Magnum Rifle Primers

[truck driver]

Just starting to load for a 338Wm and was wondering if I need to use magnum primers in my load work up?
The powder of choice is Alliant Reloader 17 and H4350.
Thanks for any help.

 

[243winxb]

I would guess, use a mag if ball powder??

http://www.shootingtimes.com/ammo/ammunition_st_mamotaip_200909/

We tested loads at both maximum normal pressures and at the starting loads (some labs calculate start loads—we shot them). Standard primers caused no ignition issues at the max load but posted higher extreme variations in pressure and velocity in the lower pressure regimes of the start loads. In extreme cases, the start loads produced short delayed firings—probably in the range of 20 to 40 milliseconds but detectible to an experienced ballistician. Switching that propellant to a Magnum primer smoothed out the performance across the useful range of charge weights and completely eliminated the delays.

Read more: http://www.shootingtimes.com/ammo/ammunition_st_mamotaip_200909/#ixzz4jnb4TMxW

 

[John S]

My .338 Win Mag is a HAMMER and has accounted for a number of one shot kills. It is a Model 70 Classic with a 24" Kreiger.

I use Federal 215 Primers, Lapua Brass with Barnes 210 TTSX's and IMR-4831. I run the Barnes TTSX 0.060 off the lands. Groups for three shots at 5/8".

225 gr AccuBonds work great with 70.0 grs of H-4350 and Federal 215's. The AccuBonds are seated almost touching and are giving 2750 fps.

YES use Magnum primers..............................

 

[truck driver]

Thanks for the links and info. This is my first real adventure with a magnum rifle cartridge and though I do use magnum primers with ball powders I never had to us them with most non magnum rounds.
The 338Wm is a hammer in more ways then one. I have gad it in three different stocks trying to get it to group consistently. First I thought it was me or my reloads but then I noticed it would shoot good for a few groups and then start jumping around. I could feel the rifle flexing when it fired so I tightened my grip thinking I was holding it too loosely on the bags. This helped a little but not much so I put it in a pillar bedded Hogue stock thinking the pillars would settle it down. There again I noticed the same effect and the felt twist was even worse. Put it back in the factory synthetic stock and filled the forearm with carbon arrow shaft pieces and epoxied the entire forearm and barrel channel. The groups improved but still not great so I worked on the action bedding around the tang since it was tight in this area and could cause a second recoil lug. Put it back together torqued the action screws and the groups improved but as I shot it the POI would start to wonder. Brought it home took the action out of the stock to see if there where any rub marks and put back together. Took it to the range for a optimum powder test of ten rounds to see if I could find a node. Half way threw I noticed the POI was wondering, While waiting for the barrel to cool I retorqued the screws and found the tang screw was backing out so I reset it and the group stopped wondering.
So now I knew what 90% of my problem was.
Stopped at a local gun shop to get some thread locker and they had a H-S Precision stock on the rack with a full metal bedding block for it so it followed me home.
I put the barreled action in the new stock after minor sanding and went to the range. Group size shrunk and it held POI with every load tried. The screws didn't back out of the action since the action was now tightened down to metal on metal.
The rifle which I failed to mention earlier is a Ruger 77 MK II Hawkeye all weather. It is now shooting 3/4" groups with it's favorite load.