"Doug White" wrote in message
...
I am attempting to lighten the ejector & extractor springs in a couple of
AR-15 based target rifles. My wife and I shoot in a league in May, and
it's all standing (offhand), one shot at a time. I would prefer A) not
to bounce hot brass off adjacent competitors, and B) not have to hunt for
brass flung all over the place.

One guy on our team has gone so far as to remove his ejector completely.
He ends up having to fish hot brass out of his action, which I view as a
good way to cook your trigger finger.

I have about 6 different brands of extractor springs to compare. These
are a bit special, and are conical & have to fit properly. The ejector
spring is a simple straight compression spring. I measured one, and it
is 0.103" in diameter, and just under an inch long. It's is very stiff.

For the extractor, I was thinking of comparing their strength by stacking
two of them on an 2-56 screw with a washer in between. I can use a nut
to provide some arbitrary amount of compression, and then compare how
much each one compressed. This should give me some sort of relative
strength numbers. I'm mostly interested in finding the feeblest one, but
it would nice to be a bit more quantitative.

The big problem is the ejector spring. 0.103" appears to be an odd
diameter for a spring, and it only gets compressed about a 10th of an
inch, so shortening it doesn't do much. I really need to get a softer
spring. It's awfully long & skinny to try to wind my own. Assuming I
can find someplace that will sell me small quantities in the right
diameter, I need to specify a spring constant, i.e. pounds per inch.

Does anyone have any neat tricks for measuring spring constants, and/or
suggestions for comparing the strength of small springs? I'd also like
suggestions for spring vendors who sell small quantities. I've checked
McMaster Carr, and they don't have anything that small. Brownells has
0.088" diameter, and I'm a bit concerned that is small enough to kink in
the hole. Alternatively, how can I wind a spring that small?

Thanks!

Doug White

Hi Doug

It can be easy to measure spring constant with a weight measuring scale
and a distance measuring ruler. You could probably get good enough
accuracy of the "weight needed" to compress your springs some "given
distance" by placing the spring on a postage scale of the appropriate
sensitivity and push down on the spring . First, force the spring to move
some small distance and record a weight and a length reading. Then add
some force to compress the spring a little more. Those force and length
numbers provide all the data needed to identify "Pounds per Inch" of each
spring.

Jerry
..

Jerry