Do plastic sabots ever dry out?

[tpcollins]

I shot some old Knight bullet/sabots the other day that had to be at least 15 years old. I picked some spent sabots up and noticed they were distorted, missing petals, and didn't look like the nicely opened sabots I've normally seen. They were a bit oversized and seating them was really difficult.

I used to supervise I/P assy at Ford's and we used a plastic push-in peg to retain a rubber steering column ring. The peg was inserted into a hole, then smacked with a rawhide hammer to drive the pin into the lower retaining portion to lock it in. There were thousands in a plastic bag inside a box and over time they would "dry out" and would break off before being seated.

Whenever this occured, we'd pour a cup of water into the bag of pegs and let it sit overnight. After absorbing moisture overnight, they'd work perfectly the next day. I'm just wondering if the plastic sabots are succecptable to drying out and would be more pliable for loading if subjected to moisture?

 

[Semisane]

Now that's something I don't know TP. I've never noticed it. But then, I've never had sabots around long enough to get really old.

I guess you could take a dozen of your oldest sabots and weigh them on a powder scale. Then soak them for a day or two, dry them well, and weigh them again to see if they absorbed moisture.

 

[sabotloader]

tpcollins

I shot some old Knight bullet/sabots the other day that had to be at least 15 years old. I picked some spent sabots up and noticed they were distorted, missing petals, and didn't look like the nicely opened sabots I've normally seen. They were a bit oversized and seating them was really difficult.

Couple of things to remember... sabots that old were made of a completly different formulation of plastic - so they will not behave the way todays polymere sabots do. I would think they would very suseptible to the old plastic fouling stories you use to hear.

 

[Anonymous]

The polymers used for sabot manufacturing are not affected by moisture or humidity.

tpcollins........the plastic part you referred to in automotive assembly was probably nylon. Nylon is a hygroscopic polymer. It does absorb or lose moisture content dependant on the ambient conditions it is exposed to. Nylon must have a small percentage of moisture in it to exhibit or produce it's ideal properties. "Dried" nylon becomes essentially brittle.

There is a property of polyethylenes and propylenes, common sabot materials, that does effect sabots concerning cracking or petal loss ...... ESCR..."Environmental Stress Crack Resistance"

When I started making sabots back in the early 80's I went thru a steep learning curve ! The sabots I produced for the first few years honestly had poor ESCR. This property did not exhibit itself immediately after molding...it "surfaced" after the sabots were around 18 months old. Advancements in suitable polymers with superior ESCR cured this problem. I have kept production samples every year since 1985. Sabots produced before 1990 can exhibit poor ESCR properties.