Component variations

1

1000mstudent

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Due to the increased cost in components, I am wanting to know how much I need to reduce the load I am now using when I introduce a new lot of Berger 165 gr bullets into my rifle's diet. I'm trying to avoid the load redevelopment process. What is the biggest change that you had to do due to lot changes.

I'm just starting to compete in F-Class and could use a little info. I'm using Varget as a powder and soon will need to purchase some more, so, the question applies to that.
 
Well, when you are initially working up the loads you should keep the chrono data for the velocities at all charge weights. That way you can back off a grain or two when checking out a new lot of powder, bullets, brass or primers and see how it compares to your original data. And it will give you a rough approximation of what it will take to get back to your target velocity.

I've never noted any great difference between different lots of the same bullet, for instance the Sierra 2155 has been pretty much the same ever since they brought it out. The 139 Scenars that I use have never required any adjustment in powder charge. I've never had to change my load for the bullets I use.

Where I have had to alter my charge a little is for barrel and throat erossion as the 6.5 eats into a barrel pretty rapidly and I end up chasing the lands. Nowhere near as bad with the .308 or .223.

I can certainly not say the same for powders. Varget in particular has shown major variation from lot to lot over the years. I'd certainly back off 1-1/2 grains when going with a new lot# of powder.

Brass can change quite a bit too, for instance the old Lapua .223 brass was quite a bit heavier than the Winchester and took about 1/2 gr less powder. Recent production is quite a bit lighter and can take more powder. A good reason not to mix headstamps or lot numbers of brass.

But one thing I recommend is keeping your data, expecially chrono data and temperatures when chrono'ing loads.
 
Thankyou for the info Rust.

From what understand, I should target the velocity and the accuracy should remain the same. As a precaution, back off 1.5 gr on the powder charge to make sure the pressures aren't too high, and build back up.

I do keep an accurate record of all loads created and data during development, so I'm ok there. I have a crony, so this shouldn't be too hard.
 
I would not....

1000mstudent said:
Due to the increased cost in components, I am wanting to know how much I need to reduce the load I am now using when I introduce a new lot of Berger 165 gr bullets into my rifle's diet. I'm trying to avoid the load redevelopment process. What is the biggest change that you had to do due to lot changes.

I'm just starting to compete in F-Class and could use a little info. I'm using Varget as a powder and soon will need to purchase some more, so, the question applies to that.
Click to expand...

I would not be concerned with changing your powder charge for a different lot of 165 Berger's. These are target bullets and should shoot the same as your present lot with no further load development.
 
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