I've done a lot of load development with 270s and 4831sc. It is a great powder for 130 and 140 grain projectiles. If you want to go faster than what you are getting with the 64 grains which is the correct load judging from your target of the 7mm WSM, I would switch to a slower powder. When I changed from the 140 Accubonds to the 150 VLD Bergers in my 270 Dakota, I had to change powder from 4831sc to a slower powder equivalent in burning rate to Retumbo.
Nosler Accubond Long Range problem
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Engineering101
Well-Known Member
longarm
You are correct, H4831SC is a bit on the fast side for the 150 grainers in the 270 WSM. I've also used Magnum, IMR 7828SSC, and others. Right now I don't need faster since whatever powder is being used, when the velocity gets around 3,000 fps, things go bad in a hurry. Pressures are fine judging from the easy bolt lift and primers that are not very flat. Once I get this all sorted out I'll likely pick whatever powder gives me and accurate, temp stable load with the lowest ES.
You are correct, H4831SC is a bit on the fast side for the 150 grainers in the 270 WSM. I've also used Magnum, IMR 7828SSC, and others. Right now I don't need faster since whatever powder is being used, when the velocity gets around 3,000 fps, things go bad in a hurry. Pressures are fine judging from the easy bolt lift and primers that are not very flat. Once I get this all sorted out I'll likely pick whatever powder gives me and accurate, temp stable load with the lowest ES.
royinidaho
Well-Known Member
TJ,
Here's my plan.
1. Greet the mailman
2. Open package
3. Visually inspect
3a. Compare w/140 & 150 offerings
3b. Dissect and compare w/AB & Ballistic Tip jackets
4. Based on 150 BT loads load the ABLRs to destruction or 3600 FPS @ 10' or 'my' max pressure limit, which ever occurs first.
4b. 300 yard accuracy will be recorded during 4.
5. Determine optimum accuracy load @ reasonable Allen Magnum velocity expectations. (BTs shoot exceptional @ 3500+)
6. Using the accuracy load do terminal performance tests from 300 yards to as far as I can hit the media container, in 100 yd increments. (150 BTs preformed as expected from 100 to 400 yards.)
This should pretty much use up a day.
With the survivors I'll head to my LR spot and validate bc to 1200 yds.
That'll be a whole other day and a great opportunity for the goats to pack the rifle, shooting gear, vituals, water and camping gear.
I'm kinda looking forward to this.
Steps 1, 2 & 3 complete.
What's not to like about the looks of these suckers.
First comment is that while the tips are the best shape I've seen except for my brass ones
, they aren't precisely centered. The ones I performed the "finger nail" test they are perfectly flush on one side an just a hint of a ledge on the other.From my read of Kirby's thread on re-tipping bullets this very small offset should make NO noticeable impact on anything.
Have to move a washer and dryer, will get on the following steps asap.
The tell-tale sign for me is that your velocities became more erratic once you loaded more than 64 grains. This would explain why groups opened up. I would like to see whether you are getting consistent velocities with a slower powder at above 3000 fps and still getting the huge groups. Note that I have got erratic grouping (5 shots in 0.75 inch at 100 yards to 5 shots in 3 inches) when I exceeded my optimum load of 59.5 grains 4831sc with the 130 grain slugs in a 270 Winchester.
Fiftydriver
Official LRH Sponsor
I bit curious how you can say that 64.0 gr is the load that should be used in a rifle you have no experience with? Not trying to flame you in any way but its impossible to tell someone what load will work best in their rifle.
H4831SC is on the faster side of burn rate for a 150 gr 270 WSM but it should work extremely well.
Again, no disrespect, just impossible for someone to tell someone else what is best for their rifle without testing loads in that specific rifle.
Fiftydriver
Official LRH Sponsor
If your using the 7mm Dakota parent case for your 270 Dakota, your case capacity is far larger then the WSM and for that application, I would agree, that H-1000 or Retumbo would be better choices but for the relatively small case capacity of the WSM, H-4831 or its SC version are just fine. I think your focusing to much on powder choice. Powder selection will not take a 4" group down to a 1/2" group.
Fiftydriver
Official LRH Sponsor
If the standard ballistic tips had NOT been tested with similar results, I would have to say that the problem lies in the bullet design. Looking at the cross section of the bullet, I would think that the possible problem is a very thin ogive jacket and no real support under the tip which seems to allow the bullet to set back at velocities over 3000 fps resulting in very inconsistent accuracy.
Unfortunately, there were similar problems with the standard Ballistic Tip which is not known to have ANY issues with anything you want to throw at it velocity wise.
Think we all need to set back and just wait to see what happens with these bullets are driven to higher velocities from those that will be testing these new bullets. If this bullet will survive the 270 Allen Magnum full velocity loads, it will handle anything. If it is a bullet issue, likely the bullet will come apart in flight so testers, WATCH YOUR CHRONOS!!! I have had test bullets come apart and they always seem to find their way right through my chronographs!!!
Unfortunately, there were similar problems with the standard Ballistic Tip which is not known to have ANY issues with anything you want to throw at it velocity wise.
Think we all need to set back and just wait to see what happens with these bullets are driven to higher velocities from those that will be testing these new bullets. If this bullet will survive the 270 Allen Magnum full velocity loads, it will handle anything. If it is a bullet issue, likely the bullet will come apart in flight so testers, WATCH YOUR CHRONOS!!! I have had test bullets come apart and they always seem to find their way right through my chronographs!!!
Fiftydriver
Official LRH Sponsor
Still would recommend switching things up but not with powder choices. Powders could produce SLIGHTLY different group sized but your generally not going to see DRAMATIC reduction in group size with a simple powder change as long as all powders are in an appropriate burn rate range for the chambering being tested which all mentioned have been.
I recommended long ago to switch bullet designs and see what happens. I would love to see what this rifle would do with the 150 gr Bergers. Being a rifle manufacturer, I tend to look at solving rifle accuracy problems instead of bullet accuracy problems so my goals are generally directed toward finding what a specific rifle prefers more then trying to figure out why a specific bullet WILL NOT shoot. It will be good to find out the problem though.
Again, switch things up dramatically with a completely different bullet design and see what a conventional cup jacketed/lead core bullet will do in the same rifle.
I recommended long ago to switch bullet designs and see what happens. I would love to see what this rifle would do with the 150 gr Bergers. Being a rifle manufacturer, I tend to look at solving rifle accuracy problems instead of bullet accuracy problems so my goals are generally directed toward finding what a specific rifle prefers more then trying to figure out why a specific bullet WILL NOT shoot. It will be good to find out the problem though.
Again, switch things up dramatically with a completely different bullet design and see what a conventional cup jacketed/lead core bullet will do in the same rifle.
The reason I said that 64 grains is the load he should use is because he has tested the loads (see the results of his tests several posts back) and 64 grains gave the best group with a small velocity spread. It is not impossible to tell someone else what load should be used in a rifle I have no experience with, if he has himself tested that same rifle.
royinidaho
Well-Known Member
I've shot new manufacture Wildcat bullets, a couple of years ago in NV that patterned better than 8" @ 20 yards. That's a one shot pattern.
I've killed 3 chronys but it was my fault every time.
I've weighed and sorted winmag's LRABs. Their baring surface seems to be about 0.10" shorter than the 150 Bergers so I'll start out with the COAL that the seating die is already set at (same setting for 150 berger and 169.5 WC)
The initial powder charge will be 82 grains of 7828ssc which pushed the 150 Berger to right at 3500 and sub 1/2 MOA @ 200 yds.
This barrel, the second one on this action, from DerekM in Ohio, is 2" shorter and lighter contour than the original.
Differences between this barrel and possible different throat than the original barrel are:
New barrel shoots Bergers very well @ 3500. Original barrel shot the same Bergers in large banana shaped groups.
This barrel though 2" shorter produces same velocities with same charges as the original 30" barrel.
New barrel is just as accurate as the shot out original was in its hay day.
I called off my trip to the hills to tune up for going a mile with the 375 to work on this project.
Should be a fun day.
I've killed 3 chronys but it was my fault every time.
I've weighed and sorted winmag's LRABs. Their baring surface seems to be about 0.10" shorter than the 150 Bergers so I'll start out with the COAL that the seating die is already set at (same setting for 150 berger and 169.5 WC)
The initial powder charge will be 82 grains of 7828ssc which pushed the 150 Berger to right at 3500 and sub 1/2 MOA @ 200 yds.
This barrel, the second one on this action, from DerekM in Ohio, is 2" shorter and lighter contour than the original.
Differences between this barrel and possible different throat than the original barrel are:
New barrel shoots Bergers very well @ 3500. Original barrel shot the same Bergers in large banana shaped groups.
This barrel though 2" shorter produces same velocities with same charges as the original 30" barrel.
New barrel is just as accurate as the shot out original was in its hay day.
I called off my trip to the hills to tune up for going a mile with the 375 to work on this project.
Should be a fun day.
With the 150 grain projectiles in the 270 WSM, The Hodgdon Reloaders' Guide gives maximum loads as:
Retumbo 70g 3071 fps 63000 psi
H1000 67.5g 3001 fps 62,800 psi
H4831 60g 2962 fps 63,100 psi
This is consistent with my own findings that when moving to the 150 grain projectiles from 130 and 140 grains, Retumbo or H1000 gives better results than H4831sc.
Engineering101,
In your first post you stated that you used 60 grains of 4831sc with the 150 Accubond in your 270 WSM and this was accurate. This is a maximum load as seen in my post above. When you went above this maximum load,( by a few grains I suspect to get over 3000 fps) the accuracy disappeared. I think that the design of the 270 WSM case (much like Ackley Improved cases) might be masking the excess pressure so you are not seeing it by the usual pressure signs. However, I get the usual pressure signs when I load more than the maximum load of 67 grains of 4831sc with the 130 Accubond in my 270 WSM. If you switched and worked up slowly to 70 grains of Retumbo, I think you would get over 3000 fps without the problems with the 150 grain LR Accubond when using more than 60 grains of H4831sc.
In your first post you stated that you used 60 grains of 4831sc with the 150 Accubond in your 270 WSM and this was accurate. This is a maximum load as seen in my post above. When you went above this maximum load,( by a few grains I suspect to get over 3000 fps) the accuracy disappeared. I think that the design of the 270 WSM case (much like Ackley Improved cases) might be masking the excess pressure so you are not seeing it by the usual pressure signs. However, I get the usual pressure signs when I load more than the maximum load of 67 grains of 4831sc with the 130 Accubond in my 270 WSM. If you switched and worked up slowly to 70 grains of Retumbo, I think you would get over 3000 fps without the problems with the 150 grain LR Accubond when using more than 60 grains of H4831sc.
Fiftydriver
Official LRH Sponsor
I would agree, with the information he is getting, the lower pressure loads obviously are the correct ones to use. It seemed like you were recommending a load from your experience, my mistake.
I do feel that 4831SC is a very good powder for this combo however.
Also, the OP wants to find out whats wrong with this bullet or rifle as there should be NO problems pushing a Nosler bullet over 3000 fps, hell, 4000 fps should be fine. The goal is not to pick the best of these loads. Whats to find out why everything is coming totally apart at +3000 fps which a lot of us want to know.
