need some help with 260 rem

[big_matt_duq]

I am going crazy trying to work up a load for this new to me rifle. Gun has roughly 250-300 rds down the pipe. Previous owner gave me 2 targets that are one hole groups at 100 yds. Rifle is rem short action, krieger barrel 26 in, mcm a5 that's bedded. My components are h4350, 140 amax, fed 210 primers, rem cases. I shot a ladder from 40 to 45.5 at 300 yds. I saw a slight ejector mark at 45.5. I then made up 4 rounds of each 43.5, 44, and 44.5

Ladder results
chrono 15 ft temp 60
40 2614
40.5 2656
41 2666
41.5 2726
42 2732
42.5 2772
43 2824
43.5 2855
44 2879
44.5 2898
45 2936
45.5 2949 slight shiny ejector mark

day 2

temp 71 deg
43.5 gr
1. 2807
2. 2824 grouped 1.4 inch ctc @300 yds
3. 2830
4. 2807

44 gr
1. 2873
2. 2867
3. 2824 group ~3 inches
4. 2849
5. 2842

44.5 gr
1. 2879
2. 2858
3. 2867 group > 4 inches
4. 2873

today temp 84 deg

43.5 gr
1. 2824
2. 2824
3. 2836 group 1 group size grew to ~3-4 inches
4. 2818
5. 2807

6. 2824
7. 2824 group 3
8. 2830
Didnt fire last 2 because 3 of previous 8 had ejector marks.

43.6 gr
1. 2818
2. 2807
3. 2824 a few had light ejector marks, group ~3-4 inches
4. 2830

I cant figure out why a supposedly temp stable powder would show pressure signs when it's only 10 degrees hotter temp.
the other odd thing was that i was getting some powder residue on the shoulders of a few of the cases. I'm not positive but I think the first 2 days i was finishing up the brass the previous owner sized. Since I have an older rcbs press, I reset the depth of the dies when I got them home to bump the shell holder. Could oversizing cause the pressure signs? Im thinking that the sooty shoulder means I did oversize. would that be why my accuracy went to shit and the pressure signs developed? shouldn't the chrono show a bigger jump if pressure signs appear from the temp swing? On another note, are the cases with a faint ejector mark of to throw back in with the other brass or should I pitch them? I just would like to get back to the under 0.5 moa groups I know this rifle is capable of.

Thanks in advance for any help or insights.
Matt

 

[Proarc]

I think your to hot on the charge.
I have had numerous 260s and 43gr H4350 is a stout charge. I would not go over 43.5 in any of my guns
Your killing primer pockets and brass life. If you want/need to go faster than 2775-2800 you need to go 6mm

 

[oldfatguy]

You might want to do an OCW work up. Might verify what your ladder test is telling you.

OFG

 

[ShtrRdy]

Did the original owner give you the load that worked well for him?

I've only had a 260 Rem for about 6 months. The load my rifle likes uses 41.7 gr of H4350 behind a 140 gr Berger.

 

[robp5t]

How close to the lands are you running the 140 Amax's?

 

[Garvey]

I think you have sized your brass too far. Get a headspace guage, measure the shoulders of your fired cases and set the die to bump the shoulders .002-.003". It takes energy to flow brass forward in your chamber. I learned the hard way with a .308, and a .260 I also think you are loaded way too hot. My .260 shoots 140 A-maxes at 43.2 gr of H-4350 and makes 2800 fps with a 24" barrel. That's fast enough for me.

 

[big_matt_duq]

Im jumping them pretty far. The are set to mag length. i would have to go downstairs and pull out the data but its definitely not close to the lands.

so could the oversizing cause extra pressure then?

 

[big_matt_duq]

the original owner gave me a ton of loads but he was too much of a tinkerer. he had like 8 different loads and most used odd powders. most of what he gave me were all different charges like you would for load workup. he just didn't get out and test them. the best scenar loads used n160 i think but i don't have any of it. most of his loads were really light though. i still want to shoot deer with this gun so i wouldn't mind the extra energy.

my goal was to find 2800 - 2850 but accuracy is most important. i figured with a 26 inch barrel it would be easy. i was averaging 2815-2823 with 43.5grains

 

[leadbullet]

loose the rem brass and get some 243 win brass, neck it up a nd use 43gr of H4350 with your 140 and let us know how it went.
cheers.

 

[seanhagerty]

Powder Valley has 260 rem lapua brass right now. Get some of that and work up an OCW load. Do not chase speed, chase accuaracy.

It will be worth the effort.

 

[308Gunner]

I load 43.5 max and get .3 moa it is running 2804 out of a 22 shilen I have tried going hotter but as stated above it proved to be hard on brass.

 

[bjay]

I load 42.7 on 139 scenar.42.8 140 smk.i did try load them a litle hotter but i stoped at 43.8 presure sign.with lapua brass 44.00 i think is your max with 140 grainer

 

[260rem]

I am maxed out with 43.3 gr of H4350 using a 139 moly scenar. Very accutrate but no more than a .010 to .020 jump. Any more and accuracy goes out the window.

 

[Swift]

Definitely get in touch with the previous owner and ask if they did any load development. I was given a recipe to the T when I bought mine used and it shot lights out if I did my part. I agree that your charges are too heavy, esp with a 26. I run 42gr 4350 under 140s with cci br2s and I'm launching at 2890fps with plenty of pressure left over to ramp it up if need be. Also take a headspace measurement to check if you're over or undersizing your brass.

 

[big_matt_duq]

I must have a really slow barrel then. 42 grains did 2732 in the ladder test. the previous owner gave me the 2 loads that he finalized with the scenars. I am trying to work up amaxs now. if you guys say im over on the powder charge I believe it and backing off is in order. some winchester or lapua brass is probably a good idea too but i hate to throw away 160 pieces of brass if I could avoid it. accuracy is my first priority but would like to keep it as fast as I can since it will be more than a paper puncher.

so tell me if this is a good idea...
buy bump gauge and set dies correctly to bump 0.003ish and resize fired brass
then load 43.5 gr again as highest charge and maybe 43.2, 43, 42.5 and shoot groups and check for pressure.
the 43.5 may still be too hot but it shot so good the first time i think its worth the gamble.

on a side note, I cleaned the gun just like I do after every range session and it was really dirty. I ran a bunch of kg1 through it and then ended up using sweets and let it sit wet like 5 min and couldn't believe how dirty the patches were again. needless to say I think its pretty clean now.

 

[psmith]

The key to accuracy is consistency. Start with generally accepted practice. There is nothing wrong with rem brass. Order lapua if you desire but loads in lapua will be .3-.4 less due to reduced case capacity. Size your cases with a .002 bump and load from there. I am running 43 gr of 4350 with a 142 smk and getting 2830-50 so you are certainly within the ballpark. Make sure you dont have any lube in the cases or oil in the chamber when you are looking for pressure. Both will cause false readings. Don't be afraid to try different seating depths. I have had good luck being close to the lands (.010-.020) with many rifles.

 

[6brshooter]

My tikka sporter is slow also, 23.75" barrel. Nosler brass cci br2, 142 smk, and 44.5 gr h4350 yield2785 fps. On the 5-6 reload on brass. Temperature was 50* when doing load work ups. Shoots in the .3-.4 range and 1/2 moa to 600. Maybe not the best way to set fl die to rifle but... i typically screw die down until it bumps the shellholder, then back off 1/4 turn. Lock it down and size a piece of brass fired in that chamber. Try chambering it, if it is hard to close the bolt turn the fl die in a smidge and size a different piece of brass. Try it in the chamber , the goal is to just sneak up on the bolt closing with just a slight hint of resistance. This technique is more a feel . This technique has worked for me for a decade or so. And yes if u resize too much the shorter then chamber brass can slam bacjk on the boltface giving u ejector swipes. Just like an ar10 will show similar overpressure signs when the timing is off and/or overgassed.

 

[2clicks]

142 SMK's run 2850 in my 260 26 inch Barrel using 43.3 H4350. Found my RCBS chargemaster wasn't exactly dead nuts on the powder throwing. Observing the chargemaster I noticed extra powder falling out of the tube so I dump out each charge and reweigh all loads it's a bitch but my deviation is super low now. Remington 260 and Winchester resized 7mm-08 brass. FWIW I use the Redding bushing die.

 

[HarryBallz2029]

Theres nothing wrong with remy brass, I use it with 43.5 gr H4350 wolf/tula primers propelling a 142 SMK and shoot the best groups I have personally ever shot.

 

[big_matt_duq]

Thanks for all the help so far everyone. Just ordered some headspace gauges, bullet comparators, oal gauges, and some cleaning stuff to try and remove all the variables out of my reloading. Its amazing that I thought I knew how to reload pretty well and now after doing some research, I feel like a dumbass. Its amazing how much you can learn even when you think you know enough. I'm glad there are places like this to get real advice from people way more experienced. I may not post much, but i learn a lot just reading the site.

thanks again and ill report back when I get everything set up and get to shoot again.

 

[lte82]

Thanks for all the help so far everyone. Just ordered some headspace gauges, bullet comparators, oal gauges, and some cleaning stuff to try and remove all the variables out of my reloading. Its amazing that I thought I knew how to reload pretty well and now after doing some research, I feel like a dumbass. Its amazing how much you can learn even when you think you know enough. I'm glad there are places like this to get real advice from people way more experienced. I may not post much, but i learn a lot just reading the site.

thanks again and ill report back when I get everything set up and get to shoot again.

Reloading is 90% trial and error, 20% voodoo... yes, I did the math on that.

I personally think oversized brass will cause a wide range of issues that affects accuracy. To be honest, my best loads have been when I set the shoulder back as little as possible and still get the bolt to close without forcing it, IE, zero excess headspace.

Case in point today, I shot 6 groups of three with my 338 today, 3 of the groups with brass that was sized to zero excess headspace, and 3 of the groups with brass sized with somewhat more than zero excess headspace. The zero group shot .25 moa to .75 moa, and the excess group shot .75 to 1.5 moa. Neither shot "terrible" but the zero excess group shot REALLY well.

I also was oversizing some 308 brass that was getting flat/smashed primers even at below recommended minimum powder charges, and shooting between 1.5 and 4 moa depending on the load. I stopped bumping the shoulder (well, it may have bumped .001 at most), and I magically stopped getting flat primers, and my groups tightened WAY up... 0.75 moa is pretty easy even from my ar-10 gas gun.

Try this... take 12 of the fired brass and resize them (set the FL die to where it just touches the shell holder at the top, and don't turn it down anymore). Lube and press the shell until you hit the shoulder, which is probably at the bottom of the stroke, leaving a thin gap between the shell holder and the die. You'll know when you hit the shoulder because you can't press anymore with significant effort. Check to make sure the bolt will close on the resized brass. It *should* close with just a bit of resistance, but if not, give the die a 1/32 twist and resize again. Once you can get the bolt to close with just a small bit of added resistance, you are good.

Load up 3x of 40, 41, 42, and 43 gr, seat bullet to 2.80", and do not crimp. Run the ladder again. My guess is your problem goes away.

I've run into many people who say that headspace shouldn't cause major accuracy issues, but to me, more than 1 moa with a target rifle is a major accuracy issue.

 

[msiebert]

"needless to say I think its pretty clean now."

Without a borescope it is hard to tell. Getting out the powder fouling is great, but getting out the copper is even better if you want the best groups. Just because a barrel is broke in don't mean it wont still smear copper down the bore. Without a borescope try this...get as much sloppy wet Shooters Choice in the bore as you can. Usually a fairly loose fitting or worn out bronze brush works best. Just dip it in the SC a few times and while its dripping wet run it down the bore. leave it set level over night and wipe it out with a nice white patch the next day. If the patch comes out blue you got copper. If it comes out a little tan from the SC but no blue/green you are probably nice and clean. Here's the thing...you can clean with Sweets until you see no more blue and hit it with the SC overnight and still see blue. Strange but true and unless you have it all out the bore just picks up that much more copper with each shot. More people have changed scopes and barrels and triggers and ammo because of copper in the bore than anything. As to brass... Personally, I have had pretty good luck shooting Remington brass and have tried it all, but in most cases didn't really see a big upgrade {other than price} with some of the off the wall brands. The alloy might be better and they will stay softer longer.

 

[deadnbrkn84]

I'm getting 2812 with a 22" Rock Creek and 43.5gr H4350 and 142smk. There seems to be a node with these in the 43-43.7 range.

 

[deadnbrkn84]

"needless to say I think its pretty clean now."

"Getting out the powder fouling is great, but getting out the copper is even better if you want the best groups. Just because a barrel is broke in don't mean it wont still smear copper down the bore.

I couldn't disagree more. Leave the copper in your barrel, clean the carbon out but the copper can stay. You'll see the groups open up sometimes after cleaning the copper out then shrink back down after you build up some copper in the lands.

Todd Hodnett said the same thing in the precision rifle magpul video.

 

[big_matt_duq]

Ok I got my gauges and with the .400 bushing in the headspace gauge I get 1.624 for the cases with slight ejector marks and 1.622 for the other cases. I had a few pieces the previous owner sized and they were 1.619-1.621. Does this seem too short or am I in the ballpark? I sized 15 cases to try. I'm also going to make sure there is no lube in the chamber really well this time. I set my die to bump to 1.620. I measured what I was previously sizing to and it was like 1.615 ish.

 

[big_matt_duq]

Can anyone verify my measurements seem to be in the right neighborhood?