Air Gun Home :: View topic

Steve Cover · Member

Not being shy about exposing my lack of knowledge, I need to ask a couple of more basic questions.

My FWB 124 is being rebuilt.
The Airgunsmith, (Eddie) advised that my factory spring had a bend in it.
He suggested that I had been shooting pellets too heavy for the gun.

Question #1:
What weight range do I need to use in an 830 FPS/7.9 Gr Pellet airgun?

One of the pellets that I had intended to try out for hunting is the H&N Crowmagnum.
However, they weigh 8.80 Gr.

Question # 2:
In your opinion, is this pellet too heavy and would it damage my rifle?

Question # 3:
What is you opinion of the Crowmagnum pellet for hunting?
(Est velocity <800 FPS)

In my quest for a heavy hunting pellet for larger small game, I bought a tin of Crosman Ultra Magnum 10.5 Gr pellets.
Now, after hearing that I may have damaged my FWB 124 by shooting too heavy a pellet, I am concerned about this much weight.

Question # 4:
In your opinion, is this pellet too heavy for my rebuilt 124?

I got great answers to my last quandary, and have purchased some of the suggested pellets.
I'm just like I'm a kid rediscovering a new (OLD) toy.... I wish to maximize it's potential, but have no technical experience in this field.

Also, while I trust all the advice I got from airguncamo explicitly, I also am interested in the opinion of as many other experienced air gunners as possible.

Take care,

Steve

Alstone · Moderator & Site Supporter

You can use any pellet weight within reason 7.2g-11g should be no problem, I doubt that the pellet weight bent the spring, it could just be wear and tear as the FBW 124 has a longer and lighter spring than normal, also springs tend to bend on compression rather than expansion, you could have had bit of oil in the barrel at some time or other, and this had dieseled causing the bent spring.

Al

SMP · Silver Status Member

Steve

I personally think the idea of pellet weight breaking springs is simply legend and lore.
Example
If you were to tap and install a solid plug into the transfer port then cock and fire the gun. The spring would begin to accelerate the piston and almost as quickly it would begin to decelerate as the pressure in front of the piston increased. Eventually as the pressure in front of the piston was equal to the force behind the piston, the piston would come to a gentle stop on a cushion of air. As far as the spring and piston were concerned this would be the softest ride they ever had.

That scenario would replicate a pellet so heavy that the piston could not move it.

Next example

Remove the plug and fire the gun with a pellet so light its not even there.
This time the piston is going to accelerate for the entire length of the compression tube and come to an instant stop as it slams into the tube end. There will be a violent harmonic sent back through the piston and into the spring. Causing some form of damage to at least the face of the piston.

Therefore a heavier pellet will give a higher peak pressure on the air cushion which will slow the travel of the piston and spring before it comes to a stop.

The only time I could envision a heavy pellet causing damage is if the gun was dieseling badly and the heavy pellet caused a pressure spike which was large enough to reverse the travel of the piston. It can happen and in this case it is not the pellet but the deiseling which is doing the damage

Of course this is IMHO

sniper · Silver Status Member

@ #3, I run them through my crosman storm at exactly 800 fps
and are good at close range (under 20 yards) but at longer ranges lack the velocity for expansion and act like wadcutters.

A domed pellet 8-9 grains will be the "happy medium".

Steve Cover · Member

Thanks Guys,

When I first took my 124 out of storage, it dieseled for the first several shots.

Since it stopped after a few, I didn't worry much about it.
However, I too believe that was what bent my spring.
I just wanted some other person to suggest it as I am not well versed in spring airguns.

Steve