H4831 loads for .280 Rem A I and 139/140gr bullet

[jackfish]

What are your 139/140gr bullet, H4831 loads for the .280 Remington Ackley Improved? I've been told the maximum is around 62.5 grains. Does that sound about right? I have arrived at a starting load of 57 grains. How about that? Or could I start at 59 grains with H4831, which is a max load for a standard 280.

 

[danr55]

Jackfish, Welcome to Moosie's Hunttalk. It's been my experience that Hodgdon's 4831 is too slow for the 140 grain bullets in 280 AI. It works well for 150 and 160, but I believe that the IMR powders word a little better. I haven't tried the SC in this particular caliber,so I can't comment on that. I won't be back until later tonite, but I will check the red book and let you know what history I have.

 

[danr55]

Jackfish, My Red Book says that 55 grain of IMR 4350 and 56.4 grains of IMR 4831 both give excellent groups and top velocities. Both were loaded in RP brass with WIN LR primers and 140 grain Ballistic Tip bullets. One rifle was a Remington 700 the other a custom Mauser. The Rem. preferred the 4350 load while the Mauser liked the 4831 load. The 4831 load chrono'd at 3080 avg. for four three shot groups. Don't have a record on the 4350.

 

[jackfish]

To continue my inquiry. I have a Weatherby Mark V Lightweight Synthetic with a 24" barrel. I loaded H4831 in fireformed and neck-sized R-P brass, WW primers and the 139gr Hornady BTSP. I have reached 62gr (.5gr increments from 57gr) for 3040fps average, 13fps spread, .8" 100 yards 5 shot groups. There are no signs of excessive pressure with this load. Through web correspondence I have recently been given a 64gr maximum load for this combination and am wondering how to proceed. Can I keep going with .5gr increments or should I use smaller increments while approaching my rifle's maximum? How would you proceed? What is your experience with H4831 in the .280 Rem Ackley Improved with 139/140gr bullets?

 

[danr55]

Jackfish, My experience says that 64 grains of H4831 is way too much. I've got notes that show bolts sticking at 62 grains and primers blowing at 61.7 grains. If you are looking for max load, I would proceed in 1/2 grain increments and stop at the first sign of pressure.

 

[jackfish]

Well, I was hesitant to go this far. But, shot .280 Rem A I loads up to 64gr of H4831, 139gr Hornady BTSP, R-P brass, WW primers today. Absolutely no signs of excessive pressure. Average velocity was 3160fps and first 3 shots went into .75" with the 5 shot group going 1.2". This is a hunting rifle and I may not have to look much farther for this season, time is getting short. I definitely love this .280 Rem A I stuff! After the season I'll try some other powders and bullets, ie: 162gr Hornady BTSP, 175gr Partition, Reloder 22, VV 560.

 

[danr55]

Well JF, I'll mark that in my red book. Out of curiosity, is there any freebore in the barrel??

 

[jackfish]

I don't really know the difference between a long throat and freebore. The Hornady bullets now have the secant ogive so they may not engage the rifling when seated to the cannelure. I seated the 139gr Hornady BTSP to a COAL of 3.265". The neck just catches the bottom of the cannulure and they are not crimped. I think I calculated it correctly that the bullet is .05" off the rifling. I don't think Weatherby uses freebore on standard cartridges in their rifles.

Whereas I said there were no signs of excessive pressure I did notice the primers are flattened slightly but there is still a small rounded edge where they meet the primer pocket. So I don't think they are flowing excessively to fill the primer pocket. Also, a very slight crater is produced around the firing pin indentation. No heavy extraction, or bright extraction marks. Perhaps I should measure case head expansion but I don't have a blade micrometer. Maybe I'll take some cases into my gunsmith and have him measure them.

<FONT COLOR="#800080" SIZE="1">[ 10 September 2001 10:49: Message edited by: jackfish ]</font>