Bolt action subsonic 300 blackout vs semi subsonic 9mm carbine

[dohalysh425]

My question is:

I currently have a 300 Black Out that I strictly shoot suppressed subsonics out to 100yds with, roughly 2.5 inch or better groups. I have an AR setup to be a "straight pull" bolt action, it has a closed gas block.

It is quieter than subsonics that would cycle a AR 300 blackout due to the type of powder I use. I am finding myself thinking about a semi 9mm carbine for 147gr suppressed subsonics.

My question is, do you think a suppressed subsonic semi 9mm carbine is as quiet as a bolt action load subsonic 300 blackout and capable of similar accuracy out to 100yds? The benefits to the 9mm are cheaper ammo and possibly being able to have semi capability that is as quiet as bolt action 300 black out loads.

[pd_3307]

I have a cmmg 9mm mk9 (9mm ar15) and have loaded subsonic 147 xtp's and lead 147s. Shot themthrough my suppressor and they are quiet but no where near as quiet as my bolt 300 blackout. I use a 178 gr load with unique powder so its super quiet. To me it seemed like most of the noise was coming from my bolt cycling on the ar-9. It may seem quieter if your not the one shooting. Benefit to the 9mm was the xtp's are cheap compared to any expanding bullet in 30 caliber. Accuracy for the ar-9 was around 3-4 inches scoped at 100 yds. I added more weight to the buffer to slow the bolt opening and it helped the blowback from the bolt opening but seemed to make the bolt have a more hammering sound on cycling.

[hardcase]

I have a cmmg 9mm mk9 (9mm ar15) and have loaded subsonic 147 xtp's and lead 147s. Shot themthrough my suppressor and they are quiet but no where near as quiet as my bolt 300 blackout. I use a 178 gr load with unique powder so its super quiet. To me it seemed like most of the noise was coming from my bolt cycling on the ar-9. It may seem quieter if your not the one shooting. Benefit to the 9mm was the xtp's are cheap compared to any expanding bullet in 30 caliber. Accuracy for the ar-9 was around 3-4 inches scoped at 100 yds. I added more weight to the buffer to slow the bolt opening and it helped the blowback from the bolt opening but seemed to make the bolt have a more hammering sound on cycling.

I would echo the same results.

I have a bolt 16" 300 BLK. I have an 9mm AR SBR (Bullseye and 147 X-treme plated) and a 300 BLK AR SBR (Reloder 7 and 220 Leatherhead or Sierra 220 match). Both the ARs in this comparison have 8 inch barrels suppressed with the same suppressor. My opinion is the ARs in the 300 BLK is quieter. The action cycling on the 9 mm has a lot more clang noise plus as a general rule, the smaller the diameter of the bore, the quieter you can expect it to be. This is believed to be true of any rifle, other factors being equal. Of these, the bolt is the quietest (longer barrel and smaller diameter bore).

The 9 mm is cheaper to shoot in an AR since I don't cast bullets and I tend to lose 3-4% of my brass.

The ARs in both are a hoot to shoot

[dohalysh425]

Thank you so much you two for the quick and informative response.

I am shooting the 180 rainier wedge HP with 5.0gr of Unique out of a 16" AR , which I have a closed gas block and no gas tube. It is very quiet. I like it a lot. I have an oversized charging handle latch and working the bolt between each shot isn't that bad.

I think I am just coming to the conclusion that there is no single gun or configuration that will give accurate, semi, cheap, expanding and extra quiet(close to bolt 300 sound level).

If either of you had to choose between your semi 300 blackout and your semi 9mm, which would you pick?

[hardcase]

Thank you so much you two for the quick and informative response.

I am shooting the 180 rainier wedge HP with 5.0gr of Unique out of a 16" AR , which I have a closed gas block and no gas tube. It is very quiet. I like it a lot. I have an oversized charging handle latch and working the bolt between each shot isn't that bad.

I think I am just coming to the conclusion that there is no single gun or configuration that will give accurate, semi, cheap, expanding and extra quiet(close to bolt 300 sound level).

If either of you had to choose between your semi 300 blackout and your semi 9mm, which would you pick?

Semi 300 BLK without a doubt. Much more versatile, it can be used for things other than ringing steel. And it is quieter

If I didn't already have a .22 suppressed, I'd pick a .22 over a 9 mm for plinking.

[dohalysh425]

Thanks hardcase. I agree and thanks for the 9mm input.

I do have a suppressed 10/22 and I already knew I would not get a 9mm carbine for plinking, I can ring a 5" plate at 100yds with subsonics every shot from a bench with bags.

Maybe I will have to get another 300BO upper for times when I think I would really want the semi function and sacrifice for a bit more noise. I did play around with my AR at first with Lil' Gun for cycling, it was fine, but I couldn't go back once I tried Unique and heard the sound difference.