Umarex Accuracy VS FPS consistency (Notos and Avenger)

Hello!

I have had an Air Venturi Avenger (Bullpup) for a while now, and have been reasonably happy with it (more below), but I recently purchased a Umarex Notos. It has some things I really like, but also seems to have an accuracy issue.

Notos - I love the size and weight. Additionally, the left cocking lever I find nice (I shoot lefty due to a left dominant eye). I'm impressed with the regulator, and am getting very good FPS consistency across the 21 or so shots. It is almost always +/- 1 or 2 FPS across the string (around 762 using CPHPs). The issue I am having is accuracy. Five shot groups at 25 yards are commonly 2" or more. I haven't done an exhaustive test of pellets, but multiple different types and manufacturers seem to more or less have the same issue. The best I have ever gotten is ~1" group, but with multiple on the 2.5-3" happen too. This is from bench rest (bags and a rear squeeze bag), with a 9x scope. I can pretty confidently say its not just me missing (I do fine with other pellet guns). Also, this is using the single pellet loading tray (because the magazine is surprisingly bad - I'll have to get aftermarket ones). It is also not just fliers causing the broad groups. Groups are usually shotgun pattern (e.g. near the center, 1" high and left, 1" low and right, 3/4" low left, etc.). I have reached out to Umarex customer support, but haven't heard back yet (probably understandable due to the weekend and time of year). I don't think I am being unreasonable expecting better groups at 25 yards (Umarex pellets are among the ones I tested, so they can't just blame the pellets :) ). Since the FPS are so consistent, does this suggest a barrel or crown issue? Did I get a lemon? (most people seem to rave about the accuracy)

Avenger Bullpup - As I mentioned, I am generally happy with my Avenger. I can't rave about it being a tack driver, but I've found a point where it is acceptable. I've settled on 2000psi on the regulator and two turns of the hammer spring for CPHP. This gives me around 925 FPS, and 10 shot groups at 25 yards that are generally touching (the CPHP sometimes give a flier, but most in a group). Not a "single ragged hole" that some people boast, but often a single large hole about the size of a quarter. I'd like it to be better, but I've settled for that using CPHPs (yes I could get better pellets, but I like getting them locally for cheap). I've tried other pellets, without really significant improvements (except for not having a random flier). I have been a bit disappointed with the regulator of the Avenger though. FPS have a much broader range that I expected. If I shoot a 10 shot group (3-5 sec between shots), the FPS at the best of times the spread is 10-15. It is nowhere as consistent in FPS as the Notos. Additionally, in between magazines (when there might be a few minute before shooting again), the FPS can jump as much as 40-50. This is noticeable in the regulator pressure, which can creep up slowly to a max is you wait longer between shots. Watching it carefully, sometimes is "resets" the pressure within a second or so, while other times it rises slowly and takes 10+ seconds to stabilize. By stabilize, I mean over a short time. If I wait a few minutes, it will very slowly creep up a bit more. With it set at 2000psi, if I wait overnight, the regulator will usually go up to 2300psi or so. Additionally, I get what I think is a reasonably significant drift as the cylinder pressure goes down. When set to 2000psi with the cylinder at 4300psi, if I shoot down to 2500psi, the regulator will only show 1500-1700 (not always consistent, but consistently lower than the 2000psi set). This means that while I get 100+ shots on the regulator, speeds averages slowly drop over the string. Overall spreads for even 80 shots can be as much as 70-80.

Hopefully Umarex can help with the accuracy issue I am seeing, because I really like the Notos otherwise. It just struck me as strange that it is so much more consistent in FPS than the Avenger but significantly worse in accuracy. If that can be fixed, I'll definitely be shooting it a lot. I have been spoiled by the Avengers 100+ shots though. 20-21 between fills is nowhere near enough. I'm going to have to get a reserve bottle to do refills, because 20 shots is not enough at a sitting...
 
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ok..I shortened my notos and I found two things in the process..or 3.. it didn't have a good crown so recrown helped a lot.. now it's also not choked but either way it shoots better than factory.. it's got a 4" moderator in the shroud so the barrel is actually 4" shorter,I wanted it for a pistol..
there's also a place already drilled and tapped for a second set screw but you have to drill a little hole in the picayinny rail so you can put a Allen wrench in to tighten it up.. makes the barrel much more secure.. I drilled the hole just big enough for the Allen wrench and got the screw in the threaded hole and then put the rail on that way it stays a small hole in the rail..
other issue was when I pulled the barrel it has two o rings and one was completely crumbled and missing parts.. the other one crumbled when I touched it.. I assume they were poor quality and deteriorating before I got it from pyramid air..
they are metric, the whole gun is metric.. but they are not a common size..
another member here, good guy.. firewalker ordered a batch of them and I was able to get some from him.. fits and better quality..
I was so frustrated trying to find the barrel o rings that I almost chucked the barrel back in the lathe and made standard o rings.but much easier just getting ones to fit from firewalker.. he does a lot of modifications on the notos and zelos..
I'll attach a couple pictures of the notos I did..
I never installed the stock, just open factory sights and pistol grip
Mark

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Like said above about cleaning the barrel and also check all screws and the barrel assembly screws, a friends got loose then tightened them up and voila, accuracy was spot on again!
I did clean the barrel after the first shooting session. The parches came out dirty, not horrible but dirtier than is should be for something the doesn't burn powder. The cleaning didn't do anything for the accuracy though. I didn't disassemble it or check any further. I'll check screws now.

While I was waiting for Umarex to respond, I decided to contact Pyramyd Air (where I bought it). I did a online chat with them and explained what I was seeing. Their response was an RMA, and did I want a replacement or a refund? I went with replacement since I really did like it other than the accuracy. Hopefully I get luckier on the second round.
ok..I shortened my notos and I found two things in the process..or 3.. it didn't have a good crown so recrown helped a lot.. now it's also not choked but either way it shoots better than factory.. it's got a 4" moderator in the shroud so the barrel is actually 4" shorter,I wanted it for a pistol..
there's also a place already drilled and tapped for a second set screw but you have to drill a little hole in the picayinny rail so you can put a Allen wrench in to tighten it up.. makes the barrel much more secure.. I drilled the hole just big enough for the Allen wrench and got the screw in the threaded hole and then put the rail on that way it stays a small hole in the rail..
other issue was when I pulled the barrel it has two o rings and one was completely crumbled and missing parts.. the other one crumbled when I touched it.. I assume they were poor quality and deteriorating before I got it from pyramid air..
they are metric, the whole gun is metric.. but they are not a common size..
another member here, good guy.. firewalker ordered a batch of them and I was able to get some from him.. fits and better quality..
I was so frustrated trying to find the barrel o rings that I almost chucked the barrel back in the lathe and made standard o rings.but much easier just getting ones to fit from firewalker.. he does a lot of modifications on the notos and zelos..
I'll attach a couple pictures of the notos I did..
I never installed the stock, just open factory sights and pistol grip
Mark

That looks pretty cool. Hopefully my next one is good, but I will probably use it as is at least through the warrantee period. After that, who knows :cool: I'm envious of your lathe. I'm moving about every three years for work (military), so getting heavy equipment (mill and lathe) is out until I am done. As soon as I am in a permanent place, I'm hoping to have a mill and lathe be among the first purchases.

Thank everyone for the replies!
 
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Complaining about accuracy while insisting on shooting CPHP is inconsistent. There is no airgun that won't shoot better with another pellet. Cheap pellets are just not going to be the most accurate. I am not arguing your first Notos was OK, just suggesting you need to seriously look at other pellets if you are serious about accuracy.
 
also make sure your scope is attached above the receiver.. the rest of the shroud over the barrel has too much flexibility..
and the o rings but that would likely show lower power and variation.. mine only had one barrel set screw and it was not even snug.. it's worth it to get a second set screw from the hardware store.. much more secure.. the barrel is actually what is supporting the entire shroud.. the shroud does little to nothing to support the barrel.
Mark