Don't I wish I were that young to be called son.
What is the typical air pressure a IR121 gun is used with ?
I start it up against work, but it goes through the work and
continues to be moved to the side for more work. So it isn't
Always on work. And can't be.
My concern was if I was over pressuring it and thus the hammer
was throwing the chisel to hard and it beat up the spring.
Regarding the heat - process wasn't completed - never annealed ?
If not crystalline like it might be soft metal.
The new ones are stronger steel. The screw on was the same pitch, but
it took more force to thread it on as it also spread the spring.
The previous spare part was in a poly bag - likely bulk supply.
Now the new ones - same part number - come in poly/cardboard - MADE IN USA
with the plant name and state.
I suspect these will last. I suspect the previous two (gun 1st) and optional
spare - were from China and not to spec.
Those are screwed on chisel retainers. I assume you mean by getting away
from me is pounding air with it.
Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/
Larry Jaques wrote:
On Sat, 23 Feb 2008 20:14:33 -0600, with neither quill nor qualm,
"Martin H. Eastburn" quickly quoth:
Ok - here goes.
Own one - like it - good gun.
I broke two springs in one day. The spring looks like it broke
from a shear impact.
You need to learn better gun control, son. Even if you switched to a
solid, screw-on chisel retainer, you'd end up splitting the end of the
housing if you let the chisel get away from you that often.
HINT: Don't push the chisel against the piston and pull the trigger
without something against the chisel tip. 
I now have 4 new ones on the shelf and noticed a change in supplier.
What is the typical pressure used in these ?
"Huh?" he queried, with a dumb look.
I took the idea on the springs - that they might not be tempered or
treated post winding or post heat treatment.
If they weren't heat treated, they probably would be unwinding and
bending out of shape, not breaking cleanly.
---
Every moment is a golden one
for him who has the vision to recognize it as such.
-- Henry Miller