Charges and Seating Depth

[steezo757]

After this weekend, I've decided to to use H4227. I loaded up 10 rounds with 10 grains behind 220gr SMKs. Used the first 5 to check for function (cycling and bolt holding open) and sighting in (so my chronograph doesn't get damaged).

Here's what the last 5 did:

1096
1081
1102
1087
1090

The accuracy was excellent.

I loaded up the next batch at 9.9grs to hopefully bring the velocity closer to 1050 - 1075. My Lee powder measure likes the texture of H4227. The finer powders will leak out of undesired areas.


BTW, here's my setup.

AR with a 10.5" barrel and .100" gas port in the pistol position

[JFettig]

Pug, I did check out the loads there but OAL isn't listed.

Am I corect when I assume that air space in these rounds with H110 should be kept to a minimum? This is what I am assuming when I see that charges should be kepth within 3% of the specified load and that I am seeing lots of deviation in my rounds which I carefully measured out all of the charges but maybe seated too long?

Steezo, thanks, I'll look into that powder.

Is Lil Gun the ideal powder to use? I've read a lot about that powder around here lately.

When I get back to the shop in 2 weeks, I'll open my gas port up a little and possibly make an adjustable gas block.

Thanks,
Jon

[pug]

I would try some more loads before opening the port up. Perhaps someone has some AA#9 you can try. That worked well with subsonics also.

[JFettig]

I measured my port and it is .083" according to my calipers, I think tp555 driled it to .08 if I remember correctly.

I'll look into AA#9. Not sure if I know anyone who has any. Until I buy or find some, I'll stick with supersonic loads and take your advice against opening it up. The plan was to open it to .090 max.

Thanks,
Jon

[pug]

Each gun is different but I would think you should be able to cycle subsonic loads down to 180gr bullet weight with that. You had mentioned shooting a lot of 147gr bullets and I am pretty sure it will not cycle those subsonic unless you open it up. Opening it up will allow you to cycle the lighter bullets but on the other hand you shave more bullet and will require adjustable gas to shoot supersonic.

[320pf]

Originally Posted by JFettig

I measured my port and it is .083" according to my calipers, I think tp555 driled it to .08 if I remember correctly.

I'll look into AA#9. Not sure if I know anyone who has any. Until I buy or find some, I'll stick with supersonic loads and take your advice against opening it up. The plan was to open it to .090 max.

Thanks,
Jon

I have all on my 300-221 fireball barrels drilled out to 0.083. The gas ports in my rifles is in the pistol position and I can reliably shoot 165 gr bullets sub-sonic.

Pug is right on about the suggestion to use AA#9. That is the powder I use. I have also have some success with Alliant 2400.

You now have my curiosity peaked. I wonder if I can get my rifles to shoot 150-155 grain bullets in the sub-sonic realm? I think that I will give it a try this weekend.

320pf

[pug]

My notes from early on indicate that I was using H110 with the 150s. That was before I drilled out the port I am pretty sure. They list 150gr set to cannelure with 8gr H110 would cycle but not lock back. 8.2gr would cycle but not lock back. 8.5gr would cycle and lock but went supersonic after barrel warmed up. The only notes on #9 I kept seem to be for the 255gr hollow points. 8.9gr of #9 would push the 255gr HP at 1033 fps. Doesn't do you much good but thought I would throw it in there.

[JFettig]

I took some friends to the range to shoot up some of my ammo and I brought the whisper along to put a few more rounds through it... forgot the subs though.

I put about 10 rounds through it, 4 of them failed to eject, some failed to extract... I had my .223 AR with so I decided to pull the bolt carrier out of that and put it in this just for the hell of it and sure enough, it ran perfectly. I then tried to put the BC I had in the .300 in the .223, released the bolt and it would not go into battery all the way! It was hell to get it out! I think I found the culprit, I'll be sending that bolt carrier back to DPMS as soon as I get it back to my dealer.

If all goes well this week, I'll load up some more subs and see if I can get them to cycle.

Jon