7WSM 160 AB's Nosler 2nds VS 160 AB 1st's

[SJB358]

Well, my 7WSM went from the Penthouse to the Outhouse with a bullet swap. I had stocked up on a bunch of Red Tipped 160 AB's from SPS awhile back. I developed a load of 67gr of RL22, CCI250's and WW cases. Well, as I started getting low, I bought a few boxes of 1st's since Nosler was having a sale with them..

Well, I loaded up the rest of my red ones and opened a new box of the 1sts and continued jamming bullets. Right off, I noticed the 1st's were loading to a longer OAL. The 2nds ran 2.950 and the 1sts running 2.975.. Didn't think it was too big of a deal since I am seating off the ogive.. Well, turns out I was dead wrong.. I took them out and shot the new 1st's.. Not the same.. I am not sure what is different, but they are different. I went from groups with the red tips that would easily shoot into 3/4"s pretty easily to somewhere in the 1.25 to 1.5" mark.

Here is typical red tipped 160's..

So you can see, most of the time, when I do my part, they stack on one another. If I am a little shaky they run about 3/4's to 7/8's.

Well, I measured the white ones and they are about .012" longer than the red tipped 160's. I called Nosler and spoke with Mike Harris about it and he asked me to send him 5 of the new ones and a red one for comparison. I went back out today and decided to vary the seating depth with the white ones to see if a small depth change could bring them back.. It seemed to help, but they aren't in the same league yet.

2.950"

2.940"

2.930"

2.920"

2.910"

2.900"

So I ran them down and got some decent results. Looking at the 2.920" load, I could probably work with that. It is certainly hunting accurate, but it still kinda chaps my butt as the red tipped ones shot so well! I wished I would have bought a 1000 of them! Anyhow, all the loads are the same, even the same LB of powder.. I reshot a few of the loaded red tipped ones I had left and they clustered as they always do. Anyhow, for you 160 AB shooters who have any good red tipped loads made up, I hope the white ones shoot the same for you, but something about my rifle is wanting them in a completely different spot..

 

[DrMike]

That is pretty significant, Scotty. My 7 WSM went south this past fall, and I'm in the process of working up a new load. I can't blame seconds versus firsts, as I have no seconds. However, it was a new lot of bullets. I'll have to make a few measurements and see if I can find a difference at that point. In any case, I'm in the process of reworking my loads.

 

[SJB358]

That is pretty significant, Scotty. My 7 WSM went south this past fall, and I'm in the process of working up a new load. I can't blame seconds versus firsts, as I have no seconds. However, it was a new lot of bullets. I'll have to make a few measurements and see if I can find a difference at that point. In any case, I'm in the process of reworking my loads.

Yeah, I am not blaming anyone, just bummed as it was such a good shooter with the old bullets. Ah well, I will get it and figure it all out eventually..

 

[SJB358]

I think I am going to run them into 2.860" in .010" increments and see if anything pops out. I have tried them up close so maybe they wanna be run further. After seeing Heath's post about the 162 AMAX, I am thinking he may be onto something.. It worked for the 270WSM too..

 

[DrMike]

You've got lots of room in your magazine, Scotty. There is certainly room to seat the bullets out a bit, and it may just be the ticket.

 

[Guest]

I don't know all you've tried up to now, Scotty, but I've heard from a number of folks that Accubonds do well with more jump (shorter COL). You might try seating deeper if you've been seating out close to the lands so far.

I can tell you the only rifle I've worked up Accubonds so far was a 7mmRemMag, and it did not like them in any flavor or configuration. Of course, truth be told, that rifle didn't like much. I finally found a 175gr Hornady bullet over H1000 would go into about 1" consistently, but only if you ran them at 2650-ish. Why on earth a 7mmRemMag with a 26" barrel was only accurate in that one configuration is beyond me, so down the road it went. I've still got brass, bullets, and dies, and will eventually stumble upon a 7mmRemMag I can't live without. I'd really like to get one of the new South Carolina 70s with the 26" barrel, but I don't have $700 to blow on it right now...

Good luck with the new ogive profile. I hope you can find a decent load.

 

[SJB358]

I don't know all you've tried up to now, Scotty, but I've heard from a number of folks that Accubonds do well with more jump (shorter COL). You might try seating deeper if you've been seating out close to the lands so far.

I can tell you the only rifle I've worked up Accubonds so far was a 7mmRemMag, and it did not like them in any flavor or configuration. Of course, truth be told, that rifle didn't like much. I finally found a 175gr Hornady bullet over H1000 would go into about 1" consistently, but only if you ran them at 2650-ish. Why on earth a 7mmRemMag with a 26" barrel was only accurate in that one configuration is beyond me, so down the road it went. I've still got brass, bullets, and dies, and will eventually stumble upon a 7mmRemMag I can't live without. I'd really like to get one of the new South Carolina 70s with the 26" barrel, but I don't have $700 to blow on it right now...

Good luck with the new ogive profile. I hope you can find a decent load.

I will probably do both upon next load work up. I will run them from .010" off the lands and then skip where I have been and run them down short.. Should be able to find something. If not, I will move on to the PT's...

 

[DrMike]

My 7WSM has shot ABs very well, but it also liked 160 grain Sierra HPBTs as well. Truth be told, at 3000 fps, about any good 160 grain bullet will give you good performance on game.

 

[SJB358]

My 7WSM has shot ABs very well, but it also liked 160 grain Sierra HPBTs as well. Truth be told, at 3000 fps, about any good 160 grain bullet will give you good performance on game.

Mike, I just checked and I am at 3.00 to the lands with the 160 AB. My previous loads using the newer 160's were measured at 2.975".. Do you think it is worth going back to the lands? It wouldn't hold a 3" group at 2.975?

 

[DrMike]

Clearly, 0.025 inches is a big difference, and it can make a significant difference in accuracy. So, let me understand. Your previous OAL was 3.000 inches and your current OAL is 2.975 inches? Is that correct? If you measure from the ogive, what is the difference? And if you measure the bullet length, is there a significant difference? Since you had success at the longer OAL previously, I'd be inclined to look at approximating the lands. But, then, I'm stubborn that way.

 

[SJB358]

Clearly, 0.025 inches is a big difference, and it can make a significant difference in accuracy. So, let me understand. Your previous OAL was 3.000 inches and your current OAL is 2.975 inches? Is that correct? If you measure from the ogive, what is the difference? And if you measure the bullet length, is there a significant difference? Since you had success at the longer OAL previously, I'd be inclined to look at approximating the lands. But, then, I'm stubborn that way.

This might be hard to explain.. My previous load with the 2nds was loaded to 2.950".. That is the best shooting load I have had thus far!

Now, when I loaded the firsts, the first time, with the same die settings, they loaded to 2.975".. Which is .025" off the lands. Those didn't shoot worth beans.. 2-3" random groups. Now, I could take them back out and retry them at 2.990" Plenty of room in the magazine, but do you think there would have been a node that is that thin? Meaning, between 2.975 and 2.990" that would be worth looking or investigating in?

I know its probably confusing.. I know what I am thinking, but the word picture probably isn't lining up right!

 

[DrMike]

In short, I have found on a few rare occasions, nodes that were as thin as 0.010 inches or less. I had a 300 WSM I worked up last spring that shoot 0.20 inch groups at one particular OAL. When I went 0.005 inches either direction, the groups opened up to MOA. The effect was reproducible, so I'm pretty confident of the data. I wound up working up a load with a different bullet and powder, and found a broad node that gave me 0.10 inch groups. Yes, on occasion you can find a node that is extremely sensitive. I suspect, however, that the firsts have a different bearing surface or allow for loading to a different OAL to the ogive.

 

[SJB358]

In short, I have found on a few rare occasions, nodes that were as thin as 0.010 inches or less. I had a 300 WSM I worked up last spring that shoot 0.20 inch groups at one particular OAL. When I went 0.005 inches either direction, the groups opened up to MOA. The effect was reproducible, so I'm pretty confident of the data. I wound up working up a load with a different bullet and powder, and found a broad node that gave me 0.10 inch groups. Yes, on occasion you can find a node that is extremely sensitive. I suspect, however, that the firsts have a different bearing surface or allow for loading to a different OAL to the ogive.

Yeah, I guess I can break em down and try them up close again Mike. What the heck, its only a few more rounds down range anyhow!

 

[DrMike]

Just a thought! Has neck tension changed due to difference in seating depth?

 

[SJB358]

Just a thought! Has neck tension changed due to difference in seating depth?

No clue Mike. Using the same dies I've always used.

 

[SJB358]

Well, I went back out today. I loaded up a bunch of various combo's for the 7WSM using the newer 160AB's. I also a group of them at 2.990" which is about .010" off the lands in my rifle.

Next up was 2.890 (I already loaded from 2.900-2.960" in previous tries)

2.880

2.870

2.860

So as you can see, messing with seating has gotten me back in the same league. I am going to reshoot 2.990" tomorrow and see if I can get similar results. About the time I get this figured out I will need more bullets!

I also not sure if I shouldn't reshoot 2.860 and maybe load it a little shorter as well to see what it does? So many combos.

 

[DrMike]

It does seem as if your rifle is telling you a story worth heeding. Man, at 2.990, that will be an excellent load. I'm pulling for you to witness it be consistent.

 

[SJB358]

I hope it is Mike. Any other combos you see in there that look to be worth pursuing? What about the group at 2.860. I had a couple of bad shots, but it looks decent as well. Concentrate on 2.990 or push to the shorter depths?

 

[DrMike]

It is quite possible that you are approximating a second node at 2.860. I'd be inclined to look at it rather than just dismiss it. Frankly, at 2.870, the group is good enough (if the standard deviation supports it) to look at.

 

[JD338]

Scotty,

Reshoot 2.990" and if its there, call it done.
Nice speed too.

JD338