Custom. Chambered by Jon Beanland. I asked him what he chambered to and he said he didn't take any notes at the time.
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Throat length on 6.5 Creedmoor chamber
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Custom. Chambered by Jon Beanland. I asked him what he chambered to and he said he didn't take any notes at the time.
Well then everything is a guessing game as it could have been any of the chambers. I wouldn't worry about it now as what it was doesn't mean anything. Just what it is now.
Well I'm having a new barrel spun up and I want to basically clone this one because it shot so great. I don't hand load. I'm shooting factory ammo only. So if this one had a non-standard chamber, I'd like to see if there's any way to figure out what it was. But the math, if I'm doing it right, suggests 0.030" jump.
What does that translate to for freebore?
I think that would equate to a 0.169" freebore? And that's exactly what many people are reporting they like. 0.199 - 0.03 = 0.169"
Just checked my notes and took some measurements. A fresh chamber cut with my sammi reamer touches a 140 ELD at 2.173 bto. The factory hornady 140 eld ammo I have here is 2.139 bto, so .034 jump.
I don't believe theres any magic to freebore length with the creedmoor, especially with the 140 ELD. In other words, a precise number slightly shorter or longer than saami will get you nothing. Many other more important factors.
I don't believe theres any magic to freebore length with the creedmoor, especially with the 140 ELD. In other words, a precise number slightly shorter or longer than saami will get you nothing. Many other more important factors.
My 140gr ELD-M ammo measures 2.196 BTO. That's a bit different from yours.
You say 0.03 jump is normal for SAMMI
Rob says 0.05 jump is normal for SAMMI
So I don't know what to make of it. If you're right, 0.03 jumps is SAMMI spec. If Rob is right, 0.05" jump is normal. If you're right, my chamber had a .199 freebore. If rob is right, my chamber had a .169. Maybe my smith will know what's up.
It doesn't matter if you load your own ammo. But because I do not, it matters a bit more, no? I can't chase the lands and I can't load for a specific jump. I'm stuck with what I got. And while the difference on paper at 100 yards might be 0.12 MOA vs 0.3 MOA... it matters to me because I'm able to shoot in the teens with factory ammo and not have to worry about hand loading. Some people are happy with a 0.25 - 0.35 MOA. But I get a lot of satisfaction when I get a one-hole group in the teens.
Also, how's that barrel working out for you? It's been a while, but I remember that Hawk Hill I had went to you?
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Youre measuring with different tools than I am. We can only compare the jump results here, not the numbers which were used to get there. Factory ammo in my fresh saami chamber jumps .034.
No, I dont think it matters. The shorter chambers are typically used for people who shoot berger 140’s, which have a much longer nose. Those users cant get anywhere near the lands in a saami chamber. Neither here nor there, your barrel shot well because Jon did his job and you had a premium barrel, not because of a shorter freebore. Id expect it to be exactly the same if the freebore was .225.
Ok got it. I'm just trying to get all the variables the same for my next barrel is all.
Four just have him make the barrel with the .169 and he can always lengthen it if you have problems which I don’t see happening. I have shot 140 factory ammo in a .169 and no jamming into lands. ETA: An even better idea is ask your smith what he would recommend as he already did one barrel for you. See what he says would be best for shooting all factory ammo with a shorter jump to lands. Then go that route.
My numbers are from my experiences with multiple different smiths and barrels and SAAMI chambers with .199 freebore. I stand by my numbers but you got to do what you think best.
My numbers are from my experiences with multiple different smiths and barrels and SAAMI chambers with .199 freebore. I stand by my numbers but you got to do what you think best.
Hmmm, just got off the phone with Hornady Tech Support. They said with SAAMI 0.199" free bore, I should expect 0.098" jump. Seems rather far. Almost 1/10 inch.
I'll have to measure my chamber again once my new gauge arrives.
I'll have to measure my chamber again once my new gauge arrives.
That’s close with the 147 in the SAAMI chamber but with 140 depending on factory oal it’s closer to .070 to .050” from all my factory ammo lots and barrels.
Found this: https://preferredbarrelblanks.com/best-6-5-creedmoor-chamber-prefit-barrel-comparison/#SAAMI
Very interesting. Chambered three different barrels using different freebore and then measured/shot with a bunch of factory ammo to see how the jump affects things, rather than seating bullet in/out to tune. Exactly what I was interested in. They saw 0.055" jump using Hornady factory 140gr ELDM in a 0.199" freebore.
Very interesting. Chambered three different barrels using different freebore and then measured/shot with a bunch of factory ammo to see how the jump affects things, rather than seating bullet in/out to tune. Exactly what I was interested in. They saw 0.055" jump using Hornady factory 140gr ELDM in a 0.199" freebore.
Didn't read it but not shocked by the number. Was probably some ammo loaded at about 2.815" OAL from the factory. The stuff that was about 2.800" I had was about .070" off.
My first long range rifle was a 6.5 CM Savage LRP, it is still one of the most accurate rifles I've owned. If I remember correctly the factory 140 eld's were jumping about .070.
Well then that settles that. Kind of why I said talk to your smith about what he used. Lol 
On another forum, someone took a look at SAAMI reamer specs and suggest I try this:
1. Use micrometer to scribe line on bullet at 0.262" diameter (0.262 x 2.187" from bolt face is SAAMI spec and they said measuring 0.002" under groove diameter is more reliable than OAL).
2. Measure base to that line and subtract from 2.187"
3. That's the jump in a SAAMI chamber.
When I do that, scribe line at 0.262" diameter = 2.157" = 0.03" jump in SAAMI chamber. And that's the exact number I was estimating based on my jump/erosion at 600 and 1000 rounds. How about that.
1. Use micrometer to scribe line on bullet at 0.262" diameter (0.262 x 2.187" from bolt face is SAAMI spec and they said measuring 0.002" under groove diameter is more reliable than OAL).
2. Measure base to that line and subtract from 2.187"
3. That's the jump in a SAAMI chamber.
When I do that, scribe line at 0.262" diameter = 2.157" = 0.03" jump in SAAMI chamber. And that's the exact number I was estimating based on my jump/erosion at 600 and 1000 rounds. How about that.
So this makes a strong argument for 0.169" - both given say factory Hornady OAL reporting here, seeming indifference of the jump with 6.5cm, and the net factor being a bit more barrel longevity? If I could get a logic check (I may have not sorted the information on the thread to a gnat's butt ;-)
Following up with this. New barrel is chambered and on. Confirmed the reamer is 100% dead nuts SAAMI spec. Jump in freshly cut chamber with factory Hornady 140gr ELD-M rounds is 0.039 and change, give or take. I will measure again when I'm not tired. But this confirms what I was saying before. 0.050" jump is not in line with what I'm seeing. Previous barrel's jump of 0.03xxxx doesn't seem to be an anomaly.
I'm glad this new barrel doesn't have a 0.050" jump! I don't hand load, so I have a bit more life out of the barrel as the throat erodes.
Well... then the ammo itself is the culprit because I'm measuring random factory samples from many thousands of rounds of Hornady ammo to get my BTO measurement. Anyway, doesn't matter as long as it shoots.
