Originally Posted by
CFJunkie
Pardon me in advanced for this long post, but I believe that the data will let you see that there is no easy answer for which bullet will perform best in your new barrel.
I believe that your rifle is telling you that it might shoot bullets in the 69 and maybe up to the 77-grain range better than the lighter bullets.
You might also try the Hornady 73 gr ELD-Ms or the 75 gr ELD-Ms. They aren't as expensive as the Berger, Nosler or Sierra heavy bullets.
Here is some data that might let you see how one particular rifle barrel performs with different powders and bullets, no matter how confusing and illogical it might seem.
The 73 gr ELD-Ms shoot more accurately in my Savage 12 FV rifle with a 26-in 1:9 twist barrel than the 75 ELD-Ms.
But my 1:9 twist consistently shoots 77 gr bullets accurately so the 75 gr bullet weight shouldn't have caused the difference.
The same 1:9 twist rifle shot 77 SMKs to a 0.235-in average for 10 5-round groups at 100 yards using N540 powder during my last session. (We'll see if N540 accuracy holds up for a larger sample.)
77 SMKs averaged 0.292-in average for 90 groups with IMR4166 powder, and 0.289-in average for 83 groups with N140 powder.
77 TMKs averaged 0.279-in average for 205 groups with IMR4166 powder, and 0.282-in average for 61 groups N140 powder.
77 Nosler CCs averaged 0.280-in groups for 12 groups with H4895 powder, and 0.227-in average for 9 groups with IMR4166 powder.
77 Berger OTMs averaged 0.282-in average for 17 groups with N140 powder.
73 ELD-Ms shot a 0.264-in average for 8 groups with H4895 powder and 0.273 for 7 groups with N140 powder a few months ago. (I need to find more of these.)
75 ELD-Ms shot 0.375-in average for 4 groups with N140 powder at about the same time. (I was surprised that the 75 ELD-Ms did so poorly.)
69 SMKs shot a 0.235-in average for 21 groups with N540 powder.
69 SMKs shot a 0.289-in average for 32 groups with N140 powder and a 0.292-in average for 93 groups with IMR4166 powder.
69 Nosler CCs shot a 0.310 average for 13 groups with IMR4166 powder.
69 RMR shot .0296-in average for 11 groups with N140 powder.
(2000 69 RMR bullets cost about the same as 500 SMKs so if you want a bargain heavy bullet that shoots pretty well, this might be your best bet.)
In comparison, lighter bullets didn't shoot as well in my Savage 12 FV.
50 gr Berger Varmint FBs averaged 0.390 with N133 powder.
52 gr Hornady ELD-Ms averaged 0.333 with N133 powder.
52 Berger FBs averaged 0.466 with N133 powder. (Can't explain why the Berger 52s did so poorly in this barrel. My CZ527 24-in barrel loved them.)
52 Nosler CCs averaged 0.367 with N133 powder.
52 SMKs averaged 0.343 with N133 powder.
52 Hornady V-Max averaged 0.363 with N133 powder.
53 SMKs averaged 0.376 with N133 powder.
55 Berger FBs averaged 0.343 with N133 powder.
My data shown above tells me that bullet weight, shape and length will determine what bullets your rifle will shoot best.
Bullet weight and powder combinations do seem to matter, however illogical that might seem.
Individual barrels are particular, and preferences will differ, even for equivalent barrel lengths - I have identical rifles with different preferences.
I have found that some powders just shoot better with particular bullets than others in particular barrels, and the same powder will perform better with a particular bullet weight compared to another bullet weight. regardless of the powder's burn rate.
The only way you will be able to determine what works for your barrel is to try different combinations of bullets and powders.
When you find several combinations that your rifle likes, shoot them most of the time.
I just was able to purchase some N540 and, to my surprise, it is getting better results than N140 and several other powders, using the same bullets that I have data for.
As a result, I will be experimenting more with N540, hoping that its performance will continue to shine.
Caution, my results might not transfer to your particular rifle - ever barrel is different.
Consider this - in a large rifle maker, a run of barrels on a particular day is made one after another.
(For a specialized barrel maker, a single barrel might be cut for each set up, but the reamer is reused until it is too worn to be reused, so the example below still holds.)
The barrel blank is of a particular lot of steel so the steel mix is the same, but the next lot will be very slightly different.
The barrel bore is cut using a reamer.
The reamer for the first barrel in the run is new and exactly the bore diameter.
By the time the last barrel bore in the run is cut, the reamer is slightly worn and the bore dimension is slightly smaller.
The same holds true for the reamer used to cut the chamber.
Now you see why no two barrels can be identical.
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