Nosler Accubond Long Range problem

[Fiftydriver]

Kirby,

Thanks for the warning. I've got 100 rounds down the tube of my Savage 300 RUM and so far so good. I'll make the barrel nut a regular preflight check point. The gun shoots surprisingly good considering it cost me under $100 for the barrel (I wondered why it was so cheap!)

It was that price because it cost Savage about $25 to make that barrel!! Not a slam on Savage. Them along with Remington, Ruger and most other modern barrel makers spend between $25 and $50 on their barrels, especially if they make them in house. With modern barrel making processes and the shear volume of barrels they make a year, their cost is very low.

For what they have into their barrels, it is amazing how well most of them shoot but its also no surprise that occasionally you get that one real STINKER of a barrel as well.

It was probably a couple years back that Savage started having problems with their RUM chambered rifles. There were three very public reports of total rifle failures due to the barrel lock nut cracking and allowing the barrel to screw out slightly within a couple shots fired with no warning to the shooter. This allowed headspace to dramatically increase and then the cases would rupture causing catastrophic rifle failure. I believe there were a couple reports here on LRH but can not remember for sure.

The problem was that Savage increased the diameter of the barrel shank for the RUM chamberings and as such, the barrel lock nut had to be made thinner. With a bit of over torqueing, these thinner nuts could crack and then its all over!!! If I recall correctly, every rifle that came apart was a stock rifle.

Just be careful and keep an eye on the lock nut and you should be fine.

 

[Fiftydriver]

That't because the core is bonded to the jacket so it will stay together well even under terminal impact . I agrree with you the bullets are not blowing up but they could be out of balance .

If the bullets are strong enough to handle the launch velocity and RPMs, they will generally shoot better as they go faster. You mention they may be out of balance. I do not think this is the problem because if they are shooting well at a lower velocity, when you push them faster, their RPMs go up and stability should improve.

Only time I have seen this is with thin jacketed match bullets when they reached their velocity limits and could not handle the stress of the high RPM load. This is a tricky one. I would be curious to see if the rifle performed the same with say a Berger 150 gr VLD. The 270 WSM should not be able to push any modern bullet fast enough for bullet integrity to come into play but who knows. Will be interested to see more testing with this one.

 

[Engineering101]

Since the Bergers can be a little picky, I think I'll use a box of 150 Nosler BTs that I have sitting here to see if there is actually a velocity level where the rifle quits shooting in dramatic fashion with those bullets. If I can make that happen then the problem is with the rifle and not the bullets. That is in fact what I expect to find because 3,000 fps just isn't that fast and a 1 in 10 twist isn't either. Also, Nosler doesn't make flaky bullets.

The only reason I even starting looking at the bullets is because the gun goes bad so dramatically. I've never seen anything even close to this bad unless the scope broke. Usually a group will open up and inch or two when you get to a velocity that doesn't work but 2 feet with only a 50 fps step up in velocity – that was a surprise!?

I do however find it interesting that no one has come forward to say that they have run this bullet past 3,000 fps with no problems. Nosler's tech guy should call me back tomorrow to let me know how fast they ran them and that will be good info that I will pass on.

 

[Engineering101]

Kirby,

With regard to the stock Savage 300 RUMs blowing apart. Mine is NOT a large shank barrel so I have the thicker original barrel nut on the rifle. I'm thinking I kind of like that based on how you described the problem. I may have accidentally built a version of the Savage RUM that won't have that problem.

 

[Fiftydriver]

I still build on the occasional Savage receiver but when I do I fit the barrel in the same manner as a Rem 700 so that I can use a larger shanked barrel. Plus it cleans up the looks of the rifle and also allow better bedding around the recoil lug area of the rifle.

It also eliminates any possible problems that MAY happen with the lock nut.

Your thicker lock nut should not have any problems but still keep an eye on it, that is THE weak link in the Savage rifle design.

 

[JD338]

The ABLR's shoot pretty good but they do like a lot of jump.

Almost there, need to seat a little deeper. This group went .690".
My 280 AI has a long throat and I am .155" off the lands.

JD338

 

[Fiftydriver]

wow, that is a long jump. Are the groups consistant? I would be a bit worried with that long of a jump but if the throat is dimensioned properly, a long throat does not hurt much at all, just makes life harder on the bullet being slammed into the lands after they have gained some linear velocity.

The ABs jacket is very heavy though so that should never be an issue.

 

[JD338]

I'm still tweaking the load but the accuracy is there.
This rifle shoots the other Nosler bullets, 140 gr BT/AB, 150 gr PT/ET, and 160 gr AB .3 or less.

JD338

 

[Fiftydriver]

I'm still tweaking the load but the accuracy is there.
This rifle shoots the other Nosler bullets, 140 gr BT/AB, 150 gr PT/ET, and 160 gr AB .3 or less.

JD338

That is interesting, do the other Noslers need the jump for good accuracy in your rifle? Maybe these bullets with the more aggressive ogive need more jump. Time will tell as more bullets get out in the field. Unfortunately, many will seat them to the lands and test them and if they do not shoot good will just give up on them instead of actually doing a complete load work up as your doing. Your doing it right!!!

 

[Engineering101]

Just got back from the range with the results of shooting 150 gr Nosler Ballistic Tips in the 270 WSM. I started with a clean/cold barrel and fired 1 fouling shot followed by 4 three shot groups at 200 yards. I let the barrel get slightly warm but never more than that. The ES of velocities for all groups was right around 20 fps – so not horrible. Loads (all Ramshot Magnum), average velocities and group sizes were as follows:

68.5 gr/2,984 fps/2.218"
69.0 gr/3,005 fps/2.906"
69.5 gr/3,038 fps/2.343"
70.0 gr/3,067 fps/4.531"

All groups but the one with 69.0 gr had two shots about 0.5" apart and then one flyer to open up the group. A classic indication that there is some barrel vibration going on.

This performance sucks and I need to see what these bullets do running closer to 2,900. I'm guessing that they will shoot a lot better as did the 150 ABLR bullets however all shots today landed on my 8.5" X 11" target paper whereas the ABLRs wouldn't stay on 4 of those targets thus I don't know what group size they shot when they went bad but it had to be at least a foot to miss all that paper.

Conclusion: The 150 ABLRs shoot MUCH WORSE than the Ballistic Tips in this rifle while running similar velocities. What does that mean? Beats the hell out of me. Maybe this barrel does have a harmonics issue as Kirby suggested and the 150 ABLRs just really hate barrel harmonics. Now what? I suppose I'll run them down around 2,850 fps and call it good. Then again, with all this messing around I'm about out of them so the problem may just go away for this hunting season as I likely won't be able to get any more of these ABLRs until Nosler does another production run next year.

 

[JD338]

What it means is that the 150 gr ABLR wont stabilize in your rifle, which most likely is a 1:10 twist.
Nosler recommends a 1:9 twist for this bullet.

JD338

 

[JD338]

That is interesting, do the other Noslers need the jump for good accuracy in your rifle? Maybe these bullets with the more aggressive ogive need more jump. Time will tell as more bullets get out in the field. Unfortunately, many will seat them to the lands and test them and if they do not shoot good will just give up on them instead of actually doing a complete load work up as your doing. Your doing it right!!!

Hi Kirby

The only bullets I have had to seat deep for more jump is the 150 gr E-Tips and the 150 gr ABLR, everything else is seated long as you can see in the picture below. The 160 gr AB went .092".

JD338

 

[MontanaRifleman]

What it means is that the 150 gr ABLR wont stabilize in your rifle, which most likely is a 1:10 twist.
Nosler recommends a 1:9 twist for this bullet.

JD338

I'm not buying that. First, he was getting OK accuracy at a lower velocity and increasing velocity would only help stability. Next, run the numbers in a twist calc like Berger's and a 10" twist will give about a 1.25 SG which is not ideal but plenty good for target shooting. Bullet manufacturers recommend an SG of 1.5 for hunting which is what a 9 twist would give.

 

[JD338]

Good point Mark. I scratching my head on this one.

JD338