switching the primer on load data

Mr. Friendly

Mr. Friendly

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the Lyman manual says no-no on that, being a primer change can create a very different response. so with that in mind, what does one do when they want to try a different primer than the one the load data is built on? for example, a lot of the data in the Lyman is based on Winchester primers. what do I do if I want to try CCI?
 
myself i would drop a grain and work up. if its a max load already drop 2 grains. never found primers to make that much difference.
 
I always go with mid range loads and been using CCI for primers. I refer to Lee reloading book as well as hodgdon’s. When I did switch primers to winchesters, didn’t see any noticeable changes - don’t have a chrony though.
 
roadcarver said:
I always go with mid range loads and been using CCI for primers. I refer to Lee reloading book as well as hodgdon’s. When I did switch primers to winchesters, didn’t see any noticeable changes - don’t have a chrony though.
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well the Lyman manual was quite clear in its warning that using the same data but different primer is a no-no, but they didn’t advise on what to do if you wanted to change the primer.

however, they also say not to go below the starting load as doing so could result in a charge that is not adequate to exit the barrel, and yet that’s the recommendation Im getting here, which is ironic. :p

but as mentioned, better safer than sorry!
 
primers do not make a big difference, unless it is a load that needs a magnum or hot primer, like a light bullet over ball powder.

For ordinary loads I would try the new primer with the old load and also plus or minus a half grain to see what works best.

In your case, the Winchester and CCI primers are quite similar. Just change and carry on.
 
I've loaded many thousands of rounds of ammunition and have never once ran into problems because I changed primers, even when going from a standard large rifle primer to a Federal 215, which is arguably the hottest primer on the market. If you've worked up a load to where pressure signs have become visible, flattened primers, or a shiny extractor mark, but short of a sticky bolt, then back off a full grain and call that your working load, you have taken care of variances in bullet weight within make and style of bullet, case capacity, lot to lot powder burn rates, and primer bisance.
 
Ganderite said:
primers do not make a big difference, unless it is a load that needs a magnum or hot primer, like a light bullet over ball powder.

For ordinary loads I would try the new primer with the old load and also plus or minus a half grain to see what works best.

In your case, the Winchester and CCI primers are quite similar. Just change and carry on.
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Agreed. The only time I change up is if switching to / from a magnum primer.
 
The inconsistencies from brand to brand , type to type make this almost a non issue in my opinion.

Some "magnum" primers burn colder than some "standard" ones and vice versa.

http://www.6mmbr.com/primerpix.html

The only thing I can say is consistent is inconsistencies between types/brands and their designation.

I have switched primers flat out on proven loads for my rifles.Years ago I posted results on here from my 338, I will try find the thread...wish me luck.

https://www.canadiangunnutz.com/for...200-primers-photo-comparison?highlight=primer

Not exactly what you were asking but there was some difference.I should do this test again with the chronograph for a few proven loads.

By my calculations that change in point of impact equated to 50 ft/sec and 1.7 less velocity in the load, hardly anything to wet the bed over safety wise.

I'm sure in a smaller case it could be slightly more pronounced.
 
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I ordered primed brass 308Win with Fed 210Match primers. They did not have 40,000 Federal primers, but did have Winchester standard primers. I tested with those and found velocity was 25fps faster with similar SD and ES numbers. What's that? About 1/10th of a grain of powder difference?
 
There's a difference but not enough to warrant a full rework of your load. I'd only be weary if the load was over max. I recently went from CCI 400 to Federal 205M in .223, with Varget the optimal load was 0.2 grains lower with the 205M. So yes, as has already been suggested, start 0.5 grains under your current load and take it from there. Unless you're at near or max load, then I'd be more careful.

Changing casings is a whole different story though. Again in .223, switching from Federal (AE) to IVI (16) resulted in an optimal load 2.1 grains lower than the original. There's a significant difference in case capacity between the two though.
 
I only load pistol at this point. I have used magnum large pistol primers where a standard was called for when using slow burn powders like H110 or Lil Gun, but I've never worked up to max charge... always stayed near the lower end when a magnum primer was in because they aren't called for in any of my loads... but they sure group better.
 
If your approaching max or at max back it off and try the new primers. Primers can have a huge impact on certain load combinations. If it's particularly hard to tune round I will back down again. A friend of mine was having crazy issues with Fed 215M in his 7MM Rem Mag, he decided to switch to CCI and it went from patterning like a shotgun to shooting solid groups. Powder, charge weight, brass prep, and bullet weight and seating depth all stayed the same. We could never figure that one out really, sometimes just taking yes for an answer is the solution.
 
I don't bother with load alterations with primers. Sometimes I'll chrono loads for IPSC shooting but generally if it hits the target satisfactory I"m good.
 
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