Mac1 Mrod, to bstaley or not?
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Mac1 Mrod, to bstaley or not?
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Topic: Mac1 Mrod, to bstaley or not? (Read 2936 times))
tehsquirrel
Plinker
Posts: 132
yes
Real Name: Jake
Mac1 Mrod, to bstaley or not?
«
on:
October 07, 2014, 07:42:16 AM »
Since I got everything put together (my backstop and chrono light setup) I ran a string through the mrod with JSB Kings 25.39gr:
1 834
2 837
3 840
4 840
5 844
6 846
7 840
8 845
9 830
10 844
11 843
12 841
13 839
14 836
15 819
16 817
So it seemed pretty good and I'm pretty sure I want to keep it to 2 magazines (16 shots). It seems flat for stock (having Mac1 do their basic crown + replace oring), not sure if Tim put an easy tune on it, but I'm not sure if I should mess with it or leave it... I have some orings already to do the bstaley. I plan on using the gun for larger critters and eventually getting some 30gr pellets or slugs to test out. 840 seems like a reasonable target speed.
Thoughts?
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Maine
Sandspike
Vive Le Infidel
Sharp Shooter
Posts: 712
Each air gun is a gateway to another!
Real Name: Kyle
Re: Mac1 Mrod, to bstaley or not?
«
Reply #1 on:
October 07, 2014, 08:24:22 AM »
right now you are at 16 shots. If you were aired at less than 3000 I recommend that you air up to 3200 and try that tune again.
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bstaley
Plinker
Posts: 299
Re: Mac1 Mrod, to bstaley or not?
«
Reply #2 on:
October 07, 2014, 12:17:49 PM »
Not.... the mod does nothing for a stock. 25 unless you want to downtune it significantly.
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wilsonj1018
Expert
Posts: 1526
Real Name: Josh
Re: Mac1 Mrod, to bstaley or not?
«
Reply #3 on:
October 07, 2014, 12:40:12 PM »
I would try what spike suggested, I see a possible whole other magazine in there maybe.
Josh
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Hickory, NC
Habanero69er
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Posts: 18978
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Real Name: Dave
Re: Mac1 Mrod, to bstaley or not?
«
Reply #4 on:
October 07, 2014, 01:19:15 PM »
You need to ask yourself if you want to drop or raise your power or shot count. Using 25.4g @ 840fps =39.81FPE. Seems a little low for a .25 to me. My Mrod .22 is getting 30 shots @ 32FPE.
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tehsquirrel
Plinker
Posts: 132
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Real Name: Jake
Re: Mac1 Mrod, to bstaley or not?
«
Reply #5 on:
October 07, 2014, 05:18:36 PM »
Thanks for the input, that was @ 3000 psi, but I can run it at 3200 and see...
I'm pumping it so of course increasing the shot count would be nice, but I have other rifles for messing around and this is for larger critters up to 60-70 lbs. The power/distance and accuracy are my main concerns with the mrod. I would like to be able to push a 30-33gr pellet/slug at around the same speeds for about 50 FPE. That means I'm looking to add around 20-25% FPE, and I'm not super worried about the shot count.
I'll pump it up to 3200 this evening and get a string through it as is. The 830 fps (shot 9) I think was an odd pellet because when I first put it into the magazine I had to tap it some for it to fall through where the other pellets all just fell through.
I'm open to changing the hammer spring and doing some tuning but I can't blow too much on it.
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Maine
tehsquirrel
Plinker
Posts: 132
yes
Real Name: Jake
Re: Mac1 Mrod, to bstaley or not?
«
Reply #6 on:
October 10, 2014, 07:57:46 PM »
Took me a bit to get to getting a string, but I pumped it up to 3200 (the gauge on the gun was maxed out), and went for it. The string itself is stuck on my laptop (finally setup the prochrono software) and the laptop went off the network. It was weird! It started at 810, after 2-3 shots went to 825, peaked at 837, and then after 3 clips it was 810 and I stopped. The graph looked like a pair of lips with 2 peaks @ 837. I had expected to get higher velocity shots with higher PSI. When I ended my gauge was only slightly lower than when I started last time.
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Maine
Habanero69er
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Real Name: Dave
Re: Mac1 Mrod, to bstaley or not?
«
Reply #7 on:
October 10, 2014, 10:34:38 PM »
It really sounds like your Mrod is pretty conservative on air. I've always heard that the .25 is an air hog. 3 clips is pretty good from what I've read. Maybe Tim tuned it down?
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45Bravo
Self confessed addict of anything with a trigger..
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Real Name: Ian
Re: Mac1 Mrod, to bstaley or not?
«
Reply #8 on:
October 11, 2014, 12:37:15 AM »
I don't know if you missed the third message in this thread, (it was short and to the point)
but it was from the man himself..
He said no, since the mod is named after him, I would think he would know...
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Houston, Tx.
I make 2 predictions;
ON THE DATE WHEN US TROOPS ARE ISSUED AN Energy Pulse Weapon,
1. The US Soldier will have on his person a version of the Colt 1911.
2. He will be aiming the NEW Weapon at someone carrying an AK47.
45Bravo
Self confessed addict of anything with a trigger..
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Posts: 2953
3 people can keep a secret, if 2 of them are dead.
Real Name: Ian
Re: Mac1 Mrod, to bstaley or not?
«
Reply #9 on:
October 11, 2014, 12:47:28 AM »
And more psi doesn't mean more FPS, it can actually slow you down.
The reason it started at 810 is you were starting to get valve lock,
(too much air pressure in the tube and valve, doesn't let it stay open long enough.)
as the pressure in the tube and valve started dropping per shot, the valve stayed open just a little longer each time. the speed went up, until it hits a point where it is self regulating,
then starts dropping as the valve stays open longer as there is less pressure in the tube to close it.
Tuning the hammer spring preload, striker force, and the transfer port restriction all have an effect on how it shoots.
I have a .22, and not too familiar with the shot counts on the .25.
P
I have set mine to work with a 2000 psi fill, and get over 800 FPS with 14.3's
«
Last Edit: October 11, 2014, 12:57:44 AM by 45Bravo
»
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Houston, Tx.
I make 2 predictions;
ON THE DATE WHEN US TROOPS ARE ISSUED AN Energy Pulse Weapon,
1. The US Soldier will have on his person a version of the Colt 1911.
2. He will be aiming the NEW Weapon at someone carrying an AK47.
tehsquirrel
Plinker
Posts: 132
yes
Real Name: Jake
Re: Mac1 Mrod, to bstaley or not?
«
Reply #10 on:
October 11, 2014, 08:36:34 AM »
That makes sense about the valve lock and your explanation was very helpful Bravo. I had seen bstaley's response and haven't done the mod based on that. I was just reposting a string to see if anybody could help explain it. I'll try pumping to 3100. Maybe I need to get a replacement psi gauge for the gun. I think maybe increasing the transfer port a little might help but I'm not sure where to start. I'd like to be increasing my power and dropping the shot count some.
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Maine
Habanero69er
GTA Senior Contributor
Posts: 18978
2A Supporter Striving To Keep America Great! 🇺🇸
Real Name: Dave
Re: Mac1 Mrod, to bstaley or not?
«
Reply #11 on:
October 11, 2014, 08:46:44 AM »
Remove the stock & that will give you access to the TP. There should be a small grub screw on top of the actual TP screw. Remove that & I'd turn my TP screw clockwise until it bottomed out. Make note of how many turns you make before it bottoms out so you know where you started. *Be careful not to over torque the adjustment screw* Full wide open is 5 to 5-1/2 turns counterclockwise from bottomed out. Depending on where you started, maybe open it up a half a turn more & see what happens. Be sure to replace the little grub screw! BTW, clockwise closes, counterclockwise opens the transfer port.
«
Last Edit: October 11, 2014, 08:48:42 AM by habanero69er
»
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Ormond by the Sea, Florida, USA 🇺🇸
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45Bravo
Self confessed addict of anything with a trigger..
GTA Senior Contributor
Posts: 2953
3 people can keep a secret, if 2 of them are dead.
Real Name: Ian
Re: Mac1 Mrod, to bstaley or not?
«
Reply #12 on:
October 11, 2014, 10:57:33 AM »
Also when you install the grub screw be careful, when you just feel it touch the adjustment screw, stop.
If you keep turning, it will turn the adjustment screw and will eventually bottom out again..
They both are the same size, and both turn the same direction..
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Houston, Tx.
I make 2 predictions;
ON THE DATE WHEN US TROOPS ARE ISSUED AN Energy Pulse Weapon,
1. The US Soldier will have on his person a version of the Colt 1911.
2. He will be aiming the NEW Weapon at someone carrying an AK47.
tehsquirrel
Plinker
Posts: 132
yes
Real Name: Jake
Re: Mac1 Mrod, to bstaley or not?
«
Reply #13 on:
October 11, 2014, 12:40:27 PM »
Thanks so much guys! I love this place. Do I need to gas it down at all before I take the stock off?
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Maine
45Bravo
Self confessed addict of anything with a trigger..
GTA Senior Contributor
Posts: 2953
3 people can keep a secret, if 2 of them are dead.
Real Name: Ian
Re: Mac1 Mrod, to bstaley or not?
«
Reply #14 on:
October 11, 2014, 12:42:25 PM »
No, no need to degas it before doing any adjustments to the spring preload, striker, or transfer port.
All can be done with Allen wrenches.
Logged
Houston, Tx.
I make 2 predictions;
ON THE DATE WHEN US TROOPS ARE ISSUED AN Energy Pulse Weapon,
1. The US Soldier will have on his person a version of the Colt 1911.
2. He will be aiming the NEW Weapon at someone carrying an AK47.
tehsquirrel
Plinker
Posts: 132
yes
Real Name: Jake
Re: Mac1 Mrod, to bstaley or not?
«
Reply #15 on:
October 13, 2014, 06:35:19 PM »
So I adjusted to what I thought was 4.5 turns out on the valve screw and then increased the spring preload by 1/4 turn. I lost the 2nd shot in the string because I think it was a double load but was 540 fps and missing a shot, then I accidentally deleted the last 2 in the string while trying to delete the 2nd one in the software.
1 812
2 832
3 835
4 836
5 840
6 846
7 846
8 846
9 844
10 853
11 844
12 853
13 851
I stopped @ 15 (2 clips with the missing shot), but it looked like it could keep going. It used about 400-500 psi. I checked the valve screw and it seemed to be back where it was (must have tightened the grub screw too much?), so I put it @ 5.5 out, and then adjusted the hammer stroke 1/4 turn increase, pumped it back up to 3200 and got another string...
Velocity # Velocity Power Factor Foot/Lbs
1 832 21.124 39.022
2 836 21.226 39.398
3 843 21.404 40.061
4 848 21.531 40.537
5 843 21.404 40.061
6 848 21.531 40.537
7 844 21.429 40.156
8 852 21.632 40.921
9 851 21.607 40.825
10 855 21.708 41.209
11 858 21.785 41.499
12 858 21.785 41.499
13 861 21.861 41.790
14 854 21.683 41.113
15 856 21.734 41.306
16 860 21.835 41.693
Seems pretty good but still need some more power to it. I wonder how many more shots I would have gotten... Any thoughts on where to go next?
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Maine
Habanero69er
GTA Senior Contributor
Posts: 18978
2A Supporter Striving To Keep America Great! 🇺🇸
Real Name: Dave
Re: Mac1 Mrod, to bstaley or not?
«
Reply #16 on:
October 13, 2014, 07:47:10 PM »
Try another half a turn on the preload & half a turn on the hammer throw. Hammer throw is increase by turning counterclockwise. I don't see why you can't get her up to + 45FPE.
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tehsquirrel
Plinker
Posts: 132
yes
Real Name: Jake
Re: Mac1 Mrod, to bstaley or not?
«
Reply #17 on:
October 14, 2014, 02:13:44 PM »
I opened up the valve a little bit more (I would say 5.5 turns, grub screw doesn't have a lot to grab), and then made half a turn increase on preload + hammer throw.
Statistics/Velocity Report
String #: 3
High Velocity: 881
Low Velocity: 869
Average Velocity: 875
Extreme Spread: 12
Standard Deviation: 4
Grains: 25.39
Velocity # Velocity Foot/Lbs
1 869 42.570
2 873 42.963
3 876 43.259
4 876 43.259
5 872 42.864
6 872 42.864
7 879 43.555
8 879 43.555
9 879 43.555
10 880 43.655
11 881 43.754
12 880 43.655
13 880 43.655
14 876 43.259
15 871 42.766
16 870 42.668
It's a little short of where I'd like to be power wise (I'd like to have few shots but be closer to 50 fpe). The statistics are really nice and this is a great looking string. I wonder if a stiffer spring would do the trick to get me to 50 fpe?
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Maine
Habanero69er
GTA Senior Contributor
Posts: 18978
2A Supporter Striving To Keep America Great! 🇺🇸
Real Name: Dave
Re: Mac1 Mrod, to bstaley or not?
«
Reply #18 on:
October 14, 2014, 02:55:09 PM »
That's not a bad start though. Play with it a little more. I would try another half turn on the hammer throw & see what she does.
«
Last Edit: October 14, 2014, 02:59:16 PM by habanero69er
»
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Mac1 Mrod, to bstaley or not?