257 STW Primer Problems

[bjlooper]

I have a 257 STW that I can only get 3 Loads before the Primers are loose. Ihave tried reduced loads with thesame results. I have a friend with a 257 STW made by the same smith with the same problem. Is this typical for the 257 STW or is thier something else wrong.

Thanks
DR B

 

[Steve Shelp]

bjlooper,
One other thing that it can be is what is the diameter of an new unfired peice of brass measured right in front of the belt? Then what is the chamber diameter from your gunsmiths print? To much clearence will not help with primer pockets.

I can't say for sure this is your issue, just opening the door saying that it is possible.

Are there any other signs of excessive pressure with your loads at all? Excessive velocity, accuracy went away, cratered primers, flattened primers, sticky extraction, etc etc? The question really is.... is this caused by excessive pressure or soft brass and/or mismatch of your brass to the raw brass diameter?

Only you can determine that.

Steve

 

[257speed]

I agree with Steve on this, that it almost sounds like it COULD be a reamer problem. If the chamber is cut oversize, it will cause this, but the easy way to tell is how hard is it to full length size brass. If the chamber is in fact oversize, than it makes sizing very difficult, lots of lube and elbow grease. If you aren't experiencing this, and they re-size easily, than it is most likely a soft brass issue. What load are you using?

 

[bjlooper]

We checked the chamber and it is of correct demensions. My smith talked to several peple who shoot the 257 STW and they also have problems with loose primers. 3-4 loads max before the pocket is loose. This is with any brass manufacture that they have tried. One of the peole that is having primer problems is shooting a Kirby Allen rifle.

So should I assume this is normal for the 257 STW?

DR B

 

[Steve Shelp]

bjlooper,
What is the diameter of the unfired brass? Yes, the chamber may be within SAAMI spec chamber or even a tighter custom chamber, but the critical dimension is the difference between the cut chamber and the unfired brass you are actually using. Not what a book says or nothing, but actual real measurements on the unfored brass.
Brass manufacturing isn't always done the same and this dimension can vary. Sometimes you might purchase Rem brass that measures .5115" but Winchester measures .5090", and Weatherby brass might measure .510. A year later this MIGHT change. When you play with a custom hotrod like a 257 STW these are things you have to consider. I've played with several 6.5 hotrods and there is always lessons to be learned. Some are harder then others. Sometimes harder on your brass sometimes harder on your pocketbook!

But if this difference is still within normal limits and you are still getting loose primer pockets in ALL brands of brass tried, then pure and simple you are shooting to much pressure for this chamber/brass setup. Don't read me wrong. I'm not trying to be a smart@#%. But if all brass primer pockets open up and everything is within spec, then the brass can not handle the pressure you are putting it through.
So you need to determine do you want the speed/accuracy results that you are getting now and throw the brass away after 2-3 loadings, or do you want to try slower powders or somehow reduce the pressure to gain case life at the expense of possibly not getting the velocity/accuracy you had?

That is the million dollar question right now.

Steve