Model 70 .270 WSM load exploration

[Curly]

It does sound like the chronograph is in the ballpark.  And I agree with Rad, no over pressure signs on there, I didn't see the pics earlier, just read about the split necks.  I don't have a WSM only a wssm so I'm no expert either, just throwing things out there. 

It sure seems like there is something wrong with the chamber if factory loads are difficult to extract.  You just shouldn't have problems with factory rounds; they don't want over pressure issues and suffer lawsuits so they are careful to keep them within spec. 

[BOWHUNTER45]

You may want an Ultra mag 

[lablover]

After doing some more research on some of my issues, I realized I have overlooked a huge factor in reloading; PSI in the case. As I have mentioned before, I am relatively new to reloading (4 years) and still have a lot to learn. I feel so stupid. Understanding that a 150 grain bullet with 64,000 PSI is going to shoot much slower than a 130 grain bullet with 64,000 PSI, I feel juvenile. I was trying to force the bullet out faster expecting nothing to happen? come on Ryan!!!!  Not sure how or why I wasn't smart enough to think about this, but now that I'm aware of it, some of my issues make a heck of a lot of sense.

Here I was trying to get my 150 gr bullet to fly 3100-3200 fps, I have found very few loads that will allow that with a 150gr bullet. After talking with a gunsmith, it also greatly depends on the manufacturing of the rifle. Remember, this is an off the shelf Winchester Model 70, not a custom rifle so manufacturing of these rifles vary greatly depending on the batch they came from. If the rifle chamber is "tight" it will allow for very little "over expansion" in the chamber, causing cracked cases if you exceed the max PSI for a certain load.

I have learned that the chamber in my rifle is "tight" which is good, part of the reason my rifle shoots the way it does, but does not allow for much vairance when it comes to max loads. That beings said, my rifle shooting .44" at 100 yards with a speed of 2800 fps, seems reasonable with a 150 gr bullet now. Knowing that I can't get much higher becasue of pressure issues.

To confirm this, I just got some 130 gr SSTs that I will load for my brothers .270 WIN. I'm going to try several loads just under max (around the 64,000 PSI range) and see how much faster the rounds will be. I'm expecting they will be around 3100-3200, without over pressure issues. I've never shot 130s through this rifle, so it will be interesting to see what happens. I can't imagine that they shoot as well as the .44" that the 150's provided, but I will keep you posted.

Pretty cool to learn these things as I go along. Hope this is helping someone avoid the same problems I have encountered.

[lablover]

Well, I shot some 130 SST's at 65gr with IMR 7828. Had a speed of 3256 fps, and no pressure issues. So through this process, I learned that I was trying to push the 150gr bullets too fast and having to much PSI in the case. I also leanred that my lands is at 2.85". I as shooting my good groups at 2.80" so I figured I would try and get closer to the the lands reducing the "jump," so I extended them to 2.80". That was a mistake. It opened my groups up from .5-.6" to .9-1". Back to 2.80" OAL I go. I was also fortunate enough to find and buy 200 rounds of the 150gr SST's. Lucky me!

[EDT]

Great thread.  good info.

[Caretaker]

The RL22 is temperature sensitive, I stopped using it for that reason, cold/hot days would get inconsistent results.  I posted an extensive spreadsheet with the various loads and group sizes, it's somewhere on here, let me see if I can find it and link it.  I use RL17 or Magro in my loads for the 270wsm.  130gr Barnes TTSX, CCI250, 73.5 Magpro, 2.76 COAL, 3240 fps, submoa.

[Caretaker]

http://hunting-washington.com/smf/index.php/topic,59581.msg736580/topicseen.html#msg736580

[GUHunter]

I've done a lot of research on 270 wsm loads and although rifles have their own tastes, a load that showed up a lot was a 140 accubond with Retumbo. Most favored something in the 69-71 grain range. I'm working on a load in this range and have seen promising potential so far.