Would be helpful to mention what ammo you are using.

 

CCI mini mag.

 

Wow, can’t do much better than that ammo-wise. I am as surprised as you are. All I can think is that indeed the buildup was in the very limited factory testing, but geez, that would have to be terrible ammo they use. No way the Mini Mags did that.

 

Ran two more applications of No-Lead and did inspection. Found some leftover buildup on the rifling.
This is what the whole bore looked like when I bought it new. Looked like pitting and a smooth bore.

 

The first picture looks like a carbon ring. Very common on 22lr's, just google search 22lr carbon ring.
The last picture looks like a manufacturing defect in the bore.

 

If its carbon, it doesn't react to the Wipe-Out like it does on my other firearms, the patch comes out clean. Swab some No-Lead in the bore and patch turns redish. When I first use the No-Lead, smoke came out the muzzle as there was so much lead buildup.

 

Dare I suggest using copper washed bullets?

 

OP has been using CCI Mini-Mag, which has a copper washed bullet.

RCA

 

OP has been using CCI Mini-Mag, which has a copper washed bullet.

Then where is the leading coming from? Is that copper or lead residue in the pics?

Never had an issue with copper washed rimfire bullets in any of my rimfires.

 

The bore was covered with the buildup when I bought it new with just looking down the bore (no bore scope at that time). So the buildup is from the factory, who knows what they used for testing but they must of shot a lot a rounds to get so much buildup.

 

@Fart22 I just sent you a PM right before I located this thread.

Oddly the PM was a question to you about this very phenomena; excessive fouling and carbon build-up in the Umarex MP5 22LR after very little use.

I find it strange that here we have not one but two HKPro members experiencing the same issue with the same model firearm. This is very concerning.
I was informed that if I use a "quality" ammo this could help to minimize fouling and carbon build-up in the barrel.

One of the ammo brands recommended to me was CCI, which it seems you used CCI, yet you experienced the same issue using CCI ammo. Not only that but you noticed the fouling and carbon build-up after very little use of the firearm.

I am beginning to wonder what is up with the Umarex MP5 22LR?
Something just does not seem right here.


On another note: What model Teslong borescope are you using? Thanks

 

I got the buildup all removed. When out and shoot 40 to 50 rounds of CCI and bore is spotless. This pic was after just pulling two dry patches through the bore after shooting. I can't find any trace of the buildup.

My other Umarex made Walther P22 is also spotless and my cycles flawlessly after a removing the factory buildup.
It would fail to cycle the next round before the down to bare bore cleaning.

I have the Teslong NTG150HW 26-inch Rigid Borescope with WiFi
Testlong Borescope
Its the WiFi version. I like that I can use it with my I phone. I would also like to be able to use it with my MacBook but you need the USB version. I tried to mirror the image to my Mac but the pic was degraded.

Moral of this post (so far) is: get a borescope and make sure if you get a Umarex product, clean the bore down to bare metal before shooting.

 

I got the buildup all removed. When out and shoot 40 to 50 rounds of CCI and bore is spotless. This pic was after just pulling two dry patches through the bore after shooting. I can't find any trace of the buildup.
View attachment 337269

My other Umarex made Walther P22 is also spotless and my cycles flawlessly after a removing the factory buildup.
It would fail to cycle the next round before the down to bare bore cleaning.

I have the Teslong NTG150HW 26-inch Rigid Borescope with WiFi
Testlong Borescope
Its the WiFi version. I like that I can use it with my I phone. I would also like to be able to use it with my MacBook but you need the USB version. I tried to mirror the image to my Mac but the pic was degraded.

Moral of this post (so far) is: get a borescope and make sure if you get a Umarex product, clean the bore down to bare metal before shooting.

I am very much intrigued by your bore scope. Watched the video on their website, also well done. Any downsides? Can you drop the images into your Apple Photos library? It seems like a real bargain to me. Went to Brownells to see what they offered and that was a brief visit after seeing $1k and up.

 

Just for compassion, I shot 100 round of the prone to leading the bore Remington Thunderbolt lead round nose 22lr through my Sig 522. There is no wax or copper wash on this bullet. Its just a hard lead bullet going 1255 f/s. Pulled two patches through and inspected with borescope and it was spotless.

 

I assume your SIG 522 is a radial delayed blowback?

The MP5 is a roller delayed blowback.

Wonder if one system has an advantage over the other as far as using the 22LR ammo?

 

@Fart22 Thanks for all of the info on the firearm and the borescope too.

You previously cycled the firearm with ~30 CCI rounds, discovered the build-up issue in the barrel, cleaned the barrel bore to bare metal, and have now again cycled ~40/50 CCI rounds with no additional fouling and/or carbon build-up.
Seems like an obvious factory related issue to me.
What the Hell substance did Umarex leave inside the barrel bores when the firearms left the factory?

 

The copper covering on copper washed .22lr bullets is just that, copper washing.
It is not copper jacketing.
A sufficiently rough bore could remove the copper washing as well as some lead.

RCA

 

The WIFI one is the only one that works with Iphone. It has a button you push on the WIFI device that captures the pic and movie i believe (have not tried it yet to confirm). I was told by Teslong that NTG100-Q2U adapter will make the NTG150NW work MacBook.

I have has some WIFI signal delays with Iphone 7. Doesn't happen all the time but is annoying. Would assume the hard wired version wouldn't have this problem.

 

This is the bore from a new unfired (except from the factory) HK 416 22lr pistol. There is buildup from the factory test rounds and to me its quite a bit. I am willing to bet that shooting more without cleaning it thoroughly would result in a bore looking like my MP5 where it was leaded up real bad.

 

Man, that's incredibly BAD! I'd be sending that thing back most ricky tick!

 

Do the MP5 22LR and the 416 22LR use basically the same internals? I read somewhere that they do and Umarex just built a new shell around each. I'm going to be picking up a 22LR but don't have the same tools/ability to inspect to you level of detail. :\

 

Not sure about the firing mechanism, but like most .22lr versions of military rifles (Smith and Wesson MP15 22, STG 44 22, etc.) it uses a version of the Atchison/Ciener bolt used in .22lr AR15/M16 conversion kits.


RCA

 

Happy to say that the G36 22lr has no buildup in the bore. This will be the first Walther 22lr I have owned that doesn’t have buildup in the breach area of the bore of the barrel from the factory. A quick look with the borescope shows only some grease in the breach section of the bore that needs to be removed before shooting.