Does your 458Win have different point of impact with 450 and 500grn bullets?And if so, by how much?

Yes it did. As I recall the 450 gr bullets hit about 4 or 5 inches higher than the 500 gr bullets. The muzzle velocity of the 450 gr was 2220 fps and the 500 gr was 2090 fps. The 400 gr bullets hit much higher, like off the target! They were going 2340 fps.

Oz

Most big bores will shoot the heavier bullet to a slightly lower POI at 50 yds. I work at 50 yds, and most 458 Winchesters, and the rest of the "Lott", and my 458 B&M shoot the 500s anything from 1-2 inches lower at 50 yds than the slightly faster 450s. I have on many occasion worked POI with the 450s at 1 inch to 1.25 inches hi at 50, and the 500s drop to spot on at 50 with no issues. On my trip to Australia in 2009 for buffalo, I had 450 Swift and Barnes Banded 1 inch hi at 50 in my 458 B&M, and 500 Woodleigh softs 1 inch lower than that. I used both without issues and interchanged. Have done so for many years. I am leaving soon for Africa, I have another 458 B&M almost ready to go. Main loads this trip is the 420 CEB BBW#13 NonCon, and it's matching 450 Solid. These will be 1 inch hi at 50--also taking a 480 CEB BBW#13 Solid, lower velocity and it's POI is about 1 inch lower than the 450/420 combo. Also, taking a 400 North Fork Bonded, and 370 CEB BBW#13 NONCON--both higher velocity, and about 3/4" higher POI than the 450/420s.

My 500 MDM is the same with it's various bullets I am taking.

The trend is heavier slower velocity will have lower POI than lighter higher velocity. Trick is left/right!

Michael

Thanks guys, just the info needed.
I have been using the 480grn Woodleighs and have loaded some 450grn Swifts and was particularly interested to know if the change of impact would be excessive and to the side. Sounds like it wont be too bad.

IMO,there is no rule as to where a certain bullet will impact if it weighs less than the ones you usually fire,or is made out of a different material and is shot right after ones that are different and where shot almost exclusively beforehand.You could be looking at a different POI of about 6 inches or more at 50yds,in any direction.I believe it is important to know how that specific rifle will behave when a new condition is brought upon and the subjecting the bore to this condition so that it becomes stable and POI can be predicted..

quote:

Does your 458Win have different point of impact with 450 and 500grn bullets?And if so, by how much?

quote:

I have been using the 480grn Woodleighs and have loaded some 450grn Swifts and was particularly interested to know if the change of impact would be excessive and to the side. Sounds like it wont be too bad.

Somewhere along about 12 yrs ago I started keeping fairly decent records. Over time I become very good at this, and improved greatly over the years. I continue to improve the process. In the course of testing various bullets, various loads and load data, terminal tests, and all sorts of other experiments, one gathers a lot of POI Data---Point of Impact Data--whether you intend to or not. Doing test work on various things, one does not sight in the sights or scope with each load, or bullet. A huge waste of time, so you normally have it close to what you want with a particular bullet, all others fall where they may during the load development or whatever tests you are conducting. So unless you change the sights, then every load, bullet that you shoot or test is recorded, and you have POI data in comparison to other loads and bullets.

Over the last 15 yrs of field shooting (hunting) I have always done POI before leaving home on a particular mission. In some cases that is only an expanding and a solid, in other cases it may be as many as 4, 5, 6 different bullets in a cartridge, or caliber that I intend to field test that I am looking at taking. If I am gathering field data--I have to know POI with each load or bullet that I intend to work with. Sometimes it is rather difficult to get some bullets to cooperate with the program, other times things just fall into place perfectly! Sometimes, you may have to manipulate things some as well.

I pulled some old targets and some brand new ones shot only yesterday, and will show you what I am talking about.

As a "General Rule" lighter faster velocity bullets from the same rifle/cartridge will print a higher POI than the heavier slower bullet. For instance in 458 caliber, a 400 at 2350 fps will be higher than a 450 at 2250 fps and that will be higher than a 500 at 2150 fps.

There are times that you can slow that 500 down further, to 1900 fps and barrel time will cause it to print higher, more in line with the 450s. Manipulation.

I recall in 2009 I was taking a 458 B&M with 450 Swifts at 2200 fps, and 450 Barnes Banded at 2225 fps. I was not happy with POI between the two, a bit too far apart. Note two totally different bullet designs, bearing surface. I did some manipulation slowing the 450 Barnes banded down to 2175 fps and they shot in the same hole at 50 yds. Height was never an issue, as both were the same.

Right now, yesterday in fact, I started shooting again for POI with two rifles I am getting ready to go to the field with, and it's a test mission with as many different new bullets we are working with as I can get to POI. One a 458 B&M again, and the other a 500 MDM. I will show yesterdays targets with those as well.

Let's start with some data I pulled in 416 Remington from 2005. Mostly the differences between a 340 Woodleigh at around 2500 fps and 400 gr bullets at 2350-2400 fps.







As you see in every case, heavy is lower, lighter faster is higher. There is some difference in windage as well, but not a lot. Keeping distances to 50 yds one could interchange these loads. However, I am a little picky about some things, and I did not do that in the field. I ended up working with 340-350 gr bullets, all much closer to POI.


Here is a couple of targets pulled from a 458 Winchester File. 450s and 500s. Again, you can see the trend.




There are many more examples I could show you over the years in all sorts of various big bore calibers, cartridges and rifles, the trend is always the same story from one file folder to the next going from 416 up to .510 caliber.

But now, I will show you what I am working on right now, some even yesterday.

First the 458 B&M that I am taking out with several different bullets I want to use in the field. Now, since I plan to bust a few buffalo my #1 sight in load is a 420 gr CEB BBW#13 NonCon HP at 2250 fps, backed by it's twin a 450 gr CEB BBW#13 Solid at 2205 fps. These are the EXACT same bullet, one hollow point, one solid, both brass, both the same bearing surface and bands.

Here is current as of yesterday.




I very much want to bust a zebra, or wildebeast or few with a 370 CEB BBW#13 NonCon HP as well, velocity is higher, lighter bullet, same bands and bearing, but prints some higher POI than the 420/450 bullets. And yes, I wish I had not pulled that one shot off to the right! But I did so...... Now this is really getting close to my outer limits of POI, but I am going to make an exception for this bullet, and the 400 North Fork Bonded Premium as well, shooting the same POI as the 370 CEB.




Moving to even lighter and faster, I knew before shooting these were going to be past my outer limits of POI, but had to test to confirm. Very high and too far out of POI to use successfully without a complete change of sights, and I really do not like to do that in the field at all.




OK lets move up in weight, and down in velocity to the 480 gr CEB BBW#13 Solid, at 2145 fps. As you see, this POI of the heavier bullet is well within working limits of POI, and I will be taking a few of these to test out.




So as of yesterday with the 458 B&M I have 5 different bullets that are close enough in POI at 50 yds for me to work with. And the trend is set as you see.

Next, let's look at the 500 MDM. Some done yesterday, some a few weeks ago. Again mission being buffalo my #1 load and bullet I want to test is a 460 CEB BBW#13 Brass NonCon HP--Matching with a 500 gr CEB BBW#13 Brass Solid. Exact same bullet, one an HP the other Solid. This will be my sight in POI bullets for this trip, other bullets working around this.

Do bear these things in mind as well, I am still in the fine tuning process, tweaking things a click here, and a click there to center up. I am picky about some things.





And yes, I wished I had not pulled that one 500 to the right! Damn! Maybe one day I will learn how to shoot?

I have slowed the 500 gr BBW#13 down to 2370 fps or so. Just don't need that much velocity with the solids in the field. Especially not a BBW#13. If I either lowered the velocity of the 460 or raised the velocity of the 500 these would be in the exact same hole--If I did my part. The 500 MDM is capable of much higher velocity with both bullets, but it is just not needed. I do want some velocity with the NonCon as performance increases with velocity there.

Now another bullet that I am EXTREMELY interested in seeing trauma inflicted is the exact same bullet as the 500/460, with the exception this bullet has a .800 deep cavity and weighs 425 grs. As you see, lighter, faster, it's POI is higher.




Today I have 4 different bullets I can work with in this 500 MDM---Main bullet 460 BBW#13 NonCon, backed by the 500 BBW#13 Solid. Kicker, the 425 NonCon Deep Cavity--I call this the lion bullet! And in addition the 450 gr North Fork CPS which also is on 1/2 inch higher than the 460 BBW#13. And the trend does continue.


That's my story, and I am sticking to it!

LOL

Michael