Ok shots stringing...bad....

[Oldmanpaintball]

Ok, I have been loading for about 16 years, this is my first "wildcat". I am using 9.1 grn H110 and a 220 SMK. Given its 29 degress out right now I might be getting excited for nothing. My first 2 shots at 100 yards are dead center of the target about 1.75 from each other the next three are about 5 inches higher and are almost touching. Am I getting this from barrel warm up or is my gun just trying to drive me insane?

BTW: It is a olympic 16" stainless with a fixed length pistol gas sytem mounted on stag lower.

OMP

[320pf]

Oldmanpaintball,

I recently re-shot some H110 loads with an ambient temp of 38 degrees and got significantly different results than I got this summer when temp was about 75 degrees.

The chrono data for the 75-80 degree day was 1813, 1817, 1836, 1869, and 1866 fps. When I re-shot the exact some load (I used the same lot of brass, primers and powder. Moreover, the powder for each round was individually weighted to within less than a 0.1 grains), the chrono data for the 38 degree day was 1710, 1768, 1747, 1765, and 1804 fps.

The velocities got faster as I progressed through the string. BOTH times. I think that H110 is somewhat temperature sensitive. I have said this before on this site and people reacted like I was a heretic.

Here is what I think is going on. As you fire the gun the chamber heats and the following chambered round warms-up in the chamber. If you are doing load development/chrono work you tend not to rapid fire (you read the chrono for that shot, check the spotting scope to se where the gun is printing etc...) so there is a significant amount of time for the round in the chamber to heat up. In addition, the gas that works the action also blows back through the magazine, heating up the ammo in the magazine. Next time you have your AR out look at the shells left in the magazine and you will notice powder residue on the brass.

If you want additional anecdotal evidence check out this site:

http://feistyrooster.com/300x221/300x221barrelsplit.html

"I pulled down the gun and looked at my barrel.... It was split – none of the previous rounds had exited the barrel... you can see for yourselves, but it looks like the add-on bayonet lug helped keep the barrel from splitting completely.... I have no idea why things didn't work like they did the day before... temperature maybe? it was 20 degrees colder... wrong powder charge or omitted charge? can't be, I intenionally inspected all the cases with a flashlight before I seated the bullets. Each charge was individually weighed and inspected..."


My two cent worth

320pf

[Oldmanpaintball]

I think your theory might make sense. I didnt have my spotting scope set up so it was take 2 shots, walk 100yrds back and fourth, then shoot again. Lots of time for the heat to soak in the round.


Are the supersonic loads any less tempermental?


OMP

[320pf]

Yes the supersonic loads are a easier to get the work the action, especially if you stay below the max loads. Both the Sierra and Hornady reloading manuals have quite a few loads listed for the 300-221 fireball/Whisper(r). For subsonic loads, I suggest that you use AA#9 or AA#7. The Accurate Arms web page lists several subsonic loads for the 300-221 fireball/Whisper(r). Any of the powders faster than H110 ie 2400 work pretty well with the subsonic loads.

Check out the loads that I have posted at ReloadersNest.Com:

http://reloadersnest.com/frontpage.asp?CaliberID=135

My loads are listed under "Not yet verified user loads" All of the loads listed I have shot and chrono'ed, except the one using the AD2205 powder... someone else produce those data.

320pf

[Oldmanpaintball]

Looks like I am buying powder tomorrow. Did you end up putting a JP adj block on yours?

OMP

[320pf]

Yes, I installed a JP low profile adjustable gas block.

I am running an AR15 with a 16 in. stainless steel barrel from Olympic Arms and a Centurion lower made by Olympic Arms for Century International Arms. I installed a JP trigger in the lower with about 3 lbs let off.

The Gas port is in the pistol position with an adjusable gas block from JP Enterprises.

[Scollins]

Oldmanpaintball,

I have said this before on this site and people reacted like I was a heretic.

320pf

BURN THE HERETIC!!!!

:tongue: :grin:

[lemmethink]

320pf-
Is there a powder for subsonic loads you would recommend that is less temperature sensitive than H110?

I just checked weather.com and they say it is -27 outside right now here in Alaska. I don't think I will be shooting today but it is easy to see how loads developed in the winter might behave totally different in the summer or even if taken to a different part of the country.

[320pf]

lemmethink-

I have not shot that many subsonic loads. The only one I have used is AA#9

You should check the Accurate Arms web site. They list quite a few different subsonic loads. If you have access to a chronograph you can run some tests.

I use 7.5 gr of AA#9 and get 1030 fps out of my AR


I read that JD Jones does not recommend any powder that is faster than AA#9. AA#5 is probably about the fastest powder that you want to try.

Here is the URL to the reference

http://www.quarterbore.com/300whisper/subsonic.html

Here is the URL to Accurate Arms:

http://www.accuratepowder.com/data/PerCaliber2Guide/Handgun/Standarddata/30Cal(7.62mm)/300%20Whisper%20page%2076.pdf

[spmorgan]

Hi 320pf,
those 2205 loads are mine, you probably cant get the powder to test them, their made In Australia. Shane

[320pf]

spmorgan,

I posted some subsonic loads on reloadersnest.com 165g bullets behind 8.5g AA#9 and a 125 g supersonic load behind 20g H110.

Do not know the burning speed of 2205 relative to H110 AA#9 or N110?

http://reloadersnest.com/frontpage.asp?CaliberID=135

320pf