# 308 Subsonic loads and range test



## Bird

I finally had the supplies and time to load up some 308 subs and get to the range. I loaded 6 rounds of each, 9.5 grain/10 grains/10.5 grains of Trailboss. Bullet is with 180 grain Sierra Round nose. Finished OAL was 2.753 which is about 0.015" of freebore in my Savage.

I started by shooting 3 rounds unsuppressed to ensure the bullet would stabilize and not cause a baffle strike. The second 3 rounds were shot suppressed. All of the rounds were stable in flight and looking at 10 and 10.5grn groups, very repeatable accuracy. Mind you I was shooting indoors at 15yds to check bullet stability in flight and grouping. FYI- the gun is sighted in at 100 yds with supersonic ammo and suppressor. 

Next series of loads will be with 220 grain round nose with pretty much the same plan except loaded up a little for the heavier bullet. I don't have a chrono yet but its on the short list.

Except for the two shots near the center all of the groups are 3 shots. I tried to mark U for unsuppressed and S for suppressed groups respectively.


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## CHARLIE

Come on Bird, 15 yards ? Guess it will tell ya that its stable or not.


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## Bird

Bullet stability was really what I was looking for. That's why I shot the first 3 of each load without the suppressor on. The grouping shows that the loads are consistent, not that I'm a great shot. Heck, shooting that close is like shooting at the ground, ya can't miss...:wink:


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## Griffin

Where are you located, you're welcome to use my crono. What savage are you shooting? I shoot a 22" barrel and with the hornaday 220gn round nose I've found that 13.8 grains of trail boss is perfect! It groups amazing at 100 yards! I've managed several sub MOA groups. What primers are you using? I've been using magnum primers, works awesome for me so far!


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## mchildress

I plan on playing too. Have the rem 700 SPS tactical 1 in 10 twist 20" . I ran some factory 180 sub cor-bons through her the other day and was impressed. Picked up some Trailboss and going to play with a few loads. ATF cashed my check 4 months ago and still in the hurry up and wait game.


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## Bird

Griffin, I'm shooting a Savage Axis SR that I've worked a bit, jeweled the bolt, slight trigger job; it's a work in progress. The barrel is 20" with a 1:10 twist. Using Fed large magnum primers. I'm going to load up some 220 grain rounds this evening. Once I get a couple happy recipes, I'm also going to play with the freebore a little to see if it makes a difference.

mchildress, only 2 months to go. Hang in there, you'll get that phone call soon enough. Would be fun to have a little 2cool suppressed shoot...


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## Bird

Ok, quick update. I loaded some more 180 grain RN subs at 10.5, 11.0 and 11.5 grains of Trailboss. I took the chronograph to the range this time but forgot the tripod so no velocity numbers but I do have some pretty good groups for sub rounds through a suppressor. It seemed to like the 10.5 and 11.0 grain loads but it could have been me getting antsy to finish the last group before the cease fire. These were at 50 yards.


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## Griffin

Looking good! Not sure but you might have some issues with the crono at an indoor range, mine isn't the best in moderate light.


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## Bird

Griffin said:


> Looking good! Not sure but you might have some issues with the crono at an indoor range, mine isn't the best in moderate light.


I went to the Texas City range, which is a nice outdoor range. I did do some shooting at 100 yds with a few sub loads after we zeroed my boys gun. They were stable at 100 too. Incidentally, my scope is zeroed at 100 yds with super sonic rounds and supressor. You can see that the sub rounds at 50 yds were about 1.5" low. As soon as I chrony them, I'll be able to get my drop charts for those rounds and then either kentucky windage or dial in the scope for either super or subs.


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## CDHknives

Can you hear them fly? That will tell you if you are sub or supersonic. Just for a gross check w/o the chrony...


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## Bird

I've found a recipe for my 220 grain subsonic loads that definitely works.

Case trimmed to 2.005" (standard)
Primer pocket reamed and flash hole deburred
Federal large magnum rifle primers
13.7 grains of Trail boss powder (I weighed each load just barely past the needle on the scale)
COAL is 2.778" which allows for 0.015" bullet jump in my Savage
Sierra 220 grain round nose bullets

Average velocity in 1060 (1064 actually but I rounded down for my ballistic calculations)
20" barrel 1:10 twist

Ballistics:
Range/Velocity/Energy/Drop (based on 100 yard sight in)
25/1045/534/1.4
50/1032/520/3.0
75/1019/507/2.6
100/1007/495/0.0
125/995/484/-4.6

You can see that the bullet really konks out past 100 yards, so I'll probably change my zero distance to 50 yards. Most of our shots on pigs are 25-50 yards anyway. The loads are all stable in flight and are all shot suppressed. They sound about like a BB gun. You can actually hear the bullet hit :biggrin: :cheers:


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## 6.5 shooter dude

I have a 26 in barrel on my 700 and would like to load some subsonic rounds. What would be your recommendation for a starting load?
I have trail boss and Sierra 220 rn already.


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## Bird

Jay Baker said:


> I have a 26 in barrel on my 700 and would like to load some subsonic rounds. What would be your recommendation for a starting load?
> I have trail boss and Sierra 220 rn already.


I'd start with 13.0 grains and move up in .5 grain increments to 14.0 grains. Your longer barrel should add some velocity compared to my recipe or Griffin's. If your barrel is a 1:12 twist I'm not sure it will stabilize 220's so you might want to also get some 180's. Don't shoot with your can on (if you have one for that rifle) until you have verified the rounds are stable. Post up your results so we can compare notes.


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## bobbyoshay

Bird.......have you heard of anyone shooting the berger 230 gr Tactical Hybrid Open Tip Match lead? Thats what we are reloading in the 300 AAC but im wanting to start loading for the 308. This suppressor could be fun


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## Bird

bobbyoshay said:


> Bird.......have you heard of anyone shooting the berger 230 gr Tactical Hybrid Open Tip Match lead? Thats what we are reloading in the 300 AAC but im wanting to start loading for the 308. This suppressor could be fun


Bobby, I'm far from an expert on this but based on my limited experience, I don't think a 1:10 twist barrel would be fast enough to stabilize that bullet. If you had a custom 308 barrel with a faster 1:9 made you could possibly have a real sub sonic shooter. That being said, that's a chunk of cash for an educated guess. Think about the twist rate in your AR, 1:8 to 1:9.

My loads are specifically for hunting pigs suppressed. I talked with one of the ballistic experts at Sierra asking about bullet expansion at sub sonic velocities with the 220 gr RN. He said he doesn't think that there'd be much expansion at all but he would expect significant penetration.


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## Griffin

Bobby- that sounds like an awesome round, do you have load data on it for your 300aac? I just finished building mine in an 8" barrel. What type powder are you using for subsonic in the 300? 
I'm guessing you 300 is 1:7 or 8 twist rate which is why you are able to stabilize that round it might work with a 308 1:10 but I really doubt it, if I can turn up a box of those bullets I'll try it out.

Bird- the 220's will take down a pig of medium size, I'll be taking down some more pigs in the next 2 weeks and let you know how it works


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## bobbyoshay

Griffin: here is the load data I am using for the 300. Very Bottom using accurate 1680
http://www.accuratepowder.com/wp-content/uploads/2010/09/300_ACC_Blackout_Data.pdf

Bird: looks like i will have a similar setup. Savage 111 Hog Hunter. 20" barrel with 1:10 twist. Looks like alot of people are using 168 gr with trailboss. Since you have a similar setup i would like first hand experience other than takin somebodies bs from another site.


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## Griffin

I'm shooting a savage model 10. 1:10 twist. Best subsonic load I've found is the 220rn bullet with 13.8 gr of trailboss with a magnum primer. It's about 1000-1050 fps out of my gun suppressed and shoots 1" groups at 100yds. I've dropped a 100-125 pound hog with it. The 168 grains work as well but if I can have the added knock down power of the 220gr I'll take it. The heavier the bullet the faster twist it takes to stabilize it that may be why some with 1:12 barrels are using 168-180 gr bullets. You'll be very happy with the 220/trailboss load it is amazingly quiet! I believe Bird ended up using 13.5 grains of TB but every gun will be slightly different. If you are in the Austin are let me know and you can come out and try the load I have worked up and save yourself some time.


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## Bird

Bobby, depends on what you want to do with your rounds. 150-160's can be very accurate. My 180 RN loads have produced some very nice groups out to 100 yards. So for plinking, they are great. For hunting, maybe not so much. As an example, at 100 yards the 220's have almost 100 ft/lbs more energy than the 180's (491 vs 400). As mentioned above though, that's my rifle but your Hog Hunter should be very similar. 

My 220 recipe and Griff's are almost identical, he's using 13.8 grains and I'm using 13.7. My avg velocity is 1060 but our numbers are so close that they are probably within the accuracy limitations of the chrongraphs.

BTW- have either of you (Griff and Bobby) measure your max chamber length? Any idea of how much bullet jump you are getting? I'm at 0.015"


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## Griffin

I sure haven't and to be honest I don't even know how to. But I will do some research and put that on the list of things to do! Last thing I did that made a substantial difference (to the gun, not the accuracy) was to strip down my bolt and polish everything then re lube it all, with I would of done that the first day!


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## od

Hello Gents,
Was reading all the reply's on the 308. Was thinking of purchasing a 308 in an AR format. Not all that up to par on all the parts and types quite yet but have started to do a little research. Have reloaded 38, 357, 45ACP, and 12 guage.
Have been looking at Rock River Arms, Daniel Defense, and Colt brands. I have quite a bit of pigs and coyotes in my small lease in Karnes county just past Goliad and need to trim some of them down. Saw 7 last year and smacked 4 but could of done better with a semi. Don't really do a heck of a lot of shooting but will be having time to sit down and work on specific loads. I have two RCBS Rock Chuckers. 
It was quite interesting reading all the post you guys have on this caliber. I'm really planning to purchase this type of shooting arm and will be leaving it to my grand son's later on when I finally quit shooting and enjoy seeing them carry on with the sport.
Planning to go the the NRA show again and get the real feel of several of these firearms.
Do you guys have any advice or ideas that may help me out with this descsion? Appreciate anything you can throw my way. Sorry for getting on the soap box.
Thanks
ODBud


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## bobbyoshay

To shoot the subsonic loads out of a semi auto you will need a supressor for it to cycle the rounds correctly. Do you plan to get a can?


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## horned frog

Not sure that many .308 semi autos will cycle properly with subsonic loads, even with a suppressor attached.

The 300 Blackout shoots a .308 diameter bullet at supersonic or subsonic velocity and cycles well with either. Just something to consider.


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## bobbyoshay

horned frog said:


> Not sure that many .308 semi autos will cycle properly with subsonic loads, even with a suppressor attached.
> 
> The 300 Blackout shoots a .308 diameter bullet at supersonic or subsonic velocity and cycles well with either. Just something to consider.


I have a 300 ar platform that I'm loading for but also shooting a bolt in 308. I know the 300 won't cycle subsonic rounds effectively without a can. Don't see why it would be any different with the 308 but we will find out soon.

Any reason why y'all are using round nose rounds? I can't find them and I ordered the Sierra HPBT 220 for the 300 which is what I'm seeing a lot of people shoot.


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## Griffin

The round noses give you more surface to stabalize the bullet. To tired to thing of all the technical terms


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## kanga69

To shoot subsonic loads through a gas type ar, you can change the buffer spring to improve the cycling. By no means an expert, saw it on a gun show one day. I talked to the guys in the Suppressor Store, here in Austin, the other day and ordered their AAC .300 upper. Also have a OBR 308. They told me it is completely possible to shoot suppressed loads in ARs. I didnt ask them about any cycling issues with the .308, but I will when I pick up my upper. My can will be here in Sept. and I need to get up to speed with my own knowledge and not rely on what I saw on TV.


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## CDHknives

Suppressors+adjustable gas blocks are the best way to run AR's if you want to go back and forth from subsonic to full power loads quickly.


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## Bird

CDHknives said:


> Suppressors+adjustable gas blocks are the best way to run AR's if you want to go back and forth from subsonic to full power loads quickly.


Beat me too it. ^^^this is how you do it. You have to use an adjustable gas block on a garand style action gun like and M1 to prevent overpressuring the action with a can and full power loads. It is also allows sub rounds to cycle. I don't know for sure about the Mini 14 or Mini 30 but I would suspect it is the same, especially for the Mini 30.


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