trim length ?

[cjmac]

So how important is trim length for the most accurate reloads ? I havent been trimming my brass every time and have had my groups open up a little. And another thing i know all powder is a little sensitive but how you keep the same or good groups year round. Do you just have to tweak your charge a little? Im thinking of trying a powder thrower at sometime just for the heck of it any have good groups using one ...

 

[Lapua40X]

Trim length might be important to some degree as an element of overall neck tension (amount of neck surface area in contact with the projectile) but more importantly to ensure the case length remains within the limits of the chamber dimensions. Use your case length gauge to determine when the case needs a touch up.
You'll find that temperatures will affect the accuracy of your load. A warm day will change performance over what it might be on a cold day using the same load.
"Throwing loads" short and fine tuning them with a powder trickler works well but don't expect a truly consistently accurate load using a powder measure.
If you don't have one of these in your caliber:
http://www.midwayusa.com/product/456614/le-wilson-case-length-headspace-gage-223-remington
you need one.

 

[Shynloco]

cjmac,
I think the issue of trim length was adequately covered by 40X. Do it as needed but you have to measure to know when it is needed. As far are accuracy, temperature and powder throwing goes, the key to best loads is CONSISTENCY. Many guys who compete in Benchrest shooting actually do loading and testing at the range so their loads are adapted to prevailing conditions so they get their best results. I don't compete in Centerfire rifle shooting, but that's where my true interests lie...in accuracy. I go way overboard to make sure each and every casing is identical (as much as humanly possible) and also use what some call "precision reloading techniques." That means a lot of detail in checking and measuring each and every casing in every detail after it has been fired. That strive for consistency would drive many shooters up a wall and certainly anyone reloading for hunting would never go to these extremes. Even some of my FTR buddies tell me I'm NUTS to do what I do. But if I can make my all my 5 shots groups (target has six benchrest bullseyes) no larger than the size of a dime (no matter the caliber) @100 yds, I'm happy and feel I've accomplished what I set out to do. You might say success is in the smallest of every detail of reloading.

Good luck and stick with it. Do some reading, testing and learn from others who have had success. It takes time, but you learn as you go and its also about having fun which is my key ingredient in target shooting.