yep, i agree you need to get a measure and scale......i could not get the 95 grainers to shoot as well as my 120 to 140 grainers
Wanted to add my support to this. If you are shooting one of the old 6.5X55's e.g. M38, M96 etc. they had a twist around 1 in 7.5 (not exact) which meant they preferred heavier bullets like 140 or 160 grains. So, a bullet change might actually make things go better. The lightest bullet I loaded for the 6.5 was 129 grains. So, I don't know from experience how these lighter bullets will look.
I stuck with cartridge overall lengths given in the manuals until I had become confident with other reloading processes, e.g. working up loads by changing powders, changing primers, trying different bullets, etc. So, it isn't the place I see a guy logically starting. Still, depth that a bullet is seated can be an important variable and if someone wants to vary it I think it is important to go about it in a systematic way. It wouldn't hurt to have someone experienced check out what you are doing for awhile too.
The first thing is to choose a starting point in relation to the lands in the rifle. To do this you have to measure the location of the lands. There are various ways of doing this and various tools have been developed to help. The way I do it is by starting with a COL that wont chamber and progressively seating the bullet further and further in until it will chamber and the engraving marks from the lands just disappear. This is always my starting point. It isn't the only starting point one might choose, and not necessarily the best, but it is a consistent starting point. The next thing I do is measure the position of the shoulder of the bullet when it is seated according to the way I have just described. I measure this using a comparator and a vernier caliper and I record this measurement for future use. (Note: I will do all these measurements a number of times to get some idea of what the average figure is.) I find measuring the position of the bullets shoulder rather than the tip is a more accurate way to measure as tips of bullets vary more than the shoulder and can be deformed much easier. It also allows you to accurately measure the change in location of the lands due to wear by repeating the measurements described above over the lifetime of the barrel, and it allows you to locate bullets of different weights and shapes at the same position in relation to the lands. In other words if you take the measurement for the shoulder of the bullet you can always put the shoulder of different bullets at the same place in relation to the lands by measuring the position of their shoulder while seating them and this is the part that first engraves on the lands when you shoot. Now when you go to vary cartridge length you have a systematic place to start from. There are a couple of things you should watch out for when changing cartridge overall length. One is to make sure your bullet length will fit your magazine if you are using one. The old 6.5X55's were forgiving in this regard, but many hunting rifles aren't. Another is to always start from your manual's low load for the powder bullet combination you are using and work carefully up when you are working close to the lands. If you leave a bullet engraved in the lands, or if you adjust so the bullet engraves into the lands, you can get high pressures pretty quickly sometimes and this could be hazardous. Another thing is that I never use loaded bullets when taking all these measurements, just a sized, unloaded, unprimed case with a bullet seated at different depths.
Well, I'm not convinced I have discussed everything here. Maybe someone else will pick up something I have missed. Hope this is useful.
