Airgunsmith O-ring Chart


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O-Ring Information & Duro-meter Hardness

This is an example of hardness as the quality and hardness will very from one manufacture to another according to the compounds used

Shore 00 20   30 35 40   50 55 60   70   80      90



Shore A               10 20   30




  60 70





Shore D                                 19 22 29









        Medium Hard            


Rubber band:  35 Shore  A         Rubber tire:  55 Shore A          Rubber shoe heel:  70 Shore A             Tool Box Wheel:  95 Shore A

Buna-N (Nitrile/NBR)
Abrasion Resistance Good 
resistance Fair
Temperature range:  -30 F to +230 F*

Synthetic Lube Resistance good
Compression Set
resistance Fair
One of the most common seals in airguns
Black in Color
The higher/Harder 70-90 duro,
compression set is affected
I have successfully used Buna-N in sub zero temperatures 70 duro holding up better then the 90
Viton (Fluorocarbon)
Compression set low.
Temperature range:  -20 F to +400 F*


Viton ETP (Viton Extreme)
Excellent chemical resistance vs. standard Viton
Other properties
similar to
standard Viton.
Basic temperature range: -5 F to +400 F*


Compression set resistance Good
Poor tear and abrasion
resistance strength.
Poor resistance to oils.
Temperature range:  -65 F to +400 F*


Not much use for this ring in airguns
Red In Color
EPDM / EPR (Ethylene Propylene)
Compression set resistance  Good
Abrasion resistance Good

Temperature range:  -65 F to +250 F*
Excellent temperature range.:  -250 F to +450 F*
Various chemical and fuel resistance.
Low coefficient of friction.
Excellent tear and abrasion strength
Compression Set is Fair
White in Color
Good for CO2 wet or dry
Some are replacing this ring with  Buna-N 90
Neoprene (Chloroprene)
Good resistance to petroleum oils.
Low compression set and good abrasion strength..
Temperature range:  -40 F to +225 F*
Urethane (polyurethane)
Excellent wear/abrasion resistance.
Tearing resistance Good

compression set & chemical resistance.
Basic temperature range:  -20 F to +180 F*


Do not require Back-Up Rings.  Excellent Wear & Tear Resistance,
1000 to 3000 Pounds Max PSI Depending on Rating 00-70/00-90
Halocarbon Compatible
Silica Thickened
*Polymer Thickened alkali, hydrofluoric and fluorinating agent SAFE
PTFE Thickened
Ethylene  Propylene rubber Polymides Polyvinyl alcohol
Polycarbonates Neoprene Flurosilicones Teflon plastics
Cured epoxies Rigid PVC Urethanes Rigid CPVC
EPDM Viton plastics    

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