Major Difference in Primers

[DKSDonnie]

I recently found a very good shooting combo in my 7MM WSM. I was using WLRM Primers and following the Nosler book for my load development and had discovered a sub 1/2" group at 100 yds. I sat down and loaded a few shells to now sight the rifle in for deer season. Expecting some very satisfying groups, I was sadly disappointed. I recently ran out of WLRM primers so I used CCI 250 primers. Reading diff blogs I found that some reloaders found very minimal changes in their ballistics and groups and thought, What the Hell, let's see what happens. The load was the low end of Nosler's powder listings so I saw no need to lower any further. I wasn't worried so much about velocity changes as it shot so well in the rifle. I have included a pic of the group shot that I intended to use with the WLRM Primers and a pic of the groups i shot this past weekend with CCI 250 primers. Unbelievable difference. Nothing was changed other than the primers. All groups were shot with exactly the same form and time between shots. Notice also how I marked each shot and how the same number in each group is basically in the same spot on the target for that group. WIERD! Anyone else ever seen this. I was surprised to say the least at such a diff.

 

[badkarmamib]

With only horizontal stringing, I would look at the scope rings and bases for tightness.

 

[Blue68f100]

Did you have a different ambient temperature? I've shied away from RL-## powders due to high temperature sensitive, some have almost 2 fps/deg. I've had loads that shot like yours at 80F, but at 95 looks like your CCI primers changes. I also started blowing primers too at the higher temp, was not at max load either.

 

[Nature Boy]

Primers make a difference.

I recently did this as a part of my 6BRA load development

 

[ArchAngelCD]

I shoot a lot of 30-06 and use both CCI200 and WLR primers, they are not magnum primers but they are CCI and Winchester large rifle primers. Under the same conditions I can't shoot the difference.

I agree primers can and will make a difference but I have never seen quality primers show such a large difference. Something else must be at play here other than primer brand IMO.

 

[Nature Boy]

Here’s another example of the difference primers make with a different rifle (FN SPR .308)



In my opinion, if you’re loading for optimal accuracy you have to include primers in your development routine

 

[DKSDonnie]

Did you have a different ambient temperature? I've shied away from RL-## powders due to high temperature sensitive, some have almost 2 fps/deg. I've had loads that shot like yours at 80F, but at 95 looks like your CCI primers changes. I also started blowing primers too at the higher temp, was not at max load either.

The sub 1/2" group was shot at temps in the low 50's and the (3) groups I shot this past weekend were shot at around 80 deg. We shot in the shade. Ample time in between shots. Gun was laid barrel up with bolt open and I made a fan for cooling the barrel from an air mattress pump. Barrel never got hot enough that I couldn't put my hand on it and leave it there indefinitely. The fps jumped all around the place. 1st group ES-52 fps, 2nd group ES-68 fps, 3rd group ES-46 fps. The lowest fps was 2,857 and the highest was 3,183. The very first shot coldbore was 2,882 fps. All ammo was kept in a cooler to keep ammo cool and was never put into the chamber until ready to pull the trigger to keep ammo from cooking. You would think the fps would climb from 1st to 3rd shot if it was heat related, but it didn't. Sometimes the 2nd shot was faster and sometimes the 1st shot was faster. So the real only variables were the primers and the ambient temp. Primers looked perfect. Still had rounded edges with no cratering and no flattening at all.

 

[DKSDonnie]

With only horizontal stringing, I would look at the scope rings and bases for tightness.

Rings and bases are tight. Checked that also. Notice each shot though. The 1st shot of all 3 groups is in the same basic place and so on. 2nd shot location and 3rd shot location of each group. I'm right handed and I figured stringing would walk to the right if it was trigger pull. I think it was harmonics.

 

[Nature Boy]

Here’s another I shot with my FN SPR



I know there’s some that subscribe to the opinion that any old primer will do as long as it goes “bang”.

I’ve observed enough to believe otherwise.

 

[SamT1]

Hows the float on the stock? A pattern of horizontal stringing that’s that consistent screams hardware issue.
Since it returns to zero between groups I’d bet it’s heat related.

 

[DKSDonnie]

Here’s another I shot with my FN SPR

View attachment 801629

I know there’s some that subscribe to the opinion that any old primer will do as long as it goes “bang”.

I’ve observed enough to believe otherwise.

I never thought about it, but groups like this have opened my eyes to something I would have never thought would make that big of a diff. I've always used winchester primers and it looks I will continue to do so. Thanks for your pics.

 

[DKSDonnie]

Hows the float on the stock? A pattern of horizontal stringing that’s that consistent screams hardware issue.
Since it returns to zero between groups I’d bet it’s heat related.

Sam, the more I keep looking at the groups I really think it had a lot to do with heat. If u just look at the first shot in each group and then just the second and finally the third, It's not a good group, but not a bad group when u group them by number together. It screams heat on the location of each shot and maybe diff primer on the tightness of the groups. Maybe just a combo of both. Great point. I've read where some guns will shoot for a long time very well when hot but others don't. I have a 270 wsm and it has a much thicker barrel and it will shoot very well hot or cold. It's a Savage Model #11. This gun is a Browning ABolt 2 in 7MM wsm. It has a pixie stick for a barrel. It's also bedded from factory. From the replies on this, it seems that changing primers primarily change group size but are not causing stringing. I'm going change the only variable back to WLRM's and wait till it cools down some because here in Maryland where I live, it's 102 with a heat index of 122 today. I'm not even going to shoot my crossbow in this heat. Thanks for the reply!

 

[DKSDonnie]

Here’s another I shot with my FN SPR

View attachment 801629

I know there’s some that subscribe to the opinion that any old primer will do as long as it goes “bang”.

I’ve observed enough to believe otherwise.

Incredible how much hotter those Fed's are! Almost 300 fps gain. Am I reading that right. I believe it's time to include primers in my load development. I read on another website, a fellow shooter shot 1/2" groups with Winchester primers and tried CCI primers and his groups went to 3 1/4".

 

[Nature Boy]

Incredible how much hotter those Fed's are! Almost 300 fps gain. Am I reading that right

No, that's my chicken scratch. The Fed 210M was 2,532 fps

 

[cougar1717]

The sub 1/2" group was shot at temps in the low 50's and the (3) groups I shot this past weekend were shot at around 80 deg.

The good thing is that you definitively found a combination that your rifle doesn't like.

As a THR poster and because someone hasn't said it yet, I feel obligated to say, "Start low and work up, even for just a primer." haha

It's time to shoot a "control" group with the WLRM against the CCI 250's to see if the WLRM's remain sub-moa at 80 degrees. The WLRM load may not shoot the same at 80 degrees either.

Or work the load back up with the CCI 250's.
Or wait for a cooler day to check the WLRM load.
Or leave it be since all groups are plenty accurate for deer hunting

 

[DKSDonnie]

The good thing is that you definitively found a combination that your rifle doesn't like.

As a THR poster and because someone hasn't said it yet, I feel obligated to say, "Start low and work up, even for just a primer." haha

It's time to shoot a "control" group with the WLRM against the CCI 250's to see if the WLRM's remain sub-moa at 80 degrees. The WLRM load may not shoot the same at 80 degrees either.

Or work the load back up with the CCI 250's.
Or wait for a cooler day to check the WLRM load.
Or leave it be since all groups are plenty accurate for deer hunting

I'm going to try to pick up some WLRM's and shoot this weekend. It's supposed to be the same weather and temps as last weekend. That would give me a control group. Well, like I stated, the load i found to be very accurate was the lowest load for that powder in the Nosler book so I left it at that load not worrying much about pressure problems. That's why I usually like to shoot during the winter when it's cold and you can take the heat variable away. At least if I look at the first shot on the 3 groups, that would kill any deer just about anywhere.