7.62x39 question on change in point of impact

[je265]

I just received a 7.62x39 barrel from the factory and went to shoot it today. I started shooting UMC 123 gr FMJ to get the scope close and then I switched to Winchester soft point ammo which I plan to use for hunting.
 
I shot two groups of 3 shots each at 50 yards with the Winchester ammo with my second 3 shot group dead center (after a scope adjustment) and basically a 1 hole group. I then shot a 3 shot group with the UMC just to see the change in impact and discovered it shot about 2" high. 
 
I then went back to the Winchester and my first shot was about 2" high, the second shot was about 1" high and the third shot was back in the x-ring. All the shots felt good and the scope was good and tight and I allowed the rifle to cool between shots.
 
I then fired another 3 shot group with the Winchester ammo that was once again centered and could be covered with a dime.
 
I'm obviously done switching back and forth between the ammo and will stick with the Winchester as I bought this barrel as a hunting gun. I was wondering if this is common when switching brands of ammo for it to take some rounds for the rifle to settle in. I know there are many here with lots of experience and I appreciate any thoughts.

[Airsporter]

I have a Remington (Baikal) single shot in 7.62x39.  I initially sighted in using 123gr ammo to get 'on target,' then switched to some 150gr handloads.  Impact moved almost 6" at 50 yds! 

[Jimbo47]

Yes, it is not uncommon when switching ammo.
 
Just like handloaders try different loads and variations of bullet type and grains of powder that can vary from a grain or so can make the difference between a one ragged hole group or a group that is all over the target.
 
When reloading it's called working up a load, and looking for the perfect combination, but when using factory ammo, it's just a shot in the dark so to speak, to come up with a load your rifle likes, and when you stumble onto one, you stick with that bullet type and brand and don't change.
 
Sounds like you've got a shooter, and have found the right ammo!

[Gaz-52]

I have a Remington (Baikal) single shot in 7.62x39.  I initially sighted in using 123gr ammo to get 'on target,' then switched to some 150gr handloads.  Impact moved almost 6" at 50 yds! 

              Just curious . What sort of groups are your 150grainers getting ? I have just recently bought a Baikal , have just "shot the barrel in "and have had some FTF issues . I think I am on top of them after a bit of Dremel tool surgery to guarantee proper lock-up and hammer travel.
  Hopefully I will get to the range on the weekend . I will load up some trial rounds and see if I can find an accurate load with the 150gn Lee cast bullets. 
     Cheers Gaz 

[mtbugle]

I think the OP was asking about the shots working back to the original grouping. This sounds a little strange to me that it would work its way back to the group area on switching loads. If barrel cleaned between groups yes, but usually fouled barrel is fouled barrel in my experience. I would try to recreate the situation to see if it really is working its way to the group location or a fluke.
Thanks Don.

[je265]

Don
That's exactly what I was looking for feedback on. I've never experienced this before. I have a Ruger m77 in 6.5x55 that shoots real good with Federal ammo but I bought Winchester and Remington ammo before I settled on Federal. After I clean my rifle I'll usually shoot one round of the Winchester or Remington ammo to foul the bore so I don't waste the Federal ammo as it's hard to find in that caliber. After that fouling shot it always prints right where it should with the Federal ammo.
 
This is going to be a work in progress and I'll report back on any progress.

[Jimbo47]

I've found over the years and with many different barrels, that they are not all the same and they have their quirks.
 
I wouldn't worry about it unless it is something that continues to repeat after using the same ammo.
 
To put your mind at ease, you can do a good cleaning of the barrel, and use the ammo that you intend on using and after firing a few fouling shots, then shoot for groups, and stay with that ammo until your satisfied that the barrel has settled in.
 
Just remember that not all barrels are the same, and what one barrel likes, other barrels may not, and once you find what works in yours, just stay with it, and you'll be a lot happier that way.

[gcrank1]

So you are cleaning it after each session?

[je265]

Nope. I learned this lesson early on with my other handi rifles. Every time I would clean them it took a bunch of shots for them to shoot back to point of aim. I asked that question a while ago and the overall view was to just shoot them until accuracy got bad. It was hard for me to do because I'm used to cleaning my rifles every time I leave the range but once I get the Handi's to shoot where I want them I don't clean the bore.

[n8dawg6]

this is my experience.  your issue may have to do more with the ammo you're using but maybe this will help.  my handi is a .44 mag.  it shoots several inches high and to the right on the first shot from a cold bore.  as i continue shooting it walks the shots down to my point of aim and by the time the barrel is warm (usually 3rd or 4th shot) it prints the next several shots into a nice group.  if i keep shooting until the barrel is hot, shots go all over the place.  initially i chased the bullets all over the target with scope adjustments til i figured out the pattern.

what i have done for hunting purposes is sight the barrel in for the cold bore shot.  i have to let the barrel cool completely down between shots (literally a cold-to-the-touch barrel) to get a group, but it is repeatable.

the fact that my point of impact moves as the barrel heats makes me think that the barrel is contacting the forearm such that forearm pressure on the barrel is changed as it heats.  i'm thinking that floating the forearm and using the washer or o-ring trick might help with the issue, although sighting in for the cold bore shot is a fix that works for hunting (where the first shot will always be from a cold barrel).

YMMV

[ratdog]

had the same problem yesterday with my  357 handi kept adjusting scope to try to get to group better now it wont adjust up or to the left at all scope is messed up.