SmallCaliberCentral

I have my ideal load worked out using 26gr RL 10x under 39SBK and was using CCI magnum primers. I still have plenty of the magnums left, but was wanting to try the Remington 7-1/2's. My loads previously have worked very well, but I have seen some of the primers get a bit hairy. My thoughts are that this was temperature related even though 10x is supposed to be stable.

My question is theoretical. Would magnum primer tend to be more aggressive and maybe the 7-1/2 tame things down a bit? IIRC the magnum is a thicker primer so I hate to see the thinner Rem primer give out. I know I know work up to it, just looking to theorize a bit...

TDM, I've used 7.5's in my 223 case family cartridges since they were introduced in the early 70's with perfect results, using 10X, H335, W748, H322 and the other powders suitable for this case.

On the other hand, even with ball powders, I have never used a magnum primer in the 223 case family in my entire life....never seen the need in such a small case.....they're just not usually necessary. (In some very cold conditions with ball powder, they may be useful, or with some difficult to ignite powders). I use Rem 6.5's in all my Hornets for the same reason....small case, mild primer.

You'll have zero problems with cup thickness using 7.5's in the 204 Ruger, it's about as perfect match as you could get. Not sure why you ever went with mag primers in the 204 in the first place. I've never seen them recommended in any manual for the 223 case family. You must have had a reason, I'm just stumped trying to figure out what it may have been.

These were my first primers, and I read the primer comparo showing wall thickness. I forget who, but you know the one. Also availability. They were available locally. Magnum means bigger and bigger is better better right

Got it....was not aware they were the first primers you ever purchased....sorry.

The 7.5 primer was developed for the high intensity 17 Remington, and as such was designed with a thicker cup as you note. When I use Fed 205M's with the same load, I clearly see the pressure difference because of the slightly thinner cup.

You'll have no issues with the Rem 7.5 in the 204 Ruger in regard to cup thickness/pressure with any book load.

I stocked up a while back and got 5,000 7-1/2's along with 5,000 Federal 210? large rifle BR and 5,000 CCI BR for large rifle. I'm set for a while as I don't shoot all that much.

I have hundreds of the CCI Magnums in small and large to use up.

Thanks for clearing up the 7-1/2. I had stopped with 40 samples thinking I'd hate to run the loads and find out the primers weren't up to the load.

I remembered reading a good article about primers that should cycle through here once in awhile. Here ya go in case you haven't seen it. Take particular note of how hot the Rem 7 1/2 primer looks in the pics, and the pressure standard deviation on the 7 1/2 in a chart towards the bottom. I've read about how old boxes of 7 1/2's were labeled MAGNUM, and how it used to be considered a magnum primer, because it is rather hot, and does have a thicker cup, like the CCI 450. The way the article reads, none of us should ever use anything but 7 1/2's, but I suppose as each rifle is different, and what is good for one isn't for the other, everybody has their favorite primer for a given task. I haven't been reloading long enough to notice much difference in accuracy from any of them, so I can just go by what I read most of the time.

Interesting article. I'll try to read it thoroughly soon. Too bad no CCI 450 magnums

TD-Max wrote:Too bad no CCI 450 magnums

Yeah, I noticed that, but figured it might be of interest anyway. That pic of the flame coming out of the 7 1/2 sold me. I'd bet the 450 isn't that hot. I also wonder if it may not really matter what it looks like when it has plenty of oxygen to burn outside the case like that.