My 260 rem load development

[Bobby B.]

Here's the situation; last October I drove down to Calgary with one objective in mind, to leave my Sako Hunter to be rebarrelled to 260 Rem. I live in Edmonton so there was some expense involved. The gunsmith said he could have my rifle ready for me in 2-3 months. I responded by saying I wouldn't need it until the end of March at the earliest and sometime in April would be just fine.

Towards the end of March I called the gunsmith to check when my rifle would be ready. I was told to call back in a month. I called back and was told it would be ATLEAST another 2 months. I said that this would not work for me and asked my rifle be shipped back to me. And, it was, at my expense. No big deal. However, this seriously put me behind schedule as I wanted this rifle ready for High Power Silhouette. Obviously, it wouldn't be.

I contacted a gunsmith here in Edmonton who's begun producing his own barrels. He and I discussed what it was that I wanted, he informed me of the price for his work and services and I agreed. The barrel is a 24", Sako Hunter factory contour with a 1 in 8.5" twist.

After securing 200 Lapua .243 Winchester brass, I resized it up to 260 Rem. I first passed it over a .25 sizer button then over the standard 260 button. I prepped the cases. selected three powders and 1 bullet, the Berger 130 VLD. The bullet was seated slightly into the lands.

I charged 3 cases with 46 gr. of RL 19, 3 with with 46.5 and 3 with 47 grains. I also charged 3 cases with 45 gr of IMR 4831, 3 with 45.5 and 3 with 46 grains of IMR4831. The third powder loaded was 3 cases of 44 grains of H4350, 3 of 44.5 grains and 3 of 45 grains.

Today, I fired some of the loaded rounds over my CHRONY chronograph, here are the results; RL 19 46 grains: 2908 fps, 2918, 2892. Cleaned the barrel after each round. The first round of 46.5 grains of RL 19 showed an extractor mark so I stopped there with RL 19. Cleaned the barrel.

The second powder tested was IMR4831; 45 grains produced 2911,2930 and 2892 fps. Again the barrel was cleaned after each round. I decided that 2900 fps was sufficient velocity so did not chrono the remaining rounds.

The third powder I tested was H4350 and here are the results; 44 grains 2870, 2860 and 2873 fps with the barrel cleaned after each shot. The 44.5 grains gave 2865, 2906 and 2907 fps. The barrel cleaned after each shot.

Then with a clean barrel, I tested the load with 45 grains of H4350 powder. The barrel was NOT cleaned after each shot but only before the 3 shot string. The velocities were 3014, 3026 and 3022 fps. This is with a 130 Berger VLD and a 24" barrel.

In summary, I expected velocities to top out at 2850-2900 fps regardless of powder selected. However, H4350 is producing velocites with a 130 grain bullet that one would expect from a .270 WCF.

These velocities are the result of preliminary testing and do not correlate to any indications of accuracy at this point although the small ES spread suggests some potential.

Logically speaking my next step is to test for accuracy now that I have some fireformed cases to load for.

The scope to be mounted is the Swaro AV 4-12X50 BT scope. I have this same scope on my 7RM and am quite pleased by the optics it offers.

Bobby B.

[260 Rem]

Bobby---Jeeze i hope this sends..just lost the first one. Karl just installed one of his barrels on a trued rem action. I used a 260 rem reamer with standard feebore and .292 neck. Load develpoment started last week. All 5 shot groups @ 100M. Started with 120SMK's / .010 off lands / H4350. Started with 43.5 gr and went up to 46.5 in .5gr increments. Nothing showed much promise until i got to 45.0gr...but then it would put 4 under a dime and one outside flier. At 46.7 the flier tightened up a bit but was still there.
So, today i loaded some 120 Bergers .003 off the lands. First (five shot) group with 46.0gr went into 0.6" and the second into 0.29" --- At first I was blaming the bulk rem brass for the fliers, but it looks like it is more likely that the SMK's are not going to be consistent...so I will not fight it, and switch to the Bergers. I don't use a chrony so don't know the speed of the 120's.

[Bobby B.]

Five shots into .60" at 100 meters is damn impressive and 5 shots into .29" is truly exceptional. So many shooters limit their groups to 3 shots. I believe this is a strategy to obtain the sub MOA groups which distinguish great accuracy from acceptable accuracy. It's a form of cheating. There was a time when everyone shot 5 shot groups for standard cartridges and 4 shot groups with magnums.

After reading your post, I'm doubly curious to see what accuracy my rifle will produce with one of Karl's barrels. IMO, Karl is an excellent gunsmith and very comfortable to deal with. If his barrels prove to be the shooters I believe they'll be, the usual aggravations of having a rifle rebarreled are a thing of the past.

Bobby B.

[260 Rem]

Today's groups using the Ber 120's and 46.5gr of H4350 were 0.64 and 0.54 @ 100M.. using the Rem brass...and like with the SMK's there was a flier in each group that opened up a group that was in the 3s. Maybe it is the brass.
I also had one group loaded the same, but using Nosler brass...but only shot one shot. With exactly the same load, the Nosler brass gave me heavy bolt lift, flat primer, and a very shinny extractor mark on the base. Guess those Noslers must have less case capacity than the Rem.
It will be intersting to see what your Lapua brass will tolerate. I think Lapua has thinner walls, so you may not have any pressure signs at near the max end. Did necking up produce any visible donut?

[Bobby B.]

My understanding is that donuts are formed during firing but I'm no expert on this. Haven't had a chance to inspect the fired cases so am unaware of the existence or not of donuts. Do you have a preferred method for determining the presence of donuts?

Bobby B.

[260 Rem]

If donuts form, they would so so when reszing the brass. They occur at the neck shoulder junction when part of the thicker shoulder brass is pushed/pulled up into the neck ...and from the outside, look like a little (fatter) ring at the junction....but the problem is really on the inside of the neck where they can protrude...so when bullets are seated with the bearing surface deeper than the N/S junction...it increases the tension. But, if you are getting acceptable accuracy, who cares.

[260 Rem]

B---Groups from my 260 Rem with 120 Bergers...looks like I still have a bit of tinkering, but they are getting close. The group on the right was with Nosler brass and a full 2.00gr of H4350 than the groups I shot using Bulk Rem brass...You can see I stopped after 4 shots as the bolt lift got pretty heavy and on shot #4, the ejector mark got too shiny! The two center groups are with Rem brass and H4350. The group on the left is with RE 19...

[209x50]

Good stuff guys! I have a 260 AI being built right now and Im excited to get it out on the range.

[rightroad]

Sounds like a pretty deadly system you built!