# precision reloading



## Savage260 (Oct 21, 2007)

I was at the range yesterday shooting my Encore 7mm over my beta master chrono and found that the loads were not consistant at all. I am using a Lyman DPS III to measure my loads, then rechecking them on my Hornady balance scale. They are all reading basically the same so why is the velocity so different? I thought I was being careful!!!
Barnes 140gr TSX over 63gr H4831SC. All brass trimmed the same, all CCI 200 primers, all loaded to 3.682 ogive.

2942
2918
2892
2878
2871
2822
2859
2852
2870
2875
2889
2864
2861fps


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## southdakbearfan (Oct 11, 2004)

Is the brass all of the same lot? Different lots of the same make of brass will definately give different pressures, i.e. different velocities.

Some calibers and rifles will give larger standard deviations in velocity for no given reason, some 222 loads will do this and still give very good accuracy.

What is your load density? Most of my loads, if I get below 85% density, they show larger standard deviations. Try holding the rifle straight up in the air so any pockets in the powder are in the front of the case and not the rear.

80 fps is not really that big of variance over that many shots. All but two are within 31 fps, so I would say you are fairly normal there, might have had two cases that were different. Weigh your empty brass and see what you get. Even in bags of 50 from the same lot, I will get 2 or 3 cases that seem to be heavier than most, meaning more brass, in turn meaning higher pressures and velocities with the same load.

By hodgdon's data online, 63 should put you in the 2920 range, but there is not data on how long of barrel they were using, which makes a big difference with slower powders like H4831SC.

Another thing to check is if you are getting differences in primer strikes. Check your fired cases and see if there is a noticeable difference in the primer indent. CCI primers are noted to be harder.


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## Savage260 (Oct 21, 2007)

southdakbearfan, 
I guess I thought the 80 fps was a huge difference. I wish I would have been able to keep the info in the chrono to give me the SD and all, but a guy at the range wanted to check out the display on my Beta Master and hit the forget button so I lost it all before I could write all the other stuff down. Primer strikes all seem to be the same, I am shooting out of a 26" Encore barrel, so I expected a higher end velocity. Thanks for the info!!!

The brass is the same lot, but I didn't weigh them. I just trimmed them all to the same length. I got decent accuracy though, this is my first string of 5. The bottom hole is 3 shots, then the fourth after I adjusted my scope is on the white line, then the fifth in the red after adjusting again. I got similar accuracy on the 15 I shot over the chrono with the last 3 shooting a similar group as the bottom 3 in the pic.


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## southdakbearfan (Oct 11, 2004)

80 isn't great, but if you take those two above 2900 out, you are running about 30, which isn't 1000 yd stuff, but ok. I would bet you have a few cases that are a little heavier.


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## Savage260 (Oct 21, 2007)

Excellent, I will check them out this go round. Thanks!!!


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## maranatha77 (Oct 27, 2008)

Hey, I was wondering if barrel temp could cause the velocity differences. I see that the 2 fastest were the first 2 listed. I plan to start reloading and I am checking out a few forums to pick up some hints. I do plan to reload with an experienced reloader but I want to understand a little first. God bless, Paul...<><


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## Savage260 (Oct 21, 2007)

maranatha77, I don't see any way barrel temp would cause the variation, but maybe. I have only been hand loading for about a year so I have a lot to learn. It was about 43 degrees during shooting with a light NW breeze. I had 5 min between shots 1&2 then loaded my muzzle loader and shot that and checked the target. Approx 10 min, then started a cycle where I shot the 7mm, ran 1 wet and 2 dry patches in the muzzy, and reloaded it, then shot the 7mm again, then the muzzy, checking the 100yd target each time. I did this for all but the last 3 shots which I shot with about 2 min between each. The barrel was quite cool to the touch each time I shot.

Does shooting from a clean bore affect muzzle velocity to any degree? I thought maybe that would account for the first 4 being highest and decreasing as the barrel fouled to a certain point. Any ideas on that? I know that doesn't explain why the 2822 is in the middle, then the MV spiked again at 2889, but just thought it might come in to play a little bit??


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## Csquared (Sep 5, 2006)

The bearfan has answered your concerns accurately, as always, but I just thought I would echo his thoughts and add my :2cents: . I think your numbers are perfectly normal. Many are surprised, as you are, that velocities do vary so much. But the velocities you're getting are low for a 140 gr bullet so you should be nowhere near optimum chamber pressure yet. In my experience you won't see consistent velocities, hence low standard deviations (sd), until you've found your optimum pressure. So I would expect that as you increase powder you will see a smaller spread, lower sd's, AND tighter groups. That's USUALLY how it works.

You're a wise man for buying a chronograph this early in the game. As far as I'm concerned it's almost as crucial as your press for handloading. You can learn SO much. As you gain experience you'll learn to trust chrono info more than any other single sign to determine max loads.

Good luck!

Dan


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## Csquared (Sep 5, 2006)

Wow, I just checked Hodgdon's site to see how close you were to published max...and my eyes were opened! I've been doing this so long I rarely see new info, and it appears to me the industry has reduced things even more. When I was shooting a 7 Mag I used H-870....I believe 80gr (all that would fit in the case) with a 160gr Partition for an avg of 3015fps in a 24" Rem700. VERY safe load. Low sd's and I never had to discard any brass. I don't shoot it anymore because I can get almost the same with a 165gr Partition in my 22" 30/06, but the point is....times have changed! :wink:


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## iwantabuggy (Feb 15, 2005)

Your data seems pretty normal to me. I have seen ES's in the 80-90's fairly often. I prefer to see them in the 50-60's. I even have one rifle that the ES is about 35 over a 10 shot string with an average velocity of 3915 (22-250). You may find a load that will provide better consistancy, but if your accuracy is good enough, then you are good to go. If not, keep experimenting. It all depends on what you consider good enough.

I have seen velocity trail off a little as the barrel heats up. I don't believe it is uncommon, either.

That's the great thing about reloading. You can make it pretty simple and save a few bucks, or you can take it to the extreme and try for constant improvement. I find I am somewhere in the middle.


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## Plainsman (Jul 30, 2003)

All good information above. I will add that I have always found Federal cases to weight more, hence have less powder capacity, hence give higher breach pressure and higher velocity.
The H4831SC works wonderful in my 270 Winchester. However, when I have used it in high capacity cases it velocity deviates more than in the 270. That is normal for all powders, but I find that R22 does give me about 30 to 40 fps standard deviation. Like the others have told you 80 fps is not unusual, but some powders are better than others. 
I have also noticed that match primers or bench rest primers more often give consistent velocities. Then there is always the rifle that defies that and my 300 Winchester shoots great with CCI. So good I have not even tried another load. 
I don't think I can give you a solid answer, only suspicions, and reiterate that 80 fps isn't that out of line.


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## Savage260 (Oct 21, 2007)

Hey, thanks guys for all the info!!! I really was not sure what to expect as far as velocity ranges. I am glad I am not too far off the mark.

I stopped load testing for now because I am getting pretty good accuracy from this load and since I am going to Western ND for a mulie buck on Monday I needed to get a good shooting load quickly. If I do my part I can keep this load around 3/4 inch for 5 shots regularly. I will resume my loading after I fill my extra doe tags with the muzzle loader. I did make one big mistake in my typing on the first post, I am using Winchester WLRM primers for the 7MM, not CCI 200's. Thanks again for all the info!!!

Does any body have any clues on how much fouling affects velocity???


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