Not all is lost. You have two data point temps and their respective velocities. They show an average of 2fps per degree of change. An easy calculation that can even be entered in many ballistic calculators.
You can even verify this by shooting at another data point temp and seeing how close that gets you.
So I bought a Tikka 260 CTR with the ideal of building a 280 AI. However I threw some loads together (139 Scenars/ 42 grns H4250) and after a quick zero, shot a .4 group. I decided I would postpone the 280 build and use it for deer hunting this season. I have been trying to work up a load with some 142 grn ABLR's. I've been to the range a couple times and the last 3 rounds I fired were 43.2 grns of H4350 averaged around 2550 fps ...slower than expected. I plan to bump the charge up to 43.6 - 44. I'm hoping for 2750 - 2800 fps.....am I asking too much for the CTR's 20in barrel and does anyone know of another powder that might get me speed.
Why don’t you just use the 139 Scenars for hunting? I’m pretty sure that @coldboremiracle was using them successfully on many hunts.
You should be able to easily get 2750-2800 with those and they are very consistent shot to shot.
You should be able to easily get 2750-2800 with those and they are very consistent shot to shot.
I could use the 139's but I have about 190 of the 142 g ABLR's. Anyone killed a deer with a 139 Scenars ?
I was wrong above and meant to reference @psinclair as the person who used 139s for a long time with numerous kills every year. He spoke highly of them.
If you want to check out this 10+ year long thread on 24hour campfire, you’ll see the consistency I’m referencing.
Also search here on SH as there are a number of threads discussing similar.
This one very briefly:
Hunting & Fishing - 6.5 139 grain Lapua Scenar for hunting?
Anyone use this bullet with success (or failure)? Was thinking about using it for an upcoming Coues deer hunt in AZ - since these shoot so well in my DT SRSA1.
www.snipershide.com
Thanks....really enjoyed the 24 hr thread,I was wrong above and meant to reference @psinclair as the person who used 139s for a long time with numerous kills every year. He spoke highly of them.
If you want to check out this 10+ year long thread on 24hour campfire, you’ll see the consistency I’m referencing.
Also search here on SH as there are a number of threads discussing similar.
This one very briefly:
Hunting & Fishing - 6.5 139 grain Lapua Scenar for hunting?
Anyone use this bullet with success (or failure)? Was thinking about using it for an upcoming Coues deer hunt in AZ - since these shoot so well in my DT SRSA1.
Ive used Scenars for hunting, but not the 139. I'd have zero issues trying them though based on my experience with other Scenars as well as other hunters experiences.
I've used a variety of other 140 glass match bullets, like the Barnes Match Burner, Hornady BTHP, and Sierra Match Kings.
I’ve had similar results, but did incorrectly reference you when I meant @psinclair . I’m actually most fond of the 136g Scenar Ls, though they are not inexpensive at all.
Got 2575 today with 43.5 gr, H4350 / 142 ABLR no signs of pressure, Just loaded 2 @ 43.7 & 2@ 43.8 gonna try them tomorrow.
The max SAAMI pressure for the 260R is 60,000psi.
I ran your loads in QuickLoad and every one of them is significantly over pressure for a 20" barrel, but I don't know your seating depth. I initially ran the loads at a seating depth of 0.680 and each was over pressure. I understand QL is conservative, but you should be getting faster speeds with your loads if you're using that seating depth and charge:
43.2grs of H4350 with the 142 ABLR is calculating overpressure @ 68,495psi, but speed should be in the 2723fps range. You're only getting 2550ish so something else is slowing you down or your seating depth is higher.
43.5grs is calculating 70,070psi @ 2741fps.
43.7grs is showing 71,451psi @ 2751fps.
43.8grs is showing 71,683psi @ 2760fps.
I re-ran the calculations using a seating depth of 0.50 and the pressures were significantly lower, but you're still not getting the speeds you should:
43.2grs was 60,483psi @ 2648fps.
43.5grs was 62,152psi @ 2665fps.
43.7grs was 63,044psi @2671fps.
43.8grs was 63,494psi @2683fps.
If your seating depth is reduced from 0.50 to 0.40, then each of your loads is under pressure but even your 43.8gr load is calculating 2683fps.
Good info....Before loading I checked the OAL with a Hornady OAL gauge the 142 it was 2.99 touching the lands. I loaded the ammo to 2.82
2 things:
Did you account for the particular brass he's using to get an idea what the average case volume might be, or . . . did he already provide the case volume?
Being a new gun, new barrels tend to be slow, where it take 150+ rounds down the tube before the velocity settles in at 100 fps or more higher.
Prime Brass (New) ....Starting to wonder about my Garmin. For reference I loaded some 142 ABLRs for my 6.5 CM w/41.5, 41.6, 41.7, 41.8, & 41.9 H4350...they shot 2680 - 2730 FPS...the last couple were on the hot side.
When one is using QuickLoad, to get a more accurate rendition of a load, it's best to input the case volume of the particular brass being used after they've been fired. It can make a significant difference in the QuickLoad calculation as the default case volume it uses is not always close the what's being used.
This is why I asked.
My point was to gently suggest you may be loading too hot. Nosler load data caps out below what you tested for the 142s, and they tested in a 24" barrel, which adds about 20fps in speed per inch over your 20" barrel as the powder has more time to be fully consumed.
There are several variables affecting QuickLoad outputs, and the QL data tends to be conservative, but I'd suggest you're chasing speeds you may not attain in a 20" barrel (even after it speeds up) and to offer that your loads could be overpressure.
Recheck your Garmin settings as there are probably tens of thousands in the field and I've not seen any reports of faulty speed captures. You could move the unit from one side of the rifle to the other, or over the barrel to try to confirm consistency.
Question for you. I am trying to help a friend load for his .260. I started working with 140gr bullets. I have now found out that this rifle( GAP build from about 16 years ago) is running a 1:8.25" twist rate. This seems quite slow to me. Do I need to be working with lighter bullets? The reason I ask is I have had pretty poor results so far with 140gr bullets (Hornady and Berger).
Berger 130 AR. Shoot great out of my LMT 260. Tried heavier and was not great, good. With the 130 gr shoots lights out.
One to 8.5 is fine for 140 grain
BR shooters, use slower twists for maximum accuracy at short range - you can overspin a bullet and destableize it.
Inadequate twist can adversely affect the ballistic coefficient and the Tranzonic transition but with a 260 that usually won’t matter unless most of his work is out past 800 yards
BR shooters, use slower twists for maximum accuracy at short range - you can overspin a bullet and destableize it.
Inadequate twist can adversely affect the ballistic coefficient and the Tranzonic transition but with a 260 that usually won’t matter unless most of his work is out past 800 yards
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Even a GAP that is 16 years old may be in need of a new barrel. What's the round count?
It's actually a low round count rifle. I don't have the exact number but between 500-600 rounds. He got frustrated trying to load for it so I offered. Now I am feeling the same frustration! I load for many other calibers, this one just has me stumped. I have read quite a bit of this thread and what I was working with has been mentioned many times with success.
Well, that’s different than a typical good .260 barrel. I’ve no doubt that there’s something not right with the chamber or barrel. Even good brands can mess up now and then. Try 130s as mentioned, even 123s if you want to continue down the rabbit hole.
Then suck it up and put on a new barrel. Life’s too short.
good luck.So ironically there is a 130 Berger load that the rifle really likes. He was just hoping I could come up with something 140gr that would work well. So, I suppose it's best to just stay with the 130! You are right! Life is too short and all of us could more time shooting vs development or testing! Thanks for your advice!Well, that’s different than a typical good .260 barrel. I’ve no doubt that there’s something not right with the chamber or barrel. Even good brands can mess up now and then. Try 130s as mentioned, even 123s if you want to continue down the rabbit hole.
Then suck it up and put on a new barrel. Life’s too short.
41-44 grs. Of N160 or 560 with Hornady 140 sst’s grouped 1”@100yards for me with a 26” 1:8 twist barrel since 2003.
Interestingly, though mine shoots both 140s and 142s fine, I’ve been a fan of and using 136 Scenar Ls for now on three barrels. I’m very much of the opinion that .260 generally likes the 123-140 range, but is easiest to load for the 130 range.
Waiting on my .260 to get here, but I agree and will extend that to my couple of 6.5x47s.
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For an 8.5 twist barrel at 260 rem speeds the Stability factor is 1.36 for a 140 RDF. Stability is considered effective either a stability factor 1.5 or greater. How unstable a bullet becomes if below 1.5 is dependent on a lot of factors. However in general it is not good. So an 8.5 twist barrel is probably not going to perform well with 140 class high BC bullets. Which in term I would limit the rifle to 130 class bullets.
Conversely 8 twist barrels are good up to 147 gr ELD M’s . With 150 SMK’s and 153 Berger’s 8 twist barrels have stability factors of 1.4 . This is why 7.5 twist barrels are recommended for these bullets.
It is the race for extreme perfection in all calibers that keep pushing longer heavier projectiles. It is why you can’t stabilize a .277 Berger 170 gr EOL bullet in a standard twist 1-10 270 Winchester. Never had these 30 years ago. Today you get a 1-8 twist barrel for your 270win and you are good to go.
Just realize that twist rate does in large part determine what class bullets you will be able to effectively maintain performance with.
Conversely 8 twist barrels are good up to 147 gr ELD M’s . With 150 SMK’s and 153 Berger’s 8 twist barrels have stability factors of 1.4 . This is why 7.5 twist barrels are recommended for these bullets.
It is the race for extreme perfection in all calibers that keep pushing longer heavier projectiles. It is why you can’t stabilize a .277 Berger 170 gr EOL bullet in a standard twist 1-10 270 Winchester. Never had these 30 years ago. Today you get a 1-8 twist barrel for your 270win and you are good to go.
Just realize that twist rate does in large part determine what class bullets you will be able to effectively maintain performance with.
calculate your twist rate stability using your own DA. If you're up in the mountains, no sense in using sea level, and it matters if it's a summer gun or a winter gun
Put in realistic numbers for YOUR environment. A 140 ELD-M is stable at 2650 fps down to 0 degrees Farenheit as long as you're above 4000 feet, which many of us out west are. If you're in Florida, not so much, but you also won't be getting to 0 degrees, so....
Plug in your own local atmospherics
Put in realistic numbers for YOUR environment. A 140 ELD-M is stable at 2650 fps down to 0 degrees Farenheit as long as you're above 4000 feet, which many of us out west are. If you're in Florida, not so much, but you also won't be getting to 0 degrees, so....
Plug in your own local atmospherics
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I wish I could be of more help but it is NOT the twist rate. Remington helped kill the cartridge commercially by offering rifles with 1:9 in the 90s. I'd try the Berger 130 hybrid as a last effort. If they won't shoot I'd replace that barrel. Have you looked at it with a borescope?
I did look with a scope. The barrel was OK. Before I started load development, I fully cleaned it. There was a mild carbon ring but I took care of that and verified. Definitely running 130's as my next test.
I'd run a patch or two of JB paste or Simichrome (or Iosso or Flitz) through it just to remove all fouling and make sure that's not the issue.
That's the first thing a manufacturer or gunsmith will do if you send a barrel to them saying "It won't shoot!"
That's the first thing a manufacturer or gunsmith will do if you send a barrel to them saying "It won't shoot!"
I'm really liking 260R after only a few rounds. Seems very easy to find a decent load, a lot of my pressure/velocity test loads were touching or very close. Running a 142gr SMK with N550 at mag length of 2.900", 40.5gr or thereabouts looks promising.
Been playing around with my new TRG A1 in .260 lately. Rifle now has 157 rounds through it.
Went through a box of 130gr ELD-M, trying to see if it would shoot with VV N160. It did, but was pretty picky until I hit the 44.7 - 45.0gr window. Well...it shot amazing down around 42.5gr...but the velocities were just way too slow. Grendel shooters would have been excited though.
44.8 is where I stayed at, and I tested it again at 300 and 650 where I trued the velocity to basically 2,800 FPS on the nose. SD was under 10, but not by much. It shot a half-minute at 300, and 2/3 MOA at 650...which is perfectly fine for me. The low shot at 650 was me, but it wasn't out of the group enough to discredit it.
Having ran out of 130gr ELD-M, I tried the 130gr Norma Golden Target this afternoon. I kept the charge weight of N160 the same at 44.8gr, and just messed with seating depth a little. There is a ton of room in the throat of that TRG. 2.925 was my max mag length, and I still wasn't at the lands. (2.925 OAL = 2.310 CBTO).
It's looking promising, so I'll split the difference and try again soon to verify. I didn't chronograph it today either.
Specs:
26" TRG A1
130gr ELD-M/Norma
Virgin Peterson LRP brass
Fed 210
44.8gr VV N160
2.210 (ELD-M)/2.290-2.300 (Norma)
2,800 FPS
19 ES*
9 SD* (when I chronographed the ELD-M)
Went through a box of 130gr ELD-M, trying to see if it would shoot with VV N160. It did, but was pretty picky until I hit the 44.7 - 45.0gr window. Well...it shot amazing down around 42.5gr...but the velocities were just way too slow. Grendel shooters would have been excited though.
44.8 is where I stayed at, and I tested it again at 300 and 650 where I trued the velocity to basically 2,800 FPS on the nose. SD was under 10, but not by much. It shot a half-minute at 300, and 2/3 MOA at 650...which is perfectly fine for me. The low shot at 650 was me, but it wasn't out of the group enough to discredit it.
Having ran out of 130gr ELD-M, I tried the 130gr Norma Golden Target this afternoon. I kept the charge weight of N160 the same at 44.8gr, and just messed with seating depth a little. There is a ton of room in the throat of that TRG. 2.925 was my max mag length, and I still wasn't at the lands. (2.925 OAL = 2.310 CBTO).
It's looking promising, so I'll split the difference and try again soon to verify. I didn't chronograph it today either.
Specs:
26" TRG A1
130gr ELD-M/Norma
Virgin Peterson LRP brass
Fed 210
44.8gr VV N160
2.210 (ELD-M)/2.290-2.300 (Norma)
2,800 FPS
19 ES*
9 SD* (when I chronographed the ELD-M)
Very nice! I will definitely find time this year to resurrect my .260. I miss it.
I went 17 years between this and my last one. I feel like I'm stepping back in time, playing with the cartridge again.
Seems quit slow for that length barrel.
My 19" 260 is doing 2800fps with 130 ELD-Ms with H4350.
My 24" 6.5CM had them 2800-2950fps without any trouble with H4350.
I’m more of a slow and steady guy, but also use H4350 and get a casual 2750 with 136 ScenarL right near 41.8g in a 26” barrel. The N160, I understand to be a bit slower and could help barrel life.
For me, 2750 was so consistent and predictable that I stayed with it for many barrels.
It is slow. I've yet to hear of anyone breaking any speed records with a Sako/Tikka barrel though...usually the opposite.
I've gone as high as 45.3 without any signs of pressure forming...but accuracy was starting to fall apart again, and I doubt that I'd get back into it before I did run into pressure. N160 just isn't a speed demon powder anyway. If I were chasing velocity in the .260 I'd be using a cut-rifled barrel and the rest of my RL-16 up.
My 6.5x47L is basically the same speed (2,785) with the exact same bullet, same barrel length (but Bartlein), and only 38.8gr RL-16.
N160 is one of the cooler-burning powders around, and will absolutely wear less on your barrel than the comparable N555. Here's a chart that I still have on hand. That being said, H4350 is pretty good too regarding temps.
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