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Mk1 .25 project https://www.airgunforum.ca/forums/topic89460.html |
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Author: | killercrow [ Thu Sep 09, 2021 3:56 pm ] | ||||
Post subject: | Re: Mk1 .25 project | ||||
More pics
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Author: | killercrow [ Thu Sep 09, 2021 3:57 pm ] | ||||
Post subject: | Re: Mk1 .25 project | ||||
And some more
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Author: | TCooper [ Thu Sep 09, 2021 8:29 pm ] |
Post subject: | Re: Mk1 .25 project |
Looks good. Lots of power! What is the barrel length? Did you keep the OEM valve return spring or go with something lighter? |
Author: | killercrow [ Thu Sep 09, 2021 9:33 pm ] |
Post subject: | Re: Mk1 .25 project |
Thanks! I kept the original spring. I don't see any reason to change it. The barrel is 9" from breech to crown. I think the shroud bushing adds 1/2" Nice weight to it anyway. Another thing on the list is a trigger overpull adjuster/spring perch. Anyone fiddling with mk1s knows of this spring. |
Author: | JayDee24ca [ Thu Sep 09, 2021 11:29 pm ] |
Post subject: | Re: Mk1 .25 project |
Wow! That is great! Now you've got me thinking I need one too! I think you are right about it being a gas hog. Have you thought about an HPA tank instead of CO2? You sure do beautiful work. JD |
Author: | killercrow [ Thu Sep 09, 2021 11:55 pm ] |
Post subject: | Re: Mk1 .25 project |
Thanks JD. I have thought of the hpa tanks. I just personally hate the way they look. I've been toying with the idea of putting a regulator in the handle and making a small air cylinder to thread into that. It would be a small vessel though... But 3000psi regulated at 850 is sweet. I have another, one of my older builds which I run bulk co2. It does good. I'm using a custom plug with a foster nipple on it, so no gain in volume there. |
Author: | Hobbyman2007 [ Fri Sep 10, 2021 7:52 am ] |
Post subject: | Re: Mk1 .25 project |
Nice work on that. I love the quarter bore especially in pistol form. I’ve never had my hands on an MKI but have always thought of getting one, they seem to come up for sale from time to time so I might have to splurge on a winter project. |
Author: | TCooper [ Fri Sep 10, 2021 10:21 am ] |
Post subject: | Re: Mk1 .25 project |
I remember back when Dennis Quackenbush was making the .25cal conversions for the Cr2240. I guess that would be a 2540. I met Dennis back in 2001 at an airgun show in Minneapolis area. Great guy. http://www.quackenbushairguns.com/2240.html http://www.quackenbushairguns.com/2240.html https://www.pyramydair.com/blog/2012/06 ... ol-part-2/ A .25cal Mark 1 is definitely a step up from the 2240 platform. I'm looking forward to reading about accuracy and any velocity tweak you do. Maybe you will find setting the pistol for slightly less power gives much more shots per powerlet. I bet it has quite a bit of muzzle flip! Tin cans beware! |
Author: | killercrow [ Fri Sep 10, 2021 1:47 pm ] |
Post subject: | Re: Mk1 .25 project |
Yes the quarter bore! I love my 25-06, the do all rifle from gophers to deer ( and debatable for elk). They do still come up for sale quite often. I usually have an eye on one somewhere, picked up some gems this year just on Kijiji and gunpost. Yes I remember Dennis Quackenbush, He was one of the guys who really knew co2 guns. Had some nice stuff going anyway. As for any velocity mods, the only thing that really needs to be done is to seal up the transfer port. I have an idea but it will be fiddly to get it right, and its not the oring on the valve port. I'll probably use delrin, countersink the barrel port to fit the delrin tubing, and maybe flatten the valve port. Use barrel set screw to add tension and voila. Might work. Gotta take it out and see how it shoots. The shot cycle does seem a little nicer at 450fps though, that's where it sits now. |
Author: | Leonardj [ Fri Sep 10, 2021 3:08 pm ] |
Post subject: | Re: Mk1 .25 project |
Nice job on the .25 cal. Mk I. This is a .30 cal. Mk I that I built about 35 years ago. It uses a tap loading system for breech loading. It has a 10" long barrel. The barrel is turned about 1/4 turn, allowing it to move forward, the lead ball is dropped into the loading port, and the barrel moved rearward and turned back 1/4 turn to seal the breech. Shooting at ~ 350 FPS. Attachment:
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Author: | killercrow [ Fri Sep 10, 2021 4:28 pm ] |
Post subject: | Re: Mk1 .25 project |
Wow that's nice! I get what you mean with loading, very innovative. I have not yet looked at a tap loading gun... Looks like its a shooter as well. So at 10" of barrel, is that measured from the crown to the frame, or to the preech? |
Author: | Leonardj [ Fri Sep 10, 2021 5:23 pm ] |
Post subject: | Re: Mk1 .25 project |
killercrow wrote: Wow that's nice! I get what you mean with loading, very innovative. I have not yet looked at a tap loading gun... Looks like its a shooter as well. So at 10" of barrel, is that measured from the crown to the frame, or to the preech? Thanks. That target was shot at 10 yards. The 10" is from breech to muzzle. |
Author: | killercrow [ Sun Sep 12, 2021 1:38 am ] |
Post subject: | Re: Mk1 .25 project |
Ok, it must be the tapered barrel. It just looks long. I like it though. Did you machine the shroud yourself or are you using a tapered shaft? Golf club shaft? |
Author: | Leonardj [ Sun Sep 12, 2021 3:43 pm ] |
Post subject: | Re: Mk1 .25 project |
killercrow wrote: Ok, it must be the tapered barrel. It just looks long. I like it though. Did you machine the shroud yourself or are you using a tapered shaft? Golf club shaft? Actually, the barrel isn't tapered. That is the OD of the .30 cal barrel, which has been painted gray. On another custom Mark I that I built, with a 12" barrel, the shroud is tapered. Machined using the offset tailstock method. Inserted a piece of heavy wall aluminum tube between the appropriately altered original shroud ends, and machined to suit. Attachment:
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