While you are on the site, in your browser find and click "Add to Home Screen" A CGN beaver app icon will then be created to your phone that is directly link to the site.
Note: This feature may not be available in some browsers.
Hi all! I've been checking some factory ammo with my chronograph so that I can order a custom cds dial from Leupold. Within a box ammo is very consistent within 40fps but I noticed from some older ammo I had from a previous order shot on average 100 fps faster. Is that a normal difference between batches of ammo?
Thanks!
Depending on the lot number anything is possible. Then when you switch brands it changes again.
A few years ago I needed some 338WM and picked up three boxes of Speer Nitrex. I was mostly after the brass as the availability at the time was poor. I also like Speer bullets for the most part.
Each box was a different lot number and even though they each had bullets of the same weight the velocities varied by over 150fps. The velocities and POIs were fine from the same box but as soon as a different box was used POIs shifted as much as 4 inches at 100 yards. The POIs changed both vertically and horizontally.
When I chronographed the loads I used ten rounds from each box. Close enough to get a rough idea of what to expect. I was hoping that they might be suitable for an Elk hunt I was planning. They weren't IMHO.
I then pulled the bullets from all of the remaining cases and weighed each of them as well as the powder charges and case weights. The bullets all weighed within .25 grains of 225 grains. The cases varied in weight by as much as 5 grains throughout each lot. The powder on the other hand was the real difference was. Not surprisingly, all three of the lots used obviously different powders. They were all extruded but different in diameter and length of grains.
When ammo manufacturers make up a numbered lot of ammo, they use components that will be safe and deliver relatively close performance to another lot. It may or may not shoot well in a particular firearm.
When powder is manufactured it is never or very seldom is exactly the same as the previous batch or batches. The same goes for every other component. About the only component that is relatively consistent these days are bullets from the same manufacturer. Powder on the other hand is a constant variable. That's why some handloaders will take their powder from different lots but the same type and mix them all together to have one large/consistent batch.
I have had people come to me stating something has gone wrong with their rifle/scope because it keeps shifting POI after a sighting in session. The rifle/scopes are usually fine unless they haven't been cleaned properly or fouled to the best accuracy sweet spot. My advice to them is to purchase more than one box of ammo with the same lot number. That rankles those that are financially challenged.
This was a bit long winded but that should give you the gist of what goes on.
Drop the muzzle velocity to 2850 fps (so -100 fps) and you get
@ 200 -3.4 (or .3" lower)
@ 300 -12.5" (or 1.1" lower)
@ 400 -28.2" (or 2.3" lower) - all still within the vitals of a deer/moose/bear even if zero'd to the higher velocity
@ 500 -51.4" (or 4" lower) - which would still be in vital area, albeit on the extreme edge of a deer if your aim point was the center of the vitals - still lot's of room on a moose
After that (so 600 yards and beyond) either your BDC reticle or custom dial WOULD BE considerably off target - but we are talking 600 yards. And if you plan to shoot that far you should probably be reloading to "match your dial" not trying to match a dial with a pre-rolled load.
If you are going to get the dial cut to factory ammo, perhaps shoot a few different boxes to try and mitigate any variations, and choose a speed smack in the middle of all that you shoot. That way a variance of +/- 50 or 60 fps will have a minimal impact all the way out to 500 yards - further than "many of us" have any business shooting at an animal anyhow...
Thanks guys! Sounds like some good advice, Hornady quit producing the round I use when they were having trouble keeping up but it is available again so that was between the two I checked, I'll average them all out and split the difference, this rifle is a Varmint rifle shots will not get much past 350 or 400 yds even coyotes deserve as clean a shot as possible. Thanks!
