.257 PT vs Accubond - drastic difference in point of impact

[bullwinkle]

:? I have used 120 gr partitions in my 25-06 for years with great success; always flawless performance. However, I felt compelled to try the new Accubonds, so I bought a box of 110 gr. In the past I have shot several brands/weights of bullets through my Ruger M77 and have always had them group close enough to the PT to hunt with, 2 inches difference @ 140 yards at the most between the PT and others. I was shocked when I shot the Accubonds and did not even cut paper at 100 yards!!! After shooting three or four Accubonds, I shot one of my PT just in case something had happened to the rifle. Perfect dead center and 1.5" high....spot on. Turns out the Accubonds group fine (maybe great!) just 6+ inches high. Obviously I can adjust for this, but I prefer not to make the adjustments since all other bullets seem to group together and then they would all be way off without re-adjusting.

Anyone else have this experience? Any suggestions to limit the difference? Or do I just make the sight adjustments and use the Accubonds? FYI, I tried three different powders with basically the same results.

 

[Guest]

I think what you're experiencing is a combination of barrel harmonics and velocity causing the higher POI. Remember that the 110 is going to be going noticeably faster than the 120. Maybe downloading the 110 to 120 velocities would help? (Of course, that really defeats the purpose, doesn't it?)

 

[FOTIS]

First off welcome to the forums. Glad to have you. As far as your dilemma goes I have seen this one other time with 180 PTs and 180 AB in a win 70 300 Winnie. At 100 yards the ab's did not cut paper at all while the 180 PT's (both federal make) were 2" high at 100 yards. What can one say? Guns will be guns and all are different.

 

[RemmyTim]

I think the lighter weight and the difference in ballistic coefficient is what you are seeing. Lighter bullets moving faster will usually shoot higher and then when you mix in the fact that the AccuBond has a higher BC and therefor flies flatter, you will have a higher POI.

By the way, welcome to the site.

Tim

 

[bullwinkle]

Thanks for the welcome and replys! You make some good comments that all have merit. I did actully load the Accubonds with LESS powder than the PT, just because I was experimenting. So they should not have been hyper velocity. I have previously shot Hornady 100 gr bullets that were blazing fast that shot to pretty much the same POI as the PT (actually killed a deer with one of those 100 grs).

May just be a fact of life. As you said, guns will be guns....And I do remember that my rifle hated factory ammo when new; 4-5" groups if you can call it that. Since I started handloading the rifle has never seen facotry ammo.

 

[FOTIS]

............ Since I started handloading the rifle has never seen facotry ammo.

Same here, I have killed 2 animals with factory stuff. Both over 5 years ago.

 

[bacova]

I have a Ruger 25-06 and it won't shoot the AccuBond worth beans either, it'll shoot about anything else I feed it though, Partitions, Ballistic Tips, Sierra GameKings, Barnes TSX, everything except the AccuBond. A few months ago I thought I'd finally found a recipe for the Accu using Retumbo, but it was a false alarm, couldn't dupliucate the initial results.

About all I can come up with as an excuse, LOL, is that the AccuBond is a really looooong bullet for weight and maybe my barrel twist rate isn't right for it. I've compared it visually with all the other .257 bullets that my rifle shoots great and the Accu is noticably longer.

Don't get me wrong, I can get the Accus to group well enough for 95% of Deer hunting situations, but just not as well as any of the others. I've quit messing with it and decided to stick with the Partitions and TSX.

 

[JD338]

bullwinkle

Welcome to the forum.

You might try a different powder to change your POI. May get you closer to your other loads.

JD338

 

[flyfish]

I am shooting 110AB out of my Ruger 257Roberts. They are shooting VERY well. I had similar groups with the 115 BT. The partitions shot well but groups were not quite that of the AB or BT bullets. As for different weight bullets having the same POI, never been able to do that. One reason, I always assumed different bullets/powder combos would just be different. From my limited experience it proved to be that way when I shot them. I have to admit I never thought about or consider it was possible to have different bullet weights have a common POI.

For what it's worth my M77 Ruger loves 110 gr. AB and 33.0 grains of IMR4895. That will be in my rifle this Nov. Hope to see how the ABs do on a Vermont whitetail.

 

[buckfever]

My 25 06 Ruger M77 all weather likes 50 gr of IMR 4350 with the 110 AB it will shoot from .50 to 1.0 @ 100 yards depending on if I'm doing my part and holds close to the same point of aim as the 120 PT @ 100 yards.

 

[bsmith]

FlyFish, was the 33 grains of 4350 a typo? That seems like an awlfully light load of powder for a 25-06. If I try 4350, I'm planning on starting with 46 gr.

 

[flyfish]

I'm loading for a 257 Roberts not a 25-06. The load came from the Nosler #5 reloading manual for 115 gr BT.

 

[bsmith]

Apologies FlyFish. My bad for not following the thread close enough.

 

[flyfish]

not a problem!

 

[flyfish]

I am very imbarassed and must apologize. I have posted a couple times that I was using 33 grains for IMR 4350 in my .257 roberts. This is INCORRECT! It is 33 grains for IMR 4895 with the 110 gr AB.

I went down to reload tonight and realized what I did. :roll: