Suppressors Problem with subsonic keyholing

T

TLong

Sergeant
Full Member
Minuteman
Nov 10, 2009
272
2
Alabama
www.1042blue.wixsite.com
#1
Hey guys. I finally got out to try some subsonic ammo in my FN. I have some 208 subsonics, and tried them. They were keyholing bad. I believe my twist rate is 1:12, but it may be 1:10. I'm guessing it's not fast enough to stabilize the 208's. What would you guys recommend?
keyhole.jpg

The top hole is a 168AMAX. The bottom 3 are the subsonics...they all keyholed and at different angles.
Is this bad enough to have a baffle strike if I were to attach my suppressor on it?
 
#5
Re: Problem with subsonic keyholing

I am running the 180 grn. Hornady RN. Its not super accurrate at 100 in my 5R but its good enough. I tried to go lighter with some 150 grain Noslers and they were keyholing like crazy. I may get around to trying something heavier at some point.
 
#6
Re: Problem with subsonic keyholing

I'm guessing .308win here?

208's can be made to shoot in a 12 twist, but not as good as a 170-180 rd nose. Depending the max range you want you have lots of choices. If your max is going to be 130yds an under, not many combos will out group a 175smk in front of Trail boss. If your looking for a straight up subsonic killing load from store bought components, a 170 to 180 gr round nose will get the job done to 300 w/o much problem.
 
#7
Re: Problem with subsonic keyholing

I run Hornady 180 Grain SP's with 10.2 Grains of Trail Boss at 1030 fps and they work like a champ. I have to add 8 MOA from my normal zero with sonic rounds.

You did the right thing by testing them on paper first before putting the can on. If you would have done that this thread would be about baffle strikes. Drop the bullet size and I bet it will work.
 
#10
Re: Problem with subsonic keyholing

For the same bullet weight, a bullet that is: shorter OR has more mass distributed further away from the centerline axis will be more stable at a given twist rate. Generally this means a blunt nose hunting bullet is your best bet at any given bullet mass.
 
#11
Re: Problem with subsonic keyholing

For those that say to turn the bullet backwards;
1) does the bullet type make a difference, (i.e. ballistic tip, h.p., soft point)
2) Are these still effective on game such as hogs/coyotes? Will they tumble after impact, or be more like a solid?
Thanks for the info guys.
 
#12
Re: Problem with subsonic keyholing

Try the Southwest Ammo 175 gr subsonics. They stabilize fine in my 1/12" .308 (20" barrel). Accuracy is about 1.5 MOA at 100 yards with 2.5 MIL drop from 100 yard zero. I have been pleased with them.
 
#13
Re: Problem with subsonic keyholing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TLong</div><div class="ubbcode-body">For those that say to turn the bullet backwards;
1) does the bullet type make a difference, (i.e. ballistic tip, h.p., soft point)
2) Are these still effective on game such as hogs/coyotes? Will they tumble after impact, or be more like a solid?
Thanks for the info guys. </div></div>

I've shot FMJ, Soft Point, OTM's (BTHP) and polymer tipped stuff backwards without issue.

They penetrate better backwards and they're more than effective for killing animals.
 
#14
Re: Problem with subsonic keyholing

Published velocities are only worth the paper they are printed on; worthless. Always use a chronograph to make sure they are 1000-1100 fps.

It is not the mass of the bullet but the length that matters. A round nose bullet is going to be more stable than a pointed one of the same weight. A round nose bullet is only going to lose a bit more speed compared to a hpbt at subsonic speeds even if it has a much lower BC.

I tried loading bullets backwards in my 1-12 twist k-hornet so I could use heavier bullets. The groups sucked even more than when loaded the proper way.

I get good groups with 220 grain RN in a 308 with a 1-10 twist, but need to go down to 180 RN with my 1-12 twist.

Do not waste money on match bullets at subsonic speeds, load your own and use a chronograph. Always test your loads unsuppressed.

Ranb
 
#15
Re: Problem with subsonic keyholing

I tried the 208's backwards, and like Ranb said, they sucked even more! They were completely sideways at 100 yards. I think I'm going to stick with some 168-175's. I had a few pulled 175SMK's and used 10.0 grains of TB and had very good results. They averaged at 1015 fps, which is good enough for me.
 
#17
Re: Problem with subsonic keyholing

TLong are you planning on hunting with the 168-175 bullets or just plink?

my 175 sub load shot great 3/4" @100yds, but it didnt do shit to a rock chuck @50 yds. just a little pencil hole all the way through no "real" damage.

im glad i hit him in the head
 
#18
Re: Problem with subsonic keyholing

Alan, just plinking really. It's illegal to hunt suppressed in AL still, but hopefully that will change. And even if I could hunt suppressed, I would still use full-strength loads. What was your fps / ftlbs for your load on the rock chuck?
 
#19
Re: Problem with subsonic keyholing

Not sure on ft/lbs but clocked about 1100 fps, my 180 gr load is 975 and im impatiently waiting for chucks this season ( about 2 more weeks).

Range report to follow
 
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