Yesterday I took my cut down 2.57” spring out of my .177 Akela and swapped it into my .22 Cayden…. BTW, The entire spring fit INSIDE the Cayden - it sticks .5” OUT of the Akela - so there are differences between the two guns - it may be a .177 vs. .22 difference rather than an Akela vs. Cayden difference.
On my two 22 Akelas, a 2.5" spring fits inside the gun, with the adjuster, in full CCW, and no preload on the spring. I would not have suspected that kind of difference in the 177. I don't think it would be the breech, which would drive other part differences, and suspect the pocket depth on the hammer. On mine, I had measured 1.1" depth. What was the stock spring length of the Cayden? I thought the air tubes on the Cayden and Akela were the same (280cc), but if you could check the length, that would be great.
The tubes no my Akela and Cayden are both just a little longer than 16.75 inches. They appear to be the same size.
Quote from: rkrr20307@comcast.net on January 01, 2022, 05:11:17 PMThe tubes no my Akela and Cayden are both just a little longer than 16.75 inches. They appear to be the same size.Thx for confirming. If it was larger I might have pondered getting one for the 25 Akela. I am interested in what Ed finds. None of the parts on the schematic are indicated as unique to 177. even different hammers wouldn't make sense over just using a plug. And why more pre-load in the 177 with same spring?
With a Harbor Freight digital caliber the .25 spring is 4.17 inches or 106.11 mm. The .25 hammer is 2.1275 inches or 54mm long. The spring depth measured 1.169 inches or 29.69mm.The outside front and rear ridges on the hammer measured .626 inches or 15.9mm. Hope this helps.
Ed, Keep the info coming. Love it. JFYI: When using the hammer spring adjuster for pre-load, keep an eye on it. It tended to move during the shot cycles, especially with little or no pre-load. I used a drop of blue loctite, but vibra-tite should work, too.
Measurements: Depth of hammer spring chamber on .22 Cayden is 3.3” deep (I measured this carefully – multiple times)Depth of hammer spring chamber on .177 Akela is 2.25” deep (measured carefully – multiple times)
Ed, thanks for all of the work and posting your results trimming the Akela .177 springs.I decided to post here rather than posting another thread. A few of us are late to the game. I almost bought the .177 when Utah Airguns had them on sale in September but deferred. On Tuesday I decided to get one after all, as I need something to pest in or around barns possibly. I haven't received a shipping notification yet. When I do I will be trimming the spring. I tried to order a couple of extra's from Benjamin, but couldn't find them on their website. I left a message on their Customer Support page. Hopefully someone will notify me before they ship.Thanks again, Ken
Just thought I would share this with Crosman/Benjamin Akela owners… My .177 Akela is new, less than 300 pellets through it. I also have a .22 Cayden, I am very familiar with the “cliff” declining shot strings of these guns.My Akela was shooting hot – at ½ power on the Power Adjuster, it was shooting Crosman 10.5g at 968fps dropping quickly to 890fps at the end of 2 magazines (shot 28). For all the information that follows, my power adjuster knob is ALWAYS at ½ power (I never touch it during testing) and my hammer spring adjuster is ALWAYS backed all the way out. If I shortened the hammer spring on my Cayden 22 I would only get 500 fps on an fac full power gun my hammer spring is set at 6.5 turns in cow or 59% preload to get a Jsb hades 15.89 gr to shoot at 895 fps My Akela was way worse than my Cayden for air efficiency as it would drop from 3200psi (yes, I tried overfilling to 3200psi to help the shot string) to 2000 psi after just 40 shots (this is with the power adjuster set to ½ - it does not seem that lowering the power via the adjuster improves air efficiency, so the adjuster port must be AFTER the valve). Today I thought I would try shortening the hammer spring to improve the Akela’s shot string. I was BLOWN AWAY by the results!My stock hammer spring measured 3.5” (see photos). My first try I shortened it to 3 1/8” – I then ran a shot string of 40 shots. The result was still a declining shot string, but much improved. From a 3000psi fill (at ½ power on power adjuster) the 1st shot was 928fps and the 40th shot was 883fps. Air efficiency also improved as I still had 2200psi. So I took the hammer spring back out and shortened it again – this time to 2 7/8”. I then ran a 50 shot string (see photo of shot string for details). Shot 1 was 863fps and Shot #50 was 850fps. That’s 50 shots with a total spread of 13 fps!! The shot string was basically “flat” from shot #1 to shot #50 – very slight decline. So my Akela hammer spring is still not short enough to provide a “bell curve”, but I’m happy with 50+ good shots on a fill for now!! This “modification” requires a pin punch, wire snip, needle nose pliers and regular pliers. It is so simple and so quick to do. (1) Remove the stock (2) knock out pin – see photo – pin comes out easily (3) spring and adjuster will pop out of your gun – as I’m certain that your adjuster knob is ALWAYS under spring load – even when backed all the way out. (4) clip off a coil (say 1/2 inch) and pop it back in. (5) reinsert pin – line up the notch in the adjuster when putting the pin back in – you can push the pin back in with your hand – no tapping needed. The whole process takes less than 10 minutes – including putting the stock back on – if you have all the tools in front of you. After I cut the spring, I flattened the end. I don’t think this is absolutely necessary, but its easy to do. Grab the cut end of the spring with flat nosed regular pliers so that a bit of the cut end is visible. Use the needle nose to bend the cut end “down” so that it is flatter. It takes less than 2 minutes to grab the spring in a few spots and bend until it’s the flatness that you desire. If you have a file handy, you can take a few seconds to smooth the cut end of the spring as well. Note that I did my shortening of the hammer spring with the power adjuster knob at ½ power. I also used a “heavy” pellet (10.5g is a heavy .177) when measuring results. This gives you plenty of “headroom” to increase your velocity – so you don’t have to worry about cutting too much off the spring (I’d still suggest that you do no more than ½ inch at a time – then chrono the results). Reminder - my hammer spring adjuster is backed ALL THE WAY OUT for all of my testing. Before you knock the pin out, make sure that you unscrew the hammer spring adjuster all the way out (counter-clockwise is out). Even when I shortened the hammer spring from 3 1/2 to 2 7/8 inches, the spring still required me to compress it when putting it back in the gun. This shows HOW OVERSPRUNG these guns are. I removed 5/8 (.625) inches of hammer spring total and the shortened spring is still under some load – even with the hammer spring adjuster backed all the way out! I hope this info helps Akela/Cayden/Kratos owners. Finally, I don’t care about “voiding” the warranty. If you want to keep the warranty, order a couple hammer springs from Crosman and keep the original – and use the replacements to test different lengths.
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