Umarex No going back now!!

[madeintheuk]

So I decided I needed to be intimate with the workings of a pcp. After a few years I’m the sport, I’ve never had the balls to completely tear down, or modify beyond accessories any gun I’ve owned. Well that changed today. I’ve been unhappy with the notos I picked up and decided, with what they cost, why not tear it apart, and put some sweat equity into it to make it better.
Today was tear down day, as well as cutting off the factory moderator.

The crown doesn’t look terrible, but it is a little rough. I’m thinking between polishing up some happier and trigger parts, installing a mod adapter, swapping some orings that look questionable, and polishing the barrel and crown, I think this thing will turn into a decent shooter.

With that, I need some advice on polishing both barrel and crown. I’ve never done it before, and would like some advice moving forward.

Thanks!

 

[MongooseV8]

I hope you have a special parts drawer just for air guns. Thats where they go when they die lol.

 

[madeintheuk]

I hope you have a special parts drawer just for air guns. Thats where they go when they die lol.

This one is far from being dead. It’s extremely easy to work on.

 

[EmptyTin_Tim]

With that, I need some advice on polishing both barrel and crown. I’ve never done it before, and would like some advice moving forward.

Looks like my Notos is gonna be yours' twin this weekend! Got a Buck Rail LDC and that plenum kit to install. Chopping off OEM mod.

To your question: If you haven't done a crown or barrel polish before definitely read @nervoustrig 's article on the subject

Barrel troubleshooting and accurizing how-to - Airguns & Guns Forum

Barrel troubleshooting and accurizing how-to, Air guns, Airgun Forum

www.gatewaytoairguns.org

He is really knowledgeable and helped me with my Avenger crown that I messed up and I'd say for this definitely read a lot then go to work on it. Polishing can't really hurt it only improve but messing up the crown for sure can. When fixed, it was a huge improvement on my Avenger and I'm looking forward to seeing what it'll do to my Notos. Not sure I'll do crown (haven't seen mine yet) but got my new bore brushes for a polishing session!

 

[madeintheuk]

The crown doesn’t look terrible. Just feel like it needs polishing up with the barrel. I was going to try the brass screw and jb bore paste method I keep reading about.

 

[nobody1]

The crown doesn’t look terrible. Just feel like it needs polishing up with the barrel. I was going to try the brass screw and jb bore paste method I keep reading about.

I have 2 Notos and they are accurate with CPHP.
I did not even clean the barrel.

But I would also be polishing any crown for the first time.
Please, keep track of what you did since it may be helpful to the newer guys.

 

[EmptyTin_Tim]

The crown doesn’t look terrible. Just feel like it needs polishing up with the barrel. I was going to try the brass screw and jb bore paste method I keep reading about.

That's the exact method I'd recommend. For the crown some people (me too) use valve grinding compound for a bit quicker result I'm not sure how long you'll have to go at it with the JB. Someone else who used that for a crown will have to say. They do the JB for the polishing of the rifling.

 

[PumaCarl]

Congratulations! It's nice to not have to depend on someone else and never having to ship your gun out. The first thing that I do these days is my homework, I only buy what I am going to keep. Once in my possession I void the warranty pretty quickly. I kick myself for the 30 years where I would send my FWB124's out to be laser tuned every couple of years, what a joke. PCP's same thing, there's no magic going on with these guns. Get the right tools, get instruction or videos, and have at it. Nobody will care as much about your guns as you will.

 

[nervoustrig]

I’ve been unhappy with the notos I picked up

Unhappy with its accuracy in particular? I'm not caught up on what the problem or problems seem to be so please elaborate if it goes beyond an inability to print good groups.

For now I'll assume it is limited to accuracy since your questions are focused in on the barrel. To that end, we have sage advice from Tim above, plugging my troubleshooting guide But I just wanted to call particular attention to SPA's track record of using a piloted crowning tool and smearing the rifling near the muzzle so check for that first and foremost. Most everyone seems to be happy with their Notos so presumably they finally addressed that problem. I just know workmanship is something that requires diligence forever, and I've seen examples of trashed rifling from guns that were purchased years apart.

From what I can tell of the photo, the crown itself doesn't look too bad by SPA standards. But even the best of photos can only reveal so much. Pushing a few pellets through will tell the real story. With an unchoked barrel, the pellet should emerge from the muzzle with no more resistance than you feel pushing it through the bore. If you pick up anything at all that can be perceived as a hitch just as the head emerges, there's a burr that needs to be cleared.
Anyway, the point I wanted to make is don't waste your time trying to correct the crown if the rifling has been scored / smeared. That would need to be addressed first, either by replacing the barrel or by cutting it back to clean rifling. FWIW, the first one I ever fixed was prior to getting a lathe. The barrel was utter garbage so I figured what do I have to lose. It was tedious to fix with my improvised method but oh boy is it a shooter now.

A couple of previous threads on the topic if you're interested:

Login - Airguns & Guns Forum

Login, Air guns, Airgun Forum

www.gatewaytoairguns.org

Damaged rifling in SPA barrel (Mrodair Plinkster) - Airguns & Guns Forum

Damaged rifling in SPA barrel (Mrodair Plinkster), Air guns, Airgun Forum

www.gatewaytoairguns.org

If you have access to a lathe, taking the muzzle back to clean rifling is trivial, and then the crown can be formed using the brass screw technique. My experience with SPA barrels is the steel is pretty gummy and therefore prone to leaving a burr, so I cannot emphasize strongly enough to use a light touch for the last little bit of forming the bevel. The article speaks to this topic a little but if you have questions, fire away.

 

[madeintheuk]

Yeah, so there are currently 2 problems with it that I’m trying to address. First is accuracy from the barrel (I’m assuming), and second is the crappy trigger, which is also causing me to pull shots. I’m adding a standard moderator to the front, and I figured a good barrel polish and addressing the crown if anything wouldn’t make accuracy any worse.
My hopes is it helps make it less pellet picky, and maybe a little more accurate with the cheap crosman pellets.

I’m also planning to detune it to around 12-15fpe with the 14.3gn pellets. Not necessarily for accuracy, but it’s the plan to make it a low power setup with good shot count, and accurate out to about 35yds max.

 

[Vetmx]

I’ve probably crowned a hundred barrels on my lathe but I will say that if there is not an issue with a crown, I don’t touch it. A crowns bevel, if that’s what you prefer, doesn’t have to be all shiny to be good. We only get to hear the hero shade tree crowning stories on the internet. I would bet my truck that more guys screw up a crown than improve them. We just don’t see topics started about that. It’s embarrassing. Good luck with your project and remember, you can always remove material, you just can’t put it back. Go slow.

 

[madeintheuk]

I will inspect the crown and rifling at the end of the barrel, and decide whether or not I’ll Address it. I do still want to polish the barrel though. I would like to make sure burrs aren’t in it, and see if it improves its pickiness for pellets.
I remember a post the @Bigragu did about using a shoe lace with knots tied in it and jb bore paste to polish it up.
Any other recommendations for a total noob?

 

[Vetmx]

Guys always want to look at the muzzle or think they need to chrome plate the bore if they are having accuracy or picky issues. Take a real good look at the part of your barrel where it all begins. Inspect the transfer port hole for burrs. Inspect what they did after the transfer port. Does the rifling have sharp edges where it begins? Or did their reamer cut nice little ramps up onto the lands. If your leade/chamber (for firearm guys) is cut too deep, meaning your pellet isn’t seated deep enough with your probe, you can have flier or pickyness issues. If your leade is too deep, it’s one of those can’t put material back issues I spoke of. Barrel is to be placed in garbage can.

 

[Bigragu]

I will inspect the crown and rifling at the end of the barrel, and decide whether or not I’ll Address it. I do still want to polish the barrel though. I would like to make sure burrs aren’t in it, and see if it improves its pickiness for pellets.
I remember a post the @Bigragu did about using a shoe lace with knots tied in it and jb bore paste to polish it up.
Any other recommendations for a total noob?

Ha ha! That wasn’t me, sir.
If I can remove a barrel it’s always on a padded vice with a Dewey rod and mops running thru it. I do own a great pull thru kit from airtanksplus but very rarely do I use it on a barrel. Only in an emergency or if I can’t pull the barrel out(or just don’t want to, lol)

 

[nervoustrig]

Ha ha! That wasn’t me, sir.

Must say I’m relieved to hear that

 

[Scotty1]

I will inspect the crown and rifling at the end of the barrel, and decide whether or not I’ll Address it. I do still want to polish the barrel though. I would like to make sure burrs aren’t in it, and see if it improves its pickiness for pellets.
I remember a post the @Bigragu did about using a shoe lace with knots tied in it and jb bore paste to polish it up.
Any other recommendations for a total noob?

Sub 12 Airgunner has a video on this with an Fx liner.

 

[Firewalker]

Yes, the half dozen barrels I have removed the housings from had no rifling up to the barrel end and the "crown" was just a quick polishing of the barrel to round the end.

I have one still and I cut it back 1/2" to get good rifling and used my 11° .22LR crown tool (pilotless) to reshape the barrel end.

I'll do another tonight on a full conversion and will snap a pic of the barrel end to share.

 

[Bigragu]

Must say I’m relieved to hear that

Yup, no hack type work coming from me, lol.

 

[nervoustrig]

Yes, the half dozen barrels I have removed the housings from had no rifling up to the barrel end

Oh wow, that sounds like their crowning process is worse now than ever. A few years ago at least there was a decent chance the rifling would be undisturbed.

Which is a tacit admission from both Umarex and Diana that they don’t care enough about quality to fix this very basic workmanship issue that has been around for over 5 years. What a shame.

 

[madeintheuk]

@bugragu, no disrespect on your work. I apologize for misusing your name. I must have saw it somewhere else.