Marlin Firearms Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter · #1 ·
Hi everyone,

I have to figure out what went wrong the last time at the range and I need a little help from more experienced person. I reload for my 336 MG 30-30 and make light load for target shootin most of the time. I usually use a 165gr lead bullet in fron of 6-8 gr of pistol powder, blue dot, green dot trail boss etc. My rifle is zeroed with these loads at 50 meter iron sights. The problem is, I made a few loads with FTX bullets and 28.7 up to 29 gr of IMR 4064 and the bullets POI is about 12 inches higher! Even at 200m my bullets hits high. Are they supposed to hit higher by this much?
I have read from different people that recoil could affect the POI. Sounds plausible to me, because the light loads have no recoil at all and the IMR4064 does, but I tough bullets were out of the barrel way before you can feel any kind of recoil?

I know I could get a taller front sight to fix this problem and elevate the rear sight for my light loads, but I like to have answer to my "whys" before trying to fix the problem.
 

·
Premium Member
Joined
·
17,018 Posts
Hey Dake,

Welcome to MO.

There are many reasons for this. "Barrel Harmonics", powder "speed", velocity of the bullet........

Most folks "record" their sight settings with the different loads they use.

My "BO" 1895 with a Micro Groove barrel shoots the "soft" loads "low", and a couple of inches "right", compared to the jacketed bullets.

On the recoil thing, the "slower" bullet is in the barrel "longer", than is the higher velocity load. This is more noticeable with the "straight" wall cases. 45/70, 38-55....than it is with the "bottleneck" cases.

Hope this helps.

Later, Mark
 

·
Registered
Joined
·
3,465 Posts
You can get a variance between different lots of ammo. Exactly the same mfr, model, weight and speed but different lot numbers will shoot to different points of aim. A soft hand load can be very different than a powerful one. It could be 12" high or 12" low. There is no way to tell till you shoot it.
 

·
Administrator
Joined
·
23,796 Posts
At 50 yds that light of a load will be necessary to raise the sights to your point of aim. Don't know what your fps is with 6-8 gns of your powder but it is slow and will drop fast.

I would up that load to an area of around 1100 -1300 fps reset your sight then go to the FTX ammo.

Depending on your loads. Here is a link to what you may be doing. Lever Gun Performance Studies

Click on the 30-30 170 gn bullet wgt and you will get the fps in Gregs studies.
 

·
Registered
Joined
·
5,448 Posts
Yes, the harder recoiling loads will tend to start the process while the bullet is still in the barrel, giving more rise and higher impact. Example of one. I load a light weight .243 with a 70 grain bullet to somewhere around 34-3450 fps. The bullet strikes dead center at 100. I also load a 100 grain Nosler Partition to about 3000 fps. That load has the greater recoil and strikes exactly three inches above the first load.

Good shooting,
 
  • Like
Reactions: dirty low down

·
Registered
Joined
·
3,379 Posts
Rarely will different bullet weights, coupled with higher velocities, shoot to the same point of impact.
 

·
Administrator
Joined
·
23,796 Posts
Figure it like this. Zero a light load at 25yds to impact at point of aim.

You are already from the distance of the center of the bore to the front sights high.

Couple that with zeroing with light cast loads moving slowly.

Now that same zero with a extreme high speed loaded bullet, that bullet at 25 yards will likely shoot low, but at 100 will give you the high impact point you are shooting.

You align your sights to shoot uphill against gravity, which causes a bullet to drop as soon as it leaves the bbl.

This might help explain. Bullet Trajectory
 

·
Registered
Joined
·
402 Posts
You can change point of impact without even changing the load. Just touch your barrel with a front rest in different places when you shoot. Just like playing a guitar with your fingers on different parts of the string, the pitch changes on the string and the impact point changes on the barrel.

Harmonics.
 

·
Registered
Joined
·
1,050 Posts
I load a range of bullet weights in my set of M336's. In my .30-30, I use 110/130/150/170gr jacketed bullets, and I have a couple thousand 150gr Magnus cast that shoot well over Unique or Herco. That range is actually hard to cover without different from sights, and is about 3' vertically.
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #12 ·
This make sense Swany. I didn't realize my light loads had a higher arc of trajectory, and I had to compensate by having the barrel pointed higher than with aq faster load.
TMan51 how do you deal with this? Do you use different set of front sights or simply learn to shoot with only one?
Thanks for the help everyone, it's really appreciated.
 

·
Administrator
Joined
·
23,796 Posts
Best way I deal with it using a model 66 peep from lyman with the quick adjust push button.

I have two adjustments one for high power loads and another for light loads.

With the Lyman 66 Lyman 66 I adjust the high power load and scribe a line on the sights adjustable side plates gradient scale with it djusted for zero if possible.

Then, I go to my cast load and re adjust to it. Then scribe a new line for that load.
 
1 - 13 of 13 Posts
Top