Thread: Breaking in the 260rem and load development

Bloody odd this, 6.5's generally shoot bloody good regardless of what you throw in them, especially 6.5CM & 260. I've always found you are trying to improve on the 3 shot 0.75 MOA that they usually produce straight up.

Greetings again @Sidetrack,
You may know the standard test for bedding but just in case here it is. With the action snugged down in the stock hold the barrel and fore end with one hand and loosen the front action screw. You should not feel any movement between the barrel and fore end. Do the same thing with the rear screw and the tang and stock. Once again there should be no movement between the tang and stock. If you feel movement then strip the rifle and remove the mag well which is just a loose fit between the action and floor plate. Reassemble and test again. If there is movement with the mag well in and none with it out then the mag well is binding or is too big for its space. It is possible that the action is hung up somewhere in its recess on the underside of the action so make sure that there are no rough edges on the top of the well. You can test the rifle with the well out if you like. To me this is the most likely problem with a dud scope right behind. Action screws that are too long or crud in their holes are possible as well.
Best of luck, Grandpamac.

Loverly morning here so took some me time to catch on the 260 progress. Had already gone through the above checks, thanks GPM, and found nothing untoward so as it’s a perfect range day here, and before I toss the scope, ran 2 x 3 shot groups with some Hornady factory 129SST’s which I found in Invers last year.
They are a reasonably spicy load but like the Corelokts, about 6” high. To test the scope, I dropped 20 clicks and shot the next three. Tracked spot on and while the group is nothing to write home about, it’s consistent so will now crack on with load development.

Make sure you haven't or aren't about to run out of windage clicks on your scope,had a bit of drama with my 260 a wee while back with a replacement scope and new rings,was doubting scope but worked out I had run out of windage via the Leupols site and was scattering rounds like yours l.Then found out the rings were not true by placing some straight pipe in them and comparing to barrel,well out!.Changed rings to true ones,recentered windagef,sighted in and all good,the faulty rings were Leupolds too.

Sing out if you need any brass i have enough now and can spare some.

It’s been awhile since last update but have not long got this rifle back from the gunsmith. A number of niggly issues had to be resolved before I got on with load development.
Inspecting the brass after the last range outing, I had noticed that the shoulder was showing quite pronounced marking. Quick look down the chamber showed some pretty average machining with the shoulder heavily grooved. Not exactly Trueflite’s best work I would imagine but I guess the odd one slips through occasionally and it was a few years ago now.



Decided to have that tidied up, the feed issue sorted, barrel threaded for a suppressor, trigger adjusted, and a confirmation that the bedding was all good to go. This rifle was also destined to receive some decent optics, for my benefit as well, so lashed out on a Burris HD Signature E3 3-15x44. Even though it’s hardly high end, was damn near a $1000 more than I’d ever spent on scope!!! I think my butt’s finally stopped squeaking now
So, all systems go. Slotted it into a set of Talley lows I had, looks good, sits nicely on the rifle so happy as. Got it close to where I wanted it and nipped it up. Mounted the rifle a couple of three times to check fit and bugger!! too low, went to cycle the bolt and no, contacts the scope mid handle. That I could sort with a bit of minor grinding but the eye line is just too low. She’ll need a set of mediums and I’m back to parking it in the safe. I really should divorce the bitch but I still love her so I’ll continue to stroke her gently in the continued hope she’ll start cooperating and let me get the best out of her. Some long range shooting is calling and the weather is on the improve.

Don't discount 120-gr projos , some .260's and 6.5's love them and within their useage-range/conditions etc they absolutely flatten deer often expanding better than 140's . An early True-Flight job on one of my 6.5-rifles (many years back before it changed-hands ) was an utter crappy disaster , hopefully yours works-out ok

Thank you, my thoughts were tracking that way. I’m going to start with 129gn SST’s as I have plenty but was building up a stock of 120-123gn’s for the Grendal so will be good to be able to share across both platforms if it works out that way.

The gun gods finally shone their light on the Catlins and timing was perfect. Not a breath of wind and a stunning winter day. I’ve had my first reloads ready for months so set up in the paddock over the road and went at it. Ignore anything in the white, just the two in each target area.



Lapua brass, BR2 primers, 2209 powder, and 129gn SST’s. Couldn’t get them seated anywhere near the lands so set the length to the mag as close as I felt comfortable and still able to feed nicely. Conservatively started at 40.5gns up to 42.5. A promising start, then she wandered off a bit before gathering her skirt and closing up again. Not too shabby if I say so myself!! A massive confidence boost as well.



No pressure signs at all so guess I’ll keep upping the powder charge now till one of two things happen. Next ladder will be 43gns up to 44.5 but would appreciate any feedback before I load those up. Cheers all.

Greetings,
Glad to see that things are improving. You might want to chronograph that load before adding more powder. 42.7 is max in the Hodgdon data but with the 130 grain AB which is likely harder. You won't see any pressure signs until you have gone too far. Max velocity for a 24 inch barrel will be around 2,800 to 2,850 fps less 25 fps per inch less barrel length. More testing at 42.5 and perhaps 43 grains if your velocity is low would be worth considering. I think that chronographing is urgent as the Hodgdons data may be for an older and slower version of AR2209,
Regards Grandpamac.

Greetings,
Dug up some recent chronographed results with the 129 grain Interlock which is similar to the SST in hardness. They stopped at 42 grains of AR2209 giving 2,750 fps in an 20 inch barrel so 2,800 fps should be about right for your 22 inch, It shot really well.
GPM.

Thank you GPM, that’s the feedback I’m looking for. The ADI manual confirms your Hodgson data at 42.7gns max. It’s been awhile since loading so questioning where I got the 44.5 max figure from?? Maybe why I stopped at 42.5. It doesn’t feel as stout as the Hornady factory ammo but if those velocity figures standup then I’ll be more than happy sitting where it’s at. I want to push this rifle out as far as it can so definitely need to chrony it at first opportunity. As you suggested, the 129sst’s were a great place to start so very happy given that it really did not like both types of factory ammo I’ve run through it.
Next step at this stage is to run a five shot group to see if I got consistency at 42.5 and then leave it at that for the time being till I can test velocity.
I have some 123 and 140gn ELD-M’s which I would like to work up loads for and interested to see if the heavier 140’s will actually perform in the rifle. Thanks again.

Those 120gr Sierra's you got off me should shoot bloody well too, they did for me in 260 & 6.5CM. Best of luck...

Originally Posted by Sidetrack

Thank you GPM, that’s the feedback I’m looking for. The ADI manual confirms your Hodgson data at 42.7gns max. It’s been awhile since loading so questioning where I got the 44.5 max figure from?? Maybe why I stopped at 42.5. It doesn’t feel as stout as the Hornady factory ammo but if those velocity figures standup then I’ll be more than happy sitting where it’s at. I want to push this rifle out as far as it can so definitely need to chrony it at first opportunity. As you suggested, the 129sst’s were a great place to start so very happy given that it really did not like both types of factory ammo I’ve run through it.
Next step at this stage is to run a five shot group to see if I got consistency at 42.5 and then leave it at that for the time being till I can test velocity.
I have some 123 and 140gn ELD-M’s which I would like to work up loads for and interested to see if the heavier 140’s will actually perform in the rifle. Thanks again.

Greetings,
I had an interesting experience with 6.5mm projectiles. I was working up some loads for the 129 Nosler long Range Accubond in the 6.5-06 for a friend. The rifle had always produced less than book velocity for modern data and closer to the velocity for older data. I started with the 129 grain Interlock projectiles to get the rifle on target and an idea on velocity. Next I switched to the LRAB projectiles which produced an additional 100 fps of velocity and consequentially more pressure. The Hodgdon/ ADI data which is all produced by Hodgdon is for the 130 grain Nosler Accubond which will likely develop velocity and pressure closer to the 129 grain LRAB. There is another fly in the ointment. Around 2002 ADI increased the speed of AR2209 and the the data previously mentioned predates that. So on one hand you are using a softer projectile which will produce less pressure and velocity. On the other hand you are using a powder that is faster than that for which the data is developed. From my tests with my 6.5x55 and the 6.5-06 these two things may balance each other, only the chronograph will tell you. In my 6.5x55 switching from a tin of AR2209 packed in 2000 to a pottle purchased in 2019 raised velocity by almost 100 fps. A short learning curve for me.
Regards Grandpamac.
PS Nick Harvey listed 44.5 grains of AR2209 for the 125 grain in his 6th Edition and Hodgdon/ ADI listed 44.3 grains for the 125 grain Nosler partition.

Load 10 of the best and the worst and test those. See what you get.