Re: trimming the bullet meplay for better BC
Again sorry for the delay. Below are my attempts to answer your questions as accurately as possible.
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Have you guys experimented with cutting the tips way back, or just enough so they all clean up square vs. the wild uneven ones etc.<HR></BLOCKQUOTE>
So far, I don't see the numbers saying that cutting them back to far has any deterimental effect, but I'm sure at some point it has to have some affect on the negative side.
We have only cut back enough to cleanup the tip only when shooting across the M43.
One guy that shot in these tests with us, definitely cuts his tips back a lot further than the rest of us. But on paper he hasn't lost anything except for some BC loss. That's an experiement for the future and it would take a lot of rounds to statisitcally prove or disprove this and I'm not sure we have enough guns, barrels, bullets, and setup to tell anyway.
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Have you played with boring the HP out larger and it's effects either?<HR></BLOCKQUOTE>
We haven't specifically bored out the HP per say but after cutting the tip flat we all clean up the burr using different methods.
Myself, I use my dremel tool with a wire wheel attchement that rounds the inside and outside edges very nicely. I do deburr the inside of the HP on the 338 bullets with a small number drill first before putting the wire wheel to it.
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Do the really wildly uneven tip always reduce BC by a certain amount?<HR></BLOCKQUOTE>
There is a reduction, but I don't have the hard numbers calculated to give them to you. We not worried about the loss only about the consistantcy and that's what our tests have been concentrating on.
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Have you all established a baseline BC ES for the squared tiped bullets and compared them to the ES of random selected out of the box bullets?<HR></BLOCKQUOTE>
Yes. but, I don't have a lot of the raw data fully compiled due to work restraints right now. But during these tests we would take 1 rifle, same lot# of bullets, powder, primers etc and fire strings of unaltered, trimmed, and tipped bullets for comparison. This same test was fired for 4 different calibers between 6 to 8 different proven BR rifles/barrels.
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>I'm curious, do you guys leave the acoustic target set up, or use a stand for it that is always a set distance from the bench? I don't have this type of permanent setup, it's a real PITA to get accurate measurements without this.<HR></BLOCKQUOTE>
Unfortunetly we can't leave it setup. So all of our numbers are comparable within that particular test for BC comparison. But it's not that critical being we're only looking for relative changes within and not what the actual true BC. Though we do take out time to setup as accuractly as possible so that we are pretty close.
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>As I'm sure you're aware of, the distance is very critical for absolute BC numbers, relative ones for tests like you're doing would be easier, if that's all you were after.<HR></BLOCKQUOTE>
Oh yea... afterward we went in a plugged in some different numbers, jsut changing a distance here or there by fractions of an inch and it would definietly affect the number in a big way.
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Do you guys use a seperate frame for the acoustic target just ahead of another target frame to icsolate the sound traveling through the frame. It does travel faster through the wood than it does through the air, and often the target backer material will transfer this noise to the sensor before the mach wave reaches it.
The sensor will sometimes trigger too soon in this case.<HR></BLOCKQUOTE>
I'm trying to think exactly how these were setup the last time we did this. We did see a couple of the 338 bullets give obviously wild numbers for TOF but the velocity readings on the chrono and proof screen said everything was fine so we suspected something with the acoustic setup. We also has a slight rain come and go that morning so there were many variables to consider.
hope this answered some of your questions. BTW: I don't hear you bragging about how nice the weather is up there this year as compared to last winter! [img]images/icons/grin.gif[/img] I was chilly enough that I had to throw on a flannel shirt the other day to go to work. But we haven't had a frost yet. [img]images/icons/tongue.gif[/img]
I've got pictures of the trimmer and stuff coming shortly.