Help me Figure out what I Screwed Up - Very Weird

[CanMike]

Okay so I am stumped. I have 6.5 Creed with Hornady A-Tips (153) and was shooting amazing.. 0.4-0.6 MOA consistent. Virgin Brass which i FL Resized and loaded with 40.7 H4350 @ 2680 FPS

Now working up load on Fire formed, I ran a few groups and they shot well and decided at 40.3 H4350 to match velocity. Now I did a batch of resizing and I over bumped. Was aiming for 0.002 but ended up form 0.002 to 0.005... I realized it was a lube issue..

So here is the problem.. I decided to bump the 0.002 group to 0.004 so I would have 0.004-0.005 (Still longer then Virgin at 0.006)

I retracted the decaping pin in the FL Hornady Die just above the primers and re-bumped and all went smooth with proper amount of lube, etc.. Cleaned Die, all good...


**** I m thinking above is the issue***** Maybe touched primers, maybe resizing twice is bad...


Go to the range and I am spraying 2-3 MOA everywhere.. Up down, left right.. WTF but Velocity is ES-17 and SD of 6 (15 shots) So stable velocity and a few FPS less ES and SD then Virgin Brass.

Shoot some rounds my friend gave me to try just to see if it's the rifle / scope or something and they shoot 0.45 MOA 5 shot group @ 330 Yards. Same velocity @ 2670

So what did I do wrong. I am stumped and depressed.. LOL

I am doing a match tommorow but have enough Virgin brass already loaded. So not an issue there..

So I am thinking once I fire that I resize that and compare with some of my other stuff that wan't resized twice.

Also resize the brass that just shot like crap properly and try that with above as this will be now twice fired.

Really stumped..

Mike

 

[Doom]

If your decapping pin made contact with the anvil then it pushed the anvil further into the priming compound and away from the bottom of the pocket. This might have changed the action time between rounds. Enough to effect precision? Don't know.

 

[ShtrRdy]

With the type of resizing die you're using, could the expander mandrel/button not be doing its job since you disabled the decapping operation? Were the bullets a little harder to seat?

 

[CanMike]

With the type of resizing die you're using, could the expander mandrel/button not be doing its job since you disabled the decapping operation? Were the bullets a little harder to seat?

No I didn’t notice any difference in seating. I eye balled the expander and should have been okay but maybe by raising the ayatem it does / doesn’t do something I am not seeing.

Mike

 

[JerkyFreak]

Could be that you got lube into the neck on some cases, and not others.

Also, did you do a runout check? I tossed my Hornady sizing die due to the amount of runout I got.

 

[RegionRat]

Just like the ammo your friend handed you.... the use of a trusted standard pet load is handy to divide the problem between the gun or the ammo.

If you can keep a quantity of a pet load in your kit you can debug.

Now, with the assumption that your friend's ammo results show there was nothing wrong with the gun the obvious thing is to make another batch but this time without the issues you listed.

Odds are, if the previous results were as your described, gravity will once again point down if you go back and do it again the right way.

It is however, unusual for a rig to shoot that bad with ammo that is close to what you wanted and only slightly off by your bump issues and rework. Does this mean that the gun and ammo are sensitive to neck tension? To volume? Was the velocity of this batch way off the mark?

The difference between 40.7 and 40.3 combined with the difference in your rework of the brass is something you may want to test again in the future once you run a batch of your normal load and get the results that you expected.

If the rig is that sensitive that it jumps from 0.4-0.6 up to 2 - 3 MOA, then you are going to want to know there is a cliff in the path.

 

[redbullitt]

Might do better at another charge weight or seating depth? Edge of the node maybe and small changes show up bigger?