Seating Bullets with Varying Degrees of Stiffness

[FALex]

Hey guys, so I shot a match yesterday and I couldn't hit the broad side of a barn. Normally I do alright. Prior to the match, I attempted to establish a good zero which wasn't really happening. I just couldn't hit the bull. However, some rounds were going in the same hole, but others would then go low, or right of the bull. Mind you, these were all still really close to the bull, but far enough off to make me think twice.

As the match was going on, and I continued to miss damn near everything, I started to remember that when I was seating the rounds for this rifle, I had issues with consistency on the neck tension. Some bullets would be rather stiff when trying to seat them, others would seemingly glide in, almost like there was barely any tension.

I'll tell you my prep, this was with brand new brass, and Redding dies. First, I went through and ran the cases with dented mouths through the expander ball. I then took all of the cases and hit them with the neck sizing bushing for my desired tension. Chamfered the mouths and loaded them up.

Have any of you guys experienced this? I am assuming the difference in tension would make the rounds far from consistent, I just didn't believe it would be as bad as it was. As I type this out, I am starting to wonder if using the expander ball on some, but not all of the cases could have caused the variance? I assumed going back and using the bushing would've equalized all of them but maybe not?

Any of you folks have any thoughts or experiences like this?

ETA - I chronoed 5 rounds and they had an SD of 17 and an ES of 37.

 

[SixKiller87]

Brand new brass is always a bit funky. I like to try and at least get all my brass once fired before running them through any dies. I just run an expand mandrel down the necks de-burr/chamfer and call it good enough and load it up. My personal philosophy is with good brass less is more (for at least the first firing).

 

[Dschapp44]

I agree with sixkiller above and follow the same process with new brass. The one thing I’d add is if you decide to do anything to adjust neck tension do the same thing for all your pieces of brass. Not just half.

 

[Gunfighter14e2]

Before sizing fired brass clean the necks with a bore brush on a drill 1 bore size over you bore. After you have run the sizer in an out of the neck no matter how you size, use a VLD cutter on the neck Always,.... Always,....did I say Always? take a bore brush on a drill and run it in an out of the neck at 1k-1.5K rpm 2-3 times. you will see a major change in the way the bullet seats. The results on target an the crono, will prove this out.

 

[Juggerxxx]

I assume you already have an established load for this rifle, bullet and powder by means of some load development? If not then I would suggest doing that. If so; are you using the brand and lot of brass?

 

[918v]

Your neck bushing is too loose for new brass. Get one that’s .002” tighter. It has to do with the way brass flows through a constriction.

 

[Steel head]

I always fire once in new brass before it sees serious duty.

 

[FALex]

Yes, I do have an established load with this rifle. This brass is not the same lot as prior lots that have been used.

I think I might have just jacked everything up by only running that expander ball through some of the cases.

I do not have a VLD chamfering tool, but it sounds like a good one to have. Currently I am running the standard chamfering tool that comes with the RCBS Prep Center.

Thanks for the info fellas. As I typed my OP, I started to realize that I probably did myself a disservice by not treating each case equally.

I guess my primary question is, do you all believe that this lack of consistency in the neck tension could cause this inconsistency? I’ve been reloading for a long time and am confident I’ve run into this scenario before but I don’t remember the results being so dramatic.

 

[spife7980]

I guess my primary question is, do you all believe that this lack of consistency in the neck tension could cause this inconsistency?

Absolutely

 

[Dunraven]

Hey guys, so I shot a match yesterday and I couldn't hit the broad side of a barn. Normally I do alright. Prior to the match, I attempted to establish a good zero which wasn't really happening. I just couldn't hit the bull. However, some rounds were going in the same hole, but others would then go low, or right of the bull. Mind you, these were all still really close to the bull, but far enough off to make me think twice.

As the match was going on, and I continued to miss damn near everything, I started to remember that when I was seating the rounds for this rifle, I had issues with consistency on the neck tension. Some bullets would be rather stiff when trying to seat them, others would seemingly glide in, almost like there was barely any tension.

I'll tell you my prep, this was with brand new brass, and Redding dies. First, I went through and ran the cases with dented mouths through the expander ball. I then took all of the cases and hit them with the neck sizing bushing for my desired tension. Chamfered the mouths and loaded them up.

Have any of you guys experienced this? I am assuming the difference in tension would make the rounds far from consistent, I just didn't believe it would be as bad as it was. As I type this out, I am starting to wonder if using the expander ball on some, but not all of the cases could have caused the variance? I assumed going back and using the bushing would've equalized all of them but maybe not?

Any of you folks have any thoughts or experiences like this?

ETA - I chronoed 5 rounds and they had an SD of 17 and an ES of 37.

I believe a variation in neck wall thickness will cause a variation in seating tension. Turning necks seems to help.

 

[FALex]

So a little update...ran the rifle to my smith who ran a scope down the bore. I was also concerned about a carbon ring, which there was only a slight build up going on on the right side of the chamber, so we knocked it down. After talking to my smith (also a championship benchrest dude), he was betting that the neck tension was just too varied.

I'm just going to shoot the remaining loads and start from scratch, using a VLD chamfering tool too.

Thanks for the input all.