So you want a .177 Cayden…

So you want a .177 Cayden… and they only come in .22…
I recently bought this Reximex Daystar .177 from an AGN member via the classifieds here. It is essentially a Benjamin Cayden .177 – with a nicer shaped stock than a Cayden, IMHO.

It was bought for his wife, owned briefly and sold to me – she wanted a 12 ft/lb rifle.
I can see why she didn’t like the Daystar out-of-the-box…

…I cleaned the barrel filled to 250 bar and took 28 shots (2 magazines). It was shooting 10.5g pellets at 1,025 fps (with the “power adjuster” – transfer port restrictor on full open). It went from 250 to 190 bar on those 28 shots – so it was using a massive 31psi per shot – for 10.5g .177 !

Needless to say, with the hammer hitting the valve that hard it was loud and felt “loud”. It also had an “elephant” 2.2 pound trigger pull weight !! Turning down the “power adjuster” would reduce velocity – but not improve efficiency or loudness, as the hammer was still pounding the valve hard with each shot…

I have extensive experience with tuning these rifles, so I took off the stock (one bolt) and checked – sure enough the hammer spring adjustment screw was backed all the way out – and the rifle was still shooting WAY to fast. It was obviously oversprung – just like the Benjamin Akela / Cayden / Kratos are. I guess it’s Kral’s concession to marketing to put these oversize hammer springs in their rifles – so they can advertise “big power”.

I knocked out the pin, popping out the adjuster and hammer spring. The spring measured 3.1”. At least it was shorter than the crazy 3.5” long spring that comes in the .177 Akela. As you can see in the pictures, the spring is identical in diameter and wire thickness to the Benjamin springs – not surprising as they all come from the same factory (made by Kral).

I was on my lunch hour, so popped in a 2.7” spring that I had cut down for my Cayden (I’m currently using a custom spring I made in my Cayden). I would have used a 2.57” spring – as I know that is about optimal for .177 in these rifles – but I didn’t have one handy – and I wanted to do a quick trigger job during lunch. Eventually I will put in a 2.57” spring.

As the pictures show, the trigger is identical to the Cayden / Akela / Kratos. It’s a very nice trigger, once you polish up the contact points and adjust the sear engagement. This Reximex Daystar was finished a bit nicer on the trigger than the Benjamin rifles, as a couple of the components didn’t have the black stuff on them – they at least were semi shiny steel. I used my Dremmel to get rid of all the black coating and polish up the key contact areas to 3000 grit (mirror like).

After the polish, I was able to adjust the trigger pull weight down to about 15 ounces – turning in the adjustment screw until it wouldn’t cock and then slightly backing it off till it cocked. I like 6 ounces – so I cut ½ a coil from the end of the “1st stage” spring by the trigger and 1/3 coils (just a tiny bit) from the 2nd stage spring. Amazing difference – I was able to get down to a consistent 2.8 ounces (!) – and still pass the bump test ! I backed to off to about 4.8 ounces. Done for a quick first “trigger tune”. Everything took 1 hour. (I may go back to the 2.8 ounces – it felt freakin’ awesome).

After work I shot 7 ten shot groups – filling to just 205bar and shooting down to 125 bar. That’s 70 shots using 80bar – this equates to 16.5 psi per shot. So by cutting the spring from 3.1” to 2.7”, the efficiency improved from 31 psi per shot to 16.5 psi per shot – roughly double the efficiency with that quick change. I know from experience that using a 2.57” spring with .177 in these rifles will give an efficiency of about 11.5 psi per shot (shooting 10.3g pellets at 890fps).

Note that the 1st 65 shots had a 13 fps spread !! The rifle’s sound volume was MUCH quieter – as it was using ½ the air per shot now.

Also, I will try filling above the 205bar that I used for the shot string (max fill is 250 bar !) – I may be able to get 90+ shots with a less than 20fps spread – with the 2.7” spring (and well over 100 shots with the proper 2.57” spring).

As you can see, the 10-shot groups were all under a dime (one flyer). Groups 6 and 7 were getting tighter as the velocity dropped into the lower 890s. Next groups I’ll try shooting 870 fps – and see if the groups get tighter.

Finally, check out the tiger stripes on the Turkish walnut stock. I’ll strip the factory finish off and then hand rub in an oil finish with Tru-Oil – and this thing will look incredible !!

These rifles are super simple to work on, cost under $500 on sale and are very reliable (due to their simple design). Being unregulated, you still get an awesome flat shot string (even this quick tune got me 65 shots with a 13 fps spread) – better than many/most sub $500 rifles WITH regulators. These Krals have excellent valving and great triggers (once you polish them up). The power adjuster on this Daystar has detents and works very nicely. The barrels are accurate. I’d highly recommend these rifles to anyone getting into PCPs or for a reliable hunting rifle.

I use them for target shooting – I’ve scored 198 with the Cayden and 192 with the Akela in the “30 Yard Challenge” on AGN damn good accuracy.

I shot my 1st 30 Yard Challenge card with the Daystar tonight after work - using just a 14x scope… 189 8X … not bad since I’ve got less than 150 shots on the rifle.

-Ed

Trigger close up.jpeg


Daystar stock spring length.jpeg


Knock out Pin.jpeg


Air Use Improvement.jpeg


Beautiful stock.jpeg


HS Adjuster.jpeg


Dremmel.jpeg


Swapped in 2_7 inch spring.jpeg


Cleaned barrel.jpeg


Daystar Shot String - 2.7 inch HS.jpeg


Initial Groups.jpeg


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Some more data on the Reximex Daystar .177 (same rifle as Benjamin Akela, Cayden and Kratos)…

Shot a 105 shot string with FX 10.3g. I was actually target shooting as I did the string - so it took a few hours and the outdoor temperature dropped quite a bit… but the shot string still looks nice and steady.

Filled to 225 bar this time and shot down to 105bar. Still using the stock hammer spring cut down to 2.7”.

Hammer spring adjuster 3 turns in.
Spread was 24fps over 74 shots
Spread was 30fps over 90 shots
Spread was 35fps over 100 shots

Not bad for a 5 minute spring tune, lol.

You can see that its now shooting 1/4” groups at 30 yards since I dropped velocity slightly into 870-880 range.

Last night I tore down rifle and will do my “total polish”, hammer, hammer guide screw, inside the hammer, the hammer spring itself, the cocking bolt, inside the breech where the cocking bolt slides… you get the picture. I’ll also hyper polish the trigger. A couple hours work and it will be smoother than many/most $1,500 rifles.

I’m also gonna pop in a 2.45” hammer spring - my initial testing in an Akela with this very short length was promising- may be better than the “famous” 2.57” length for .177, lol.

Hopefully, this post thread shows you how easy it is to polish up these Reximex/Benjamin rifles - and that you can achieve awesome levels of performance at a reasonable price point.

The rifles are simple and they have awesome accuracy, consistency and reliability without requiring the complexity of regulators.

-Ed

Daystar 105 Shot String.jpeg


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I thought I’d update this thread on my ongoing tuning efforts with the .177 Reximex Daystar. As previously discussed, it is almost identical mechanically to a Benjamin Cayden. I have a Cayden and have taken it apart and polished up everything, so I know.

I recently reduced the hammer spring length from 2.7” to 2.65” - and very recently to 2.60”.

I filled to 205 bar (max is 250 bar) and took 7 zero shots (4 and 3 shot groups). I then shot four “30 Yard Challenge” cards over the past two days. Pellet was FX 10.3g.

There were 4 sighter shots between cards - so a total of 115 shots. Finished at 107 bar. Shot 116 Chronoed at 840fps.

I did NOT hold over or under across the 96 shots on these 30 Yard Challenge cards! I did hold side to side as it was breezy- especially today.

I shot a 193 (lowest score card) on the 4th card - with a significant breeze - and hit 15 Xs !! High card was 196.

That’s 116 FLAT shots (shooting precision targets) at 30 yards across 2 days with a $500 price range UNREGULATED TUBE rifle ! Yep, no bs here - you are looking at 103 of the shots in the pictures.

These rifles are amazing once you polish them up and tune the hammer spring length!

You do NOT need a $1,500+ regulated rifle to precision target shoot in your yard.

Hope this helps those looking at “mid price” range PCP rifles. Always happy to answer questions.

-Ed

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Not sure why only the Akela is offered in .177 by Benjamin.

I believe that Reximex is the parent company in Turkey and they produce similar rifles under a number of different brand names.

The Benjamin Cayden is extremely similar to the Reximex Daystar and the Kuzey K600. The K600 is sold on thebestairgun.com website.

If you want my opinion, I think the level of finish is a bit better on the Reximex Daystar and the Kuzey K600 vs the Benjamin Craftsman series rifles. As an example, the “power adjuster” on the K600 and Daystar have detents - so they are repeatable - versus the adjuster on the Cayden/Akela/Kratos that lacks any detents. I also found the Daystars trigger in a higher state of finish (as delivered) vs. my Cayden and Akela.

I’ve got the .177 Daystar really nicely tuned now. Just shot this 30 Yard Challenge card moments ago - 1st card of the day. Two warm up shots and then 195 11X … nice.

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EPG, is there a recommended spring length for the Cayden in .22?
Yes, 2.8” is optimal for Cayden .22 if you plan to shoot 18g pellets. This 2.8” length will easily let you get over 900fps with 18g, if you desire to shoot that fast (should stay at 880fps or less for optimal accuracy- but some people like to shoot higher anyway).

You can really optimize efficiency if you always use a lighter weight pellet. For example, if you always use 15.89g pellets, then I would recommend 2.65” for spring length in .22 Cayden. Then you would have at even longer, flatter shot string.

You can go as short as 2.55 to 2.60” if you only shoot lightweight Crosman 14.3g pellets for example.

If you shoot a variety of pellet weights (18g, 16g, 14g) the best way to set up your Cayden is 2.8” hammer spring. Have the power adjuster ( it’s actually a transfer port size restrictor) full open. To get 18g pellets to 880fps will be about 3.5 turns in on the hammer spring adjuster screw. Once set for 18g, you can use the power adjuster to turn DOWN the velocity when you shoot lighter (15.89 or 14.3) pellets - without having to take the rifle back out of the stock to adjust hammer spring tension.

Finally, when cutting the spring, cut it slightly longer than your desired length (about .1” longer) as it will get shorter when you flatten the end of the spring using two pairs of needle nose pliers.

Here are some sample shot strings with my Cayden using a stock 3.5” spring cut to 2.8” - using 16g H&N pellets. Its a 5 minute job and your Cayden will improve 200-300% in efficiency. Also, accuracy will be much improved as you will have very consistent velocity shot-to-shot.

-Ed

Cayden with 15g H&N shot strings.jpeg
 
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Ed, really appreciate it! When reducing spring length, I had thought to cut it a wee bit longer with wire cutters, then flatten with a bench grinder.

The “pro” way to flatten the end of a spring is to heat the end coil until it is red - using a hand held butane torch (Dremmel has one for $50 that I have, but there are $30 ones on Amazon).

Once red, you simply press down on the spring end - I use a granite countertop or glass stovetop. In truth I have not gotten significantly flatter ends this way vs. using 2 pairs of pliers and bending, lol.

I also polish the outside of the spring, as it slides inside the hammer and you want that movement to be as smooth and repeatable as possible shot to shot. Hell, I polish the outside of the hammer, inside the hammer, the spring - everything, lol - but its not necessary to make your Cayden “optimzed” - just cut the spring to 2.8” and go from there.

The 3.5” stock spring length is way too long. You will have a steadily declining velocity on your shot string with about a 50fps drop once you get to about 28 shots. Even with the hammer spring adjuster backed all the way out flush. They are just way oversprung from the factory- unfortunately.
 
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This is an excellent thread. I thought I might add that while the Akela does not have detents on the power adjuster, it does have reference marks which can be used to set repeatable settings, such as the situation you described where you use a 2.8 in spring, turn in the hammer adjuster 3.5 turns for 18 grain pellets, then use the power adjuster to shoot lighter pellets at the desired fps. Without detents, the power adjuster theoretically has an infinite number of power settings, which can be repeatably set visually rather than by detent.

Also, I would appreciate some photos demonstrating how you use needle nose pliers to flatten the spring end.