Nosler Accubond Long Range problem

[MontanaRifleman]

I have done some testing with mono solids and penetration testing and they do perform differently then an expanding bullet on penetration. The reason is that they do not expand much at all and retain nearly 100% of their original length, this causes some issues as they pass through tissue and often causes them to tumble.

This is reduced with the higher their impact RPM level is. Simply put, the faster they are spinning, generally, the longer they penetrate with their nose pointed forward. The lower their RPM level, the faster they begin to tumble. That said, I have not seen one of these bullets not tumble to some degree in penetration tests. the longer and more aggressive the ogive, it seems the sooner this happens.

The STOPPING bullets with their round or blunt nose profile seem to penetrate the straightest at any RPM level. To that point, the shorter the solid, the straight and more consistant it will penetrate, the longer the bullet, the sooner it will tumble. Just what I have seen in my own testing.

Now, to a cup jacketed bullet. Once a bullet expands, it stops having anything in common with the mono solids because the length of the bullet is greatly reduced and the frontal area of this bullet design is greatly increased. This generally can cause some very inconsistent penetration paths so its pretty hard to say if RPM levels have any real effect on terminal penetration on an expanding bullet.

The controlled expansion bullets such as the Barnes or expanding solids seem to be somewhere in between the two in my testing.

I agree that mono's have different expansion characteristics than cup and core, but not different terminal stability rules. I used to be of the mind set that good stability was required for reliable expansion, but recently, as the result of a discussion in another thread, I've found out that it seems to be the opposite. Good expansion is required for "terminal stability". In short, if bullets don't expand, they tumble. If they do expand, they go straight. That is the rule for the pointy bullets. Here's a video by Gunwerks that illustrates that.

Bullet Penetration & Shoulder Stabilization - YouTube

The video says that no amount of spin is able to keep a bullet stable once it is penetrating a denser media.

For blunt nose bullets, basically cylinder shaped, like the GSC FN's, their blunt nose shape results in the same stabilizing effect as an expanded spritzer.

If the expanded bullet has an irregular shaped front, then I'm sure it would affect straight line penetration to a degree. The longest penetration shot I ever made was a Texas heart shot on a speed goat buck at about 200 yds. The bullet (.308 180 gr Fed Soft Point) entered precisely between the hams and the remnant slug ended up under the hide of the front shoulder, The path was very straight, The frontal was a bit irregular, but the slug itself (about 40% of original weight) was only about as long as it was wide and probably acted a lot like a round ball. I still have it.

 

[Fiftydriver]

Yes all bullets follow the same rules for external ballistics but monos, expanding solids and lead core bullets all have their own set of rules for terminal ballistics.

 

[MontanaMarine]

I shot a 3 shot group of 0.656" at 100 yards using my 270 WSM with the new 150 grain ABLR and 60.0 gr of H4831SC, 26" bbl, COAL of 2.915". This load chrono'd around 2,910 fps. No pressure signs so I worked on up to 3,000 fps. That is where the problems started. In two different barrels with different scopes I've seen the same thing. Get near 3,000 fps and the bullets go all over the place. At 2,966 fps they grouped under 1.5" at 200 yards, but at 3,000 fps I can miss 4 sheets of notebook paper while aiming at the center, then go 4 inches right and then hit point of aim and then back to no bullet hole at all. I switched to Ramshot Magnum and it did the same thing – shot good slower and then went to hell at 3,000 fps. I talked to Nosler's tech guy yesterday. He has never heard of any such issues but he is going to do some checking. Anyone else seen this problem?

I wonder if the bullet is having nose slump issues past a certain velocity/rpm.

I read on Nosler's site that the ABLR is supposed to open up down to 1300 fps impact speeds. That indicates to me that the nose area is significantly softer than the original AB.

The smaller diameter (.277") ABLR might be more prone to something like nose slump since it has less mass in that ogive.

The sudden and total loss of accuracy seems to me like more than barrel harmonics.

 

[LONGSHOOTER]

As others have said, first check your barrels actual twist. Run a cleaning rod through it, checking twist rate of YOUR barrel.

 

[MontanaRifleman]

As others have said, first check your barrels actual twist. Run a cleaning rod through it, checking twist rate of YOUR barrel.

That's a good idea.

 

[MontanaRifleman]

The sudden and total loss of accuracy seems to me like more than barrel harmonics.

Especially in 2 different rifles

 

[MontanaMarine]

Those bullets were happy campers at 2900 fps. Sub-moa accurate. That's not a fluke, that's a stable and accurate.

If stability was close to the edge, things would typically improve with more velocity. The way everything fell apart at 3000 fps, just doesn't make sense for harmonics, or marginal stability.

It'd be interesting to know what's going on though, whatever the cause may be.


Nose slump is the only thing that comes to my mind that seems logical. I suppose if that is the case, there will be more accounts similar to this as more of these bullets get used.

I'd never even heard of nose slump until it started happening with the early Berger 300gr .338" when driven at warp speed. Seems Berger had to tweak the nose a bit, and got things sorted out.

 

[MontanaRifleman]

Those bullets were happy campers at 2900 fps. Sub-moa accurate. That's not a fluke, that's a stable and accurate.

If stability was close to the edge, things would typically improve with more velocity. The way everything fell apart at 3000 fps, just doesn't make sense for harmonics, or marginal stability.

It'd be interesting to know what's going on though, whatever the cause may be.


Nose slump is the only thing that comes to my mind that seems logical. I suppose if that is the case, there will be more accounts similar to this as more of these bullets get used.

I'd never even heard of nose slump until it started happening with the early Berger 300gr .338" when driven at warp speed. Seems Berger had to tweak the nose a bit, and got things sorted out.

I agree, the details of the symptoms and the fact it's happening in 2 separate barrels strongly suggests that it's not the rifle/barrels and has something to do with the bullet.

Sure would like to hear from others shooting these bullets over 3000 fps.

 

[Gone Ballistic]

I'm pushing a 200 gr.Accubond in a .300 Remington Ultra Mag at 3308fps. I am shooting a Luther-Walther 30" stainless barrel using 215 Fed. primers and Retumbo powder. I have shot this load over 1600 yards and have never had a problem.
I tend to agree with some of the others that you have too tight of a barrel twist. You haven't mentioned what it does with other bullets of similar B,C,

 

[winmag]

Tagging this thread.
If I can get my hands on a chrono ill go test the 40ish rounds I've got loaded up for load development.

Model-70 Win, 270 WSM. Factory rifle, 24" pipe.
Win brass.
Rl-22
Fed.215
150 ABLR

21 rounds @ .015 off the lands
21 rounds @ .020 off the lands

3rounds ea @ 1 grain increments, until it gets near max load, then .5 gr incriments, with RL-22. should easily break 3000, & knock on the door of 3100 ish IF I don't run up against early pressure signs. We'll see where accuracy falls off if it does, & at what speed. I'm Very curious.
I've been holding off shooting these until I can borrow another chrono, & now it seems its a necessity to help provide accurate info to help answer this issue.

Certainly can't rule out nose slump as a possible cause.
Now I'm even more curious how they'll fly. (& how many I may or may not have to pull)

 

[MMERSS]

Subscribing.

 

[gillettehunter]

I'll jump in with a little more info. I'm shooting a 7 SAUM and working with the 168 ABLR's. I tried to work up a compressed load with H-1000. The jacket was thin/soft enough that I got a "compression ring" around the bullet when I tried the compressed load. Went to a faster powder. Just shot some this AM. 61.5 gr of H4831sc with a Fed 210 primer. Should be about 2980fps. At - 40 from the lands I got a 1/2 minute group. -20 and -30 the groups opened up. The wind probably affected my groups a bit too.....
In my mind the noses are rather soft/thin on these bullets. Never had this happen before. Bruce

 

[royinidaho]

I forgot to ask in my last post – is there anyone out there that has shot the 270 ABLRs over 3,000 fps and had no issues? I'm thinking that alone would be evidence that it is not a bullet problem. How about you 270 Weatherby shooters?

As soon as I can find a box of the 150 ABLRs I'll be pushing them to way beyond 3200 FPS.

I ran 150 Ballistic Tips in excess of 3500 my 270 AM with great success to distances beyond where their little parachute opened.

 

[MontanaRifleman]

As soon as I can find a box of the 150 ABLRs I'll be pushing them to way beyond 3200 FPS.

Hope they make it to the target