Any Sig/San 553p 300 bo owners here

[jb313]

I may be thinking about picking one of these up from jdi, for what they are, i am curious about accuracy ?

I have only heard one report from one guy that his throws horrendous groups with ammo across the weight ranges,

As far as i know they have a 1/8 twist in a 12 inch barrel,
He is saying 10-12 inch groups at 50 yards, hmm

 

[GUNNER10]

Anecdotally, 300BO is not know to be the most accurate round especially sub sonic. If you friend is printing 20MOA groups, it really needs to go back to the vendor/manufacture. I would expect typical, 1 to 3 MOA for a service rifle based on what it is being fed.

 

[jb313]

Anecdotally, 300BO is not know to be the most accurate round especially sub sonic. If you friend is printing 20MOA groups, it really needs to go back to the vendor/manufacture. I would expect typical, 1 to 3 MOA for a service rifle based on what it is being fed.

I am not all that familiar with sig/san sbr platforms, but like you say, i would expect 1 to 3 moa to be reasonable,
I am not sure if he is sending it back which leaves me to question if this is typical of this platform or if the operator just needs much more training ?

 

[pinkhair]

1-8" is definitely a less than ideal twist rate for 300bo, particularly the subsonic ammo. That being said it should still shoot better than 10-12 inches at 50 yards.

 

[Plinker 73]

I have a 10 1/2” parts built 300 blackout with a Green mountain pistol gas 8” twist barrel. With 220 gr SMKs it will shoot sub moa groups. With123-125 Hornady v-max super sonic it shoots slightly better. I also have a custom built Remington action with an unknown 10” twist barrel that shoots 147 M80 pulls into one holl at 50 yards. I know this isn’t what you ask about . Just an idea of what to expect.

 

[st1650]

1:8 twist is absolutely accurate for 300blk subsonic. Shit back in the days of the 300 whisper it was all 1:8 twist and SMK240s. Just today I was testing a new bolt load on my 12.5in with VV N330 and it was sub moa at 100 yards with Amax 208 and Lapua 200 FMJBT with a SD of 4.5, zero vertical spread. I’ve had similar accuracy with anything from 190 SubX all to way to 225 eld and SMK 240.

Buddy of mine also had a Noveske that was 1-1.5in at 100 yards with a 1:8 twist 10in with factory Remington 220 subsonic.

If it’s grouping 10-12in there’s something seriously wrong with the gun or the scope. That’s like worse than shooting a pistol standing.

 

[jb313]

1:8 twist is absolutely accurate for 300blk subsonic. Shit back in the days of the 300 whisper it was all 1:8 twist and SMK240s. Just today I was testing a new bolt load on my 12.5in with VV N330 and it was sub moa at 100 yards with Amax 208 and Lapua 200 FMJBT with a SD of 4.5, zero vertical spread. I’ve had similar accuracy with anything from 190 SubX all to way to 225 eld and SMK 240.

Buddy of mine also had a Noveske that was 1-1.5in at 100 yards with a 1:8 twist 10in with factory Remington 220 subsonic.

If it’s grouping 10-12in there’s something seriously wrong with the gun or the scope. That’s like worse than shooting a pistol standing.

Now i am getting conflicting stories as to whether its 1/8 or 1/11, which i think would make a difference if it is 1/11

 

[SBRSarge]

Are the bullets keyholing or cutting perfectly round holes?

 

[Plinker 73]

My 1 in 10 will not shoot any heavy sub sonics. They always keyhole. Great with supers 147 and below but I haven’t tried any heavy ( 175 and above ) super sonic. I’m not sure they can be pushed that high without looking.

 

[jb313]

Are the bullets keyholing or cutting perfectly round holes?

Here is a couple groups he posted up, the top is 123 magtech and the bottom is 220 federal unknown.
I suppose the bottom is not too bad other then the two flyers,
Before i purchase one of these, i just want to make sure this is not what they consider combat accurate for this platform.