pellets. I was using a flat die and turned it on my lathe till it had a cup shape to hold the round ball. It makes for a nice round back for the larger .345 round ball where it was flat after sizing before.

I also shoot cast bullets from 80 to 150 grains in my .308 condor, but the roundballs are great for squirrels.

Keep us informed!!

[QVTom]

14 shots within 4% ES on 600 psi from what I can see.... The average FPE would be about 55 x 14 = 770 FPE.... Air used was 600/14.5 = 41 bar x 13 CI = 538 CI.... Efficiency works out to 770/538 = 1.43 FPE.CI.... Sound pretty good for initial trials, and sounds like there is more power available....

Bob

Bob, now that I have some heightened interest in PCPs, I have a question on your efficiency calculation.  Forgive me for asking, I know you have explained many times before.  I promise to pay attention this time   What does the 13CI represent?  Reservoir capacity? 13 CI seems too small for a Marauder.

Tom

[lloyd-ss]

Rescue35,
Very cool indeed!  I need to get out more, I don't know how I totally missed this.  When you put your mind to something, everybody better stand back and get out of the way!

Did you open up a .25 mag to .308?  Or are you going to make new custom guts to fit the .308?

As usual, very nice work!
Lloyd-ss

[rsterne]

The reservoir on an MRod is 215 cc.... 215/16.4 = 13.1 cu.in....

Bob

[QVTom]

Thanks Bob,  I would have thought it was larger.  Now I understand why the factory power levels are so conservative

Tom

[lloyd-ss]

Yes, kinda looks like they cut the airtube too short.  But it is 1.25 O.D. and .095 wall, and steel, and  heavy.

[Rescue35]

I haven't even taken the magazine out of the plastic bag. Once i get her shooting how I want I will delve into that.

I still need to turn the barrel down to fit the shroud. Although I like the look, the heavy barrel is HEAVY! I also want to open the transfer port up to .156". I need to check my notes on that though.

[Rescue35]

I have decided to leave the transfer port alone for now. Instead I opted to make a new hammer.

The stock Mrod  (.25) hammer is 77.5 grams. The one I have almost completed is 115.9 grams. All that is left is to drill and tap the cocking screw hole.


I also managed to turn the barrel down to .5" This not only makes it much lighter but gives me the option of installing the shroud.