Another work In progress. :-) It is now mostly here!
I bought a second hand Daystate Harrier as I did not have a non electronic PCP airgun. I wanted to see what the difference was between this and my MK3. I was very lucky to find a late model Harrier (Before it was changed to the Harrier X with multi shot capability) for a very reasonable price and in my favourite .177 caliber.
What follows are my experiences with a full strip of the action and a few attempts to improve a few aspects of the guns performance. Most of these tips have been gleaned from the Official Daystate Owners Club Website along with a few other sources such as the AirGunForum and the AirgunBBS .
This article on AirGunForum on the Daystate Huntsman provided me with the necessary confidence to proceed. Also download the Harrier Manual to help you ID all of the parts.
Please be aware that this gun operates on high pressure air at over 2600 PSI. Even a partially charged gun has the potential to release a massive amount of potential energy if abused. The could injure or kill an unwary tinkerer. Before attempting any work such as shown in this text be sure you understand the risks this presents. I accept no liability for anyone following this article. You do so at your own risk.
Even though this gun is 4 years old it came to me in almost mint condition. I don't think it has even had the stock removed. All of the original grease was intact on the trigger and the only sign of use were a few marks on the stock from the installed bipod and a few tiny signs of corrosion on the side of the barrel. The marks on the wood will be dealt with when I refinish the stock. But lets move onto the action for now.
The first thing you should do is empty the gun of all compressed air. You should do this by firing the unloaded gun repeatedly in a safe manner. Fitting the silencer is a good idea if you are indoors. You will know the gun is empty when there is no air blast from the muzzle. Check this on a small piece of paper not by using your hand.
Stripping the action
1.) Remove the action from the stock with the single stock bolt.
2.) Remove the filler dust cap.
3.) Undo the two hex grub screws on the Silencer adaptor and slide it off the end of the barrel.
4.) Undo the three hex grub screws on the figure eight and slide this away from the barrel air cylinder.
5.) Undo the two socket head cap screws at the rear of the action above the bolt handle.
6.) Undo the two socket head cap screws at either side of the pellet loading point.
7.) the breech assembly with the bolt attached should now lift away from the top of the air cylinder. Be careful not to loose the brass transfer port and O-rings.
8.) Remove the bolt tension hex screw, spring and ball bearing on the LHS of the action (On the top on newer Harrier X and X2).
9.) To remove the bolt from the breech housing undo the hex bolt located on the bolt shaft. This may be loctited in place. Local heating with a heat gun will help remove it,
10.) I removed the cylinder end cap to inspect the inside of the cylinder for any corrosion or debris. This unscrews by hand, but you may need some rubber gloves to get a good purchase on it. If you are unsure what you are doing I would be very tempted to leave this step out.
11.) I left the other end of the cylinder with air valve alone as you need a special long socket to reach down the air tube to remove it. If it was causing problems then fabrication of a tool would be worthwhile. See the link above for more details on this,
12.) Remove the Safety catch with the single large screw on the rear of the cylinder. Be careful not not loose the ball bearing and spring.
13.) Remove the hammer spring retaining cap with the two small hex grub screws on either side of it. Make sure you hold onto it as you undo the screws, otherwise it will fly across the room and be lost forever.
14.) The hammer spring and anti bounce weight and smaller spring should now fall out of the rear of the action.
15.) To remove the hammer you must undo the single hex bolt that is visible in the slot in the top of the cylinder. You then need to lift the front trigger sear to allow the hammer to slide out past it. Or remove the trigger parts first as detailed below.
16.) Trigger removal. Just push each of the three visible pins out with a small hex key or similar. Be careful not to loose or mix up the small springs that are located on the various parts of the trigger. The trigger adjustment will not be affected by removing the parts. But if the sear is polished as detailed below then adjustment may be needed.
You should now have a Harrier in bits!
See below for tuning tips.
I will now detail what I did to the various bits to improve the performance a little.
All the parts were cleaned of all old grease and oil using some paper towels and a micro fibre cloth.
The bolt was greased with the dark gray molybdenum disulphide grease along with the bolt tension screw and spring. Don't use too much and make sure you don't get any grease forward of the loading port O-ring.
The hammer can be polished to improve the feel of the gun when it is cocked and the consistency of the shot to shot performance.
To do this you need some fine grade wet and dry paper (I used 1200 grade), fine wire wool and some metal polishing compound such as Autosol. The object of polishing is to remove any machining marks that are still visible on the sides if the hammer so it slides better in the cylinder. Start with the wet and dry paper. I found that by placing the wet and dry on a folded cloth it curved to the fit of the hammer better. Work along the length of the hammer in even strokes and keep rotating it to get an even finish. Then do the same with the fine wire wool. Finally use the Autosol or similar on a cloth to get a shiny finish. You can spend hours going for a mirror finish but just removing any machine marks is really all you need to do!
I suggest you don't touch any of the screws on the front of the hammer!
The hammer, anti bounce counterweight and springs were re-assembled without any lubrication as this can effect the power under different temperature conditions. Daystate use Lubro-Teknik if you prefer to use something to protect the metal parts. I used a Marine Tuf-Cloth to wipe around all the non metal to metal areas of the hammer and springs. This gives a highly corrosion resistant dry finish.
The same polishing techniques can be applied to the parts of the trigger. I just very lightly polish the sides of the trigger with 1200 grade wet and dry and Autosol. Use a sheet of glass as a base to keep everything flat. I also polished the one sear face to a mirror finish. This is the flat face on the front of the pointed flattened Z shaped piece.
I re-assembled the trigger with a teflon based grease.
Re-assemble the gun using the above list in reverse. I use a tiny amount of Divers silicone regulator grease on all of the O-rings. Just to ensure they have a good seal. Do not use silicone grease or oil on any other areas of the gun as it is not designed for metal to metal contact. Don't put any grease or oil on the transfer port or pellet probe. This will effect the accuracy and possibly damage the mechanism as the oil diesels with high pressure air.
Time for a new stock. ;-)
The Beech stock the rifle came with was very nice but when I stripped it back to the wood there were still dye marks left in the grain. I oiled it to give a functional finish but I am very tempted to spray it black in the style of the synthetic stocks.
But I had my eye out for a Walnut stock for sensible money and this old Huntsman stock came along. I did not realise it at the time of purchase but it had been modified to take the action from a different gun, like an Air Arms A400. So the part that supports the trigger guard was missing. :-( Also the wood had been cut to take a longer action. The original rubber butt pad was looking a little shabby and the white plastic spacer was cracked. But I wanted a project gun and this has turned into one.
The woodwork was in pretty good overall condition. But the perfectionist in me wanted it to be better. So it got the full treatment that have done to other Walnut stocks more details of which are given here. There are still a few tiny dints that refused to iron out, But you have to look hard to spot them.
The trigger guard needed to be put back. I thought I might be able to glue some wooden blocks back into the stock. As I have a big box of various wood for my model making I found some hardwood strips and set about them with a saw and drill. They fitted into the stock with a slight push fit. I mixed up the 30min epoxy and fixed them in place. From the outside the trigger guard now looks perfect.
There was a bit of a gap behind the action where the stock has extra inletting. I thought I had better put something in to stop any movement when the gun is cocked. So another block of hardwood was added. This really could do with some walnut adding to the top of it to blend in a little more. I need to go and find some walnut.
The rubber butt pad needed replacing and I got a new one from Daystate for a very reasonable £6. They are oversize and need shaping to fit. You really want a belt sander to make this an easy job. I don't own one and had to make do with a Permagrit sanding block. This is hard work by hand and it took me several sessions to remove the required amount of material. I did chop some of it away with a sharp knife. All the effort is worth it though. It is a little off centre though as the original holes were wonky. I did not want to drill new ones as it was a bit too near the existing ones for comfort.
Hopefully this article has given you a bit of useful information. The Harrier has certainly given me a few hours of entertainment. It now looks even better in the Walnut stock and I look forward to shooting a few HFT round with it over the next few weeks. When I get chance I will try and do a chronograph string to post with this info as well.
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