7mm WSM Issues

[CraigB]

I have been working with a heavy barreled Savage in 7mm WSM. The barrel was chambered by Pac-Nor, and the rifle was assembled by SSS.

I have been attempting to find a heavy bullet combo for long range shooting, and have centered on the 162 AMax and 168 Berger. I am seeing soot on the neck and shoulder of just about every load combination I have tried to date. In a lighter load with RE25, I saw soot beyond the shoulder/body junction. My understanding is that this is not a good thing.

My loaded rounds measure just over .313, maybe .3135, at the neck. My fired rounds measure between .320 and .321 at the neck. Pac-Nor did not send me the neck size of the barrel, but my understanding is that factory standard is .321. Is the .008 expansion at the neck causing the soot problem? As a side note, I am seeing black/soot at the outer edge of the bullet holes in the target.

I have switched to a bushing neck die and am sizing about 2/3 to 3/4 of the neck in hopes of getting a better seal. I have not fired any of the neck sized loads yet. Any ideas would be helpful.

Thanks

 

[Jeffvn]

You don't say what your load is or the velocuty that you are pushing the 162 AMAX.

0.008 is pretty large gap to fill, but not exceptionally so. I would use a two stage necking process to close that gap to your 0.002 neck tension. More then about 0.004 each step tends to react poorly and with significant concentricity issues.

I had similar results with 7WSM - using the Sierra 175s and the Berger 180s - soot all the way to the shoulder joint. I was running them right at 2,800 fps. Might as I tried, I could not get rid of it until I went to a slightly faster,higher pressure) load - 2,900 fps. The load shoots good, and the soot is only about 1/2 way down the neck.

Your milage may vary, and there are lots of experienced shooters here to help. Good luck.

JeffVN

 

[CraigB]

I checked several of the neck sized rounds and they measure .311, which I find a little confusing since I'm using a .312 bushing? I shot several of the neck sized rounds and the soot is still there, but it's only on the neck, not the shoulder. I might buy some more bushings and try the two step sizing process. I'm starting to think that neck tension is part of the accuracy problem at this point.

What powder did you end up using with the Bergers?

 

[Jeffvn]

What type of brass are you using?
How many loads through the brass?
What load are you using?
Where on the neck are you measuring?

information is the key to answering your question.

JeffVN

 

[Preacher]

Sometimes annealing will help them seal better if they have been fired more than a few times....

 

[CraigB]

The brass is unfired Winchester 7mm WSM. I am measuring the neck at the mouth and about 1/2 way down the neck. The loads are in the 63 to 64gr. range with H4831 and a 162 AMax, 63 to 64 gr. with IMR7828 with a 162 AMax, and 66 to 67.5gr RE25 with a 168 Berger. I have the 162 AMax loads jammed about .005. I tried several loads right at the lands,as well as I can measure)and they stunk. I have not tried anything in the .010 to .020 off the lands range. Sorry, I should have included this info originally.

I should also add that when loading the original rounds I just opened up the necks with the expander ball. The Forster full length resizer die I have opens up the neck to right around .313, which is only slightly smaller than the loaded round,.3135). When I size without the expander ball I'm getting neck measurement around .310,,if I had the expander ball in it would open back up to .313).

 

[Jeffvn]

Thanks for the info.

I've found measuring at the case the mouth gives me inconsistent measurements,maybe its the way I measure it, but I could never get the same numbers consistently), but 1/2 way down the neck is a good spot.

your loads look fine, as does your seating depth,that one varries from rifle to rifle), and what you are doing is not out of line for loading that I see a lot of people doing.

I have a threaded die press,Rockchucker Supreme about 4 years old), and don't use the expander ball at all on any of my dies; I pull it and chuck it into the spare parts bin. I could never get consistent neck tension on new brass until I went to the Sinclair expander before the first loading.

I put a chamfer on the inside edge of the brass then run it over a Sinclair expander before I do anything else to the brass. The expander gets me to the point where I can then neck size back down to my 0.002 neck tension.

I have to agree with one of the comments above, sometimes you just can't seem to get rid of teh sooty necks. When living in Houston, I eventually gave up playing with the tension and other assorted things, as the accuracy and load were shooting great, and I simply accepted the fact that my brass was going to have sooty necks all the way to the shoulder. Then I moved to Vegas, changed my load, but did nothing else differently, and SUPRISE, no more sooty necks.

Hopefully someone else can jupm in with a prized piece of info that helps.

good luck

JeffVN

 

[CraigB]

Thanks for the info Jeff.

I just full length sized 50 rounds, trimmed them on my Wilson, lubed the inside of the neck, ran them through the Sinclair 7mm expander, and turned the necks,almost 360 degrees). I really feel like I have some runout issues, and neck tension isues. I am borrowing a friends runout gage to check everything. I am a little disappointed with the Pac-Nor barrel, it holds more copper, and is a little rougher than my first 6-284 Pac-Nor.

I also think I might buy a full length bushing die, and use it in the second neck sizing you suggested. In another rifle I own, I used a bushing neck die and there was no doubt I was getting runout from the oversized/sloppy body of the neck die.

Thanks again

 

[Jeffvn]

Keep at it and let us know how the new process is working out.

With fired brass I full-size with a neck bushing,pushing the shoulder back between 0.001 and 0.002)- this will only size a portion of the neck, but gurantees good life on the brass. I then use a neck sizing only die for the final stage neck-sizing,immediately before loading). I use Redding Competiton seating die,the Forester ultramicrometer is also good).

This process gives me very little runout as in average rounds are between 0.001 and 0.002 some a little better some a bit worse,I use the 0.003s and ocassional 0.004s for foulers and sighters only).

JeffVN