Point of impact question for 255g versus 200g 45 Colt loads.

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Lone_Gunman

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I have developed a 45 Colt load that shoots to point of aim for my particular revolver using 255 grain LRN bullets and 8.3 grains of Unique. This load has an average velocity of 850 fps.

I want to drop down to a 200g LRN bullet. If I adjust the amount of Unique to kep my velocity at 850 fps, will the point of impact be the same?

Or does the fact that the 200g LRN load moving at 850 fps will recoil less mean it will shoot lower than the 255 grain load?
 
So if I increase the amount of Unique to get the velocity higher, and therefore increase recoil, I should be able to get to the same point of aim, right?

Any idea how fast I will need to push a 200g bullet to get it to hit the same place that a 255g bullet moving at 850 fps will hit? Even an approximation would be nice, to cut down on the amount of trial and error involved.
 
Not at all sure that you can pull it off. You have to think about time in the barrel, as well as bullet mass and powder charge weight. Does the gun have fixed, or adjustable sights?
 
Ya, that is one of those funny things about guns....upping the velocity of a lighter bullet WILL increase the recoil, but at the expense of LESS time in the barrel, which might actually lower your POI.

Have seen it before with heavy bullets going higher with lighter charges. It is just one of those things that you will need to play with to see how it goes.

A lot depends on your hold and the particular guns grip shape as to whether it rolls more easily and how it responds to velocity changes.

Should be a lot of fun to play with the experiment but I think you will find the lighter projo going low no matter how fast you drive it.
 
IMHO when a firearm fires the barrel goes down in a whipping motion before recoil flips it upward. That is why lighter bullets go lower because they exit the barrel faster.
 
You are partially right. Recoil does affect point of impact, how much is another story. A lighter bullet usually prints lower due to it's higher velocity. Slowing a bullet down will usually raise it's point of impact. You may find that you may be pretty close as long as the velocity is consistent. You can slow it down further if necessary, some of the Cowboy loads are pretty darn slow. And sometimes you just get lucky and stumble on a good combination. Out of my SBH 7 1/2" I shoot a 200 grain plated in .44 Mag @ 1100 fps that has the same point of aim/impact as a 200 grain .44 Special going about 850 (my velocities are estimated). Neither load has any recoil to speak of. In theory this is not supposed to happen. Anyway, I just stumbled upon this combination while trying out a particular brand of plated bullets in 200 grain which had very little data available in .44 mag and special. I made some calculations and adjustments and stumbled accross these two loads on the same day of range trial. My point is don't be afraid to experiment (withing safe limits) to find a load that shoots where you want it. My powder of choice for the above mentioned loads is Unique as well. Bill
 
I am wondering what you are trying to gain by shooting the lighter bullet.

I shoot quite a few 200 grain bullets in .45 Colt for CAS, and find that the impact differences between them and 250-255 is negligible for that purpose, both in the revolvers and in the 1892.

So, if you are Cowboy shooting you will not find enough difference to worry about. If you are not shooting Cowboy, and are looking for more precision, stick with the 255.
 
REDUCE the powder charge on the 200's, or go to a faster burning powder and a significantly reduced velocity (ie: cowboy loads). By reducing the velocity of the 200's to below what the 255's are running, you can increase the barrel time and raise the point of impact. However, due to the difference in barrel torque from the shorter and lighter bullet, you may see a difference in lateral impact too. This characteristic of low velocity bullet behavior is greatest in the .45colt of any revolver cartridges I've loaded/shot. The high weight and low velocity vs. recoil are exagerated more with the .45.
I'd recommend 6.0gr of Bullseye for around 700fps.

Ya just gotta love the cartridge though! I loaded/shot for over 30yrs before getting my first one, then shortly had 3!.
I do prefer the 255's at 850-900fps from my Ruger Redhawk. Very accurate and adequately powerful for any reasonable use. I just don't see the point in running them any faster. Or slower, either. I like Win231/HP38 and Clays Universal for this purpose.
I don't particularily care for the 200's in this cartridge. However, with the .45acp I much prefer the 200's over the heavier weights.

ADKWOODSMAN; The only reason a revolver barrel would dip prior to recoil would be if the inertia of the hammer fall caused the forward pitching motion. Or, you're flinching ! The Colt SA's do have a long and heavy hammer fall, but not enough to significantly move the fiream if properly held. Most of the revolvers have front sights taller than the rear relative to the line of bore due to the firearm recoiling before the bullet leaves the barrel. The higher the bullet weight and lower the velocity, the greater is this effect. Also a factor is weight of the firearm, and size and weight of the shooters hands and arms which also affect the rate of recoil, hence the high demand in recent years for adjustable sighted revolvers.
 
I apologize for showing this so many times in the past, but it might help the thread poster to understand lite bullets and high velocity.

This target work in the center was done by a 2nd model S&W .45 Colt caliber gun. You should be able to read the results on the target.

Lite bullets will shoot lower while the recoil is less when bullet leaves the barrel faster in velocity travel.

My point of aim had to be at the very top of target to get shots to cluster in center.

Keep in mind these are ultra lite bullets of only 145 Gr. and HB.

Jim

rtptargetwithfulltext.jpg
 
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