308 Sub Sonic Load question

[Jackalope33B]

After loading several 308's with Varget @44 grs and finally finding my sweeet spot for a seating depth, am I going to have to chase my seating depth again when i load a different bullet with different powder for sub sonic loads?

 

[Huckleberry75]

Re: 308 Sub Sonic Load question

Subs have not been picky for me. I just jammed a 220 RN on top of 12.2gns of trail boss and seated to the cannelure. Shoots sub 1/2moa at 100yds.

 

[K_4c]

Re: 308 Sub Sonic Load question

I seat a 180 RN @ 2.625" running 10.7 grains of Trailboas... I did so to fill case capacity.... That and the 180 RN from hornady has no problem with a little jump.

Best of luck

 

[Mattrmvpd]

Re: 308 Sub Sonic Load question

^ will work VERY well.

I used 10.5 grn Trailboss and 155 Bergers.

EXCELLENT to 100 yards.

And it was chrono'd JUST under supersonic. Purely awsome with a can on as well.

 

[rkaires]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Huckleberry75</div><div class="ubbcode-body">Subs have not been picky for me. I just jammed a 220 RN on top of 12.2gns of trail boss and seated to the cannelure. Shoots sub 1/2moa at 100yds. </div></div>

Nice! I been shooting 175smk's over 10gr Trail Boss and only getting 1.5 moa at 100yds. I have a box of 220 Hon RN collect dust on a shelf so based on the results your getting I'll be dusting them off.

 

[koz]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: K_4c</div><div class="ubbcode-body">I seat a 180 RN @ 2.625" running 10.7 grains of Trailboas... I did so to fill case capacity.... That and the 180 RN from hornady has no problem with a little jump.

Best of luck </div></div>

I also use 180 but I use Hornady BTSP with 10.7 of TrailBoss. It's a good load, 18" 11.25 twist barrel.

 

[anschutz64ms]

Re: 308 Sub Sonic Load question

10.5 grns of trailboss with a 180grn rn is 1030 fps and is 1moa at 100 out of my 20" 700P

 

[Conqueror]

Re: 308 Sub Sonic Load question

As someone else noted above, subs seem much less picky about seating depth. I can even load the 170gr flat-point Hornadys to their cannelure (which is meant for 30-30, not 308, and causes a solid 0.150"+ jump) and it groups in the same spot as the ones I seat to the rifling. Since you'll not be shooting hundreds of yards with subs, it seems not to matter quite as much. I have some new 180gr Hornady interlocks to play with and I plan on just loading them to the cannelure.

 

[gunnyart]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: anschutz64ms</div><div class="ubbcode-body">10.5 grns of trailboss with a 180grn rn is 1030 fps and is 1moa at 100 out of my 20" 700P</div></div>

You 20" 700P is 1:12 twist is it not?

I have had stability issues with my 20" LTR sub loads.

Who's 180rn are you loading? What depth? Primer? etc?

 

[anschutz64ms]

Re: 308 Sub Sonic Load question

Yes it is a 1/12 twist so I won't be going any higher in bullet weight. I use the hornady 180 grn RN and 170grn FN seated at the cannelure with federal 210m primers

 

[Skigolfmike]

Re: 308 Sub Sonic Load question

I ended up using a 175 SMK seated at 2.800" with 10.5 gr of trailboss and cci BR2 primer. ~1050 fps. Here is a shot at 400 yards:

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That shot took 16.5 Mil of elevation.

 

[anschutz64ms]

Re: 308 Sub Sonic Load question

What twist is in your barrel. I always thought the smk or any boat tail wouldn't stabilize at sub velocity

 

[Skigolfmike]

Re: 308 Sub Sonic Load question

11.25 twist. I played with some 170gr round nose bullets, the they didn't group worth a damn.

 

[Force_Multiplier]

Re: 308 Sub Sonic Load question

Win Brass
Win LR primer
155SMK (2155)
10.1gr Trail Boss
2.75" C.O.A.L.


Savage 308 20" Shilen 10 twist...

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Thanks for all the info guys! I have also read that when load development for sub rounds to test them without the can on, and also to start high (grains of powder) and work to a lower grain. Why is that?

 

[BravoSector1]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mm128</div><div class="ubbcode-body">^ will work VERY well.

I used 10.5 grn Trailboss and 155 Bergers.

EXCELLENT to 100 yards.

And it was chrono'd JUST under supersonic. Purely awsome with a can on as well. </div></div>

I loaded up two batches of rounds, 168 AMAX and 150 Hornady's over 10.0gr of trailboss...still supersonic??? I'm running a Savage 10FCP-SR/5R with a 24" barrel. Barrel length making that much difference??? I'm under 500ft altitude and about 85F.

 

[K_4c]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jackalope33B</div><div class="ubbcode-body">Thanks for all the info guys! I have also read that when load development for sub rounds to test them without the can on, and also to start high (grains of powder) and work to a lower grain. Why is that? </div></div>

Squib load buddy... Don't wanna go to low and get one stuck in the pipe.

Start without your can to ensure the bullet stabilizes... Otherwise a baffle strike is sure to come.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Gotcha.. what exactly do you look for with unstabled rounds? I have heard of the "keyhole" effect, but what does it look like?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: K_4c</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jackalope33B</div><div class="ubbcode-body">Thanks for all the info guys! I have also read that when load development for sub rounds to test them without the can on, and also to start high (grains of powder) and work to a lower grain. Why is that? </div></div>

Squib load buddy... Don't wanna go to low and get one stuck in the pipe.

Start without your can to ensure the bullet stabilizes... Otherwise a baffle strike is sure to come. </div></div>

 

[K_4c]

Re: 308 Sub Sonic Load question

The "keyhole" result is nothing more then the bullet tumbling (impacts sideways or in a manner of not stabilizing).... Think of throwing a football. A spiral is a stabilized projectile and a poorly thrown football with improper mechanics results in a wobble or "duck".

When I test/confirm my subs, I shoot at a distance of 50 meters to ensure the impact resembles a proper bullet hole (.30 cal hole with no tall tail signs of the bullet tumbling). Once you've confirm your rifle and load data are up to the task throw your can on... Next pull the bolt and look down the barrel ensuring your can is aligned with the bore... If all looks good to go proceed with the fun. Ensure each round you have fired did in fact clear your barrel (impact of the projectile down range is obviously a good indicator). If at any time a round is fired and it felt different, it's best to check your barrel to see if a squib round has occurred. I try to load all my subs right below the speed of sound to ensure the round has enough powder to be reliable.

 

[Huckleberry75]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: K_4c</div><div class="ubbcode-body">The "keyhole" result is nothing more then the bullet tumbling (impacts sideways or in a manner of not stabilizing).... Think of throwing a football. A spiral is a stabilized projectile and a poorly thrown football with improper mechanics results in a wobble or "duck".

When I test/confirm my subs, I shoot at a distance of 50 meters to ensure the impact resembles a proper bullet hole (.30 cal hole with no tall tail signs of the bullet tumbling). Once you've confirm your rifle and load data are up to the task throw your can on... Next pull the bolt and look down the barrel ensuring your can is aligned with the bore... If all looks good to go proceed with the fun. Ensure each round you have fired did in fact clear your barrel (impact of the projectile down range is obviously a good indicator). If at any time a round is fired and it felt different, it's best to check your barrel to see if a squib round has occurred. I try to load all my subs right below the speed of sound to ensure the round has enough powder to be reliable.

</div></div>

Yep, sound advice for the newby sub-loaders.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Will your velocity be higher, lower or the same whether you have a can attached or not?

 

[Huckleberry75]

Re: 308 Sub Sonic Load question

Typically a smidge higher, but usually not enough to matter. Maybe 20fps-ish.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Going to pick up some Trailboss and Hornady Flatbase RN 180gr bullets (http://www.hornady.com/store/30-Cal-.308-180-gr-RN/) tomorrow.. Wish me luck lol

The recipe will be:
Win Brass
Fed 210M Primer
Trailboss (unk GR of powder)
The above listed Hornady bullet
22" Barrel, Bolt Action
YHM 7.62 Phantom Can

 

[K_4c]

Re: 308 Sub Sonic Load question

Enjoy... It sounds like your on the right path for components.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Another question lol. How far in front of the muzzle do you place the chronograph?

 

[xdeano]

Re: 308 Sub Sonic Load question

Dont forget to drill your flash holes to 9/64" debur both sides. Also dont waste your money on using match primers, or mag primers.
Xdeano

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Flash hole drilling? Huh, wtf? Never heard if this. What's the purpose of it?

 

[K_4c]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: xdeano</div><div class="ubbcode-body">Dont forget to drill your flash holes to 9/64" debur both sides. Also dont waste your money on using match primers, or mag primers.
Xdeano </div></div>

Not necessary... I've done plenty of load development with subs and have seen no difference in performance or reliability running trail boss with a standard size flash hole. Trailboss works so well due to the fact how much of the case space it fills (I've also never had a secondary/delayed charge).

I suppose everybody has there own way of doing things...

To the op... 10ft is pretty standard for running a chronograph.

 

[xdeano]

Re: 308 Sub Sonic Load question

The purpose of drilling the flash hole to enlarge it is exactly what K4C is talking about. I know Trailboss is a much nicer powder to work with because of volume it takes up in the case vs clays or tightgroup but it's always a good thing to get a really nice and even flash to ignight the powder column. It's just a recomondation. Just don't let the drilled out brass get recirculated back into your general brass population, it will cause some issues with full power loads. Only drilling 308 brass, never done 223 cases.

agreed 10ft is standard distance on chrony.

xdeano

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Just got back from the range. I thought you would hear the "crack" at any FPS above 1050 +/-.. Well, at 11gr I had Velocity at 1069, 11.5gr 1093 and no "crack." When I went to 12gr, my velocity was at 1152 and I got the "crack". Am I missing something here?

Altitude is about 50' above sea level, outside temperature is 85deg..

 

[Force_Multiplier]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jackalope33B</div><div class="ubbcode-body">Just got back from the range. I thought you would hear the "crack" at any FPS above 1050 +/-.. Well, at 11gr I had Velocity at 1069, 11.5gr 1093 and no "crack." When I went to 12gr, my velocity was at 1152 and I got the "crack". Am I missing something here?

Altitude is about 50' above sea level, outside temperature is 85deg..</div></div>

the speed of sound in dry air, at sea level is around 1125 ft/sec... the reduction to 1050 as a target velocity is a buffer, so that we'll be relatively sure that it won't go super sonic when the weather or location changes

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Ok, gotcha! So it looks like Im good to go with the 11.5gr..

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Force_Multiplier</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jackalope33B</div><div class="ubbcode-body">Just got back from the range. I thought you would hear the "crack" at any FPS above 1050 +/-.. Well, at 11gr I had Velocity at 1069, 11.5gr 1093 and no "crack." When I went to 12gr, my velocity was at 1152 and I got the "crack". Am I missing something here?

Altitude is about 50' above sea level, outside temperature is 85deg..</div></div>

the speed of sound in dry air, at sea level is around 1125 ft/sec... the reduction to 1050 as a target velocity is a buffer, so that we'll be relatively sure that it won't go super sonic when the weather or location changes </div></div>

 

[Will Fennell]

Re: 308 Sub Sonic Load question

Jackalope,
You started this thread at about the same time I got my first .30 can, and decided to load some subs.....

My rifle is a TIKKA T3 Scout CTR, with the barrel trimmed to 16.25" and a Wilson Combat Whisper Can. Factory barrel is 1/11.25" twist, so I worried a bit about being unstable with SMK 220's, so I picked up a bulk pack of Nosler 190gr's BTHP's, and a pound of Trail Boss.

Started at 12 gr's, which was supersonic, and worked down to 10.5 grs, which was borderline subsonic at around 1100 fps. Dropped down to 10 grains, got 1040 fps average, and 100 yard MOA accuracy. I'm a happy camper.

Thanks for starting this thread, and thanks to the contributors here on the Hide.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Just got back again from the range. Loaded up 5 rounds of each starting at 11gr-11.8gr in .2gr increments. Rounds were all over the place. The 11.8gr load seemed to be the sweet spot for accuracy. I dont see any evidence of Key Holing, so I guess my barrel is stabalizing the bullet. Velocity was 1128, 1090, 1109, 1121, & 1074. Yea, thats a big ES, but here is a pic of the grouping with 5 shots at a 2" target at 100 yards. There are 3 bullets within the grouping on the left.. Yesterday at 12gr, I was getting the "crack". Should I be getting better groups than this or should I accept this? The rifle is capable of 1/3" groups when I do my part. But shooting Subs, does accuracy go down? Whats an optimal velocity to be around? Seeing as how 1150 is where the "crack" will be heard, is it common to stay around 1100fps, or more so around 1000fps? Another thing I noticed was there was more than a normal around of soot around the case neck. Is this another issue? lol

For those that are curious about my Velocity about my other loads, here ya go. These are Trailboss, Win brass, Fed 210M, Hornady 180gr RN FB bullet, off the lands .010.
I dont understand why the velocity was lower with higher GR loads.

11gr - 1096, 1050, 1031, 1027, 987
11.2gr- 1002, 1074, 1040, 1009, 1019
11.4gr- 1090, 1053, 1036, 1030, 1029
11.6gr- 1099, 1091, 1055, 1067, 1067
11.8gr- 1128, 1090, 1109, 1121, 1074

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Will Fennell</div><div class="ubbcode-body">so I picked up a bulk pack of Nosler 190gr's BTHP's, and a pound of Trail Boss. </div></div>

Hate to bust your bubble, but Trailboss comes in 9oz jugs. Yea, I was pissed too when I found out also.. It looks just like the 1lb jugs.. hahaha

 

[Huckleberry75]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jackalope33B</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Will Fennell</div><div class="ubbcode-body">so I picked up a bulk pack of Nosler 190gr's BTHP's, and a pound of Trail Boss. </div></div>

Hate to bust your bubble, but Trailboss comes in 9oz jugs. Yea, I was pissed too when I found out also.. It looks just like the 1lb jugs.. hahaha </div></div>

It is fluffy stuf, no doubt.

 

[Huckleberry75]

Re: 308 Sub Sonic Load question

I am getting 1036fps with 12.2gns of TB and a 220RN prohunter. The 170 flat nose usually run with 10.5gns of TB, and I have never ever drilled a flash hole. I have read articles where guys do this when they are running Red Dot or other pistol powders to even up the burn rate, but with TB it is not necessary. If you drill holes and then run a full house charge through that case, you will possibly pierce the primer.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

When you seat to the cannelure, are you seating to the bottom of the cannelure or to the top of cannelure?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Huckleberry75</div><div class="ubbcode-body">Subs have not been picky for me. I just jammed a 220 RN on top of 12.2gns of trail boss and seated to the cannelure. Shoots sub 1/2moa at 100yds. </div></div>

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

If my measurements are correct with the hornady OAL gage, my Ogive depth is 2.275 OAL is 2.711.. I did notice that the seating stem touches the bullet near the very tip, while the Hornady comparator touches the bullet more towards the middle.

 

[josephberry]

Re: 308 Sub Sonic Load question

Wow, some of you guys are getting good accuracy with 308 subs. I've never seen them shoot better than 1.5 on a good day.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

yea, im having some issues now with my subs. hopefully it will all work out.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jdberry</div><div class="ubbcode-body">Wow, some of you guys are getting good accuracy with 308 subs. I've never seen them shoot better than 1.5 on a good day. </div></div>

 

[Huckleberry75]

Re: 308 Sub Sonic Load question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jackalope33B</div><div class="ubbcode-body">When you seat to the cannelure, are you seating to the bottom of the cannelure or to the top of cannelure?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Huckleberry75</div><div class="ubbcode-body">Subs have not been picky for me. I just jammed a 220 RN on top of 12.2gns of trail boss and seated to the cannelure. Shoots sub 1/2moa at 100yds. </div></div> </div></div>

I dont recall off hand. I will check when I get home.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Great! I appreciate it

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Huckleberry75</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jackalope33B</div><div class="ubbcode-body">When you seat to the cannelure, are you seating to the bottom of the cannelure or to the top of cannelure?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Huckleberry75</div><div class="ubbcode-body">Subs have not been picky for me. I just jammed a 220 RN on top of 12.2gns of trail boss and seated to the cannelure. Shoots sub 1/2moa at 100yds. </div></div> </div></div>

I dont recall off hand. I will check when I get home. </div></div>

 

[Huckleberry75]

Re: 308 Sub Sonic Load question

Ask and Ye shall receive.
It looks like I am loading just into the cannelure. I never tested seating depth, only got so far as powder charge and found the golden ticket. You can see that the big ol' pill sits way back in the case, which may actually help with load density, especially with the fluffy Trail Boss.

 

[Huckleberry75]

Re: 308 Sub Sonic Load question

Man, after looking at the close up picture, i might need to tumble those cases on the next go-round. Shameful sooty mess.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

looks very close to how mine are getting loaded. ill post pics tomorrow with some bullet/ case dimensions.

 

[Huckleberry75]

Re: 308 Sub Sonic Load question

BTW, I do <span style="text-decoration: underline"><span style="font-weight: bold">not</span></span> crimp those.

 

[Jackalope33B]

Re: 308 Sub Sonic Load question

Are any of you crimping your subsonic rounds? I was talking to my buddy, and he crimps his lightly..

Anyhow, I just picked up some Hornady 220gr RN.. Lets see what they can do for me..