Author Topic: Gen 2 - 25 modded Mrod + modded bolt  (Read 4997 times)

int3man

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #15 on: August 06, 2016, 08:42:06 AM »
Hi All,
           Well I am in a position to take this on.  Does anyone have a Gen 2  .25 bolt. Gen2 .22 bolt and a .25 Gen 2 Breech, I can borrow for a week?  I'll pay the freight, bothways.  You get yours for free!

My .25 is a Gen 1 and they have the grooved Probe.

Thanks!  Michael :-  )
  • Central California
WAR .22 PRod
WAR .25 Marauder
Broadening my Horizions
.22 Brocock Super 6 XL
.25 BSA Scorpion Huma Reg.
.25 Air Arms Extra FAC
.30 Kalibr Cricket
.22 Taipan Mutant Standard

WAR .22 Marauder, Huma, LW Hammer,  Rapid 70 Bull  Stolen
Flex .30  Stolen

Yes I still have an ICQ Number.  Raise your hand if you do.

Shorty

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #16 on: August 06, 2016, 10:20:22 AM »
Good Luck Michael making something happen.

I am sure there are a few guys out there that have a Hill, WAR, or Cothran valve in their 25 cal guns that would like to get over 85 FPE without a full modification of the pressure tube/upper receiver to accept full bore porting or run an impossible to pull back hammer spring or run 70+ grain slugs over 3000psi.

I am not sure if the bolt molt will get you those results but, based on my hack job "stock valve" with the modded bolt hitting 89 FPE with Eujins is a good indicator that those combinations should do better than "stock" modified parts.

This bolt mod on the gen2 is also one of the missing links of regulating the 25 too.

According to the numbers I have been collecting on my 25, "theoretically" If I pop a regulator into my 25 and run a 40 fpe tune using a stock air tube and reg setting of 1650psi,
The predicted shot count is 49 on regulation with and additional 10 to 20 shots off ending somewhere around 1150 to 1200 psi.

I am just not ready to prove it "put my money where my mouth is" just yet.
  • Palm Coast Florida

Christopher

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #17 on: August 12, 2016, 07:06:00 PM »
I've got a .25 Marauder and find this very interesting.

What if a person could set up a way to run a probeless bolt? Would we see even more gains or would we see a point of diminished returns?

The stock bolt blocked the air passage about 40%, with the mod that was reduced dramatically down to about a 20% blockage (if my math is right)
I just can't help but think, what if there was nothing blocking it?

Thoughts?

Thanks for sharing this mod.

Chris
  • dead end road KY

int3man

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #18 on: August 12, 2016, 09:07:48 PM »
I've got a .25 Marauder and find this very interesting.

What if a person could set up a way to run a probeless bolt? Would we see even more gains or would we see a point of diminished returns?

The stock bolt blocked the air passage about 40%, with the mod that was reduced dramatically down to about a 20% blockage (if my math is right)
I just can't help but think, what if there was nothing blocking it?

Thoughts?


Well the long and short of it is that a probeless bolt would not seat the pellet and you would not get a shot off. 

I'm looking for a bolt to turn down if you have one!

Thanks for sharing this mod.

Chris
  • Central California
WAR .22 PRod
WAR .25 Marauder
Broadening my Horizions
.22 Brocock Super 6 XL
.25 BSA Scorpion Huma Reg.
.25 Air Arms Extra FAC
.30 Kalibr Cricket
.22 Taipan Mutant Standard

WAR .22 Marauder, Huma, LW Hammer,  Rapid 70 Bull  Stolen
Flex .30  Stolen

Yes I still have an ICQ Number.  Raise your hand if you do.

Christopher

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #19 on: August 12, 2016, 10:02:35 PM »
I guess I didn't make myself clear enough. When speaking of a running a probeless bolt I should have said along with a retractable bolt. Just a meandering thought.......

Anyways, Yeah I've got a .25 bolt, but in my gun. Are you thinking of starting to offer this service or looking for one to buy or just try to turn one down yourself?

Chris
  • dead end road KY

rsterne

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #20 on: August 13, 2016, 11:32:11 AM »
Enlarging the area around the bolt only works when that is the source of the restriction.... If the transfer or barrel ports are the restriction, which they likely are, then retracting the bolt nose won't do much....

Bob
  • Coalmont, BC

int3man

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #21 on: August 14, 2016, 06:45:18 PM »
I guess I didn't make myself clear enough. When speaking of a running a probeless bolt I should have said along with a retractable bolt. Just a meandering thought.......

Anyways, Yeah I've got a .25 bolt, but in my gun. Are you thinking of starting to offer this service or looking for one to buy or just try to turn one down yourself?

Chris

First l was wanting to see another picture of the bolt installed from the Transfer port side.  Then some way to mark it and remove the bolt.  And another picture of the mark, with the bolt removed.

Yes I have a lathe and was thinking of a way.  I wonder what a .22  Gen 2 bolt looks like.  A sleeve would be an easier fix!

Michael :- )

  • Central California
WAR .22 PRod
WAR .25 Marauder
Broadening my Horizions
.22 Brocock Super 6 XL
.25 BSA Scorpion Huma Reg.
.25 Air Arms Extra FAC
.30 Kalibr Cricket
.22 Taipan Mutant Standard

WAR .22 Marauder, Huma, LW Hammer,  Rapid 70 Bull  Stolen
Flex .30  Stolen

Yes I still have an ICQ Number.  Raise your hand if you do.

Christopher

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #22 on: August 26, 2016, 04:25:54 PM »
Hello to all,
Just wanted to share my results of this mod.

My previous tune (before this particular mod) was 839 fps with the heavy Eunjins. Other mods include WAR H.E. valve and WAR SSG with barrel drilled out to .156 (5/32"). That was on a 3100 psi fill and got eight shots. That was about the best that I could do and have any kind of a decent bell curve to it.

My uncle is a machinist and showed him pictures that Shorty had posted about turning the bolt probe down and he said it would be no problem.

So he got 'er done and I also drilled out my barrel to .187 (3/16").

Here are the results on a 3200 psi fill:
847
845
842
855
859
862
853
858
861
848
850
846
837
845
827
823

That was two full mags of heavy Eunjins.
Over the first fourteen shots had an avg. of 850 fps. Only an 11 fps increase by this mod along with the barrel drilled out. But I did gain six more shots so I'm pretty pleased with it. Just have to fill an extra 100 psi to get it. I can get alot more speed but not curve whatsoever, just a cliff.

If i wanted to use an eight shot string, I could knock off the first three shots, probably fill to about 3000 and have an avg of 856 with an ES of 14 fps, which is 1.6%.

Thanks,
Chris
  • dead end road KY

bnowlin

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #23 on: August 26, 2016, 05:03:12 PM »
I ordered a new gen 2 25 cal breech and bolt from crosman because mine was getting kinda sloppy.  got it last week and the bolt didn't even have a tip on it. A first for me.   Appeared to be broken before being anodized.  They are sending another.
Bobn

int3man

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #24 on: August 26, 2016, 09:00:18 PM »
I ordered a new gen 2 25 cal breech and bolt from crosman because mine was getting kinda sloppy.  got it last week and the bolt didn't even have a tip on it. A first for me.   Appeared to be broken before being anodized.  They are sending another.
Bobn
Would you be willing to donate your old parts for the cause?  I lost my Gen 2 opportunity!

Thanks Michael :- )
  • Central California
WAR .22 PRod
WAR .25 Marauder
Broadening my Horizions
.22 Brocock Super 6 XL
.25 BSA Scorpion Huma Reg.
.25 Air Arms Extra FAC
.30 Kalibr Cricket
.22 Taipan Mutant Standard

WAR .22 Marauder, Huma, LW Hammer,  Rapid 70 Bull  Stolen
Flex .30  Stolen

Yes I still have an ICQ Number.  Raise your hand if you do.

Shorty

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #25 on: August 27, 2016, 05:15:23 AM »
Christopher,
Glad you tried it out. Your the only other person besides Aceflier that I have read about that has done this.

Let's see,
75% increase in shot count with an additional 11fps increase in speed and 1-1.5 fpe increase in power.

That's pretty incredible in my book. Welcome to home-brew mods. Your uncle did you an awesome solid.

Acefliers 50 fps increase was due to max power shots. I don't think your SSG will allow you to test for max power with your set up. It's not designed to do that. 

Here's what I was able to do with all stock modified parts with my gen2 25:
43 Eujins (73fpe)
3000psi to 2400 psi
Shots   43.2 Eujin
1   869
2   879
3   877
4   876
5   872
6   880
7   872
8   870

ES: 1.3%
Efficiency: 1.08
Average FPE = 73.2
  • Palm Coast Florida

bnowlin

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #26 on: August 27, 2016, 05:16:54 AM »
Let me get my new one in and I'll let you know.
Bob

int3man

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #27 on: August 27, 2016, 08:17:58 AM »
Let me get my new one in and I'll let you know.
Bob
K
  • Central California
WAR .22 PRod
WAR .25 Marauder
Broadening my Horizions
.22 Brocock Super 6 XL
.25 BSA Scorpion Huma Reg.
.25 Air Arms Extra FAC
.30 Kalibr Cricket
.22 Taipan Mutant Standard

WAR .22 Marauder, Huma, LW Hammer,  Rapid 70 Bull  Stolen
Flex .30  Stolen

Yes I still have an ICQ Number.  Raise your hand if you do.

Christopher

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #28 on: August 27, 2016, 11:51:36 AM »
Impressive Shorty, and I thought I was doing good.

I don't really have much load on the SSG. Had to really reduce the preload in order to get any sort of a curve. High as I ever got was 924 fps but an incredible decrease in ever shot after that. Also with allot of preload I had pretty sporadic readings on my fps second on shot to shot.

Thinking about trying the F.A.M.E. mod next to help with the cocking roughness. I like the idea of it and it doesn't seem like that much trouble.

Chris
  • dead end road KY

Aceflier

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Re: Gen 2 - 25 modded Mrod + modded bolt
« Reply #29 on: September 04, 2016, 07:04:54 PM »
Shorty you are really making me want to open the ports a bit more. But I'm good with 75fpe  ;)
  • Indiana
1377 .177
Daisy 880
Ruger Blackhawk
'72 Dan
NP XL1100
.25 Mrod 75FPE (Stock parts mods by Shorty tuned by me)
Airforce Texan .457