how much has anyone decreased or increased in a group size just by using a different primer with the same powder charge..?

This ought to be a lively topic.

I recently tried CCI BR2, Winchester Large Rifle Magnum and F215M's in my 300WSM to see what the difference was. All loads were the same other than the primer. The only difference I got was the POI. The point of impact changed but the groups all looked pretty much the same. Other than this brief experiment, I have never really tried switching primers.

I have found out recently just how important the right primers are. I think that it could have a effect. I will be changing the primers in my 270 load to mag just to see what effect it has. People way smarter than me think primers can do something because they make so dang many of them. If you are talking a small volumne I would use small primers ( the primer is suppose to ignite the powder not move the bullet) I would talk Alston at CCI about case volumne to primer if I was you.

quote:

how much has anyone decreased or increased in a group size just by using a different primer with the same powder charge..?

Once upon a time, I'd worked up a load with 200gr BT's and H4350 with my .338 Win Mag. It was consistantly shooting submoa, but then all of a sudden it went to 3" groups at 100 yards. I checked EVERYTHING, and couldn't figure out what had happened. That's when I realized I'd accidently changed to Fed215 primers, when I had been loading WMRP's.

I switched back to the WMRP, and the groups returned to sub moa.

In my STW with the Ball surplus powders, it will group 1/2 moa with Fed 215's, but not worth a darn with any other primer.

In my .270, and my wife's with H4831, and NBT's the between WMRP and CCI 200 is MOA with WMRP to 3/8 MOA with the CCI 200.

Yes, it can, but will not always, make a huge differnece.

A S do you think the federal are much hotter than say CCI 250. Is there a big difference in Federal 215 and 215m. I'm just wonder if the 215m would tighting up my 7mm rum groups.

MD, Yes, I belive the Fed 215's are the Hottest over-the-counter primer we can buy. I think they are even hotter then the 215m's. In the STW I thought I might improve my groups by going from the 215 to the 215m, but the groups enlarged a bit, so I went back to the standard 215's.

Rumor is that Remington has a hotter primer they use in their RUM ammo, but it's not sold to the public. I'd sure like to try it and see how it works.

Somewhere there is a thread that shows the briance (if that's a real word) of the different primers against a dark background. There are some dramatic differences.
However, what effect the different intensities would have has to be determined in each rifle.

quote:

Originally posted by wasbeeman:
Somewhere there is a thread that shows the briance (if that's a real word) of the different primers against a dark background. There are some dramatic differences.
However, what effect the different intensities would have has to be determined in each rifle.

Here is a link someone on 6mmbr experimented:
http://www.6mmbr.com/PrimerPix.html
Wish they had done so with a larger selection
of primers, though.

Has anyone run the primers over a chronograph see if any difference in velocity that might effect accuracy.

Recently I was working up loads for two different 223s; one a 24" heavy barrel varminter, the other an 18 1/2" light weight. Chronographing identical loads with CCI standard and magnum primers, the magnum primers were consistently about 50 fps faster. Loads using H335 were more accurate using magnum primers; loads with Varget and Benchmark were more accurate using standard primers.

Large Rifle Small Rifle
HOTTEST

FED 215 hottest larg rifle

FED 205 hottest small rifle

WLRM - LR
REM 7 1/2 -SR

CCI 250 - LR
WSRM - SR

REM 9 1/2 M - LR
WSR - SR
WLR - LR
CCI BR4 - SR

FED 210 -LR
CCI 400 -SR

CCI BR2 -LR
FED 200 -SR

CCI 200 -LR
REM 6 1/2 -SR

REM 9 1/2 coolest -LR

Rem 7 1/2 was more accurate than CCI400 in 223 Rem. The CCI also showed pressure signs sooner. Article on Primers

quote:

Has anyone run the primers over a chronograph see if any difference in velocity that might effect accuracy.

Tom, in the .270 I've got 100 FPS difference between the CCI 200 and Winchester Mag Primers.

But the CCI's shoot better, so that's what I use.

Depending upon yout expectaions and tolerances, that is--if you consider .1 MOA a significant change, or if you are trying to shoot a can at 100 yards or a deer at 200----

In custom built BR F-class and varmint rifles:

If you work up a load using one set of components and get it to the best grouping--velocity and chronography notwithstanding, then suddenly change one of the components--you will get a different result.

A hunting/plinking/off the shelf rifle may not show much if any, change.