Subsonic Reloads

[Insayn]

I recently tried my hand at reloading some subsonic .308 ammunition just for fun. I found the 168 grain SMK I was using was starting to yaw when it reached the target (100 yards). I may try and up the bullet weight to 175 and/or 180 grain SMK to see if there are any variances. I am concerned that my 1:12 twist will not stabilize a 200 or heavier bullet. I've also read that subsonics should be backed off the rifling, any concerns I should have? These were all unlubed loads...I may try to lube the bullet just for kicks.

Remington 700
24" Shilen SS 1:12

Winchester Nickel casing
168 grain SMK
10.0 grain Trail Boss
OAL 3.268 (Seated onto rifling)
1037 fps average out of a 5 shot string

Winchester Nickel casing
168 grain SMK
10.3 grain Trail Boss
OAL 3.268 (Seated onto rifling)
1048 average out of a 5 shot string

Winchester Nickel casing
168 grain SMK
10.6 grain Trail Boss
OAL 3.268 (Seated onto rifling)
1107 average out of a 5 shot string

 

[Tangodown911]

Re: Subsonic Reloads

I would back off he rifling too. Try the infamous 10.0 of trail boss with 175smk if you have em. But make them 2.800". It worked for and they were not yawing. They shot 1.5moa in my 5R. Not great and I intend in messing with them some more to see if I can get them to hold 1moa.

 

[glocker17]

Re: Subsonic Reloads

I had much better luck with Titegroup than Trailboss. I dont know why it isnt more popular. Titegroup doesnt fill the case, but isnt position sensitive. About 8.0 and a Sierra 180 RN will shoot well in a 1:12.

 

[Insayn]

Re: Subsonic Reloads

I just used what I had on hand, but have read a lot of loads with the round nose bullets. Is there a reason round nose bullets are used so often? I'll try the 175 SMK's and 180's this week.

 

[Tangodown911]

Re: Subsonic Reloads

The round nose bullets fly better at subsonic speeds

 

[coldboremiracle]

Re: Subsonic Reloads

I tried 150's 180's 200's and 220's, they all worked good, but my twist is a 10. I wouldn't go over 190-200 with the 12 twist. oh and definately keep em off the lands.

 

[SSC]

Re: Subsonic Reloads

i could stabilize Hornady 180 RN's down to around 1030 but below that they would start showing keyholes on the target. I have an SPS with a 26" barrel. I am going to try something lighter.

 

[Insayn]

Re: Subsonic Reloads

Another question, I am seeing some reloaders recommending drilling the flash hole out to 9/64" and to use the magnum primers. Is that something I should attempt with the Trail Boss load?

 

[megs1585]

Re: Subsonic Reloads

I have worked up some 175smk mollys over 10gr of trail boss, I'll report back with vel and accuracy later this week.

 

[bohem]

Re: Subsonic Reloads

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tangodown911</div><div class="ubbcode-body">The round nose bullets fly better at subsonic speeds </div></div>

This is right on spot. To add to it, Try loading some regular BTHP's backwards in the case if you don't have any RNs to work from. Test with the suppressor off to verify stability down range and THEN put the can back on. This way you don't risk a baffle strike while working with new loads.

 

[Hummer]

Re: Subsonic Reloads

12 twist will easily stabilize 190 MK to 1000 yards if YOU KEEP IT ABOVE MACH 1 to run 1000 yards. The MKs when they drop below MACH 1 will lose stability a bit after 900 but accuracy will still be there.
Trying to keep them subsonic for a longer range is really an iffy proposition.