Norma 221 brass in the 20 VT

[Harold M]

I've fired over 2000 round in the 20 VT using all sorts of brass. I never had a primer squished flat until I fire-formed some Norma cases. To rule out a headspace issue, I measured them for length using a barrel stub and they went in within 0.001 of fired case length. Same loads (tried a lighter load after the first few - same flattening) and with the F205 primers I've always used. Not a problem, but has anyone else had a similar experience? Oh, and new primers seat just fine after the forming.

Harold

[chris allen]

Have you checked the volume of the cases compared to some of the other brands ?
chris

[Bill K]

Could be that the inside volume of the Norma brass is smaller, therefore they are generating slightly higher pressure. Even over the normal small volume of, say Military brass sized down. Check that out and see if this could be the reason from the other's you have used, prior. Bill K

[Bob Acker]

Have 300 pieces of Norma brass in various stages and have not experienced any problems. Using M205 primers, H4198 and 35 gr. Bergers. I believe its all the same lot because it came in a sealed box of 12, 25 piece boxes. Unfortunately there isn't a lot number on the individual boxes and the large box got recycled.

[fotohunt]

Harold,
Might want to measure the neck thickness. It could be causing too much neck tension resulting in a little higher pressure. I know with the new Norma .284 brass, the necks were so thick I had to turn them way down to equal the Lapua brass. Just a thought.

-Darrell

[sgtg]

Ya its like Lapua brass, less volume. I've had this in 308 and 22-250,(Never used Norma 221 brass, but sounds familiar) had to reduce charge some. There could be other factors ( thickness, hardness, neck thickness ?) but I think volume is most of it.
Also, in reducing necks they usually get thicker.
good luck, keep us posted sgtg out

[ramos]

No way to reduce neck diameter without increasing wall thickness. Just a fact of life, or physics, or something.....

[hemiallen]

Any chance the primer holes are bigger in the Norma brass Harold?

Allen

[pwdrbrn]

Different lot of primers? Just a thought. Tom.

[foxhunter]

the only time i have seen what you are describing was when there was excess headspace. the primer jumps back against the bolt face and then the case stretches back and pankakes the prime.
looks really bad but the fact the pockets are still tight says it's not excess pressure. seat the bullets hard into the lands will force the case back against the bolt face and make the shoulder blow forward and form.
i think you already figured this out, i had iot happen opn a 257 roberts ai.

Originally Posted by Harold M

I did not neck-turn these cases. According to my notes, the necks after sizing to 20 VT measured from 0.0125 to 0.0130 with 0.0127 being common - that's measuring several locations along and around necks on several cases. I hadn't had any problems or indications of high pressure with cases made from 223 and Lapua 222 cases turned to 0.013. That said, I now turn to 0.0127 in my chamber to be on the safe side. The chamber is a nominal 0.232, but is actually cut a few tenths larger. I learned this by measuring the neck diameter in the stub that was cut with the same reamer that I use for setting seating depth and ensuring necks of loaded cases are OK.

I'm thinking now that I didn't have the bullets seated to a hard jam, and what I see is a classic excess headspace condition, since others have formed these cases without issue. I must have done something strange without realizing it. Like my throat is a little deeper since the last time I tried these bullets for case forming.

Harold