I have always stayed with what Sierra has tested and printed with no problems but recently I have found that their load data for the 300 SAUM does not work in my rifle. I was loading 60.5 grains of H4350 and used the magnum primer as recommended and loaded the 168 TTSXs. The velocities were averaging 2920 and the groups were very good (.135 and .162)at 100 yds. The problem was that the recoil was very bad and the rifle would almost jump out of the front rest.

With the powder charge well below max I assumed that the CCI 250 primer was too much that weight of powder for my rifle.

I decided to load a faster powder (760) and try and standard primer. I used 61 grains of 760 and a CCI BR2. What a huge surprise. The first shot with a clean barrel and grafoil was very smooth with straight back recoil and no muzzle jump as before. I looked and the chrony and to my surprise it showed 3014. This had to be a fluke. Second shot was 3020 and nice recoil again. Then 3032, 3036 and 3044. My first shot is always slower after using grafoil so the numbers are correct. The best part yet is the final three shots after fouling were a 1.25 group at the 300 yd target.
Another thing that I noticed was no carbon on the necks as before. Not sure how to explain this but the necks must have sealed quickly as the burn started.

I believe that when a case is borderline magnum capacity that the magnum primer is just too much starting power. At least in this case.

I have no experience with the 300 SAUM at all, but I have to question your quick assumption that the primer used was the reason for the change in performance.

If I read your post corrrectly, you changed two parameters at the same time. You not only changed primers, but you changed powders as well.

I totally agree that the magnum primer is not needed in the 300 SAUM. However, maybe it was just the combination of 4350 and the magnum primer.

I am glad you are happy with the results, but changing two or more parameters at once often creates more questions than answers.

I have been using magnum rifle primers for a while now in all of my rifles and have experienced no problems.

I did try the 60.5 gr of 4350 with the standard primer and the velocity was 2850 and the recoil did calm a bit but not as much as the 760 and standard primer combo. The speed difference is still quite a surprise at over 3000 and less recoil. The good thing is that I stumbled across something that works great and thought I would share it.

I shoot 270 & 300 WSM and noticed long ago that both give better performance with standard primers.

Dwight,

You have an over-active imagination when it comes to recoil. The fundamental physics simply won't support your perception that recoil was substantially different.

Dwight, sometimes changing primer won't make a nickles worth of difference, other times, the difference can be very profound.

In general, single base stick poweders, like H4831, or H4350, will prefer standard primers, where a ball powder such as w760 will tend toward something hotter, like a match or magnum primer.

Ultimatly, it's up to your rifle to decide what it likes.

No over active imagination on recoil. The different loads had very different effects. It was like two different rifles. I think the column must have a lot to do with it. The old typical magnums are longer and these short fat cases are different and short on volume. The SAUM is on the short end of the magnum list anyway. I am just glad I tried something different that had a great benefit for this rifle. It may not work for another rifle but then it may so that is why I posted in the event someone else may want to try it.

primer heat chart

Federal 215 Hotter
WLRM
CCI 250
Rem 9-1/2 M
WLR
Fed 210
CCI BR2
CCI 200
Rem 9-1/2 Cooler

By coincidense I posted a thread on the reloading forum asking "How many here use standard rifle primers instead of magnum primers in large magnum cases?".
I was wondering what others have experienced, especially those in much colder climates. I previously used mag primers on my hunts in CO, Wy and Utah in my 270s but am starting question the need for same in even larger cases like a 338 WM and 375 H&H or anything for that matter.

I chrony a fair amount of my loads and I have never been able to see much if any difference between the magnum primers vs. the standard primers as far as veloctiy or noticable pressure signs. In many instances the velocity has even gown down some using the mag primers.

I did have a instance with H-414/CCI 200 std. primers in some 30-06 cases the were very mild loads. I was playing with the Lee powder dipper using Lee's recommended load. There was some serious "hang fires". (I found out that I DID NOT have a flinch though as I still shot MOA - LOL) I haven't tried the same load with mags but think I will do so just to see.

Take a look at my 9.3x62 post and I got exactly the opposite. Go figure.

Brad

Brad,
I never have really thought of the X62 as a magnum. I was more asking in the reverse, a non-magnum primer in a so-called magnum case like a 300 winney or 338 wm or even larger. I tried some CCI 200 primers in my 338WM and the velocity was virtually identical to the 250 primers. But then again I am using compressed loads in the winny cases.

I use magnum primers in my 22-250s w/H-380 and in a couple of my 270 Win. and a few others. All go boom just fine and no problems. And no noticable difference in accuracy. A couple of times I've had the groups open with the mag primers, then I would load everything the same except used non-mag primers and the groups are almost identical which told me it was time to clean or it was the wind or heat related distortion of the target image in my scope.