Need help with ES/SD spread

[brguide]

Okay guys. I have been reloading like bench rest guys. I have 2 custom built 6.5 Creedmoors. Both shoot under .25 at 100 yards and under .75 at 300 yards. I am VERY ANAL about reloading. I have spent thousands of dollars on the best of the best. My first CM can produce .25 or less groups at any yardage and has an ES of 10 and a SD of 3. I anneal after every firing, I use bushing dies, I ream primer pockets, I use Nosler cases, CCI-BR2 primers, H4350, and Berger VLD. I do not have any problem in my first build has a Shilen 6 groove 1:8 twist. My second rifle has a 4 groove ratchet 1:8 twist and this is the rifle I am having es/sd problems with.

I can shoot 1 hole groups with this gun have done the ocw test, seating depth test, ect. I found a great grouping load BUT my ES/SD starts out at 95 fps and ends up usually at 30 fps. But I can produce .75" groups at 300 yards. I have a V1 and V2 magnetospeed chrono. I have noticed a few things that may be the problem

1) Some of my primer pockets still feel really new I use the 21st centry primer to seat them. I usually go by feel and all primer pocket are reamed to .130 EVERY SINGLE ONE. but when I check the depth of the seated primer some are .003, .005, .0065. Could this be the problem?

2) Maybe I could have a bad batch of primers?

Could someone please tell me what would do this? I have tried 41.5, 41.6, 41.7, 41.8, 41.9, 42.0, 42.1, 42.2, 42.3. I use 42.0 because it is the best. Ocationally I get ES of 10 over 10 shots and I did not change anything. The next round could be 50 fps slower than normal and then even out again for 2 rounds then the next round be 40 fps faster than normal. What the heck is causing this? Only this I could think was maybe the primer are not seated all the way. I loaded up 10 round and made sure I set my priming tool so no matter what they all measure now .0065 depth.

Next question:

Why is it when I go out in the morning 27.00 station pressure, 48% humidity, 70 degrees i get velocities of 2788 fps but when I go out at 1:00 pm 27.00 station p, 48% humidity, 92 degrees i get 2830 fps? I have tested H4350 5 rounds in a plastic bag on ice and 5 rounds in the sun and got the same speed 2788? I am not letting them sit in the chamber too long either.

I have done over 2000 rounds of load development and testing total to numerous guns but this gun is the only one that is throwing the ES & SD crazy. I have never seen this. The last part different speeds at different times happens to every gun I have tested.

 

[BoydAllen]

Take a look at the trigger/striker assembly. Not everything comes from the load. If you can manage to switch striker assemblies and then triggers, something may show up. Differences in how the pin falls, from shot to shot could be related to your problem. Also, get a hold of some primers that seat by feel to more consistent depths, just to test that. I don't think that that is your problem, but think is not know. Test.

 

[Keith Glasscock]

I don't have all of the answers, but I would take a good look at the firing pin spring. Light strikes can be as bad or worse than poorly seated primers.

Regardless of what the chronograph shows, what do the groups look like at longer range? I mean 600+ yards... Do the POIs align with having a big ES? 95 fps would definitely show up as vertical.

On your last question: The difference between your test and the environmental difference is that the rifle is warm or cool. Simulated hot day conditions have a tendency to not be very good simulations unless you run a rate of fire that gets the barrel warm. We all know that metal changes dimension with changes in temp. How much, and what effect it has on any rifle barrel can be difficult to predict. I've had barrels that slowed down with heating, and ones that speed up.

 

[brguide]

BOYDALLEN
I have adjusted the spring on my savage to hit harder because that is what I had read somewhere else but that did not improve anything. The primer pockets are tight and thats why some are hard to feel bottom out and others are easy to feel. So of course that is my next test I have them ready just need to get out and shoot.

BUSDRIVER
That is what I figured on the barrel temps but I have also shot the barrels till they were very warm and velocities did not change. I also kept one barrel in ac and took out immediately into the warm afternoon air and it did show 30 fps faster than normal thats where it really puzzled me because I too also thought that it could be steel getting warm but with the steel cold on a warm day it did it.

Thanks for the answers guys.

 

[dkhunt14]

Putting shells in ice or a cooler isn't the best thing to do. As soon as they get in the warm air they start to sweat. Inside and out. Matt

 

[jlow]

Agreed. A wet case can result in a permanently damaged case as the moisture flash evaporate during the firing and prevent the case from griping the chamber and resulting in a case head damaging bolt thrust.

 

[brguide]

Okay understandable but I only did this once (5 rounds) to test the es/sd of H4350 of course there was none. I take it out of bag into gun fire and back out within 3 second. Really no time to sweat in gun. But I get what you guys are saying about the case. This is what I was told to do to see if the powder was temperature stable. Of course the manufacture says it is and it is. Theory proven

 

[dmoran]

If the chronograph data does not simulate/pattern with the actual target to some degree, the data is in error.
Typically such error will be do to a setup issue, but could be the unit itself.
Reading what you all described in your scenario's, my input would be the chrono setup to be the culprit.

My 2-cents
Donovan

 

[jsthntn247]

Agreed. A wet case can result in a permanently damaged case as the moisture flash evaporate during the firing and prevent the case from griping the chamber and resulting in a case head damaging bolt thrust.

I did this not too long ago. Could read Lapua on my bolt face. Not good.

 

[brguide]

Dmoran

Thank you. thats all i could figure too. I will shoot her out to 500 to 1000 and see what she does.

 

[brguide]

Found out what the problem was. It was the primers. I have 3000 primers all the same lot number but I decided to try another 1000 round box and sure enough those all shot within 11 fps ES. So the primers are just bad.

 

[Joe Salt]

Now start weighing the primers, you may find that will help even more!

Joe Salt

 

[jlow]

Wow! That is a huge difference from ES 10, SD 3 to ES 95 and SD 30! I wonder what was different about that batch of CCI-BR2 primers?

 

[Steve Blair]

Found out what the problem was. It was the primers. I have 3000 primers all the same lot number but I decided to try another 1000 round box and sure enough those all shot within 11 fps ES. So the primers are just bad.

[br]
Concluding that they are bad is unwarranted. They did not perform as well as the other lot in this particular combination. Change powder lot or type and you may have the opposite result. [br]
If I run an initial charge series and cannot obtain low ES near full pressure, the test goes no further and I try different primers. I have never found a situation where some primer did not produce acceptable ES with a powder I know is effective in that component combination.

 

[brguide]

Found out what the problem was. It was the primers. I have 3000 primers all the same lot number but I decided to try another 1000 round box and sure enough those all shot within 11 fps ES. So the primers are just bad.

[br]
Concluding that they are bad is unwarranted. They did not perform as well as the other lot in this particular combination. Change powder lot or type and you may have the opposite result. [br]
If I run an initial charge series and cannot obtain low ES near full pressure, the test goes no further and I try different primers. I have never found a situation where some primer did not produce acceptable ES with a powder I know is effective in that component combination.

Yes granted but they started out fine. In the beginning that bad 1000 round count started out around 2800 to 2810 but when i broke into another 100 count pack it went down from 2744 to 2834 were my spreads. Thats why I concluded it was the primers. ALSO again this lot number of the bad primers 1000 count box is EXACTLY the same lot number in the good batch of primers. I think they may all not be bad because some of them started out good but one 100 round count was bad.

 

[brguide]

Okay now next question since I have the primers figured out.

The first target below is with 42.0 with the bad primer 95 es (2744 to 2834) seating depth 2.175 (30 off lands)
The second target below is with 42.0 with the good primers 11 es (2802 to 2813) seating depth 2.175 (30 off)
The third target below is 41.7 with good primers 24 es (2773 to 2797) seating depth 2.175 (30 off)

So of course as you see the first target is what I am trying to achieve (smallest group with a GOOD es 15 es or less) but that was with the bad primers. Now with the good primers I am printing anywhere from 1/3" to 5/8" and it was consistent from load 41.7 and 42.0 load. SO my question is now do I mess with seating depth since I know this gun can do one hole groups but the seating depth was the same throughout all testing. This first target is not the only one with the bad primers that I shot 1 hole groups I shot this over and over did about 7 groups just like this on different days so it was not a fluke group to say. I know if I mess with seating depth it will change my es/sd a little hopefully not much. Or should I stick with 42.0 with 1/3 to 5/8 and shoot it at 400 to 700 yards and see what the groups look like there since I have a low ES/SD?