another test gas check vs no gas check

[jsam]

2-1-2014

I did another test today to see the effect of using gas checks vs no gas checks. Once again I used a Ruger #1 in 30-30.

Range conditions 23 degrees overcast 5-10 mph wind from the NW.

As is most always the case, after the testing I have more questions and dont pretend to have any answers as to why things are as they are.

Lee FP weighing 178 grains (weight before lube and gas check ) with gas check sized .3095 carnuba red lube.
9.2 grains Herco
CCI 200 primer

4 5 shot groups at 100 yards averaged 1.4 inches ( best group 1 inch )

average velocity 1225
es 52
sd 12

Lee FP unsized LLA no gas check
9.2 grains Herco
CCi 200 primer

4 5 shot groups at 100 yards averaged 2.5 inches. ( best group 2.1 inches )
average velocity 1268
es 51
sd 12

I had never chronographed gas checks vs no gas checks before this week. While the sample size is so small no conclusions can be arrived at,

but, so far the sized bullets with gas checks and conventional lube are slower than the unsized bullets with no gas checks and LLA. The question

that I have is is it the difference in lube, difference in sizing, or perhaps just an anomloly?

The Lee FP 178 grain bullets averaged 43 fps slower sized with gas checks lubed with carnuba red vs unsized lubed with LLA.

With 150 grain saeco 316 the difference in average velocity recorded for 20 shots was 81 fps less for sized with gas checks carnuba red lube vs
unsized lubed with LLA.


The standard deviation and extreme spread for the Lee FP are almost exactly the same only the average velocity is different. The previous test with Saeco 316 the sd and es were close but not as close as the Lee bullet test done today.

[Hondo 60]

Very interesting, very interesting indeed - spoken in a mock German accent - lol

But seriously, I'd be interested in more results so that the sample size CAN give results.

[dverna]

20 shots each is enough to be statistically significant. You will learn very little by changing more than one variable at a time.

You had:
GC - no GC
Sized - Unsized
CR - LLA

Don Verna

[cwheel]

Just a guess here, but I don't think much of a difference will show until you push them up to 1800 or more. Think the major point of the gas check is to get a little more speed without leading, cleaner shot. Sure you can mess with the alloy or the lube, but I don't think it will prove anything until you get some speed, use the same alloy and lube. As always, I can be full of it. Larry Gibson seams to be the expert in this area, he has done lots of good work with 30:30 and others.
Chris

[dhain]

This is good stuff. I've read too many things, even by guys who write in gun magazines, that sum things up with statements like "good accuracy" without any real data to go along with it. I agree with you that this does create some more questions.

[Ed K]

You will learn very little by changing more than one variable at a time.

You had:
GC - no GC
Sized - Unsized
CR - LLA

Don Verna

Agree... suggest you size all bullets (assuming you must for the GC) and settle on one lube, then re-test.

[happyret65]

I have good luck using 4227 (new formula), unsized bullet, no gc, pan lubed and 14 to 14.6 grains powder (with a clean barrel). Under 3/4" groups.

[popper]

I'd suggest LLA & size both, easiest. Sample size is fine. Your accuracy is poorer without GC, sizing May improve it. Still pretty good shooting for a cold windy day.