Brass ?

[wisconsinteacher]

I had a load for my 22-250 using Rem brass that shot .334" Today I used the same load but used Win brass and got 1.25" as my best load. Could changing the brass change the group that much? It was the only thing different between the two loads.

 

[SJB358]

Yep, without a doubt, you are dealing with different internal capacity so pressures are going to change from one batch to another. If you wanna run RP brass, you will have to recreate your most accurate load. Scotty

 

[JD338]

Yep, without a doubt, you are dealing with different internal capacity so pressures are going to change from one batch to another. If you wanna run RP brass, you will have to recreate your most accurate load. Scotty

Well said Scotty.
This is also the reason when you change any component, you should drop back a couple grains and work up. Pressures can climb quickly.

JD338

 

[DrMike]

WT,

You were just given a great lesson that cost you little. As Jim and Scott have stated in their reasoned responses, learn from what you observed. Always drop back a few grains when changing any single component and work up again.

 

[wisconsinteacher]

Thanks guys. I will keep that in mind for here on out.

 

[efw]

Scotty is right on, but there are other factors to consider such as whether you included that rifle in your cleaning regimen with the '06. I've not really experienced this, but have heard of rifles that need 15-20 shots to foul the bore before groups tighten up.

It is most likely the brass as others have said, but this is something else to keep in mind. Depending upon the components and temperature, heat can also have a negative affect on a load developed in different conditions.

Shooting journals are your friend with regard to these issues. I keep detailed notes on each shooting session and with rifles I know well I can just about predict what'll happen on my next outing.

 

[BK]

I hate to pee in somebody's Cheerios, but how many groups made up that .334" average? Good groups can be just as much of a fluke as bad groups. Go back to your original component list and shoot that combo again, for eight or ten groups. That will give you a better idea of what your rig is actually capable of.

 

[wisconsinteacher]

BK, I understand what you are saying and that is my plan. I am going to copy that load and try it for more groups. I hope it was not a fluke.

 

[BK]

That would be a serious bummer if it was. Sub-.5 MOA rifles are so cool!

 

[Ridge_Runner]

get the win cases up to the same MV and they should shoot close to the same groups.
RR

 

[Antelope_Sniper]

WisConTeach,
More important then the change in group size, changing brass can drastically change your pressure levels. A change fm Winchester to Remington brass can be a 8k psi difference in pressure. Anytime you change to a thicker brass, it's best to back off and work up again.

 

[BeeTee]

I had a load for my 22-250 using Rem brass that shot .334" Today I used the same load but used Win brass and got 1.25" as my best load. Could changing the brass change the group that much? It was the only thing different between the two loads.

A change in accuracy between brass manufacturers could be due to neck wall uniformity, primer pocket uniformity, or variations in annealing (bullet grip). If there's a significant difference in case capacity, it should be reflected in both weight and bullet velocity.

I've shot Lake City Mil, Winchester, Remington and Federal brass in my 223 (recently bought some new Nosler brass to try next). The most uniform brass I've shot so far (Winchester) print the best groups - no surprise, but even the worst Lake City will allow my VS to print 3/4" groups. I've found I need to clean/polish the inside of all fired case necks to get more uniform bullet seating, and the carbide expander button pulls through so nice without lube during resizing.

While still performing up to the speeds listed in most loading manuals, I don't load to the limit in pressure/velocity in my rifles, so I don't worry as much about load variations between brands of brass. The safe recommendation is to back off 10%, then work up when changing a component.

Jim