Confused with my reloads

[Jiggy300]

Not sure how to start this thread but hear it goes.

The rifle is a Ruger M77 Mark 2, .308

I have the rifle sighted in at 100 yards using sand bags and PMC 150 gr 308.

Ok, now I am fairly new to reloading and this is where my confusion sets in, I started with my first load of 3 bullets, 168 gr nosler ballistic tip, 42 gr IMR 4064. The 3 bullets hit the target 2.5 in low and 1.5 in left. Next 3 were 42.4 with about the same results, did 3 more loads of 3 up 43.6 grains and every one was low and to the left.

Now my question is can a heavier bullet ( by 18 gr) affect the aim that much and should I just start with a load of 168 gr with 43gr of powder and re sight the rifle than start with a new load development.

Any help and criticism will be great. Thanks

 

[Astocks2622]

Any change in components or charge weight will change point of impact. Even a change of projectile brand while keeping the save weight will change poi. When you develop a load, you don't really care where on the target they land. What you are looking for is a tight group. You can adjust your scope to match later. So pick a spot and aim at it the same every time. Then pick the load that groups the best, and adjust your scope to sign point of aim and point of impact. Occasionally you'll find 2 loads that will shoot to the same poi, but that's a lucky break for you, not something you can really control.

Sent from my MotoG3 using Tapatalk

 

[Unclenick]

Yes, you'd think the heavier recoil of the heavier bullets, combined with longer barrel time would mean higher POI, but due to long barrel (longer than a handgun barrel) bending deflections, it isn't always so. It depends on what direction the muzzle is pointing when the bullet exits and that's a function of barrel time. The exact direction the barrel whips in is determined by recoil moments, stock contact points and similar factors.

With a sporting rifle, if the barrel doesn't float, when you shoot from the bench the pressure on the front rest or sandbag can also be a contributing factor. Try moving the front support back under the magazine well and see if that makes a difference.

Assuming this is a hunting rifle, I also recommend you try grouping it from any field positions you expect to use, as the angle of your shoulder on the stock can have some effect, too. In match shooting, I always had a couple of moa change in elevation to come up going from standing to sitting, and had to add a couple moa right when I went from sitting to prone. Just the shape of me and how my mass centered behind the butt stock. But it was always consistent, and as long as I remember to make the changes, Iam golden. Other competitors would not have to change anything. Still others would change different amounts or even in different directions. You have to tune your sight adjustment routines to yourself.

 

[Reloadron]

Ok, now I am fairly new to reloading and this is where my confusion sets in, I started with my first load of 3 bullets, 168 gr nosler ballistic tip, 42 gr IMR 4064. The 3 bullets hit the target 2.5 in low and 1.5 in left. Next 3 were 42.4 with about the same results, did 3 more loads of 3 up 43.6 grains and every one was low and to the left.

With bullet weight and POI (Point Of Impact) well covered I will suggest the following. I would load ten at a time using the same bullet and different powder charge weights. I would shoot five shot groups. Don't worry about POI as much as the group sizes. You work for small tight groups. When you make ammunition you really should only change one thing at a time. For example if I am loading 168 grain match king bullets, using the same brass and primers I will choose a powder and only change charge weight within that combination. Look for the tightest (smallest) group. I happen to like using five shot groups. Once you have a real good combination of components giving you tight groups consistently then change the sights or scope to move those tight groups to the target center where POI is POA (Point Of Aim). Just something to consider.

Ron