Gaining ground on the STW.

jmad_81

Handloader
Feb 14, 2007
2,938
3
So I have some new brass on the way, along with some 7828, and some 162 Amax to play with in the STW. I'm still set on making the 160 AB shoot, as I want to use that bullet for game (mostly elk). I had tried some H1000 a while ago and it showed some real promise. It was doing the two and one deal, but not really bad. So I shortened them .020" of an inch to 3.605" and broke my loads down to .5 gr increments instead of 1 gr. The velocity was not what I was hoping for out of an STW, but I'm getting tired of trying to get both scroching speed, and sub .5 MOA groups.

I started at 79.5 gr of H1000 and got this group. Average speed was 3144. I was still getting extractor marks on the back of my case, but I honestly can't think of a load that I didn't (more on that later). Here is the group. Up to this point this was the best 160 AB group I have got this rifle to give me.


View attachment 2012-08-16_06-56-44_938.jpg
Next up was 80 gr. Same thing, 3159 fps, and same extractor marks. Not sticky bolt lift or anything. This load did not get as much of a chance to cool as I would have liked between shots. I was getting to be late for work, and had to get going. But as you can see, it shot even better that the last group (ok, about the same really)
View attachment 2012-08-16_08-24-23_807.jpg


So my questions for you guys that know more than me (pretty much all of you) are the following.
1. What could be causing such excess pressure in my gun? Another guy I know is shooting 80.5 gr of H1000, getting 3250, and no pressure. A different guy I know is getting almost 3300 with the 160 AB. Both of these guys are shooting factory STWs. I can get 3250 with Retumbo, but its not near as accurate, and appears to be just as hot pressure wise.

Could it be that my smiths reamer has tighter tolerences that a factory reamer?
Could the difference be the three groove barrel over the factory?
Could my chamber be dirty? (I clean it every time I clean my barrel)
Any other thoughts?
Do I need to look at an even slower powder that Retumbo or H1000 to get the speed one should expect from a STW?

Overall, I'm happy with these groups. I'll take this kind of a groups over an extra 100 fps anyday, (unless its a 270 WSM, in that case I won't be happy until I turn it into a 270 Weatherby :roll: )

If you see this with no pics, they are on the way. They are on my phone, I'll add them in a few. If I tried to type this on my phone you guys wouldn't see it for another month :?
 
Jake

It could be a tight bore, tight chamber, slow barrel, or a combination of them all. It happens from time to time. Remington brass is pretty crappy and doesn't live long at high pressure.
 
IdahoCTD":39u4h6rv said:
Jake

It could be a tight bore, tight chamber, slow barrel, or a combination of them all. It happens from time to time. Remington brass is pretty crappy and doesn't live long at high pressure.

What brass would you recommend? I have tried some nosler brass in a few other rifles, and it appears to not last to long either if things are warm. Now, on my .243 where its not to warm, I'm at 10 firings and still going strong.

But it looks like in this particular rifle, I would have to be at 7 mag speeds to not have any presure signs.

I got my new brass this morning. If I can get four firings out of it before it goes bad, I can live with that.
 
Shoot a couple of your rounds through your friend's rifle to see if there's a difference with ejector marks.

Sounds like soft brass... Soft brass does a couple of things. 1- Soft brass is more likely to form tightly to the chamber and not relax as much after the shot. The bolt will then swipe more forcefully against the case head as the bolt is lifted. An rough ejector hole on the bolt face will make it look worse than it is. 2- Soft brass will be more likely to flow into the ejector hole.

I had this soft brass problem with factory Wby brass a long time ago. I could load newer brass a lot heavier without getting ejector marks.

What do the primer shoulders/indents look like? They get noticeably more flattened and cratered with excessive pressures.
 
I'm with BeeTee about the soft Remington brass. I don't think I own a piece of fired Remington brass that did not show some form of mark on the face of the case and this includes factory ammo. I guess for me when using Remington brass I tend to put more faith in over pressure signs in things like higher than normal expected velocity, stiff bolt lift, cratered primers, flattened primers ect than the face of the case head.

As for speed? All barrels are different and as my luck I always seem to get the slower barrel (300 Rum excluded as it was about dam time :grin: ). If I was given a straw for spit wads my straw would be slower than everyone else.

From what I see your groups look great and I realize the caliber is a 7 STW and other than book velocities I don't know what "real" velocity one can expect but those speeds seem great for a 160 AccuBond.

Bill
 
I have fire formed 300h&h and 375 h&h Winchester brass with much better results but it's nearly impossible to find now.
 
It could be a tight bore, tight chamber, slow barrel, or a combination of them all. It happens from time to time. Remington brass is pretty crappy and doesn't live long at high pressure.

My sentiments, exactly.
 
try win. 300 H&H brass, thats what layne simpson always used. My 160 load is 95 gr of wc872 for 3340 fps but its not brass friendly.
are your primers flat? are you fl sizing or just partial? you gettin just wipe marks or a definate ejector pin indentation? seems to me any high pressure sign should be accompanied by a flat primer.
RR
 
Jake,

I like RR suggestion of FF WW 300 H&H brass. It may be worth the extra effort.
Evan at 3159 fps, that is one beadly load for even the biggest of elk.

JD338
 
Just a word to the wise on fire forming 300 H&H, anneal it first. I've cracked necks/shoulders doing it before. It has to stretch much further than 375 H&H brass. Another option is RWS 375 H&H brass. I haven't tried it yet but it is suppose to be tough as nails at the expense of reduced case capacity and thick walls.
 
Jake, it seems like your rifle won't take as much pressure as most factory rifles. Seems odd, cause if it had a tighter chamber (it should attain the same speeds with less powder, I think), it shouldn't show as much pressures as it is. I wonder if your necks are too thick? Have you tried turning them down, or maybe measuring them. If your chambers neck is tighter... Well, pressures would pop up a little quicker. Just a thought.
 
One of my favourite rifles never shot to the velocity I thought it should generate. However, it was exceptionally accurate. I knew I could generate more velocity through a variety of steps, but I opted to focus on the accuracy. None of the game taken with that old 280 have ever been aware that the impact of that little bullet was fully 150 fps slower than it should have been; all died quite quickly. After about 250 rounds, the barrel finally settle in, and velocity stepped up a bit. I still have that rifle, and it is still a favourite.
 
Too Tall":1nt7t06m said:
I'm with DrMike, go for the accuracy.

I agree. This is the best group that I have ever got with the 160 AB in this rifle. Up till now things have been right around that .5" mark. I was not really happy with that, as I knew the rifle could do better. I'll get a chance to shoot this load tomorrow at the long range gongs and see how it does.

nvbroncrider":1nt7t06m said:
How far are you off your lands?? That could be a culprit too.

I don't think that being to close is the issue. This load is about .150" off. A few of my laods in the past have been closer, but mostly .030" of farther. The nice thing about this load is that I can use it like a repeater and not have to single shot everything.

I just got a new box of Rem brass, so once its gone I'll try something different. I got 500 shots out of my last 100 brass. Now that I know kind of where top end is, I should be able to make this next 100 last a bit longer. Hopefully this load repeats itself this weekend and then I can start working on a 162 A-max load for fun shooting!

Thanks all for your advise.
 
Good luck Jake. I hope you find what you are looking for buddy.. I know you got the speed demon riding your shoulder.. I am not pointing fingers either, the little demon doesn't go far from me either!
 
Kind of my thoughts.

I ran them over the chrony today and they were running 3235. I think the sun was screwing with me last time I shot them. It was early morning and the chrony was acting funny. I took that same load out to the gongs today and got a drop chart worked up out to 800. I'll do some more practing this evening and early mornings all this next week. Should give me a great idea about how this load is going to work.

Sure looking good so far!
 
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