160 Grain Accubond in .280 Remington - - Seating Depth

[RiverRider]

This afternoon I shot five groups with my [cheap] custom built on a VZ-24 action. I will not disclose the powder or the charge because it will lead to an altogether different discussion. I'll disclose that I am getting about 2870 fps fifteen feet from the muzzle, and that I am using a quite-slow burning powder.

What I learned today is that the seating depths I have always worked with don't work with the AccuBond---in my rifle. I decided to try something a little different and it has paid off. I had always tried to stay within about .010" to .045" or so off the lands, but today I shot 3-shot groups, bullets seated at depths of .050" to .090" in in that order and in increments of .010". Resultant group sizes were 2.50", 1.64", 0.18", 0.91", and 1.04". I though I was seeing things (or rather not seeing things) through my 2.5-8x Leupold, but when I was able to get close to the target I could see that the third group was for real. It looks like two bullet holes overlapping, but there are three shots in there!

I had tried 140-grain Accubonds when I first acquired this rifle and they did not shoot well. I am wondering how they would do if I was to seat them a little deeper. I really don't see the point, though. I have a 150-grain Partition load that shoots five shots into well under an inch (but this is with bullets seated at .025" off the lands).

Do you guys find that Accubonds generally shoot better when seated more deeply, or is this just a peculiarity of my rifle?

 

[JD338]

RR,

Sounds like you hit the jack pot with that load.
I just loaded up some 160 gr AB's for my buddy's 280 Remington. My COL was 3.330".
I will develop a load for him with this bullet tailored to his rifle next spring.

JD338

 

[DrMike]

RR,

So far, I've treated ABs like I would any other cup and core bullet and they have shot acceptably. The 140 grain AB in my 280 is loaded to 0.010 inch off the lands, and it gives me great groups. I shoot the 160 grain AB in my 7mm WSM, and again I'm loading to 0.010 inch off the lands and getting fantastic groups. I do believe that most rifle/bullet combinations have a couple of nodes that give the best performance. It certainly sounds as if you found the sweet spot on your rifle with that load.

 

[Jim1 AB]

Just throwing this out for comments. Could there be a correlation between pressure and accuracy. This seams to me, a person that hasn't loaded for the 280 a bit on the warm side. As Weatherby has done, allowed for a bit of a bullet jump and was able to generate high velocities and not increasing pressures a lot. My 358 STA gets higher than normal velocities with all given loads. The gentleman that cut the chamber and well built the rifle never said if he cut it deep on purpose or not. When I started the reloading process and went to take the "oh so critical" measurement to the lands and found out that I was unable to even come close to the lands because of the limitations of the detachable magazine size I called him. All he said was go shoot it and if it doesn't shoot accurately he'd re place the barrel and cut it to the depth I wanted. He never had to replace the barrel. There may very well be a certain pressure that works well in a given rifle. The 257 Bee that I load for needs that "jump" for accuracy.

Jim

 

[hubcap]

River rider; In my .270 I was forced to load the 140 AccuBond at least .050 off the lands due to magizine limits. I got tiny little clusters at .063 off those lands. With the 130 AccuBond I got tiny groups at .098 off those lands. My 300 WM delivers those tiny little groups at .015 off the lands with 180 crack-u-bonds. I,ve always loaded PT.s within .025 of the lands. With accubonds, if close don,t work try seating deeper. This why I think accubonds are more fickle to load than partitions but when you find the sweet spot its worth the effort.