Browning 1886 SRC 45-70 hitting high

[Slooshark1]

I have recently acquired a Browning 1886 SRC and tried shooting some 300 gr Hornady’s that shot well out of my Marlin, however they shoot really high (10” at 50 yards) with the Browning. The standard rear sight isn’t adjustable for elevation, other than flipping it up (I don’t want to do that) and I don’t want to file down the front sight so I’m thinking of experimenting with some 405s to see if they hit lower. Does anybody here have any experience or can you recommend a load? I can pull one out of the book but thought I would check here first.

 

[vagrantviking]

Filing the front sight would make it shoot even higher. Conversely a replacement sight that is taller will give a lower point of impact.

Experiments with the load are a good idea if you aren't constrained by other priorities such as hunting bullet performance.
The effect can sometimes be different than you expect though. For example, a heavier bullet might recoil more and cause muzzle jump that makes it shoot even higher. It depends on quite a few variables.

 

[Ganderite]

Try cleaning the front sight with some brake cleaner and then putting a dab of solder or epoxy on it. File to shape and paint black.

At range, it should initially shoot low. Use a file to lower the sight in steps until it shoots POA. Use as is, or measure sight height and order a new one.

 

[jethunter]

What velocity?

Speeding the bullet up will make it shoot lower but 10" at 50 yds is a lot to be off. Heavier bullets would make it shoot even higher I think. Or install a taller front sight.

 

[jethunter]

I have a Tradeex-bought M46 Husqvarna 9.3x57, same action as the M96 Swede. It has fixed sights so need to regulate the load to match the sights instead of the usual adjusting the sights to match the load. Some of what I saw with that goes against intuition and seemed wrong. Shooting at 100 yd target this is what I saw:

Increasing the velocity (adding more powder) LOWERED the POI.
Lowering the velocity (reducing powder charge) RAISED the POI.
Heavier bullets had a HIGHER POI than lighter bullets.

Handguns do the same thing and are even more noticeable because of the lower velocity. Most shooters ands even some experienced shooters will tell you that's wrong, but it's not.

 

[9.3mauser]

Increasing the velocity (adding more powder) LOWERED the POI.
Lowering the velocity (reducing powder charge) RAISED the POI.
Heavier bullets had a HIGHER POI than lighter bullets.

This is the total opposite of what I've experienced, with several different rifles, calibre and bullet weights. In my experience increasing the velocity raises the point of impact, heavier bullets lower it. I've also experienced different points of impact using factory ammo with different lot numbers.

 

[jethunter]

This is the total opposite of what I've experienced, with several different rifles, calibre and bullet weights. In my experience increasing the velocity raises the point of impact, heavier bullets lower it. I've also experienced different points of impact using factory ammo with different lot numbers.

What I said does seem completely backwards. "Everyone" knows that a heavier bullet will shoot lower and that a faster bullet will shoot higher. But it doesn't work that way unless you adjust the sights. The reason for this is recoil and what happens when the bullet is travelling down the barrel. After the shot is fired the recoil starts to lift the rifle before the bullet exits the barrel.

More recoil from a heavier bullet causes the barrel to raise more than a lighter bullet. So the position of the barrel is higher when the bullet exits the barrel.

Higher velocity bullets spend less time in the barrel so they don't raise the barrel as much as a slower bullet of the same weight. This is called "dwell time".

You won't notice this so much with light bullets and higher velocities. The difference between .223rem 55gr and 62 gr might not be noticeable. But it becomes noticeable with heavier bullets, and more so in slower shooting cartridges like 30-30, 45acp, 9.3x57, 45-70.

If the rifle has no muzzle lift - perfectly neutral balance or compensated - then there would be no muzzle lift upon firing. But any firearm that has muzzle lift upon firing will be affected.

This is a better explanation than I can give: https://www.thefirearmsforum.com/threads/sight-adjustment.26026/

Fixed Sights

With really fixed sights, you're at the mercy of the gun's designers. They decide which bullet weight and velocity to use to regulate the gun and its sights. Many years ago, when there was only one load for a cartridge, this really didn't matter. Today, however, there are many choices. Consider the .38 Special. For generations the "standard" load was a 158 gr. lead, round-nose bullet with a velocity of 760 fps. The height of the front sight was set so the load would shoot to the point of aim. But a significant change in velocity or bullet weight could and did have an effect on elevation.

This "dwell time" relates to the time the bullet spends in the barrel. Even though this time is measured in milliseconds, it affects the elevation, The barrel will rise, due to recoil, before the bullet is completely out of the barrel. So the height of the front sight is established for a "standard" load, based on a bullet that takes "x" milliseconds to exit the barrel. If we increase the velocity of the load--either by reducing the bullet weight or increasing the powder charge--we reduce the amount of time the bullet is in the barrel and the load will shoot low.

Perhaps the best-- and worst-- example is the .38 Special. You can buy ammunition loaded with bullets from 110 to 200 grs. and at velocities between 730 and 1,000 fps. There is no way all of the loads are going to shoot to the same point of impact in a revolver with fixed sights. And there really isn't very much you can do about it except to stay with "standard" loads. If you want to shoot really light, fast bullets, you have to either accept that they're going to shoot low or modify your front sight.

Semi-autos are more forgiving than revolvers when it comes to point of impact shifts, and many of them have front sights that can be replaced. Here's the rule: If the shots are low, you need to lower the front sight; if they're high, you need to raise it.