Hello and I need some advice

[Kentucky Drover]

Let me introduce myself- I'm Kentucky Drover and I have been "lurking" on this site for a couple of months. I recently acquired a Model 1 Sales 300 Fireball Kit and have assembled it and started some load analysis. I formed brass from Remington commercial brass. The gas port is in the carbine position and I verified that it is at max. (.125). I installed a JP adjustable gas block and it was also .125.

I plan on using this platform for suppressed fire only. I have not received the suppressor, still awaiting BATFE approval. I would like to use the SMK 240's. I am looking for load sugestions. My loads to date that are subsonic will not cycle the AR-15 bolt. I have tried WW 296, AA 1680 and Alliant 2400.

The load needs to be subsonic and accurate. I would also like a load that would fully cycle the AR, if possible. If this combination is not possible- I can live without the cycling of the AR. That is the main reason that I installed the JP adjustable gas block.

This is a great site and I would appreciate any load suggestions offered. I own a gun shop, so most powders are "at hand".
Thanks,
Kentucky Drover

[320pf]

Kentucky Drover

Originally Posted by Kentucky Drover

I plan on using this platform for suppressed fire only. I have not received the suppressor, still awaiting BATFE approval. I would like to use the SMK 240's. I am looking for load sugestions. My loads to date that are subsonic will not cycle the AR-15 bolt. I have tried WW 296, AA 1680 and Alliant 2400.

I do not have any direct experience with a suppressor (I live in NY) but I have read that when you put the suppressor on you will get more backpressure thus more gas to cycle the bolt. I regularly shoot 8.5 gr of AA#9 or 2400 to push 168 gr Sierra matchKing bullets to 1080 fps.

If you could list some of your load data that would help

320pf

[pug]

Try the 4227 load for the 240s since it is single base powder. All of the velocity generated comes from gas pressure with a single base powder. There is a load on quarterbore.com but if you don't see it start at 9gr and work up. You could also try N110 which is single base.

Make sure before starting that your action is smooth operating. The bolt/carrier should be able to be inserted and extracted with just the force of little pinky and should not drag at all also gas system lines up correctly as I'm sure you already know. Hope you get it going and you will need to use the really heavy bullets.

[Kentucky Drover]

320 pf and Pug,
Thanks for the responses. I did a quick check of the twist rate and it came out to 8.5:1 instead of the advertised 8:1??

I guess I need to slow down until my suppressor arrives. I realize there will be some degree of "back pressure" by the use of the suppressor, but I am thinking it will not be much considering the low amount of powder in the subsonic loading.

I started out with 12 gr. AA 1680 but the velocities averaged 1233 FPS which is a little fast. That load seemed to be accurate. I was adjusting the scope with this load.

I tried 11 gr. AA 1680 but the accuracy at 100 yards was not acceptable. @ 3". This is a guess since it was raining and the target was falling apart.

8.5 gr. 2400 gave similiar accuracy.
Since the barrel twist is 8.5- it might be difficult to stablize the 240's at the slower subsonic velocities??

I need a couple of nice days and the suppressor!
Drover

[Pitt300]

I've got the same upper & am getting about 1" supersonic load groups.
I'm also waiting on BATFE to approve my can before I shoot ANY subsonic loads.
Paul @ M1S says that it should operate fine w/supersonic loads (which mine does) & w/subsonic loads W/A CAN ON IT!
They are single shot w/subsonics & NO can.
I'm using H110 & good accuracy so far w/supers but I did have the pressure problem that M1S is working on.
Haven't fired a single 220 or 240SMKs.
The barrel is 16"+.
If you mark the top of a cleaning rod & put a tight patch on it & push it thru, it should rotate 2 times before it comes out.
Mine did as I checked it.

[Kentucky Drover]

pitt 300
I called Model 1 Sales today- did not get the name of the fellow that I spoke with. He also stated the upper should cycle with a suppressor. I got the adjustable gas block to shut down the cycling to make it as quite as possible. I would also like to have the option to fire suppressed semi mode also- not that it would be a requirement- it would just be "cool"!

I marked a cleaning rod in the "12 oclock" position and measured the twist in my barrel and it came out to 1:8.5".

To me an accurate and suppressed load is the goal- if it would also cycle the AR- that would be "icing on the cake".

Thanks,
I will post my loading data once I get the suppressor in and some range time.