6.5X284 Realistic Velocity

[Taxman1002587]

I am going to be working up loads for two new 6.5X284s. One gun is a Cooper Arms with a 26 inch barrel. The other gun is is a Savage with a 27 inch barrel. Both barrels are 1X8 twists. I only plan on shooting 139 gr.-142gr. bullets and plan on trying H4831sc, H4350,ReLoader 22 and N165 in that order. In a 26-27 inch barrel what would be a reasonable range of velocity,FPS) to expect? I have never worked with this cartridge before and most of the loads I have read about the individuals are using barrels 2-5 inches longer. Thanks.

 

[FatBoy]

If this is your first 6.5x284, try this.

Take both rifles to the range and set the chrono aside.

Shoot for groups. At least 10 shots,two groups of five) for each load. Shoot all 10 without cleaning, then start with a freshly cleaned barrel for the next 10.

Work up your loads until you start to see signs of pressure. That is your top end. Back off of it about .3 to .5gr.

When you have three loads that group good, shoot 10 more of each for groups, over the chrono and see what your numbers look like. Hopefully, they all agg about the same in group size and SD/ES, and you can load for the center charge. When you find the load, play with seating depth some, but I have found 142's to do well from .015" to .30" off the lands, with most of my rifles are .020" off.

Don't worry about the muzzle velocity. I've shot the 6.5x284 as slow as 2850 and as hot as 3100fps. The speed isn't nearly as important as the accuracy.

Now, to answer you question, you should expect between 2800 to 2950, with realistic pressure. You may see slightly higher or lower MV, depending on the barrel.

Chris...

 

[oldjad01]

Very good answer Fatboy. JimDee

 

[FatBoy]

Jim,

Thanks.

My first 6.5x284 had a 26" barrel, and I fought with it trying to get 2950fps. I could shoot it from 2800 to 3100 depending on the powder, but all the testing and messing around, ended the barrel at just over 700 rounds. ,BTW, 50.5gr H4831SC and a Rem 9 1/2M primer was the golden load for that rifle)

I pushed my next couple of barrels to try and keep them running accuratly at 3000fps,30" barrels) but I'd always get the uncalled flyer at the WORST possible time. I tried so hard to beat the wind, my grouping suffered. I'm on my 7th, maybe 8th) 6.5x284 and in my last three or four barrels, I've backed my loads off and I'm not running them over a chrono unless I see something odd at 1000y. I know that H4350 and 210m's are going to net me single digit SD's with 142's, so I shoot for accuracy, and if I'm 50 or 75fps slow, I write it off. I have found it better to have a consistant load with a nice round group and no unexpected flyers, than a 3050+fps screamer that will throw one to the 8 ring once every 15 to 20 shots.

Chris...

 

[bcott]

FB: Well written description of an outstanding methodology. I normally do not chrono until I have the accuracy load/loads for any of my rifles. The speed is just additional info, but not really necessary except for figuring drop and wind tables. bcott

 

[ChuckMiller]

I shoot 49.5grs of H4350, 210m primers, Lapua brass, and the 139gr Scenar out of a 29" barrel right at 3000fps. That is an average over a chrony in 70-80 degree temps. I get no cratering and could probably go up 1-1.5grs, but that's where I get my best accuracy. Among the guys I shoot with that's a pretty std load and a favorite of many. Except most of them shoot the 142MK's, a bullet my barrel hates, nice round 1" groups @100yds. I've seen some barrels shoot faster with the same load and barrel twist/length, and some slower.