Why is my new 6.5 Creedmoor so slow?

[earl39]

Some have eluded to it but not stated it is that there are fast barrels....ie... a barrel that will show a faster than normal speed with a set load of know average speed... and there are slow barrels that are just the opposite as they using the same load will have a slower speed.. You could just have one of those slow barrels. As has been said a slow hit is better than a fast miss any day.

[upSLIDEdown]

Raising pressure is the only way to increase velocity.
Remember that the whole "idea" behind temp insensitivity, that property can only exist for a set of certain parameters; not a general property. There has been enough actual good testing by many, including Dr. Denton Bramwell that can easily be sought out. Varget as an example. Designed for the 308 with a 150gr. Bullet. Appears foot that billing quite nicely. Although folks will swear the same, Denton has shown it to be a streaming heap in the 223. Does that make it a "bad" choice for 223 loads? No, just means that the properties you bought it for may not apply, in that setting. H4350 appears to be designed around the 30-06 with 165gr. Bullets... Not exactly identical case as the Creedmoor.

As was suggested, you could have a slow lot of powder. I bought 16# of Win 760 a while back, it to is slower than suggested. I have a load within current Hodgdon data, that does a 10-shot average of 2725fps @ 15 yards.

As for the "no signs of pressure" do whatever you wish, but keep in mind the truth about that. Compared to nothing: measuring case expansion is better, judging bolt lift is better, staring at primers is better.... However:
For the 50,000+ psi range cartridges VERY carefully calibrated copper crushers have been repeatedly proven to not accurately report pressure. To the tune of 5-7,000 psi variations, that is why piezoelectric/strain gauges are used.
Very uncalibrated cases & primers aren't going to be better judges of actual pressure. There is no single formula for cartridge brass. IF one could only build following the handbook for metals, the tensile strength for cartridge brass is @ 70,000 psi. So when you see growth and stretching, well you know what psi range you are touching.

Fair enough.


Some have eluded to it but not stated it is that there are fast barrels....ie... a barrel that will show a faster than normal speed with a set load of know average speed... and there are slow barrels that are just the opposite as they using the same load will have a slower speed.. You could just have one of those slow barrels. As has been said a slow hit is better than a fast miss any day.

I also realize that, and have thought about that being the case. I know Green Mountain stuff isn't hand lapped or anything like some of the high end blanks are, and I'm sure that makes some difference. After this match on the 6th, I may try to work up a little hotter load and see what happens. Also curious to see how things go once I get a few hundred rounds down the tube. I guess time will tell.

I'm also going to load a few rounds long, closer to the rifling and see what happens. After thinking about it, that's probably the biggest difference.

[thermaler]

Nice, educational thread.

[BillPa]

Some have eluded to it but not stated it is that there are fast barrels....ie... a barrel that will show a faster than normal speed with a set load of know average speed... and there are slow barrels that are just the opposite as they using the same load will have a slower speed.

True. A 'smith friend and I each built 308 Supers.( 30-8mag-30). For all practical purposes they were identical, 700 actions, 28" Hart barrels chambered with the same reamer. Using the same component lots his rifle averaged close to 100 fps faster than mine.

Powder? This is a bar chart I made for my 270-08 Imp during it's initial load workup. The specs, Mod 70 SA, 22" 12T LWT barrel, Sierra 130s, Win brass, Fed 210 primers. All rounds shot on the same day same range session, temps between 70-75 degrees, 35P clock.
http://i50.tinypic.com/35m1jit.jpg
Notice the two bars each for the 44-45 loadings due to a change in powder lots. I had used up what was left in a 1# then switched to a new 8#. The difference wasn't much, but the new lot produced modestly higher velocities. BTW, the 45-45.5 was the most accurate loadings.

Two examples why one can't go "by the book" or the results of others, different barrels, component lots and conditions.

Bill

[wbm]

IMO after looking at the data listed for the 6.5 CM at Hodgdon, Nosler and Hornady I don't think your 6.5 CM is "slow" at all. Looks to me like it falls within expected statistical variations from barrel-to-barrel.

http://www.gunsandammo.com/reloading/reloading-the-6-5-creedmoor/

http://www.americanrifleman.org/Webcontent/pdf/2009-6/200961145351-hornadycreedmoor.pdf

[sixonetonoffun]

I haven't had a chance to yet but am going to try some 7828ssc in my 260. Looks like 2800fps is possible from a ql post I saw on the Nosler forum. Though I'm pretty satisfied with imr4350 and H4831sc for now. MRP looked really good too but have none to try.

The Nosler brass should be good for some max load testing. Using 129gr sst's have the added bonus of not encrouching on the case volume.

[LongRange]

Someone else already said it but try reloader 17, guaranteed to increase velocity. Also try different primers...ive shot them all and CCIs seem to be the most consistent for me....ive got my 260 down to 6FPS over a 10 shot group after uniforming primer pockets and flash holes.

[upSLIDEdown]

I've got 5lbs of RL17 to try. I'm running BR2 primers. After this match next weekend I'm going to do some more load development and see how things go. We shall see. Hopefully I find the next node without issue. Either way, after that I'll be trying to RL17.