Thread: Subsonic load for 308

Originally Posted by shooternz

Photos pop up on websites once in a while of rifles having S.E.E Secondary Explosive Effect or detention, The labs have never managed to duplicate it
so it must be rarer than getting struck by lightening, The labs maybe too well controlled Temperature and Humidity wise for it to happen it may need
the right weather conditions to trigger it, One thing every one agrees on that it is light charges of slow burning powder that causes it, there are two main theories
one is that the powder lays flat on the bottom of the case while in the chamber below the flash hole when the primer fires the flash does the length of the powder
igniting it all at once, No two is that the primer fires and starts the projectile moving it stops when it hits the rifling and then the powder ignites and hits a pressure spike,
They probable other theories, Until it happens in controlled condition no one knows, So don't load below recommend start loads and you can't go wrong, well you can but that is another story.

Greetings All,
There was an excellent article on SEE in Handloader Magazine some years back from memory in line with what shooternz has given above. I will retrieve the issue from the banana box storage system and report any additional bits I find.
Regards Grandpamac.

I will flag the 208gr or heavier.
Will stick with the 150gr ones. And then leave it with the 8.5gr trail boss at 1040fps.
Might have to modify slightly with cast projectiles but not by much if any

Greetings All,
Articles appeared in Handloader Magazine in 1987 and 1990 written by Roger Stowers about loading for the 240 Gibbs. The 240 Gibbs was a wildcat from the 1950's developed by Rocky Gibbs. It was basically a 6 mm-06 Max with the shoulder moved forward and increased to 35 degrees. Roger's first article dealt with his struggles with start loads. Roger used 49 grains of IMR 4831 in fire formed cases with Speer 105 grain spitzer projectiles. This should have been a mild load but blew primers, case heads and extractors. Roger found that he could minimize the problems by elevating the muzzle prior to firing, seating the bullet backwards or increasing the jump to the lands. Velocity was 2,800 feet per second, a pedestrian load for the .243. In his second article Roger works up to a max of 57 grains of IMR 4831 with the 105 grain projectile for 3,224 fps with no problems. Roger felt that the excess air space in the case was the problem and eliminated all loads with more than 1/4 inch or more air space between the powder and the base of the bullet. Incidentally Roger had the same problem with IMR 7828 and a little less with H 4831.
So there you have it, pressure excursions with non case filling loads of a slow powder related by someone who was actually there and cleaned up the mess afterward. The factors seem to be: case large for calibre, steep shoulder? and load over 10% less than max.
Should this be a problem in the .308? No. Could we stick a projectile in the bore with a light load of powder? Definitely. .308 Mauser could be right that current powder has been improved to eliminate the problem but we should not take any chances.
Regards Grandpamac.

Sooooo, maybe slightly off recent topics but! I have gotten my hands on some of Roberts 151gr projectiles...and have loaded some into sub loads. Stupid question about to emerge from this... the projectiles are super short and only marginally seated into the neck of the case to get OAL, this is a good thing? That the projectile is only a small amount pressed into the neck?

I had trouble with them feeding into chamber from mag on my A7 due to length and olive being a long way forward.

Originally Posted by G.I_Joel

Sooooo, maybe slightly off recent topics but! I have gotten my hands on some of Roberts 151gr projectiles...and have loaded some into sub loads. Stupid question about to emerge from this... the projectiles are super short and only marginally seated into the neck of the case to get OAL, this is a good thing? That the projectile is only a small amount pressed into the neck?

I seat to the cannelure and lightly crimp the case. Other forum members have said crimping improved accuracy.

Does this look right? I’ve just wound my seating die all the way out and press them in and continue to do so until I achieve the OAL. I mean they stay in there so shouldn’t be an issue? Will add a light crimp when I know that they are seated correctly. I guess I’m just so used to boat tail projectiles seating right in the neck...

I seat so that the case mouth is at the top groove in your photo.
I don’t load to an OAL with the cast bullets, I don’t even measure them.

Roll crimping must be into the cannelure, the Lee factory crimp doesn't, and I think taper crimp doesn't.

Does shooternz casts come lubed up or do you do that yourself also how much $ are these for 100?

Originally Posted by FatLabrador

Does shooternz casts come lubed up or do you do that yourself also how much $ are these for 100?

Yep, they come lubed, with gas check. They were $40 plus postage per hundred last time I bought some (late last year), rural postage was $8.30 IIRC.

Originally Posted by G.I_Joel

Does this look right? I’ve just wound my seating die all the way out and press them in and continue to do so until I achieve the OAL. I mean they stay in there so shouldn’t be an issue? Will add a light crimp when I know that they are seated correctly. I guess I’m just so used to boat tail projectiles seating right in the neck...

Seat to the crimp groove the bullet is designed to be seated so the base is flush with the base of the neck in a .308 give it a light crimp
and you are set

if you leave them like that Joel...the lube will either fall off/wear off/melt off or pick up every bit of grit around...seat them deeper ,to the crimp groove as Robert has said or at very least untill all the red bit is inside case mouth.

Might find you will pull the bullet if trying to eject a unused round with them seated at that length,that’s what would happen with my A7 when I tried seating them long to help with feeding from the mag,the projectile was jammed into the lands due to the olgive

Hi all. Bit of a query. I have a 16 inch suppressed 308. Looking at seeing what sub loads are available, primary use being for farm jobs. It looks like the 190 sub x's are prevalent. But Trailboss isn't and looks to be less so. The Hodgson website states a list of powders possible with charges required to meet mach 1 (H322 - 13 gr, BM2 - 13.4 gr, H4895 - 13.3 gr). I have acquired H32 and H4895 lately from a relative. Has anyone used these before to make a subsonic load at their stated charges?