Help w/ OCW test

rgitzlaff · October 26, 2006, 09:30 PM

Today I conducted my first OCW test for 7mm Rem Mag. I first fired 3 sighters/fouling shots. Then proceded to do the round robin test at 100 yards with 3 shots on each target. My loads were labeled D through J with the following charges:

D=55.7
E=56.1
F=56.6
G=57.0
H=57.4
I=57.8
J=58.2

The powder is H4831SC, the primer is Winchester LRM, Rem brass, 175 gr SMK.
The Rifle is a Rem 700, Hart barrel, 9" twist, 26" long. Action has been tuned by a good gunsmith, barrel free floated in Ultimate Sniper Stock.

Upon studying my results, I fould a couple really good groups, but when I marked the centers of all the groups, it looks like most of them are pretty close to each other. I marked where I think the group centers are with an X. Can someone with more experience tell me something? Should I try the test again maybe with more shots per bullseye to get a better read? Thanks for any help.

rwilson452 · October 26, 2006, 09:44 PM

If it was me I would do "E" over again. just to see if it repeats. I don't recall you saying anything about wind conditions. Do a 5 shot group.

kingudaroad · October 28, 2006, 02:06 PM

Very interesting topic! Here is a great article by Dan Newberryon the subject of interpreting targets.

http://home.earthlink.net/~dannewber...pment/id2.html

I had to read it a couple of times to really get what he was saying, but his theory is that a bad group, or a change in POI, should be interpeted as getting very close to OCW.

In your target series your best group"E" is preceded by bad group"D". This would lend credence to his theory. So you could do another round robin with charge weights between say 55.8 and 56.3 and see how it looks.

You could also keep going, if you have not experienced any pressure signs, because your last group "J" was also starting to open up. You may have the OCW coming up.

According to my Lyman manual max load is 60gr, so you have a little room left if your not experiencing any signs of high pressure.

Be safe and have fun!

October 26, 2006, 09:44 PM	#2
rwilson452 Senior Member Join Date: June 10, 2004 Location: Tioga co. PA Posts: 2,647	groups If it was me I would do "E" over again. just to see if it repeats. I don't recall you saying anything about wind conditions. Do a 5 shot group. Last edited by rwilson452; October 26, 2006 at 09:45 PM. Reason: more stuff

October 28, 2006, 02:06 PM	#3
kingudaroad Senior Member Join Date: March 11, 2005 Location: austin Posts: 735	Very interesting topic! Here is a great article by Dan Newberryon the subject of interpreting targets. http://home.earthlink.net/~dannewber...pment/id2.html I had to read it a couple of times to really get what he was saying, but his theory is that a bad group, or a change in POI, should be interpeted as getting very close to OCW. In your target series your best group"E" is preceded by bad group"D". This would lend credence to his theory. So you could do another round robin with charge weights between say 55.8 and 56.3 and see how it looks. You could also keep going, if you have not experienced any pressure signs, because your last group "J" was also starting to open up. You may have the OCW coming up. According to my Lyman manual max load is 60gr, so you have a little room left if your not experiencing any signs of high pressure. Be safe and have fun!