Enlarged primer holes, magnum powders in subsonic rifle ammo

[Tackleberry41]

I see many advocate drilling the primer holes w subsonic ammo, as well as using magnum primers for better ignition. But it is far from a consensus. Was reading an article, can't find it now of course. But they said drill em and run mag primers. The subsonic I have been loading for my mosin, I have not been drilling them, and running standard primers. With a 200gr cast using S1000, I just have alot of it, 8.2gr gets me avg of 1045 fps. With a very low ES, last time out it was only 6.1fps. I do weigh them, vs using a measure. I can't imagine it burning better than it is now. I was trying some NOE 230gr last time, 9gr of S1000 got me avg of 1019fps, again hard to beat an ES of 8.7fps, a can on the end cut the ES in half.

Question is for those loading ammo like this, does anybody else enlarge primer holes or run mag primers? Is there some advantage other than a better burn in large cases? 7.62x54r is pretty big, Im not using any fillers and that much powder takes up very little space.

[Calamity Jake]

Never seen a need for mag primers with cast unless I was using a real slow hard to lite powder which I don't.

Have never drilled flash holes either except for some 38 special brass I used for primer propelled rubber bullets
for indoor low noise practice, drilling the flash holes kept the primers from backing out and locking up
my revolver.

In my military bench rest loads with cast the primers back out a little but it doesn't hurt anything,
drilling the FH's would stop it but why bother as I would need to keep that brass separate from all
other brass.

[Larry Gibson]

You won't need the enlarged flash holes with a rimmed case as it's to prevent the shoulder from setting back on cases that headspace on the shoulder. The mag primers are for better ignition with the slow burning hard to ignite powder you are using.

Larry Gibson

[Tackleberry41]

Solo 1000 is up there with the red dot, green dot powders in burn speed. If it was hard to light at the low load levels without fillers I would have known long ago.

The article: http://members.shaw.ca/cronhelm/DevelopSubsonic.html

The enlarged primer holes was for primer set back due to low pressure in a large case. Just curious if anybody else going to those lengths? Or found the need to? I have some S&B brass, it won't take a rifle primer, might try those to see if there's any difference in this limited application.

[35remington]

Supersonic or subsonic is not the determinant of when flash holes need to be drilled. Low pressure is.

Only some but certainly not all rimless cases apply. Do not alter rimmed rifle cases.

[Tackleberry41]

The rifles I use subsonic are all rimmed. Just curious what others are doing.

[35remington]

Have a 308 and a 35 Remington that have never backed out a primer with light loads even though some cases have been loaded 100X or more. Have other calibers that do.