Necks not expanding after firing

[godsey5]

I was working up loads in a sporterized swedish mauser.
I was using hornady sst 129 gr and 140 gr sierra match kings. I was using varget and IMR4064. Full length sized once fired FNM and privi brass. Trimmed to length, flash holes deburred. CCI bench rest primers. Loads worked up in 0.5 gr incriments of each bullet in each powder. Temp 25f

Hornady SST- cannalure - Lee factory crimp- oal 2.950
Varget starting 34.0 gr up to 36.0 gr
Imr4064 starting 36.5 up to 38.5 gr

Sierra Match King - 140 gr- no cannalure- no crimp - oal 3.030
Varget starting 32.5 up to 34.5
IMR4064 starting 33.5 up to 35.5

I had really good results with the varget and the hornady's and good with the 4064 and hornady. For the most part the smk's were not good at all and I had strange powder burn pattern on the necks of the casings I used with the smk's. I checked neck size on the fired smk cases, .290. Same size as a sized case. Neck of fired hornady cases were .300. Not all, but a lot of the smk cases did not expand after firing. I did not shoot all the smk's. I "smoked" the ogive of one the remaing smk's and chambered it to check to make sure they were not engaging the rifling and they were not. No problems at all with the crimped hornady SST.

Sooo... my question is why did the cases necks not expand? just because of no crimp to allow powder to burn optimally and case pressure to build. It was not that cold. Combination of the two factors? I have loaded .308 and .223 and not crimped with smk's and did not have this problem. I crimped my remaining smk loads and will retry them. Going by the fired neck size I know why the smk's did not perform well except one load at 35.5 gr. I am just trying to figure out why.

Thanks,

Jim

 

[USSR]

For the most part the smk's were not good at all and I had strange powder burn pattern on the necks of the casings I used with the smk's.

Jim,

Sooty necks is a sign of low pressure. Question: Why are you using such a fast powder as 4064 and Varget? The Swede likes powders in atleast the 4350 burn rate range.

Don

 

[NCsmitty]

As USSR mentioned the sooty necks, if extending to the shoulder, indicate low pressures which are not expanding the brass enough to seal in the chamber.

I don't have a problem with you using those 2 powders but I'm puzzled that the Hornady's work ok and the Sierra's do not. I don't believe crimping will solve the problem, but probably won't hurt.
There could be a couple factors going on here, one may be bullet to barrel fit and/or perhaps your chambering just needs more powder to bring up the pressure to acceptable levels. Not all rifles are created equal and the manuals are guides not gospels.
You notice that the one load that seemed to work was a max load(as listed by you). That should tip you off that increasing the load may help.
I'm not recommending that you exceed listed Max, that's up to you.
Have you looked at the Hodgdon load site for data?
www.hodgdon.com

NCsmitty

 

[rcmodel]

+1 - Not enough powder in most cases.

Your loads are below the recommended Starting loads in a couple of instances.

Hodgdon data:

129 Horn:
Varget Start = 34.0 - MAX = 37.5.
IMR4064 Start = 36.0 - MAX = 39.2.

142 Sierra:
Varget Start = 34.0 - MAX = 38.0.
IMR4064 Start = 35.0 = MAX = 38.0.

Bump it up!

rc

 

[godsey5]

I used my lee manual and cross referenced my others on the starting loads. The neck that were sooted were sooted only on 1/4 of the neck, to the shoulder. rest of the neck was clean. I was only working my way thru the bottom of the brackets on load development. 10 rounds of each bullet type in each powder. I don't know why the smk were not doing well either. I try them again in the higher powder bracket and try crimped and uncrimped.

Jim