pressure problems

[JAYB]

I think what you are looking at here is a case of listen to your rifle. They are all different, have different likes and dislikes just like us. In your case your rifle is telling you it likes the frontier brass, does not get stressed and gives a good result. On the other hand it does not like the Norma brass, gets stressed and does not give as good results.

Conclusion: You have just come to your first reloading decision, ditch the Norma brass your rifle does not like it. Don't get in a flap over it accept it, there are forces at work that you have no way of measuring other than by the accepted pressure signs, performance in your rifle and the experience of yourself and others.

Now you move on do I try other brass or do I, if you feel moved so to do, fiddle with the Frontier load or leave it alone. Me? I could live with your groups go and stalk something.

If you ever master it all you can go and teach the Black Art's, at Hogworts, Harry Potters place of learning

John

 

[ReneZ]

Hi, you need to appreciate that not all brass is manufactured the same. I don't mean tolerances within one makers batch, but between manufacturers. Although the outside sizes of the brass are clear, they can be quite different on the inside. Please understand that it is the volume in which the powder is ignited that gets you the initial pressure (and problems?). Only weighing them is not good enough as there might be differences in the material used, resulting in some brass being softer than others. What you need to do is check the volume of the cases you intend to use. You can do this in different ways, by submersion in a small cup with volume indication (just big enough to hold the round) or by using a syringe. You'll probably find that there is quite a difference. Winchester brass is known for having a higher capacity than most other manufacturer's brass. Hope that helps/clarifies. BTW my Hornady manual gives 43.6 gr as a max for your components, but understand from Snowstorm that my manual (Hornady 6th edition) is giving a too low figure for N140 (36.6 gr) as well).
Cheers, Rene.

 

[ezzy6.5]

Resizing lube on the case will sometimes cuse the symptoms your describing.

Ezzy

 

[scotspine]

I have just read this thread and thought I’d share my experience with you all. It may not help Heathrobinson but it does involve high pressure problems using VV N160.
I’ve loaded around 2000 rounds following the guide books and never had any problems until I used N160. The initial load (lower end of the scale) was fine when tested at 4degree c, but started to flatten primers when things warmed up. At one point I got smears from extractor pin hole and claw as well as enlarged primer pockets! With the help of a chrono I finally settled on a load of 38.5grains in a Lapua case with 140 grain bullets doing 2475-2525fps out of a 20inch barrel. The start load in the Speer book is 41.5g and 42.2g on the Lee data sheet!

All my loads for 129g and 120g bullets have come in at or below the published minimums.

So what happened? I’m not sure but I will always start at the minimum load in future, not close to it, plus I will always chrony every batch until the optimum load is found. It might also be sensible to develop loads in the warm weather or at least avoid developing “max” loads in the winter as subsequent use in the summer may lead to pressure problems.

Also reject any case that has been subjected to high pressure (smearing and severe primer flattening). If in doubt check the primer pocket and case dimensions (just above the web) as any “give” in these areas is cause for concern.

More of a cautionary tale than sound advice but it might help someone

ta