6ppc load help?

I can't explain it. It seems the bullet likes an extra 5-thou of engraving. Incidentally I have shot straight jam at 27.7 and 28.3 and the groups were considerably tighter than shown above...but still not as good as jam +5.

-Lee
www.singleactions.com
 
Perhaps being pushed back .005 as the round is chambered does a better job of centering and squaring the bullets to the bore. Sometimes we don't know exactly why a thing does or does not work, but that does not prevent us from taking advantage of the knowledge that it does.
 
Lee Martin said:
Boyd is right. Jam +5 is just seating 0.005" longer than the jam length. The bullet is pushed back 5-thou upon chambering. This Shilen combined with my 67 gr FB seem to like that depth across a range of charges (264 chamber, brass turned 0.0095", 0.0015" neck tension, 0.0015" neck clearance). I've been shooting both 27.7 and 28.3 exclusively at jam + 5 with good results. One caveat though. When the humidity is low, say under 60%, the gun aggs better with 28.3. When the humidity rises much above 70% it wants the lower 27.7 node. I'm still learning LT-32 but believe it can shoot in wet air.

-Lee
www.singleactions.com
Click to expand...
So, when the air is denser, lower velocity is better for this combo?
 
Boyd Allen said:
If you look at the entire top row, you will see that soft seating (seating longer than jam and letting the bullet be seated to final length as the round is chambered) produced excellent accuracy across the entire range of charge weights. This is a very good example of the importance of seating depth to load tuning. So often I read of shooters spending most of their time exploring charge weight almost to the exclusion of seating depth. This target demonstrates a better approach. While not necessarily the case with all powder bullet combinations, in this case, the difference in tuning node width was quite striking. It looks like any of the powder charges could have won a match, but 28.3 does stand out in that it showed up well in all but one of the rows.
Click to expand...

Boyd you used the term "soft seating" above. Would neck tension play a greater role when you do this? In other words, might you use less neck tension in these circumstances.? Or, at this point is trial and error the modus operendi?
 
Lee...if you remember, please tell us the order you shot these targets. If you have already done this just say so and I'll look. Read some stuff but can't really tell how you shot them....I'm pretty stupid.
 
Well...it looks like the seating depth matters quite a bit! Does that seating depth (+5) affect the bolt closure in any way?
 
You must log in or register to reply here.
Back
Top