Marksman 1790 Ammo Issue

[7ECA]

Had a Marksman 1790 Series air rifle given to me years ago, and only recently began to play around with.

Came with a scope (which was thoroughly buggered; obviously not air rifle compatible) and a diopter-like rear sight made out of plastic. The rifle also came with a partial tin of Beeman Bearcub round nose .177/4.5mm pellets.

Noticed Princess Auto had a decent price on .177/4.5mm pellets recently, so bought a couple cans of them to play with. These are Grizzly brand flat head pellets.

The Marksman will not shoot these pellets at all, just pushes them an inch or so down the barrel. No issues removing the pellet from the barrel, and they chamber just fine. Any ideas what the issue may be? I'm not particularly familiar with air rifles, so if this is a common issue with the Marksman then it is what it is; just would like to know if there's an ammo out there that this thing will be happy with.

 

[OkayShooter]

I never had issues with the Grizzly brand pellets. I'm wondering if the seals are gone? You could find some 100% silicone oil and drop it into the chamber, see if that helps.

FYI princess auto has break barrel air rifles for under 40$.

 

[7ECA]

The seals appear fine, but I'll dab a little silicone grease on them and see if that makes any difference.

I did also find another old can of some sort of .177 calibre pellets; same result.

 

[OkayShooter]

The seals appear fine, but I'll dab a little silicone grease on them and see if that makes any difference.

I did also find another old can of some sort of .177 calibre pellets; same result.

If its doing it with multiple different pellets, than it is probably the seals, or maybe broken spring.

100% silicone doesn't diesel. So a couple drops down the transfer port, to lubricate the piston seal.

 

[7ECA]

If there was a seal issue, wouldn't that cause any/all pellets to fail to clear the barrel? Same for a busted spring...

I'll see about disassembly tonight, and see if there's any obvious issues and report back.

Oddly, I've got this other completely unmarked air rifle with a wood stock, spring that is many times stiffer than the Marksman with a partially missing seal around the chamber/breach; fires any pellet you can chamber.

 

[OkayShooter]

If there was a seal issue, wouldn't that cause any/all pellets to fail to clear the barrel? Same for a busted spring...

I'll see about disassembly tonight, and see if there's any obvious issues and report back.

Oddly, I've got this other completely unmarked air rifle with a wood stock, spring that is many times stiffer than the Marksman with a partially missing seal around the chamber/breach; fires any pellet you can chamber.

Yes, if the piston seal was toast, then it wouldn't compress enough air to propel the pellet down the barrel, due to air being able to blow by. Like in a engine, that the piston seals are gone, you are going to have low compression. Also if the spring was broken, it wouldn't push the piston fast enough.

If the breech seal is gone. The one that seals the barrel to the compression tube is gone, pellets will still fly, but you lose some FPS.

 

[7ECA]

What's interesting, is that with pellets that get stuck in the barrel; after firing as you just start to break the barrel/action you'll hear a little hiss of air being released. So there is a good seal; but either not enough of a seal or not enough force to fire the pellet.

Found a little bit of food safe silicone grease and smeared that on the breach seal, took a couple of tries and a couple applications of grease but it will now fire those Grizzly pellets.

I'm of the opinion that this Marksman is getting a bit tired, and may be in need of a new/stronger spring. Probably part and parcel of being a sub 500FPS air rifle. Having said that, it's not something I'll lose any sleep over or actually feel the need to tinker with. Sure it's fun to play around with from time to time, but it's not worth spending any money on - that and it appears there's no way to disassemble the bloody thing.

That other air rifle, I'm of the opinion is well into current "PAL required" territory; completely unmarked other than someones SIN.