I have been working a load for my Bergara b14 HMR. Hornady brass, 130gr gamekings, cci 200, and 43.1gr of rl16. I went to the range today and shot 5 groups of 5 through my chrony. My groups were 12.34, 25.10, 11.63, 12.50, and 34.20 SD. The lower SD groups were shot slowwer and given time for the barrel to cool, the higher ones were fired faster. Everything else was done the same to my knowledge. Im not sure what could be causing such wildly varying group SD. The very first group was the worst. Im not sure what the culprit is here but im thinking it may possibly be a barrel heat issue but I dont know. I wouldnt think a 5 shot group would be a big deal and accuracy was fine. Any help or ideas would be appreciated. Maybe test some factory ammo shot in the same way to esstablish a trend?
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Weird SD
- Thread starter Warlok813
- Start date
It’s not barrel heat related.
If you’re using hornady brass and you’re not doing any extensive brass prep, you’re not gonna have as consistent SD as higher quality brass.
Lower quality brass typically needs more work.
If you’re using hornady brass and you’re not doing any extensive brass prep, you’re not gonna have as consistent SD as higher quality brass.
Lower quality brass typically needs more work.
My normal brass prep regiment is size/decap, trim, take any crimp out of primer pockets, deburr flash hole, chamfer/deburr case mouth, not really extensive. Are you saying my good numbers are just lucky? What other prep would you reccomend? And what would make whole groups good and not others of the same prep and loading. Thanks for your advice
To get the most out of Hornady brass you'll almost definitely want to sort it by weight. The thickness of their cases varies enough to change the weight by multiple grains (I found an ES of about 3.5 grains in several hundred pieces of 6.5 Creed brass), which affects case capacity. If you want to get really particular about your brass sorting you can measure the neck thickness as well, and either turn them all down to a consistent thickness or sort them into different groups. That will help ensure a more consistent neck tension across all rounds.
That or you could just buy some quality brass and save yourself the hassle of sorting in the first place, unless you are shooting benchrest and really need everything to be exactly perfect. Some whole groups will be good because you got lucky and picked 5 rounds with very similar case and neck thickness. Other groups will be bad because you picked 5 rounds with very different case and/or neck thickness. It's impossible to tell whether it'll be a good group or a bad group unless you either sort your brass or start with good brass in the first place.
One other thing to check would be the method for measuring your powder charge. If you're trickling with a digital scale that only measures down to 0.1 grains, the tolerance of the scale usually specifies that it's accurate to +/- 0.1 or 0.05 grains. That reading of 30.0 grains could actually be as little as 29.9gr or as much as 30.1gr and you'd never know the difference, depending on the specific scale you're using. If you throw powder from a measure without trickling then I'd be amazed at your results so far, since usually that has far higher SD's than you describe.
I hadnt really thought that my brass could be the problem. Im charging on an RCBS chargemaster lite. Ill certainly be looking into how consistant my cases are. Odd though that i have chronyed hornady precision hunter at 20 SD for just a single 5 shot group, might have to look at some more of it too and see if that was just luck. What brass would you recommend for quality? And would you recommend turning necks or anything else even on the higher end brass?
The best brass I've measured and used has been from Lapua and Alpha. Admittedly they aren't cheap, but they are consistent and high quality. Using unmodified brass from those two brands, only chamfering the necks inside and out with a hand tool, I can nearly always tune my loads to a single-digit SD. That said I do use a Prometheus powder measure, though I've had similar success with a Lyman Gen6 similar to your Chargemaster Lite.
If you're a benchrest shooter who wins or loses by less than a tenth of an inch it's worth your while to turn the necks of your expensive brass and sort them by weight down to the tenth of a grain. If you're a mere mortal, like most of us are, you won't be able to aim accurately enough to notice a difference because you're not using a vice to lock the gun in some massive lead sled. It doesn't hurt you though, and many people like to do it either for peace of mind or because they enjoy perfecting their process as much as possible.
I like to fine-tune my loads, but I also understand my limitations and stop investing more time once it's "good enough" for the positional shooting I enjoy. I need a low SD so I always aim for single digits, but realistically I'm fine with anything under 0.5 MOA. I can't shoot better than that on a barricade or other obstacle, and if I miss it'll be because of my aim and not my load. That said, I do still prefer tighter groups because who doesn't like the confidence boost of seeing your shots stack on top of themselves when zeroing?
Below is a screenshot of the final results of load development for my 6BR last year. I haven't finalized my Dasher load yet for this year, but I also haven't done much with it so far given current events. This was with normal Lapua brass, just sized, chamfered, and loaded using Varget and CCI BR4's under a 115 DTAC.
Very nice. Sorry for the tirade of questions, I seem to be ever in search of knowledge and have yet to be able to seek instruction or find a mentor willing and capable, so im learning on my own as problems present themselves. Im certainly not trying to go crazy with my groups, .5 moa would be great for me, but I do try and be the best I can and try to take as many variables out of reloading as possible. Its new to me having issue with brass, im in the high single digit SD with my .223 loads in my 20" WOA ar using austrailian surplus brass from a bulk can I bought a few years ago, br-4s and CFE 223. I dont mind using cheaper brass if there is a reasonable chance of making it high quality by trading a little extra work for the cost. I enjoy reloading as much as shooting and modifying brass sounds like a way to add to that. Do you anneal your brass?
I was always struggling with accuracy.
Tried everything possible, case prep was extrem, powder weighing, OAL, measuring again and again, it was an absolute horror.
There were always tight groups, but as well always flyers.
Sometimes (seldom) I could get 2 or 3 shots touching each other, but then the next one went off 1-2 inches.
I blamed it on me, the scope, the mount, everything.
Then I came here and was asked what brass I use.
I´ve used Hornady.
Then they told me I should weigh it, I did - and my brain exploded.
After that I made some testing with Lapua, Peterson and Starline.
The first group I´ve shot in that testing was better, than any group I´ve shot before.
Listen to these guys here.
They really know what they are talking about.
Tried everything possible, case prep was extrem, powder weighing, OAL, measuring again and again, it was an absolute horror.
There were always tight groups, but as well always flyers.
Sometimes (seldom) I could get 2 or 3 shots touching each other, but then the next one went off 1-2 inches.
I blamed it on me, the scope, the mount, everything.
Then I came here and was asked what brass I use.
I´ve used Hornady.
Then they told me I should weigh it, I did - and my brain exploded.
After that I made some testing with Lapua, Peterson and Starline.
The first group I´ve shot in that testing was better, than any group I´ve shot before.
Listen to these guys here.
They really know what they are talking about.
I do, but only once every 3 firings. If brass is fireformed or hydroformed (Lapua Dasher brass) then I try to do it after the initial forming is done as well. You can do it every time, but that hasn't been too necessary from what I've seen. It's only really after 5 firings that I start to see and feel some differences in neck tension that can be fixed by annealing. Annealing after 3 means I just don't see the issues in the first place.
That said, I also prefer to just use a Forster shoulder-bump neck sizing die rather than a traditional FL sizer. I only bump the shoulder back 1-2 thousandths each time to minimize how much I'm working the brass. Using a FL sizer each time might mean you could benefit from more frequent annealing compared to being careful about overworking the brass like I am.
For cheaper brass, sorting by weight is decent. Cheaper brass weight will be more indicative of case capacity. More expensive/better brass, weight difference is usually around the rim, so capacity sorting is best (though most don’t sort better brass as it’s pretty consistent).
Then neck turning also helps a lot more on cheap brass than it does on better brass. Neck turning works well on quality brass too.....but you’ll get more out of turning cheaper brass.
Also, the biggest bang for your buck will be using a mandrel to set neck tension. Even with quality brass, the mandrel will change things dramatically.
If you want to run cheaper brass, I’d sort, turn, and use a mandrel.
If you buy brass like lapua or Peterson, just use a mandrel.
Then neck turning also helps a lot more on cheap brass than it does on better brass. Neck turning works well on quality brass too.....but you’ll get more out of turning cheaper brass.
Also, the biggest bang for your buck will be using a mandrel to set neck tension. Even with quality brass, the mandrel will change things dramatically.
If you want to run cheaper brass, I’d sort, turn, and use a mandrel.
If you buy brass like lapua or Peterson, just use a mandrel.
I used to use a propane torch and a pan with water about half a case deep. De-prime the brass and stand it up in the water, letting the inside fill up. Torch it at night, or in a dark room, and tip it over into the water once you've got a dim and even color to the neck. I made a ring-shaped tip for the torch with holes on the inside so I could heat the necks evenly without waving my hand all over the place.
Now that I've moved into a condo with neighbors that care more about open flames I'll probably either build my own induction annealer or send my brass to a local guy who has an AMP and reasonable prices. The homemade induction rig would be a fun project, it's just a matter of whether I have the time. Either way I don't do it enough to justify $1,600 for an AMP plus a case feeder to use for myself.
Don’t anneal. You’ll just fuck it up even more. It’s not going to improve the SD.
Second, There are two variants of Hornady brass. Their weights overlap, but the newer brass is heavier. It weighs 151-156 grains and has a solid firewall. The old brass weighs 143-153 grains depending on the lot and has a recessed firewall. If you have them mixed up it could explain the high SD.
Second, There are two variants of Hornady brass. Their weights overlap, but the newer brass is heavier. It weighs 151-156 grains and has a solid firewall. The old brass weighs 143-153 grains depending on the lot and has a recessed firewall. If you have them mixed up it could explain the high SD.
You folks are invaluable. Weighed just 5 pieces of the brass I shot yesterday, without any prep, and in that group of 5 I had a spread from 148.3 gr up to 156.4 gr. That much in 5 random pieces. The least difference between 2 pieces was only 3 tenths but the rest were a grain or more. Suffice to say I wont be using hornady brass anymore.
I've noticed that too. I started reloading for my 6.5CM using the fired brass from factory rounds. Got about 2 more firings and started to notice that the inner head on some were flat and some had a bump where the inside of the primer pocket is.
