A lesson in Barrel Harmonics?

[JRWhit]

I've been having a heck of a time trying to find something useful out of Staball 6.5.
Here's what I'm working with. Shooting a Weathermark LT 6.5 Creedmoor 22" barrel, 1/8 twist. I've been Trying multiple bullet weights from what has been available and just wasn't happy with the result. I'm using Staball because it's what I could find. In general I can get decent accuracy at start load but when I work up to standard velocity groups open up all around 1-1/2" to 2". After finding a box of factory 123 gn Federals, the gun proved to me that it will shoot. Regular grouping with those are 3/4"-1/2". At that I started a ladder using Staball and 123 gn Scenars. I have been all over from start to max load and have done everything from jammed in the lands to .150" off the lands. The only way I have been able to get it to shoot worth a darn is at slower 2000-2300 fps loads. That's fine for target work but I've been trying to get a load ready for this falls hunting season. Weird thing is that Staball has had the lowest S.D. of any powder I've sent over the chrono coupled with horrible groups. After scratching my head for a bit, I dug out a pound of Viht N150 that I was saving and worked up a ladder with the Scenar 123 gn bullets and loaded them at the listed OAL which happens to be about .080" off my lands of the long throated Weatherby. The entire load ladder produced groups 3/4" and under. The best group was just over 1/4". So right there I know that the rifle will shoot. But what is the reason for poor accuracy with the Staball? Could this be an effect of poor harmonics between the barrel and the report from the powder blast? I don't know what other variable I can test out other than maybe trying a magnum primer. I would really love to get the velocity from Staball If I could figure this out. I see many posts from other shooters who have gotten really good accuracy from Staball so I know it's possible. Any ideas?

 

[dcloco]

Target at 100 yards? If so, move out to 300.

I run StaBall in one of my 6.5C with excellent accuracy and good speed with 143M and 143ELDX's.

Every barrel is different..

 

[JRWhit]

Target at 100 yds. Other info I left out as follows. Starline brass, Full length sized, CCI 200 primer.

 

[Dale Alan]

Sometimes powder and bullets just won't work together . I am stubborn and hate to admit defeat , that has cost me a lot of time and money over the years . I now move on faster when things don't gel , I never really give up I just put those combos on the back burner in hopes I never have to revisit it . What keeps me sane is having too many powders and too many bullets to ever exhaust my options . Good luck with your venture .

 

[FROGO207]

^^^^^^^^ Yep sometimes a particular barrel, bullet, or propellant combo will just flat out suck. Too bad that in these days of supply shortage this had to happen. Guess that's how I ended up with well over 30 choices of propellant to choose from. The last shortage that and my reloading log worked wonders to keep me shooting through it. I would try a different propellant if you can find something else that others have liked. Sorry I have no experience with 6.5 C though.

 

[JFrank]

I would echo the same thing, good powder just to slow for 123's ( if you haven't already) try a 140 class bullet next time.

Nicely done.

Probably not the blast rather exit timing but that's another topic or maybe that is the topic.

 

[Tirod]

I think the OP is using his noggin. Different powders burn with a different profile which creates a different pressure curve as it expands. That creates a different harmonic in the barrel, which affects dispersion as the bullet leaves the muzzle. Yes, working up a load usually does go thru a node of minimum dispersion at lower speeds then it starts to open up as you get hotter.

I don't stay at Express, I do read a lot of more informed posters, all this courtesy of them.

One method to resolve is what the OP did - change one significant factor, the powder, and yup, it got him much better results. The burn curve worked to allow minimal muzzle vibration just at the bullet exited. Another trick? Barrel weights, which also dampen vibration. IIRC Browning had an accessory that did that, great for tuning a balky load, but it hasn't been popular adding more ounces at the muzzle. Another method, chop the barrel off 1/2" and retest until you find the least shaky node. Also not popular for obvious reasons. I like the Browning concept, you just move a deadblow weight forward and back until you get the best for that load.

That kind of research is why .308 was commonly shortened to 18" barrels as it was a good combination of load, vibration, and accuracy from NATO ammo. it also goes to accuracy doesn't much change with barrel length, as the OP noted, load determined that a lot more. Think about it, as you add more grains, you get a bigger pressure rise, higher, which whips the barrel harder, and causes the muzzle to vibrate more. It pushes it out of it's optimal zone. This is exactly why its now known how shorter barrels can be more accurate than longer ones. Optimizing the powder charge and bullet selection, they can even push more lb ft down range. The handloaders working with .458 Socom and derivatives find heavier bullets actually being flatter shooting, too. It's not the stuff many of us were told in the 80s. Progress moves on.

Here's the rub - we like accuracy, we also like power, we trade off ideals to get a reasonable compromise. A hunting rifle that shoots 2MOA at 100 yards will do very well considering it's a 18MOA center mass hit zone. That is military standard - and it's pretty good by the average once a year hunter trying to hit a "pop up" deer or one moving in the field. The extra power is what might be traded off - a hundred feet per second more or less isn't going to create major differences in bullet drop, nor will it do any better than a short incremental increase in yard age where the power drops below the expansion requirement needed for that bullet construction. There's always a maximum ethical range, ask your buddy what his favorite deer rifle is. I bet he may not have a clue.

OP has pretty much solved his problem. Use the other powder. Stick to the empirical evidence when searching for solutions, look to what works, avoid reminiscing on what doesn't. Edison failed thousands of times and stated he didn't - he just discovered what doesn't work. That is still valuable information.

 

[JRWhit]

I would echo the same thing, good powder just to slow for 123's ( if you haven't already) try a 140 class bullet next time.

Unfortunately, I've been all over the map with weight as well. Tried 123 Scenars, 127 gn LRX, 130gn Sierra Gamekings, and 143 gn ELDs.

Another trick? Barrel weights, which also dampen vibration.

That would make sense. When I first worked up a ladder for this I was using a magnospeed Chrono hanging on the end of the barrel. It shot a decent group at the point of the lowest SD but I thought it was a fluke when I couldn't repeat it after loading more to sight in.

I am stubborn and hate to admit defeat , that has cost me a lot of time and money over the years .

Me to.

I now move on faster when things don't gel

I'm still trying to learn that one. I hate to admit it but I've burned through close to 300 rds trying to get something to line up. Silver lining is I've been shooting. Still enjoy it though. Maybe even a little more when there is a problem to work out.

 

[Hooda Thunkit]

Silver lining is I've been shooting. Still enjoy it though. Maybe even a little more when there is a problem to work out.

More than 4 decades of shooting, and 3+ of handloading, has shown me that trigger time trumps almost every other variable.

 

[Captcurt]

Do not despair. You probably only need some different powder. I have had 4 6.5 CM's and everyone of them was different. A Ruger Am Predator never found a bullet or powder that it didn't like. My Bergara, however was pretty finicky. I finally found a load of H4350 and 129gr Accubond LR that it likes. My M18 Mauser likes 130gr Sierra TGK with R-17. I never did get my Vanguard to shoot the way I wanted it to. Odd because the other Vanguards that I have owned shot well.

 

[lordpaxman]

I’ll try to find the reference, but, given the rifle, a specific bullet, COL, and a velocity are at a node, I didn’t think changing the powder would affect that. Good luck.

 

[Dale Alan]

I'm still trying to learn that one. I hate to admit it but I've burned through close to 300 rds trying to get something to line up. Silver lining is I've been shooting. Still enjoy it though. Maybe even a little more when there is a problem to work out

I am the same , I like a challenge . I was trying to make myself feel better . Tonights range session will be rare for me , no testing just going to shoot a known load so I can relax and chat with my son . He will be amazed when he does not see me get my test targets out .

 

[JRWhit]

Well I did find a good load for the rifle. I little over max listing but no sign of over pressure. Barnes 127 gn LRX loaded over 35.8gn of Viht N150. It patterns just over 1/2" at 100 yd. It'll make for a good white tail load this fall. Should be about 2600 out the barrel but I have to get it over the chrono and check. On range day my daughter joined me with her Savage. As it turns out hers loves the loads mine doesn't. But, just for the sake of getting answers, I'm going to try and dampen my barrel with something simple like a rubber hose and see if it makes a difference when it comes to Staball. Not that I would keep or go hunting with a rubber hose on my rifle but at this point I'm just curious enough to try it. I will post the result.