I just picked up my new BA110 in .300 Win Mag. I have been shooting .308, .338 Lapua and .408 Cheytac for sooo long I haven't a clue on the .300 WM basics (let alone any other caliber) but feel I have a pretty good start except for the primers. Some say use standard LR while others say that's absurd and use only Mag primers and then there are those that say depending on the powder. Sounds kind of odd to get so many different opinions. Being a "mag round" I figured on using a "mag primer"?

Your thought?

74.0gr of RL-22 and Federal 215 Mag. primers are my loads with 180gr Accubonds from my 300WM.

I have only used the 215 primers
If I switched, I'd still use a MAGNUM PRIMER.

I use both STD and Magnum L.R. in the .300 Win.
I experiment to gain the best accuracy using both, but feel more comfort with a magnum primer for hunting, especially in cold WX.
I've always prefered the Federal 210M and 215M but, have used others because primers are hard to get. I've never had a problem with any, except some differ accuracy wise.
I DO prefer a magnum primer for any "ball" type powder, but have used STD without any problem with the "ball" powder. One just has to experiment. GOOD LUCK .

Use what your reloading manual says!

I always us a magnum primer in a .300 Magnum regardless!

I figured a mag primer was in order here. This gun (below) will not be used for hunting but for sniper competitions (tac/range). I have been pushing my .308 out to 1000 yards then switching to my .338 Lapua thereafter but the .308 is really ideal and very consistent to 800 yards but only score in the mid A20's (6/10) with it at 1000 yards. So I choose the .300 to work in the 800 to 1100 range in hopes of picking up my score. So I plan on going through my typical load development full range ( IMR 7828, 4350, H1000, R22, Mag etc.) Starting with the Sierra 190 Grn. BTHP (MK). I have a large stock of Fed 215 so I think I'll start there. Generally I try to use only one primer in development. To me it kind of closes the variables so I can focus on powder (s) and bullets and of course all the other fun stuff like free-bore, head space, FL sizing/fire-form etc.

Thanks for the input!

I shoot a .300 Winny as does 8 of my Elk hunting buddies. We use Fed 210M primers. They kind of follow my lead and when I use Fed 215M primers I blow my group from pin point accuracy to 1 inch or more at 100 yards. These rifle are all Model 70 Winchesters and all but mine have the Boss accuracy system on the barrel. For what it is worth to you, this is the way we do it, and have for 37 years. Good shooting.

quote:

Originally posted by WhatThe:
...I choose the .300 to work in the 800 to 1100 range in hopes of picking up my score. ...

Hey WT, I've always had excellent accuracy with the Fed-215M in some Loads, the Rem 9 1/2M in some and the Fed-210M in others.

Due to my 300WinMag experience, you will have to try a few different kinds of Primers and see which one performs the best for you. Testing various Primers and Seating Depths comes at the very end of my Load Development cycle for Fine Tuning.

Normally I'm happy with which ever Primer I start with, but once the distance goes beyond 600-700yds, every segment of the Load matters much more. So, when I'm happy with the results based on an initial Random Selection of the Primer, I appreciate it happening quickly, but am typically surprised.

Best of luck to you.

If it's got a belt, I use a mag primer of one brand or another. Usually CCI. I've played around using some mag primers in standard cartridges but never got the dramatic effects that some have posted.

I tried the large rifle that the Lyman manual said but got much better accuracy with the WLRM primer.

I use Mag primers on anything 300 WM and up with a belt. 70 odd grains of powder is a lot to set off and if I end up in cold weather I want that extra spark.

Greg

Wow.. What a difference a primer can make! As I said, I would start with the Fed 215M and work my loads from there. Did a full range (min to max) on several powders for the Sierra 190 MatchKing and found that the bullet liked to be spit out at about 2950 to 3050 FPS but even inside of this it was a struggle to maintain consistent grouping. Went home with my tail between my legs thinking maybe my barrel was bent. At this point I would usually switch bullet weight (perhaps the 200) but since all the shops were closed and my stock was limited to zero, I was at a stand still. Since the only other variable I had (at the time) was to try a different primer since I had the powders and plenty of 190 Gr. bullets. My groups were immediately better right from the start and after working through the loads I think I found my load for this gun. Federal case, IMR 7828 SCC 72.8 Grns. (2989 FPS), Sierra 190 Gr. (MK) (off lands .575) and Win LR Mag primers! This group of 7 came in at 2.75 @ 300 yards. Just goes to show you, or remind you how every thing can make a major difference in accuracy!