A friend of mine has an Evol 22 with a 15” barrel. He is shooting 25.4 MRDs and recently crono’d it for the first time. He is shooting about 750 FPS which seems rather slow to me. Can anyone tell me what a OEM tune would be using MRDs?
American Air Arms Evol 15” 22 OEM velocity specs?
- Thread starter igolfat8
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OEM tune would put the reg right around 1900 psi and power right about 30ish fpe so his gun seems to be shooting well.
You are not going to get the 25.4 MRDs much faster than 900 fps before the gun starts getting a not so enjoyable shot cycle. That will be with reg at around 2250 psi.
Mine actually did very well with the JTS 22grain pellets and that's a more mild tune and enjoyable shot cycle. Speed around 895-920. The JTS and AEA pellets really seem to like around 900 fps.
You are not going to get the 25.4 MRDs much faster than 900 fps before the gun starts getting a not so enjoyable shot cycle. That will be with reg at around 2250 psi.
Mine actually did very well with the JTS 22grain pellets and that's a more mild tune and enjoyable shot cycle. Speed around 895-920. The JTS and AEA pellets really seem to like around 900 fps.
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That's around 39 fpe so you will need to bump up the reg a bit. Prob around 2100 psi will get you there. If you think about it that's really not that bad. That's about a 145 bar reg setting with a 15" barrel which is pretty good.
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My 15 burps out MRDs at ~870 at the factory set reg setting. Looks like 1950 psi to my eyes.
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Just a little back ground on the gun. I bought the gun used from a guy here on the forum. Between the previous owner and myself, the gun he about 500 shots on it.
The gun was setup for the 25.4 MRD’s from the factory.
The gun shot great when I got it. The only thing I’ve done to the gun is change out the butt stock, clean the barrel and shoot it in my local indoor 50’ winter league. After a few matches I noticed that the accuracy started to fall off a bit. That when I decided to check the FPS with the Garmin. I was getting about 763 FPS with an ES of 20.
Now I wish I would have checked the FPS when I first got it. Lesson learned? Yep.
When I get home from work this week I’ll adjust on the hammer spring to get the FPS up to around the 900 mark.
The good thing is a can shoot 70 feet in my basement now that I just finished my bench and backstop.
The gun was setup for the 25.4 MRD’s from the factory.
The gun shot great when I got it. The only thing I’ve done to the gun is change out the butt stock, clean the barrel and shoot it in my local indoor 50’ winter league. After a few matches I noticed that the accuracy started to fall off a bit. That when I decided to check the FPS with the Garmin. I was getting about 763 FPS with an ES of 20.
Now I wish I would have checked the FPS when I first got it. Lesson learned? Yep.
When I get home from work this week I’ll adjust on the hammer spring to get the FPS up to around the 900 mark.
The good thing is a can shoot 70 feet in my basement now that I just finished my bench and backstop.
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Personally I'd check the hammer spring and see what it's shooting at max HS at that setting. From what I remember I thought 1900psi with my older one had a tune of 880fps with the 25.4gr. I dropped reg to 1600psi to shoot at 30fpe. The HS might have backed out?
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Took the gun apart after I got home from work tonight. The HS adjustment back way out. I screwed it in all the way and the it maxed out at 875 fps.
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Back off your HS 3% - 5% and shoot 5 shot groups from 830 - 850 and see if you find any groups that are significantly smaller than others?
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@Buckeye68 That is a large and unusual extreme spread for an Evol. Because you seem proficient at working on it, I'd suggest removing the hammer, spring, and poppet and especially the valve assembly and clean and polish everything. Reasom being, some of the blue colored springs will chip and those chips collect on the valve stem and then lodge in between the stem and the valve body's hole causing erratic shot cycles. An accumulated amount of dirt/debris on the valve stem will gall the aluminum onto the stainless stem and cause drag also.
On my Evol Magnon I bought used it had a erratic spread that was due to age and an accumulation of debris on the valve stem. After a complete disassembly I stripped all the paint from the spring, polished it, the hammer, the valve stem, and the valve body hole where the stem rides in, then installed fresh o-rings on the valve body and no lube on the valve stem or valve body hole so it will not collect dust or debris in the future. My extreme spread is usually within a couple fps.
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After reading your comment, I decided to pull the trigger and HS to check to see how dirty they were. Wow, dirty was an understatement. The spring had zero paint on it. I cleaned everything including the trigger and reassembled everything back together. I did order a complete o ring kit on Friday from AoA. Also, I checked the seal on the pellet pusher stem when I fired off a shot with a little piece of TP. When I fired off the shot, the TP blew off the stem. I ordered an extra o ring for it just to get me up and running for next Sunday’s indoor match. Tuning is a pain in the a$$ with all the adjustments inside the stock, but I ended up clamping the receiver down in my drill press vice so I can make HS adjustments without putting it in the stock. Thanks for all help from everyone!
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