300Whisper in the AR-15

[AB8EAB8E]

Ok... So I should drill mine i guess??? Is that the only way to get it to cycle???

Would someone Please list some clean burning, sub-sonic reload data for my AR-15 300whisper for me to try...

[Crawdaddy]

So the Whisper upper that I've had since MAY has finally been mounted on a lower and even has a scope mounted to it. (M1S, carbine gas, YHM forend, not much else special)

Loaded three different bullets over various charges of AA1680 to get some testing started. Hoping to get to the range or better yet the deer lease to do some testing. (Maybe this weekend?) Too much work and not enough play makes Crawdaddy an unhappy camper.

Loads:
220 SMKs (subsonic)
220 Hornady RNSP (subsonic)
150 Nosler Ballistic Tips (AA1680 and H110 supersonic loads)
Loads based on the Sierra data sheet.

Not sure how the 220 Hornadys will feed or if I need to seat them out longer. Will fiddle with the seating depth after I test these. Displacement in the case seemed to be about the same as the SMKs when I seated to the cannelure. They do look neat in a magazine. If they feed and cycle, they might just be the ticket.

The 150 Noslers ought to do some damage and would make a nice doe round.

I also have some surplus 108gr frangibles that might be fun for plinking. I don't expect much accuracy though. Weights vary from 104.5-108.5 across around 30 of them with not more than 5 of them weighing the same. Will try to get some of those loaded over H110 or 2400 to see if they'll cycle.

Anyone have any experience with the frangibles or the Hornadys?

Pics attached...

[pomofo]

I've loaded the 220 Hornady's with AA1680, everything between 9.4 and 12.8 grains at a COAL of 2.000". According to my notes I've never had a problem with feeding, extraction, or ejection. Only tested at 25 yards with a 4MOA red dot sight so far, 10.4, 11.6, and 12.8 grain loads all put 5 bullets in one hole at that range.

ETA: This is in a 16" M1S upper, carbine length gas, unthreaded muzzle.

[Crawdaddy]

Great - that's almost identical to my setup. Can't wait to get out and get some trigger time! Will post results when I have them.

[Shadow 300]

I too have been intersted in the model 1 sales 300 fireball. I emailed them regarding gas port location, it is in the carbine position. I also asked them if they would build one with it in the pistol position but got no reply. What I am understanding from this thread though is that a couple of people have been able to make the M1S carbine relaible with 220 grain subsonic by only drilling out the gas port to a larger size. I haven't read anything that says this will mot work. Is there something I am missing?

I am also considering having something built but there is a significant cost difference that I am sure will be apparent in the quality of the two but the M1S is an attractibe low cost was to start shooting this round.

[Fritzcat]

It all depends on what you want. If you are going to use a suppresor and use as fast a powder possible to be as quiet as possible then you will need a pistol location for the gas block. And there are other tricks to get an AR to cycle with the fast powders and down to 147gr bullets for plinking.

[L1A1Rocker]

Originally Posted by Shadow 300

I too have been intersted in the model 1 sales 300 fireball. I emailed them regarding gas port location, it is in the carbine position. I also asked them if they would build one with it in the pistol position but got no reply. What I am understanding from this thread though is that a couple of people have been able to make the M1S carbine relaible with 220 grain subsonic by only drilling out the gas port to a larger size. I haven't read anything that says this will mot work. Is there something I am missing?

I am also considering having something built but there is a significant cost difference that I am sure will be apparent in the quality of the two but the M1S is an attractibe low cost was to start shooting this round.

Model 1 will put the port in the pistol location for an extra fee ($100.00 IIRC)

[Crawdaddy]

Quick update on my tests above. I had only one FTF with one of the light supersonic loads, and one of the light subsonic loads did not lock the bolt back when empty. Other than that, everything else functioned 100%. I'm tweaking loads for velocity and accuracy now.

All of this is with a M1S upper w/ carbine gas, unmodified. Will post more later...

[3006mv]

When you calleld M1S did you ask what size the their gas port was drilled to? Just wondering. Congrats, post more on your loads and pics too.

[robrob]

I have a standard 16" Model1Sales 300 Fireball carbine upper with the carbine position gas port. I removed the 4 rail gas block to drill out the port and block and found that they were already 1/8" (.125"). I installed an adjustable gas tube and had to trim the buffer spring a few coils to get it to cycle the Corbon 300 Whisper ammo. It has no problems cycling with 220SMKs and 10.5grs of AA1680. I have to give the M1S upper two thumbs up.

I shortened the spring because I couldn't get the buffer's cushion tip off. I removed its roll pin but could not pull the tip off to get to the weights. I could twist it with a pair of pliers but not pull it out. Any tips?

Rob