Charges and Seating Depth
 

I've been doing some research and some loading. I now have about 100 rounds through my 10.5" pistol.

I loaded 20 220 SMKs with 9.2gr of H110, a load I borrowed from spook, I did this only after verifying it with many other loads. I put 5 through a chronograph and they started at 940-50 and got up to 1070fps just in those 5 rounds, not very consistent. Some had flat primers and some weren't as flat. All of these were loaded to 2.220" I read that loads with H110 should not be reduced more than 3% rather than the normal 10% reduction, does this have to do with empty space and can it be fixed by changing seating depth? What is the best way to determine seating depth?

I have mainly shot 147gr Win FMJBT with 15 and 16gr of H110(started at 15), the 16gr H110 loads were mostly consistent at 1750-1780fps, I did get a few that I didn't put through the chronograph that the primers didn't flatten out as much as the rest. All of these are seated to 2.150".

From the ones that didn't flatten the primers much, the shoulders weren't blown out as much as the ones that had flat primers. I had no case head expansion on any of these cases.(formed LC 5.56 brass)

I plan to load some 165gr soft points, 125gr sp or hp, and determine what I want to shoot primarily. I don't have a can so I don't plan on shooting much for 220s, They do however have the most energy at long ranges when loaded supersonic.

What about loading light bullets subsonic, like 168 gr boat tails? The subsonic 220s I loaded were nice, light, and very quiet compared to the 147s.

Is there a more ideal powder than H110?


Thanks,
Jon

With a pistol you may be able to cycle 168gr loads you will have to try it and see. The gas port has to be larger the lighter the bullet you use but you may be fine. Since you have H110 on hand you can try 8.5gr with the 168s for subsonic and see.

Any thoughts on seating depth and charge sizes for consistent shooting?

Jon

My notes say 2.200" for 168gr SMK with 8.5gr of H110 but that is all. Not whether it is starting load or most accurate.

Thanks for the info pug, I'm more looking for that info on the 147 supersonics and primarily the 220 subs .

Shot 10 125gr TNTs at 2000fps, 2.100" OAL. All went off flawlessly.

Jon

for my 220's I have 2 subsonic loads that are in the 1020-1050 range:
8.7gr LiL Gun
11.6gr RL7- this is a compressed load

as for seating- I have not played with it much

If you are using H110 still go to www.quarterbore.com and look under subsonic and supersonic. I think I used those loads when I was trying H110.

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

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

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.