Author Topic: Mapid Mod  (Read 1163 times)

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Offline Baggawind

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Mapid Mod
« on: September 11, 2017, 01:31:49 PM »
I,ve made the decision to go ahead and modify the Mapid. , Ive ordered a 500cc, regulated bottle and asked the supplier to reset the pressure for me. Hopefully then the main, working parts of the rifle will require less drastic modification. I,ve never been happy with the trigger , having made it in a hurry, just to get the rifle working. It will be a single stage unit, based on a Webley Vulcan design. I found an original Vulcan blade along with a set back Vulcan trigger I made back in ,82. It should work. I reckon I should get around 250 -300 shots when finished. Watch this space . ;)

Offline Gambo

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Re: Mapid Mod
« Reply #1 on: September 13, 2017, 10:55:16 AM »
Iza watchin bawz!

Offline Baggawind

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Re: Mapid Mod
« Reply #2 on: September 21, 2017, 02:04:11 PM »
Well, i,ve fitted the new, regulated bottle. Unfortunately, i,m not getting the power I was aiming for ( see what i did there? ). It started off producing only 6.5fpe before any alterations. I opened the TP screw , a-la Air Arms, and wound the hammer spring in and was still getting only 7.9fpe. So I opened up the TP to 3,1mm and took out the metering screw. Now it has settled at 9,3fpe. That,s around 700fps using Sniper mediums. I think i,ll leave it at that as, with a 26yard zero, it will still be shooting within 1/2inch between 12 and 30 yards. And at 35 it will still be doing 6fpe. Good enough for now. I think the problem is twofold. One, the plenum chamber is not big enough, it was designed to run from 190bar down to around 110bar. Two, the reg is set at 950psi or 65bar. I,ll try the rifle out as is first. If it does the job i,ll leave it alone. If I require more power say, 10fpe + I can shove a couple of shims inside the reg. Oh what fun  :)

Offline Gambo

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Re: Mapid Mod
« Reply #3 on: September 21, 2017, 07:57:47 PM »
Fun....but frustration fun I reckon!!

Offline seagate

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Re: Mapid Mod
« Reply #4 on: September 21, 2017, 11:26:31 PM »
Can you machine some out of the plenum chamber and up the reg pressure ?
I plink , therefore I am.

Offline Baggawind

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Re: Mapid Mod
« Reply #5 on: September 22, 2017, 10:16:43 AM »
Can you machine some out of the plenum chamber and up the reg pressure ?
I could but unfortunately, it would mean reducing the wall thickness and, therefore compromising safety. I,ll give it a try as is then play around with the reg.

Offline Baggawind

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Re: Mapid Mod
« Reply #6 on: September 26, 2017, 10:02:19 AM »
I took the Mapid out last night for a bit of ratting but before that I had a zeroing session with it. Zeroed at 26 yards it was still good at 30 and shot about a half inch low at 35. About the same as before the mods. And, it was putting pellet on pellet at those ranges, happy with that. By the time I packed up last night I had fired around 100 shots from a full charge and the gauge had moved around one third. So, as predicted , I should get 300 shots from one charge. Result  :)

Offline IceBlerk

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Re: Mapid Mod
« Reply #7 on: September 26, 2017, 11:30:03 AM »
That's impressive performance, Baggy!
..........so I packed up and went to the pub.

Offline Baggawind

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Re: Mapid Mod
« Reply #8 on: September 27, 2017, 11:01:26 AM »
I had a chat with my good mate Dave Welham of Airmasters yesterday. He reckons i,ll be lucky to get much more power from it , given the small plenum and the very long TP ( an inch ).  But, I have a cunning plan. As well as upping the reg pressure , i,ll try extending the plenum chamber. Should give me a bit more poke. And, the mod won,t be irreversible. I took it to show a mate and we put a few more shots through it , around 60 in all and the gauge is reading just below half full so it looks like 300 shot is a possibility. All good fun innit .

Offline Baggawind

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Re: Mapid Mod
« Reply #9 on: October 06, 2017, 02:24:23 PM »
I took a deep breath and pulled the " Mapid " apart this week. The aim was to increase the power up to 10fpe without doing too much in the way of machining and also to make a new trigger. Well, I completed the task this afternoon. I drilled out a plug in the front of the plenum and shortened the hammer stroke. The trigger is now much more predictable , at last. The power has settled at 9.9 fpe, close enough. I still have the option of extending the plenum or raising the reg pressure but probably wont need to as 725fps is plenty for ratting.