mk1 accuracy issue

[mauice]

Hi all members. i am a new member to this forum. I have a mk1 rapid 17/177 that I purchased new in 1998. I used it for about a year or so and since then it has been seldom used until recently. I have recently started target shooting at home, I have a target set up at 35 yards. I've tried a number of different pellets and JSB exact 4.53 and my old premiers gave the best results. Using a bipod and a cushion on a bench (ie my shooting skill is out of the equation) it is grouping into approx 25mm circle untill about the last 40 shots from a 200 bar fill then the accuracy is noticeably better, approx 9/10 into a one hole group ie 12mm circle, untill the pressure is down to approx 100 bar and then it needs a refill. Is this normal or does the old girl need a fettle. Its never been touched from new and is 100% original but is now 23 years old. Its in mint condition and has fired no more than about 2000 pellets. I would be very happy if I could get it grouping like the last 40 shots all the way through the bottle charge. It has a 400cc bottle so doing 150 or more shots/charge. Any advice greatly appreciated.

[Daveyb]

Mk 1 are unregulated as standard kevg does regs for them so the 1st shot to the pressure drops below the reg will be the same

[mauice]

I had thought that perhaps a regulator is the answer, I'm happy to spend a few quid to get this old girl shooting as accurately as possible. If KevG reads this post, could you contact me please.

[KevG]

you are filling to high.180 bar should be the max fill pressure.
KevG

[mauice]

Thanks for info Kev. I will fill to max 180 and see what happens. It seems to get more accurate when the pressure is down to 120-130 bar. I will get more information when the weather allows, I'm shooting outdoors so need little or no wind to check accuracy. Does fitting a regulator make the mk1 more accurate?

[KevG]

potentially yes.but say you had a bad barrel or some thing other not right fitting a reg would not cure it

[Kernal]

you are filling to high.180 bar should be the max fill pressure.
KevG

Na i could correct that,....If you have KevG make a reg for your mrk 1, It will change everythiing trust me i`ve been there...

My Mrk 1 couldn`t live without it`s KevG reg now,... best thing i ever fitted to my mrk 1 thats for sure.

[Kernal]

you are filling to high.180 bar should be the max fill pressure.
KevG

Na i could correct that,....If you have KevG make a reg for your mrk 1, It will change everythiing trust me i`ve been there...

My Mrk 1 couldn`t live without it`s KevG reg now,... best thing i ever fitted to my mrk 1 thats for sure.

It say`s something when i contacted custom stocks and told them to make me a stock that will fit the mrk 1 block but have a reg fitted so i needed a mrk 1 stock with a mrk 2 front end to make it fit the KevG reg,

As you can see in the picture`s i posted with my rapid mrk 1,

You`ll not go wrong with a KevG reg trust me on that,...i`ll put my stamp on it.

[Kernal]

Here is a picture of my gun with the KevG reg  & custom stock fitted and i`ve very happy to say thankyou to KevG & Custom Stocks very well done to the both of you guys,

[mauice]

Could I fit one of your regs myself or is it a job that you have to do yourself? I am from an engineering background ie fairly handy on the spanners.

[Kernal]

Well mauice,

I`m happy to say the KevG reg is easy to fit,...Just order one from him and fit it yourself,......It`s that easy,...just remove the air flow valve and replace it with a KevG reg and you`ll never look back,

[Kernal]

Well mauice,

I`m happy to say the KevG reg is easy to fit,...Just order one from him and fit it yourself,......It`s that easy,...just remove the air flow valve and replace it with a KevG reg and you`ll never look back,

Just a quick note my reg has been on my rapid for oh,....lets say maybe 5 or so years and its never mist a beat,...I`m sure KevG will verify this when he`s on next,.......

I will put my stamp on this to everyone that`s reading this now,....

KevG`s reg`s will change your shot count and out look on how a mrk 1 perform`s,...It`s changed my mrk 1 into something else,....i wont lie,....I`ll tell you it as it is,.......


Only a few or maybe a year ago i took the KevG reg off my mrk 1,...just to see how it get`s on and to try set it up and get a stable shot count throughout the fill,....and god was it hard to do,....

It kept going over 12 lbs,...

I know ppl will say reduce your pressure in your buddy bottle but i tried from 200 lbs to 180 lbs and 160 lbs and it always found a way to creep over the 12 lbs mark,

When i put the KevG reg back on everything just came back to normal again,... 11 lbs stable and happy was my mrk 1,....

Buying the reg from KevG was the best thing i ever did for my mrk 1,....

And i`ve never took it off since,... Now thats saying something!

[Daveyb]

My .20 rapid has a kevg reg fitted by me and is spot on, actually the only thing on my rifle that is still theoben made is the barrel, block and hammer, I'm going to be getting a seal kit from kevg and also the double hammer weight system too soon

[KCE]

Here is my MK1 with KevG internals.

Regards Kev.

[Squinty]

if I recall correctly the mk1 is supposed to be good for around 200 shots in 177?
23 years old, 2000 pellets... sounds like it needs a full service and proper set up before you consider fitting a regulator.

Accuracy ;  could be as simple as needing service to get everything running smoothly. Even a hint of grease on the hammer or a  knackered inertia spring could throw it out.
I'd say that if it shoots Premier/Accupel well- then 4.53 JSBs are definitely not the best choice for the barrel... try 4.50 4.51
Prems are typically 4.50 and a harder lead compound.
A heavier pellet but maybe try 4.51s....H&N Barracuda match /FT/ Bisley Magnum or even Premier heavy which I found much more consistent and accurate than the 7.9s.

Anyways; Kev's reg is straight swap besides a larger exhaust valve to facilitate the lower pressure air from the reg... and the gun wouldn't need modifications to the block so it will otherwise remain original.   

Echoing the praise of Kev's work I have a mk2 177 that I fitted with his reg, valve and a double tap inertia which is frugal if not downright miserly with air.