Primers and Accuracy

S

Stob

New member
Has anyone ever tested different primers and realized real accuracy increases? If you are using magnum primers or regular, comparing different brands, have you found real and repeatable accuracy improvements?
 
With some of the "informal" testing I've done with loads, one change, such as a different primer (use 205's instead of 400's) with everything else the same, there are differences, but nothing earth shattering. I have to wonder [beeep] that even [beeep] everything is the same, such as same brand of brass, it's not the same case as these cases have been shot 1x time, or while still in the same "lot", it is a different piece of brass. While we "say" everything is the same, it's really not as we can't reuse that bullet from last time, nor the powder that was used. I know, going way to far on the analysis, but...

It's fun and interesting to do this, as you may a combo that works a lot better or worse. You won't know until you try.
 
My neighbor and I reload right at the rifle range, we have a heated and AC house to load and shoot from.

Changing primers on a load is very, very revealing to say the least. Primer choice can make a huge difference if you are looking for small groups. Weird thing is that it is more often than not, hard to predict what will work the best or give the smallest SD.

You can see a big difference between a Winchester primer and a CCI 200, again with the fed 215, and again with a Win mag primer.

9 1/2, CCI 200 will often give similar results, then a Fed 210 is a softer flame and will show another change.

Putting up a chronograph while you are changing primers is a reality check to say the least, as some primers may show HUGE extreme spreads, some with very low spreads, and some primers just will simply blow the group altogether.

If you have the mind set that you are going to use just one primer, you are deaf, mute, and blind.

Of course, if you are just looking for 1 1/2" groups, or shooting a rifle that has been through the Indian Wars, primers are not that important.
 
I generally do not test just primers. But I do not have 1000 yard shooting access,actually nothing over 500 yards. For big game, any load consistent under 1 moa is done deal. Fur rifles need to be better 1/2 moa is fine. 30-40 fps deviation does not matter inside 400 yards. I did try 3 different primers during load work for a 223 for last summer's prairie dog shoot. The switch to CCI 450 moved a 53 gr vmax load from .3-.5 to .25 average on 3 trips to the range. I do have one main rule, if a group vertical strings(tracked shot to shot) I always continue load work even if the group size is acceptable.
 
I have found measurable differences. It is especially noticeable with tight shooting rifles. I'll use whatever is handy for my big game rifles but I'll stick with certain primers for varmint and target rifles. Without looking at my notes I'd say the differences can be as high as .5 and .75 inches.
 
In August, I had my T-C Icon in 243w at the range. The load was WW brass, 70gr Btip, 41.5gr CFE223 (max load) with brass trimmed and weight sorted.

With a Rem 9 1/2 primer, I got a .244" group.

With a CCI 250m, the group opened to 1.54".

Guess what this years coyote load will be in the 243?

That is one of the wider accuracy swings I've seen when switching primers though.

I never know what small change I make can return large results like this.
 
I did a similar test today with my Remington Sendero 25-06. My load was 53grains of H4350, Winchester brass and 90 Sierra BlitzKings seated .015 off the lands. Three shot groups at 100yds. Also had a full value wind from left to right at about 15mph.

Fed. 210M- .812
Fed 215 magnum primer- .1.098
CCI 200- .179
Winchester standard- .839
I really didn't know a primer could make that much difference until today. Never to old to learn.
 
You fellas do realize, that you need to do a work up with each primer, then compare all the groups against each other. Just switching the primer on the same charge, shows the changes, but may not be fair to one primer over the other.

Load testing in 15 mph crosswinds? How much horizontal group spread was caused by the wind and mirage? I know your from Oklahoma, but try to do your testing in better conditions.
 
When does the wind in Oklahoma not blow? If I wait on a calm day, I'll never get to shoot. Actually had very little horizontal but did have vertical in the open groups. The CCI group was just a very small clover leaf. I was just curious if it made that much difference.
 
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If it's just one group with each primer I would be somewhat skeptical especially if conditions aren't ideal. However .179 is an awesome group, congrats.
 
I'm just saying that, using your post, you may find that when you back down a full grain to 52 grains, the Federal 215's may shoot little groups, while the 210's may shoot better with a 1/2 grain more or less powder than the 53 grain load.

Wind and mirage will do more than most think even at 100 yards.
 
Not arguing, your right about working loads. It was just one of those, lets try and see what happens thing. I just didn't think it would make the differences that I saw by just using different primers.
 
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