Was at the range today trying out two sets of reloads. 5.56 w/ 21 Gr of RE-15 and Speer 75Gr BTHP; and .308 w/41 Gr RE15 and 175 Gr Sierra Match King BTHP's. The picture below was from my last group of 308. . Interestingly enough the three on the upper left were loaded in Lake City M118 brass. The two on the lower right were loaded in Winchester M80 brass. Little things like brass manufacturer can indeed affect your groups! Just some proof that it pays to separate your brass by manufacturer.
And a picture of the culprit.
Both sets of reloads worked very well. No FTF or FTE's. I am going to adjust up and down a little on the 308 to see if I can improve the grouping any, but I am pretty satisfied that I have hit on the loads I want.
I am enjoying the carbine more and more. All shooting was off the bipod.100 yards.
Replied by NightForce on topic Why you separate brass
Sisco is spot on!
If you're looking for repeatable accuracy it's very important to sort your brass.
Internal case volume determines the amount of powder one can stuff in a case. If the volume varies from case to case so will the pressure once fired which in tern impacts the muzzle velocity.
I did a study on internal case volumes and was surprised how much they vary manufacture to manufacturer and even lot to lot! If I can lay my hands on it I'll post it here...
Replied by Siscowet on topic Why you separate brass
Thank you sir!
Actually I am going to separate my brass and use the Winchester M80 loaded up with 42 Grains of RE15 and 168 gr BTHP for my 1 in 11.25" twist AR 10 standard rifle. I am going to load up the Lake City with 41 gr RE15 and 175 gr BTHP for my 1 in 10" twist AR10T carbine. It is already obvious the rifle prefers 168 gr and the 10T seems to like the 175's. Then I am going to develop the ballistic tables for both loads out to at least 500 yards, more if I can find a longer rifle range. I have enough brass to do about 500 of each right now, along with the bullets. Should keep me out of mischief for a while.
Replied by jtallen83 on topic Why you separate brass
Many match shooters will not only separate brass by brand and lot but will also separate it by weight into sub-groups. Combine this with weighing the bullets out and you'r spending a bunch of time on the scale........
Wish I would become a good enough shooter to gain from these methods.....
Here is a great article from our own site;
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