Oddball velocity causing ES to be high

[Shaggy357]

Variance in internal case volume can cause a blip high or low in your SD. Sizing and brass prep usually resolves this, but not everyone is as meticulous with new brass as they are with their fire formed brass. I found out in my 6.5x284 with brand new Lapua brass. I wasn't shooting over a chrono tho....I was shooting chucks and every 4th or 5th round I had super hard bolt lift. My first twenty shots at home appeared to be just fine. Accuracy, velocity, and no apparent pressure problem so I loaded the remaining 80 brass. Ended up pulling about 60 bullets and starting over with lighter loads to form the brass then work back up to my load. My mistake for not loading a mild load for fire forming to my chamber before working up a hunting load.

Something else to think about.....

Steve

 

[savagedasher]

Variance in internal case volume can cause a blip high or low in your SD. Sizing and brass prep usually resolves this, but not everyone is as meticulous with new brass as they are with their fire formed brass. I found out in my 6.5x284 with brand new Lapua brass. I wasn't shooting over a chrono tho....I was shooting chucks and every 4th or 5th round I had super hard bolt lift. My first twenty shots at home appeared to be just fine. Accuracy, velocity, and no apparent pressure problem so I loaded the remaining 80 brass. Ended up pulling about 60 bullets and starting over with lighter loads to form the brass then work back up to my load. My mistake for not loading a mild load for fire forming to my chamber before working up a hunting load.

Something else to think about.....

Steve

Steve
The only thing that changes the internal volume of a case is when it is made .
You can change the volume by sizeing but it will not change the internal volume that the case originally started with .
If one case the volume was 50 and another was 51 Sizeing you still would have the same percentage variance. Larry

 

[Lone Hunter]

Once you get all the brass with a firing on them>>>>anneal the brass, prep it your normal way, use a Q-Tip to swab a bit of Imperial Dry Neck Lube in the neck prior to charging the case and seating the bullet. I would bet that you eliminate any "out-liers"..

Hate to hijack the thread but I would like an answer from you guys about putting Imperial Lube or Powdered Graphite in the neck. Never have done it,have thought about it, but am concerned about contaminating the powder. Can you give some insight or opinions please. OP, sorry about hijacking your thread but I have had some of the problems also.

 

[ShootDots]

Hate to hijack the thread but I would like an answer from you guys about putting Imperial Lube or Powdered Graphite in the neck. Never have done it,have thought about it, but am concerned about contaminating the powder. Can you give some insight or opinions please. OP, sorry about hijacking your thread but I have had some of the problems also.

It will absolutely NOT contaminate the powder. Besides, if you use a Q-Tip to swab it out, how much do you really think that will get into the case.. Worry not, you will be fine.

 

[rardoin]

It will absolutely NOT contaminate the powder. Besides, if you use a Q-Tip to swab it out, how much do you really think that will get into the case.. Worry not, you will be fine.

The Imperial dry lube is graphite. One of the powder manufacturers, I can't remember which one at the moment, gives the recommendation for adding powdered graphite to propellant to improve flow if it is clumping. Something like 1/4tsp per lb. of powder. I read it in one of their publications recently. I have been using it for a long time as an inside neck lube in one form or another. I currently dip the primed case neck in the ceramic ball applicator jar prior to charging the case.

 

[savageshooter86]

I

The Imperial dry lube is graphite. One of the powder manufacturers, I can't remember which one at the moment, gives the recommendation for adding powdered graphite to propellant to improve flow if it is clumping. Something like 1/4tsp per lb. of powder. I read it in one of their publications recently. I have been using it for a long time as an inside neck lube in one form or another. I currently dip the primed case neck in the ceramic ball applicator jar prior to charging the case.

I use it now on my 308. Since I clean cases using stainless pins

 

[Lone Hunter]

I


I use it now on my 308. Since I clean cases using stainless pins

I also clean using S/S pins and it seems the bullets seat a little bit harder. Where do you buy the Imperial Dry Lube from?? I have the Imperial Sizing Lube and it is sure enough slick. I also have some powdered graphite that I used for neck sizing before I got my Redding Dies. Thanks

 

[savageshooter86]

I also clean using S/S pins and it seems the bullets seat a little bit harder. Where do you buy the Imperial Dry Lube from?? I have the Imperial Sizing Lube and it is sure enough slick. I also have some powdered graphite that I used for neck sizing before I got my Redding Dies. Thanks

Sinclair

 

[jlow]

I


I use it now on my 308. Since I clean cases using stainless pins

How consistent is your seating pressure? Inconsistent seating pressure = inconsistent neck tension. That for sure will give you trouble with MV consistency.

 

[savagedasher]

How consistent is your seating pressure? Inconsistent seating pressure = inconsistent neck tension. That for sure will give you trouble with MV consistency.

1 kernels of powder in a case that the case volume Difference of 34 Larry

 

[jlow]

1 kernels of powder in a case that the case volume Difference of 34 Larry

?

 

[savageshooter86]

1 kernels of powder in a case that the case volume Difference of 34 Larry

Jlow don't measure seating pressure. But if one feels different it goes in foulers row. I have my 308 dialed in and low ES and load it just like my 284. I think once I get 1x fired brass I'll know something and be able to tell what is going on

 

[Shaggy357]

Steve
The only thing that changes the internal volume of a case is when it is made .
You can change the volume by sizeing but it will not change the internal volume that the case originally started with .
If one case the volume was 50 and another was 51 Sizeing you still would have the same percentage variance. Larry

Larry, I agree and disagree....we all have to assume that brass in the same lot is about as identical as you can get, but if you measure your new brass, you will find a variance in length. There is also a variance in volume. Caused by spring back, location in the storage barrel, or whatever part of the manufacturing process, there can still be a variance. The specification has a tolerance and cost dictates how tight that manufacturer is keeping their tolerance. Cheap brass vs expensive brass. But even the expensive brass still has variation. The only way to ensure your brass is as closely the same as possible is to go thru the steps of uniforming. Sizing, turning, trimming, etc. If you don't, you can get that occasional blip in the chrono. You could still end up with a blip, but they should not be the norm if you have inspected your good brass, nor should they be frequent if you are meticulous in your brass prep and loading techniques. In my experience stated above, I went through all of the normal routine, EXCEPT I did not size and prep my new brass like I should have. I paid for the error with pressure spikes every four or five shots that made opening my bolt rather hard. Once the brass was prepared properly, I had no further issues. Same load shoots fine today.

It doesn't take much variability in the case to change internal ballistics. I can go thru my shooting log and come pretty close to identifying when I full length sized some of my brass vs. neck sizing. In my 6br I neck size about 4 times, then have to full length size. After full length sizing, I have a little higher pressure which flattens my trajectory enough so my sight settings are different. A few thousandths of an inch in shoulder bump = blip. New brass is no different...in my experience...one brass a little different than the others = blip.

Steve

 

[savagedasher]

?

The question was asked why causes it.whe was loading 308 some brass would be hot and the other fine just changing brands .
. The 6.5 Wssm was by far scarey .. Larry