Reply With QuoteI want to use the magazine. The throat is so long that loaded to the lands, the bullet is considerably longer than 2.900".Originally Posted by Dave Hoback
Why such a large jump? Why not load longer? Gain case room, lower chambers to boot. After all, it was designed to run long.
I want to use the magazine. The throat is so long that loaded to the lands, the bullet is considerably longer than 2.900".
Wall, sure… but don’t you currently have them considerably shorter than 2.900”? I load 260 & use Magpul AICS mags. I can load aprox 2.850” in those. At some point in the future I’ll be using the Metal mags which allow 2.960”. Which mag are you using, and what is max length it will accept?
It's an AICS 308 mag with a 2.850" opening. If I remove the binder plate its right at 2.920, but that's longer than the distance to the feed ramp so I'd have to notch it to use bullets that long. I've been looking for a bullet jump that the gun likes that will fit in my mag with the 140 ELD match bullets. My experience so far seems to mirror this article.
https://precisionrifleblog.com/2020/...elopment-tips/
Sounds like you have a plastic mag for your 6.5mm CM.
I initially had a plastic AICS mag that would only support a max OAL that was in the range of your mag.
I bought a metal mag that allowed a 2.895 OAL.
That got my reloads into a jump range that improved the accuracy.
Now that my 6.5mm CM has 4,000 rounds down the tube and the chamber has eroded enough that I have to load out past what the mag will allow for my heavier match bullets, I have to single load them. As long as I can keep in the same jump range, the accuracy hasn't suffered, even though most would claim the barrel should be shot out.
> 2.900 for a Savage short action magazine. that makes the Dark Eagle look good. It has been said that your loads are at the bottom end and you might try something near 41.5 H4350. Adjust your seating depth.
The Dunning-Kruger effect is alive and well.
I'm still working toward higher loads, but the groups have improved with more powder and shorter cartridges. Even at 2.163 CBTO, the COAL is just short of the SAAMI spec for 6.5 CM and the 140 ELD Match bullets.
My best results are with a jump between 10 to 19 thousandths.
There were some much longer jumps that produced accuracy almost as good, but the best results were in the 10 to 19 thousandths range.
Unless you're measuring every group for every load, and are shooting multiple groups with each load, you'll have a hard time finding a difference.
I am.
Have you thought about being consistent with 2.800 and finding the load. Then work the CBTO to fine tune?
The Dunning-Kruger effect is alive and well.
No reason except I wanted to see if different loads performed differently at different lengths.
Yep, they do :)
I usually get a decent powder charge first. Then explore seat depth. Then might tweak the powder again, see if 0.1 or 0.2 gn makes a difference. Usually it does not unless the seat depth changed a lot.
I think I went about it the way I did because my main issue was COAL vs CB to the lands. I probably could have saved time and powder doing it your way. I learned a lot and got some practice in so it wasn't wasted.
And, as long as you kept the records, you still have good info.
I'd probably start over with the Criterion barrel. Did you buy it new or was it on the gun when you bought it? FWIW it looks like a thin profile so no more than 3 rounds before letting it cool. If the first series does not show improvement I'd make sure all the copper is out of it. Maybe even clean between strings.
I bought it new and it’s got a heavy threaded barrel. I’ve got 150 rounds through it now and shoot very deliberately, 5 rounds at a time. It’s never really been too hot to touch.
I finished load testing with RL-16 today and shorter CBTO and higher loads definitely produce better groups. These were all around 2610 FPS. The second group had a 4 fps spread from fastest to slowest. The others were more like 15-20 fps difference fastest to slowest. If I could just tighten up that one shot.... Despite that, I'm satisfied with my effort at reloading and shooting and will pick one of these loads, I just can't figure out which one yet. Now to move out toward 800 yards.
This one was not good
I rarely shoot a string like this.
I don't know that there is any reason to pick one length over the others since they all have four shots very close together with one separated by a fraction of an inch. I do wonder why 2.173 and 2.163 are in the red, but 2.168 is just outside when its length is in between the other two. I was aiming dead center of the red circle and the wind was almost directly behind me . I was facing almost dead north so the wind was probably gently blowing toward 350 degrees or so. I didn't touch the scope between those I posted on August 25th and today.
I agree you can pick from one of several there. Same kind of issue I have with 6BR loads. There seem to be quite a few good loads.
Some might suggest the different POI is due to barrel nodes being different by just a little bit. Just like my 90ELD X ladder showed higher vel bullets impacted lower on the target rather than higher. When shooting 103ELD X they were the opposite, higher vel impacted higher.
I went with 2.163 and made 40 rounds to try out the next time I go to the range. Trouble is, I'm just about out of RL-16 now and can't find any on-line. I bought two lbs of Winchester 6.5 StaBall and two lbs of Vihtavuori 555 powder to work with after the RL-16 runs out. Those two are also in short supply and now unavailable from Brownells, Midway USA, Midsouth, Powder Valley, and Natchez.
If you are in Northern MN, i could help you out with some powder. will only do a face to face trade. 2 LBS of each kind isn't a lot to build a consistent load. Midsouth has h4350, and you can buy 10 LBS at a time. Honestly i would go that route over RL16.
Thanks for the offer, but I live a long way from Minnesota!
"It turns out the throat in my gun is very generous, for lack of a better word."
I often wonder why Savage makes the throat so long. My 223 Axis, 243 and 22-250 all have very long throats and the bullets are a long ways off the lands, even with the heavier bullets. They still seem to shoot well though. The Savage chambers are also quite loose, or at least mine are.
I've been told that manufacturers make their guns that way to avoid liability issues with factory ammo. It's certainly more dangerous to have the bullet jammed into the lands than have to jump to reach them. I ran into two guys at my range, both shooting a Begara in 6.5 CM and they were loading and shooting just about the same length I was because the throat on both their guns were long too. They were using VHT N555 which I will give a try eventually.
Ernest T,
I think part of the reason is that calibers like .223 and .22-250 and even 6.5mm CM and .308 can shoot bullets over a fairly wide weight range.
My .223s have shot bullets from 35 grains to 77 grains for example and even my 6.5mm CMs have shot bullets from 123 grains to 147 grains.
Just for grins, measure the bullet lengths of a .35 or 40 grain .223 and a 77 grain .223. The light bullets would fall out of the neck if you tried to seat them for a short jump.
In my rifles, the 77 grain bullets can be seated into the lands but if I tried that with a 52 grain bullet it falls out of the neck.
By the way, my rifles shoot the light bullets very accurately, even if the jump is incredibly long.
But if the chamber was short enough to seat a 52 grain bullet near the lands, the 77 grain bullets would have to be seated back so far into the case that the pressure would be much higher.
The weight range of 6.5mm CM bullets is not as severe, but there is still quite a difference between the length of a 123 ELD-M and a 147 ELD-M.
I suspect that the manufacturers are trying to accommodate all of us, those who shoot light bullets and those who shoot heavy bullets.
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