I've had this happen on two very different rifles now, so I'll ask the experts for clarification <img src="/ubbthreads/images/graemlins/confused.gif" alt="" />!
Got a Mauser 96 in 270, and now a Savage 99 in 308 that I sight in with factory ammo. Several different types of factory ammo all fire the same and have pretty much the same point of impact at 100 yeards.
Now I get to reloading... minimum loads, maximum loads, different powders, different bullets, adjust the bullet seating, neck resized or full resize are all the same. The point of impact has shifted downwards a LOT. The 270 shifted downwards about 4 inches, and the 308 shifted downwards 7 inches.
Both guns group the reloads well, I'm just at a loss to know why my reloads have shifted downwards that much. Don't have a chronometer, so I'll admit I'm also worried that the velocity has dropped through the floor for some reason...
Anybody have this happen to them? Thanks in advance!
I don't think that a drop in velocity causes it to shoot low.
It might be the opposite in fact. Don't know why,but I think
thats just the way it is.
Just adjust your scope to your go-to round and hunt.Good luck.
Bart
Thanks Bart. Guess that'll be my plan..
style of bullet, wt of bullet and velocity all will contribute considerably to POI change.
shooting low is not a bad thing when comparing it to other ammo.
Some of it is barrel harmonics.
I have several relaods for one gun and always have to adjust the sights for each.
No big worries, I don't think your velocity is so low as to cause that.
The point of impact has shifted downwards a LOT. The 270 shifted downwards about 4 inches, and the 308 shifted downwards 7 inches.
Just wondering, what are the factory loadings, and what are your reloads consisting of? JAG
Blammer, yeah, I expect the point of impact to be off some, and maybe off by 6 inches if I hit a weird combo. What I didn't expect was multiple combinations of bullets/powders/cases to be consistent one way, and different factory loads to be consistent by so much another way.
Jag, I'd have to reference my notes at home. I know for the 270 I tried varying H4895 and H4831SC amounts from min to max loads with Nosler and Speer bullets, loads according to the Nosler and Hogdon guidelines. The 308 I got more creative with, trying varying mid-size powder loads with H4895, H4831 and IMR4895 with 125gr NBT, 180gr NBT and even 170gr 30-30 bullets. All reloads grouped closely together 7 inches under the factory. 308 is fairly new, so haven't had time to work the loads up until I see pressure issues..
Welcome to the reloading world.....The one thing I've learned over the years is to expect the unexpected. You keep reloading, using the OAL gauge and Chronying you stuff and magical things will happen. It takes time and patience and it really pays off in the long run. It's a hobby for a lifetime....Good luck and regards, Rick.
Don't have a chrono.. any suggestions on a "reasonably" priced one to get? Heck.. have to read the manual, have no idea how to set it up and never seen one used.
Check out the Chrony. I picked one up for less than a hundred bucks a few years back. Cabelas has them in their new store. It looks like three different models now. Mine is kind of a pain to set up at a public rifle range because you need to be 10 ft from the muzzle and that means ahead of the firing line which holds everybody up. I try to do it when noone else is around. No more guessing about velocity, you will know. Some people are more comfortable not knowing but that is them. I was shooting reloads at 200 yards yesterday
and when you have six different loads it will drive you nuts. <img src="/ubbthreads/images/graemlins/crazy.gif" alt="" /> <img src="/ubbthreads/images/graemlins/crazy.gif" alt="" />
GWN
I second the Chrony. Reliable and inexpensive. You really don't know what is happening until you chronograph your loads, and it is very easy to use.
Which Chrony do you have or suggest? I think I saw a blue one at a local store for $75.. already told the missus to throw it on my Christmas List<img src="/ubbthreads/images/graemlins/grin.gif" alt="" />.
Mine's red. It has the remote display which I would highly recommend. I mail ordered it for around $90.