Best steps to reducing variation in muzzle velocity?

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cbh560

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This may be a multi-part question.

I've been reloading for 5-ish years and I think that I have fairly consistent and concise reloading process with reasonable quality equipment, but I'm struggling to reduce the spread in velocity I'm seeing in in some of my loads. The rifles in question are custom built from high end components by very reputable gunsmiths so I'm not considering the rifles to be suspect.

My reloading equipment:
- RCBS RockChucker II
- RCBS Rangemaster 750 scale
- RCBS/CH4D match seating/sizing dies.

My process:

- mostly using Lapua brass from the same lot so little prepping required from new, but all cases are cleaned, FL or neck sized depending on number of firings, annealed every 3 firings.
- cases are typically FL sized every 3rd firing and neck sized in between.
- powder (varget - same lot) is measured out on the RCBS scale and slowly trickled until the scale just steps up to the desired charge weight. Since my scale is only +- 0.1 grs this is the most consistent I can get it.
- bullet seated using match dies. Seating is consistent within 0.001" measured with Hornady OAL gauge and calipers.
- primers (CCI 200) are the same lot
- bullets (Berger 185 JGT) are the same lot

I'm seeing roughly 30-40 fps spread in velocity measured over a Superchrono. My load is producing 2" 10-shot groups at 300 yards, but I think I could reduce it to <1.5" if I could reduce my spread in velocity.

What are the most logical/priority steps to get better consistency in velocity? Anneal more often for better neck tension? New scale with higher resolution? Bushing dies for setting neck tension better? Where would you go from here?
 
My personal biggest change in velocity and accuracy, was starting to use Lapua brass at the same time I ditched my RCBS chargemaster combo for an FX120 scale, then things just started going REAL good.
I was already using Lee neck collet die and Redding body die, so I don't know how these 2 factor in.

I Notice primers also, at the time, I had seen also a significant accuracy improvement (cannot say for velocity as I load dev'ed without a chrono) switching for regular CCI to CCI BR primers.
 
MartyK2500 said:
My personal biggest change in velocity and accuracy, was starting to use Lapua brass at the same time I ditched my RCBS chargemaster combo for an FX120 scale, then things just started going REAL good.
I was already using Lee neck collet die and Redding body die, so I don't know how these 2 factor in.

I Notice primers also, at the time, I had seen also a significant accuracy improvement (cannot say for velocity as I load dev'ed without a chrono) switching for regular CCI to CCI BR primers.
Click to expand...

Oh boy do I ever want FX120 scale, but the big $$$$ for one of those right now just isn't in the budget.
 
Switch Bergers for 175 SMKs and money saved can go towards a good scale :stirthepot2:
Just joking, don't know if your sport requires extra accuracy or not, I just know that with sub 1/2 moa 10 shot group at 300M, SMKs will get it done for MUCH cheaper, so more money for cool tools and extra components!
 
Have you ever checked your loads on a different chronograph? I've compared exact loads on same shooting days.... one would say ES of 6 fps and the other would say maybe 20.
 
Munkey1973 said:
Have you ever checked your loads on a different chronograph? I've compared exact loads on same shooting days.... one would say ES of 6 fps and the other would say maybe 20.
Click to expand...

I have not as it is my only chronograph. However, the results on target mimic the results that the Superchrono is giving me, so I have no reason not to believe it. If I input the velocities it gives me into a ballistic calculator the difference almost matches the results on paper perfectly.
 
I second what Marty says about Lapua brass and it's consistency in all respects...When it comes to the cartridge I feel that consistency in brass volume and powder charge weight are number one...Followed by the quality of primer and neck tension consistency...You seem to have all these bases covered.

BUT the number one factor in bullet velocity variation is the internals of the barrel...Even with the high end barrels some are hummers and some are bummers...That's why a Smith with an accuracy guarantee will more then not test the rifle for accuracy before shipping it.

Do you have any rifles that you are happy with ES in velocity?
 
Personally I haven’t invested in my own equipment just yet I use my uncles. Having said that I research the crap out of it so when I do start investing I’m getting right what I’m after. I’m sure my .244 is gonna be touchy and fun to play with. I’m definitely gonna neck turn ... and I herd from an old wise guy that extruded powder will give more consistency in regards to what your after. . Separate your bullies by weight on a digital might make the tiniest of difference too I’m thinking. It’s all the little things ... not sure how much help I am, but all are good for thought. Enjoy playing !! :)
 
manitou210 said:
CHECK PAGE 4
https://www.canadiangunnutz.com/for...u-prepping-your-brass?p=15797705#post15797705
Click to expand...

I also shoot at Connaught (although with a different group) and do try to get into the sub 1/3 moa with a ''modern precision rifle'', and not an Fclass rig, I am getting very close to my objective I may add.
I did read your post in the link, and will go a little off subject in OPs post, as me and him are on the same quest, having the best target results.

My process does resemble the one you posted thanks To Jerry @ Mystic Precision that mostly taught me my reload technique through e-mails.
Just that my neck sizing die is a Lee collet, which makes virtually zero runout ammo, but does end up with a 3 thou neck tension.

When you say polish brass with a krazy cloth rather than tumble, I do not see where dry tumbling could disadvantage me?
If you'd have more info on that I am ready to experiement.
I can see how wet SS tumbling is a huge pain and detrimental to brass prep, but do not see how dry tumbling can do any harm.

Is it this you are speaking of?
amazon.ca/Krazy-Kloth-Large-Size-Cadie/dp/B00D0SY6BS
 
Alpheus said:
What was your load development process? Did you do a ladder test?
Click to expand...

For a given bullet powder combo I do one coarse and one fine ladder test, the first by 0.3 gr intervals in a 308 sized case the second being by 0.1 gr intervals after I've found a node. I do these with bullets seated 0.020" off the lands. From there I play with seating depth, from a 0.020" jump to 0.010" jam.
 
I sort my .308 Lapua brass into .5 gr batches, .223 Lapua brass into .3 gr batches. I don't sort bullets in any way. Powder is thrown on an RCBS Chargemaster then re-weighed on an Acculab Vic 123 to .02 gr of the desired charge. Actually if I am looking for 46.0 gr charge I will accept 46.02 but never less than 46.0. Every loaded round in then spun on a concentricity gauge for bullet run out.
 
Something I've read lately about ES is that the more the powder fills the case the lower the ES typically is. So besides picking a powder with good temperature stability it's also a good idea to consider a powder that uses up more of the empty space in the case, perhaps that's why my Nosler manual also lists the % case capacity the powder charge uses.

And all the other stuff already mentioned by the others.
 
The FX-120 will have an immediate effect on your load's consistency, both velocity and accuracy. It's literally 10x more accurate than the Chargemaster and will weigh your load to one kernel of Varget (.02 gr).

Normalizing neck tension will also have a measurable impact. Annealing is the best place to start. After that, setting neck tension with neck bushing dies, as well as neck turning, will also help. At that point you're definitely in an area of diminishing returns though.

And as previously mentioned, I have also found that my most consistent loads velocity wise we're all compressed loads.
 
Reloader 15 or 17, Lapua case, BR-2 primer and match bullet, light crimp and under .0010 jump to the lands. Many loads get within 5 SD.
 
MartyK2500 said:
I also shoot at Connaught (although with a different group) and do try to get into the sub 1/3 moa with a ''modern precision rifle'', and not an Fclass rig, I am getting very close to my objective I may add.
I did read your post in the link, and will go a little off subject in OPs post, as me and him are on the same quest, having the best target results.

My process does resemble the one you posted thanks To Jerry @ Mystic Precision that mostly taught me my reload technique through e-mails.
Just that my neck sizing die is a Lee collet, which makes virtually zero runout ammo, but does end up with a 3 thou neck tension.

When you say polish brass with a krazy cloth rather than tumble, I do not see where dry tumbling could disadvantage me?
If you'd have more info on that I am ready to experiement.
I can see how wet SS tumbling is a huge pain and detrimental to brass prep, but do not see how dry tumbling can do any harm.

Is it this you are speaking of?
amazon.ca/Krazy-Kloth-Large-Size-Cadie/dp/B00D0SY6BS
Click to expand...

https://www.youtube.com/watch?v=kZTFGV5B1XU
 
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