Any air gunners on here

[David A]

I have a strange random question and can't wait till the shop opens tomorrow to ask. I've a BSA Ultra multishot - very very lightly used (<400 pellets through it!) and around 10 years old from new.

It has a fully metal cartridge.
I get bored of stopping to refill the cartridge so bought a spare - a new style with the shot counter. Its part plastic, blue inside too.
They are the exact same size/dimensions

Zeroed at 25 yds the old cartridge hits bullseye shot after shot.

The new cartridge when fired is much much quieter but hits about 8inches below consistently, alternate cartridges/shots same result i.e. its not the air pressure in the gun.

Clearly bloody useless to swap in out as they fire differently but is this right - is there a problem somewhere? Help !

[Kawasicki]

Could it be that the pellet bore diameter in the plastic magazine is slightly undersized?

[David A]

Kawasicki said:

Could it be that the pellet bore diameter in the plastic magazine is slightly undersized?

Under or over? It does possibly maybe feel a little looser for the pellets. Ie not as tight a fit as the original metal one.

[pequod]

David A said:

Under or over? It does possibly maybe feel a little looser for the pellets. Ie not as tight a fit as the original metal one.

^^^ I suggest this is answer.

Seldom does a cheaper (ie plastic) alternative perform the same.

[David A]

pequod said:

David A said:

Under or over? It does possibly maybe feel a little looser for the pellets. Ie not as tight a fit as the original metal one.

^^^ I suggest this is answer.

Seldom does a cheaper (ie plastic) alternative perform the same.

Hmm it’s a bsa part I think. However air should not get to that part of the gun should it. Could it be the o ring on the loading probe




Probe pushed forward for photo

[LordFlathead]

pequod said:

David A said:

Under or over? It does possibly maybe feel a little looser for the pellets. Ie not as tight a fit as the original metal one.

^^^ I suggest this is answer.

Seldom does a cheaper (ie plastic) alternative perform the same.

^^This.

Most aftermarket mags are 3D printed and not of the same OEM quality. I bought 4 printed mags for my Steyr as it munches through rounds and they all shot differently! When I ran the mic through the holes they varied between 5.44 and 5.68mm! They all went back.

[Bill]

I can't see why the magazine would make a difference.

If you load a pellet then withdraw the probe to remove the magazine what happens when you shoot?

[David A]

Bill said:

I can't see why the magazine would make a difference.

If you load a pellet then withdraw the probe to remove the magazine what happens when you shoot?

New mag - load pellet, take out mag, re-insert probe, Seems to fire/aim as with original cartridge.

Back to the new mag and still a much quieter shot and shoots lower !

LordFlathead said:

pequod said:

David A said:

Under or over? It does possibly maybe feel a little looser for the pellets. Ie not as tight a fit as the original metal one.

^^^ I suggest this is answer.

Seldom does a cheaper (ie plastic) alternative perform the same.

^^This.

Most aftermarket mags are 3D printed and not of the same OEM quality. I bought 4 printed mags for my Steyr as it munches through rounds and they all shot differently! When I ran the mic through the holes they varied between 5.44 and 5.68mm! They all went back.

See the photo below - i thought I had bought a BSA original not an aftermarket.

Still don't understand how the mag should affect it - shouldn't the probe seal it off? Which makes me wonder is the new mag maybe pushing the probe up/down/sideways ?

Edited by David A on Thursday 11th May 18:35

[pequod]

David A said:

Bill said:

I can't see why the magazine would make a difference.

If you load a pellet then withdraw the probe to remove the magazine what happens when you shoot?

New mag - load pellet, take out mag, re-insert probe, Seems to fire/aim as with original cartridge.

Back to the new mag and still a much quieter shot and shoots lower !

LordFlathead said:

pequod said:

David A said:

Under or over? It does possibly maybe feel a little looser for the pellets. Ie not as tight a fit as the original metal one.

^^^ I suggest this is answer.

Seldom does a cheaper (ie plastic) alternative perform the same.

^^This.

Most aftermarket mags are 3D printed and not of the same OEM quality. I bought 4 printed mags for my Steyr as it munches through rounds and they all shot differently! When I ran the mic through the holes they varied between 5.44 and 5.68mm! They all went back.

See the photo below - i thought I had bought a BSA original not an aftermarket.

Still don't understand how the mag should affect it - shouldn't the probe seal it off? Which makes me wonder is the new mag maybe pushing the probe up/down/sideways ?

Edited by David A on Thursday 11th May 18:35

If it's a genuine mag supplied by BSA, then I suggest you send it back and request a replacement?

[Alpacaman]

Am I the only one that saw the thread title and thought this-

[Bill]

David A said:

Still don't understand how the mag should affect it - shouldn't the probe seal it off? Which makes me wonder is the new mag maybe pushing the probe up/down/sideways ?

Seems like it. Or distorting the o ring.

[Glosphil]

I have a Weihrauch WH100 & have 2 OEM magazines & 4 3rd party 3D printed mags. No difference in accuracy with any of the mags.

As the probe pushes the pellet out of the mag into the barrel I can't see how a mag can affect accuracy, unless it distorts the pellet.

[LordFlathead]

David A said:

See the photo below - i thought I had bought a BSA original not an aftermarket.

Still don't understand how the mag should affect it - shouldn't the probe seal it off? Which makes me wonder is the new mag maybe pushing the probe up/down/sideways ?

Certainly looks like a genuine BSA part (sorry I missed your picture reply before I replied). Doesn't mean its any good though!

If the pellet to bore ratio is too large a percentage of air bypasses the pellet around the outside. This means the skirt doesn't fully inflate to seal the pellet in the chamber. Failing that I would be looking at a defective O ring in around the regulator of discharge chamber.

[David A]

Just changed the pellet probe o ring as I had a spare service kit. No difference at all. Unless there is someother way for the air to bypass that
towards the mag.

Very very confused about this !

[pequod]

LordFlathead said:

Certainly looks like a genuine BSA part (sorry I missed your picture reply before I replied). Doesn't mean its any good though!

If the pellet to bore ratio is too large a percentage of air bypasses the pellet around the outside. This means the skirt doesn't fully inflate to seal the pellet in the chamber. Failing that I would be looking at a defective O ring in around the regulator of discharge chamber.

Whether or not genuine, only way to test is to try another mag, I would respectfully suggest?

[marksx]

Alpacaman said:

Am I the only one that saw the thread title and thought this-

Nope!

[David A]

pequod said:

LordFlathead said:

Certainly looks like a genuine BSA part (sorry I missed your picture reply before I replied). Doesn't mean its any good though!

If the pellet to bore ratio is too large a percentage of air bypasses the pellet around the outside. This means the skirt doesn't fully inflate to seal the pellet in the chamber. Failing that I would be looking at a defective O ring in around the regulator of discharge chamber.

Whether or not genuine, only way to test is to try another mag, I would respectfully suggest?

I will call the shop tomorrow, i guess it will either be the same result with a change of mag or different.

What is very curious is the sound difference - much much quieter with the new mag but the shot is lower at 25yds which I also don't understand.

[pequod]

David A said:

pequod said:

LordFlathead said:

Certainly looks like a genuine BSA part (sorry I missed your picture reply before I replied). Doesn't mean its any good though!

If the pellet to bore ratio is too large a percentage of air bypasses the pellet around the outside. This means the skirt doesn't fully inflate to seal the pellet in the chamber. Failing that I would be looking at a defective O ring in around the regulator of discharge chamber.

Whether or not genuine, only way to test is to try another mag, I would respectfully suggest?

I will call the shop tomorrow, i guess it will either be the same result with a change of mag or different.

What is very curious is the sound difference - much much quieter with the new mag but the shot is lower at 25yds which I also don't understand.

Would suggest to me the pellets aren't correctly sized and thus the projectile is leaving the barrel at a lower velocity and hence, shooting low?

Try another cartridge before considering a problem with your rifle.

[David A]

pequod said:

David A said:

pequod said:

LordFlathead said:

Certainly looks like a genuine BSA part (sorry I missed your picture reply before I replied). Doesn't mean its any good though!

If the pellet to bore ratio is too large a percentage of air bypasses the pellet around the outside. This means the skirt doesn't fully inflate to seal the pellet in the chamber. Failing that I would be looking at a defective O ring in around the regulator of discharge chamber.

Whether or not genuine, only way to test is to try another mag, I would respectfully suggest?

I will call the shop tomorrow, i guess it will either be the same result with a change of mag or different.

What is very curious is the sound difference - much much quieter with the new mag but the shot is lower at 25yds which I also don't understand.

Would suggest to me the pellets aren't correctly sized and thus the projectile is leaving the barrel at a lower velocity and hence, shooting low?

Try another cartridge before considering a problem with your rifle.

I’m comparing the original mag with one delivered today. Same tin of pellets.

[EdR]

Could it not be that one of the mags slightly compresses the tail of the pellet more than the other, making the aim (and sound, due to pressure) vary? One of my air pistols has a mag that squeezes the pellet enough that the pellet is slightly deformed once it has passed through the hole in the mag into the chamber, so could be related.