working up my first subsonics

[Okoyote]

Tried some 168 SMKs in my savage 10 twist as recommended in a previous post. It was easy to get a load to shoot 1015 FPS but they didn't stabilize. Surprised the heck out of me! Accuracy was so good at 100 . . . I was in disbelief the holes were oblong.

Next is 180 hornady round nose over trial boss.

 

[madd0c]

Re: working up my first subsonics

Were the holes oblong at 100 or were they oblong at 3 feet? If the holes are round at 3 I shoot them with the supressor. It is very easy for subs to become unstable in the remaining 297 feet.

I had very poor results with a 1-11.25 twist barrel, so I got a 1-7 twist AAC barrel made for subs. Works MUCH better, and the bullet is stable to 300 yards subsonic. That is using the 200gr Lapua sub specific round with 10.8 of trail boss at ~1040 FPS.

Hope that helps,
madd0c

 

[Okoyote]

Re: working up my first subsonics

Ya know. . . I never checked closer than 100 yards. I figured if they were unstable before 100 yards the risk of a baffle strike was higher than I cared to mess with. Maybe I'm being too cautious? . . . Regardless, the 180 RN should be far more stable than the 168 SBK. I've already got some loaded up for tomorrow.

 

[244]

Re: working up my first subsonics

Okoyote- I recently worked up .308 subs with the 180 gr Hornady RN and Trail Boss. I used Speer nickle plated brass that weighed around 180 grains and Black Hills brass that weighed around 162 grains; those 18 grains of difference matter! I used CCI 200, CCI 250, and CCI #34 primers. I was a bit surprised by the results, but I carefully prepped each case, weighed each powder charge, and seated each to 2.800.

1) 11.2 gr w/CCI 250: Speer=1100 fps, BHA=1056 fps
2) 11.2 gr w/CCI 200: Speer=1092 fps, BHA=1073 fps
3) 11.2 gr w/CCI #34: Speer=1088 fps, BHA=1061 fps

The #34's gave me the lowest ES and the 200's the highest. It's my understanding that the #34's are a magnum primer with a harder cup.

I'm sure you know to work down in charge weight with subs and not to use my results without testing/working them for safety in your rifle.

 

[ddavis]

Re: working up my first subsonics

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Okoyote</div><div class="ubbcode-body">Tried some 168 SMKs in my savage 10 twist as recommended in a previous post. It was easy to get a load to shoot 1015 FPS but they didn't stabilize. Surprised the heck out of me! Accuracy was so good at 100 . . . I was in disbelief the holes were oblong.

Next is 180 hornady round nose over trial boss. </div></div>

You will find that some bullets just will not stabilize in a particular barrel when they theoretically should. I have a 1 in 8 twist 300 BLK barrel in which I've tried every conceivable bullet I could get my hands on, and all show oblong holes at any distance. Some even shoot 1.5 MOA at 100 yards, but the holes are not round. The only bullet that seems to be stabilized is the 208 A-max and the 110 grain bullets. 150 Nosler Ballistic tip was the worst, and appeared to hit at about a 45* angle. There is no good explanation as to why nothing works. Just try a few different bullets.

 

[Okoyote]

Re: working up my first subsonics

Looks like 10.8 of TB will be the load. Fun Stuff!!

 

[martin777]

Re: working up my first subsonics

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 244</div><div class="ubbcode-body">I'm sure you know to work down in charge weight with subs...</div></div>

Huh?

 

[244]

Re: working up my first subsonics

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: martin777</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 244</div><div class="ubbcode-body">I'm sure you know to work down in charge weight with subs...</div></div>

Huh?


You should work DOWN in charge weights in SUBSONIC loads to ensure you don't get stuck bullets. You want to start high and work down to find the velocity you are looking for.






</div></div>

 

[martin777]

Re: working up my first subsonics

Thanx