reloading conundrum

[rustyruntite]

I just bought a Browning X-Bolt 243 with a Leupold VX 6 scope. I've hand loaded since high school but retired now. And I ran into something that's quite ballistic.

I used some Federal 55 gr. factory loads to sight in my rifle. I got it quickly to a 3/4" group at 100 yds.

Then I had set up 13 other test scenarios with 3 bullet weights and 2 powders. All 3 shot groups.

I had a target with 9 bulls eye's. So I shot 4 groups, each being a different powder load. And went back to my factory loads for the center bulls eye to see if it was still on.

My factory rounds remained consistent to my sighted in group.

HOWEVER EVERY, YES EVERY had load shot LEFT SOME sporadically left some a bit tighter, but all went left.

I have never see anything like it. Any ideas.  

[hunter]

Was all your other bullet weights heavier than the 55 gr. factory loads?

[Deleted]

Shooting at 200yds should give you a better deviation from what load is going perform better for you....243's can shoot like lasers sometime if not all the time with low recoil...I've been wanting to find the right one for me for quite some time now....Sounds like your gun is a laser shooter as well....
Greenhorn

[rustyruntite]

Boy I wouldn't call it a laser. Some had all loads with 4831 were wildly left and high and a 6 - 8" spread. Lots were 3 inch spreads. I was sighted in at 2.5 to 3 inches high at 100 and straight up.
Nothing shot right. Some 6 inches or more left.

Bullets were 95 gr. Bergers, 69 gr. Bergers and 62 gr Barns using 48312 and H380.

[wilmsmeyer]

Possibly the barrel whip was causing the change in POI. The torque of a bullet twisting in the barrel can cause POI changes. The thinner the barrel the more pronounced. As someone else asked, and you answered, all the bullets were heavier to some extent.

Interesting observation. If the groups were tight this wouldn't bother me at all. I would pick the load I liked and re-zero for it.

[rustyruntite]

That's what I was looking for some loads that group satisfactorily, and then fine tune. But my thinking is that if it's bullet harmonics then the some of the test loads should land on the right side of center.

Oh well I picked up some 55 gr projectiles yesterday the same as in the factory. So I'll try to replicate the factory results without knowing the powder charge in them. I'll even pull a bullet and weight the powder. Maybe that will give me some subjective clue as to the powder.

I post the results on my next episode.

[sourdough44]

Sounds like a nice gun. I recently bought an X-Bolt in 7mm-08. I have also loaded up some 55 grn bullets in 243 cases. These are the frangible 'Blitz-King' bullets & not suitable for deer & such.

As is always the case, you would have to experiment some then pick a load & sight in with that load. Some loads may print close to others, but overall I would expect different points of impact. Just for general accuracy testing I often use a 70 grn match bullet with the 243. My deer ammo is usually a 95 grn partition & at times an 85 grn gameking.

[dannoboone]

Using different weight bullets I was disappointed that my Sav 12 VLP varmint in .243 would never
have the same POI with any of them. For example, with 70gr MK's hitting the center of the bull,
55gr Noslers would shoot high (no surprise) and to the left (about 3"), and 105 A-Max's would hit
low (again, no surprise) but to the right (about 2") @ 100yds.

The following info may be of help when you start loading the 55's. I haven't tried their suggested
coal yet, but plan to do so next time I do some reloading:

www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=2498658&#Post2498658

Barnes used different powders than you are using with the 62gr VG's......IMR 4350 and RL19. Would
that make a difference in accuracy?

Probably just me, but the only thing I've gotten decent accuracy with Berger boat tail bullets was
the 7mm 140 in a WSM.

[AJ]

Your barrel is whipping around with the harmonics of the load. Just because load A hits the same POI as POA, does not mean load B that may have a different weight bullet or different velocity range will be similar. Check out Dan Newbury's page on Optimal Charge Weight optimalchargeweight.embarqspace.com/ It works very well.