Where does your rifle balance? Do you have a particular preference or theory about why it should be at such and such location?

I added a lead weight to the buttstock of mine and it seems more stable for offhand, but overall it is too heavy for my taste, and hard to handle in the other positions. I am thinking of cutting down the weight just enough to get the C of G behind my support hand.

Current C of G with the weight is the back edge of the magazine.  Without any added weight, it has a heavy barrel and a clunky free float tube that makes it want to tip forward off of my shoulder.

Since I shoot left handed, there will be enough moving around that I feel the fatigue of the extra weight offsets the stability it adds. The purpose of this rifle is to try some local CMP matches, but I haven't actually tried one yet. Considering the likelihood that experience will change my preferences, I value your opinion.

Eric, start with what you feel comfortable with and go from there.  I personally started with just a lead weight in the stock, but have recently added a lead weight in the front.  The weight helps with stability, but it also takes some practice to get used to.  Keep building up and I think eventually you will find you too will want a heavier rifle.

FPNI

i use a 16 lb rifle that baances on the delta ring

I used a full butt weight and about 3/4 of a handguard weight. It balanced at the delta ring.

As heavy as you can handle it best for off hand and that is where you loose the most points.

John

I quit adding weight to my service rifle over twenty years ago. It's not worth it to me to lug it around.

What he said.

Your rifle should balance somewhere in the middle (fore-and-aft) of the magazine.

It doesn't matter what your rifle weighs if it's balanced.  Some like a heavier gun (mine has weighed up to 16 3/4 pounds) while some fatigue quicker if it's too heavy.

You can cut some of the length off a buttstock weight to balance the rifle.  An added option is to just put pistol bullets in a plastic bag and put them in the butt storage space.

Since 2010, I ran with lead in the butt and the CG was slightly rear biased about the middle of the carry handle (12lbs total) which worked well in Offhand because I lean on my front foot. The bias didn't seem to have a negative influence elsewhere due to the tight sling tension.



However, last year, my offhand was shakier and the scores weren't as good as they should've been (from 98s to 94s or less), so I added lead in the front which moved the CG to the delta ring and brought the total weight to 15lbs. That seems to have given me a couple points back, but also reduced my "bounce" in sitting. Prone is just as miserable as before.



I don't think the extra inertia or balance shift actually fixed anything though, but I don't know what changed to make me lose points.
I say run without the weight for ~10 matches. Your system and process ought to be somewhat settled at that point (your scores will be consistent). Then add the weight and do the same. Assuming your system and process stays the same, except minor adaptations for the weight, your scores should change a little bit. If they're better, go with the weight.

I for a long time, thought that the weight should be at the d ring. Makes sense right? Weight travels down through your support arm, stable this and that.


Then I heard from someone who is much better than me about having the weight/cog at the barrel end of the gun. Think about it this way. Pick up a baseball bat, or a golf club, or any longer with a disportionate amount of weight. Pick the golf club up from the heavy end, point it straight out, and move the tip so it makes small circles. Then do the same with holding the light end and make the heavy end go in circles. The light end will move faster, the heavy end will move much slower due to this requiring more energy to move its weight.

Hope that makes sense.

With a heavy front end, NPA becomes more important, but if you try it, you may like the results.