6.5 CM Load Development...Next Steps??

[Mark71]

I've got another question regarding this rabbit hole I have entered.

I measured jam at 2.261" using a Hornady OAL gauge and a Hornady modified case. I started my testing 0.020 off the lands for a CBTO of 2.241" which gives me a COL of 2.760". Nosler lists the COL for this bullet at 2.805", so I'm already slightly deeper into the case than the Nosler data.

My question is, when exploring seating depth to tune the load what is a guideline for seating deeper? How do I know when I shouldn't be seating any deeper into the case?

 

[Bc'z]

I've got another question regarding this rabbit hole I have entered.

I measured jam at 2.261" using a Hornady OAL gauge and a Hornady modified case. I started my testing 0.020 off the lands for a CBTO of 2.241" which gives me a COL of 2.760". Nosler lists the COL for this bullet at 2.805", so I'm already slightly deeper into the case than the Nosler data.

My question is, when exploring seating depth to tune the load what is a guideline for seating deeper? How do I know when I shouldn't be seating any deeper into the case?

What Jim said.
By establishing seating depth first, you also establish the amount of boiler room you'll have to work with.
Think about it....

 

[Mark71]

What Jim said.
By establishing seating depth first, you also establish the amount of boiler room you'll have to work with.
Think about it....

Sorry guys, my question probably wasn't worded properly. I understand the results will tell me when I have a depth that the charge/bullet likes. I was just wondering about seating to deep seeing as I am already seated deeper than the book notes, understanding this is just a guideline. I guess there's lots of bearing surface on these heavy for caliber bullets.

Once I settle on a charge I'll try testing in 0.010" increments and see how things look.

 

[Bc'z]

Sorry guys, my question probably wasn't worded properly. I understand the results will tell me when I have a depth that the charge/bullet likes. I was just wondering about seating to deep seeing as I am already seated deeper than the book notes, understanding this is just a guideline. I guess there's lots of bearing surface on these heavy for caliber bullets.

Once I settle on a charge I'll try testing in 0.010" increments and see how things look.

.010 increments and you'll blow right past seating windows

 

[Mark71]

.010 increments and you'll blow right past seating windows

I was planning to do .010 for rough and then fine tune?? Or just start with .003 right out of the gate?

 

[Bc'z]

.003 shoot 2, 3 ain't getting smaller, rinse repeat then you'll see your seating window

 

[RabbitSlayer]

Do a seating depth test at 40.6 starting just off of jam. Load 25 of the best and shoot em all into one big hole. Since i have been doing larger samples per Hornady, I have found the difference is not huge between similar loads. Maybe if you are shooting a benchrest rig, but not hunting or PRS type rigs.

 

[David Christian]

I've got another question regarding this rabbit hole I have entered.

I measured jam at 2.261" using a Hornady OAL gauge and a Hornady modified case. I started my testing 0.020 off the lands for a CBTO of 2.241" which gives me a COL of 2.760". Nosler lists the COL for this bullet at 2.805", so I'm already slightly deeper into the case than the Nosler data.

My question is, when exploring seating depth to tune the load what is a guideline for seating deeper? How do I know when I shouldn't be seating any deeper into the case?

COAL numbers in a book don’t mean much as that number does not relate to your chamber that you have already measured and found the lands. The tip of the bullet is floating in the air, not touching anything, so ignore the COAL once you know the distance to the lands using your bullets and your chambering.

How far is too deep when seating? Once you start to hear the powder crunch and you now have a compressed load.

 

[nakneker]

.010 increments and you'll blow right past seating windows

This is my experience too. I’d stick with shorter increments than .010, that .003 is what’ve I’ve done for years when trying to tune seating depth with VLDs.

He’s giving you good advice imo.

 

[whatsupdoc]

I've got another question regarding this rabbit hole I have entered.

I measured jam at 2.261" using a Hornady OAL gauge and a Hornady modified case. I started my testing 0.020 off the lands for a CBTO of 2.241" which gives me a COL of 2.760". Nosler lists the COL for this bullet at 2.805", so I'm already slightly deeper into the case than the Nosler data.

My question is, when exploring seating depth to tune the load what is a guideline for seating deeper? How do I know when I shouldn't be seating any deeper into the case?

I have never used Nosler ballistic tip bullets so I have no idea on them but if you are
getting a 2.261 COAL with a 140gr bullet into the lands I would re-check your measurements.

Typically SAMI 6.5 creed has a .199 throat, guys that shoot Berger 140 gr bullets
run a throat length of about .169 ish. No barrel I have had chambered for
6.5 creed with 140 bullets touched the lands with the round that short.

 

[Bc'z]

I have never used Nosler ballistic tip bullets so I have no idea on them but if you are
getting a 2.261 COAL with a 140gr bullet into the lands I would re-check your measurements.

Typically SAMI 6.5 creed has a .199 throat, guys that shoot Berger 140 gr bullets
run a throat length of about .169 ish. No barrel I have had chambered for
6.5 creed with 140 bullets touched the lands with the round that short.

I bet it's cbto, I've got measurements of
2.1930 with a Berger 140vld coal 2.833
2.1445 with a elite hunter

 

[Bc'z]

This is my experience too. I’d stick with shorter increments than .010, that .003 is what’ve I’ve done for years when trying to tune seating depth with VLDs.

He’s giving you good advice imo.

My advice is ditch the 140's and go with 123's in mid 2900's velocity will overcome any precieved loss in drop.

 

[Mark71]

I have never used Nosler ballistic tip bullets so I have no idea on them but if you are
getting a 2.261 COAL with a 140gr bullet into the lands I would re-check your measurements.

Typically SAMI 6.5 creed has a .199 throat, guys that shoot Berger 140 gr bullets
run a throat length of about .169 ish. No barrel I have had chambered for
6.5 creed with 140 bullets touched the lands with the round that short.

I measured CBTO jam at 2.261 and backed off 0.020 to get a starting CBTO of 2.241.

 

[Mark71]

I appreciate all the great advice so far. Thank you to everyone!!

 

[Bc'z]

I appreciate all the great advice so far. Thank you to everyone!!

1 last thing...
Never ever try H-4831sc between 44-45gr "brass dependent" 140gr'sh in your 6five, you'll have a hard time keeping a grin of your face.

 

[Fuj]

Try some 140 RDF's.....

 

[Chilly807]

The guys are right about several things.

One being the new barrel. Once it gets about 300 rounds on it, or at least 200 it will speed up somewhat. Probably 50, maybe as much as 100 fps.
Yours being a lapped Kreiger, that number may differ a bit.

I think I'd work around the 40.6 load for a bit to see how wide that node is, and even if it'll repeat. It may not.

Second, you're going to end up doing this process all over again for the match bullets you want to use. Using the Ballistic Tips will get your barrel broken in and somewhat "settled", but keep in mind the 6.5 doesn't have stellar barrel life. Probably 3000 rounds with a moderate load for match accuracy. That number will decrease considerably if it's pushed hard.

I used Sierra 123 match kings in my 6.5 CM for a couple years at about 2930 if I remember right, they're good bullets. Last time I checked, Hirsch Precision in NS had lots of them left. They ship.
I switched to the Lapua 139 Scenar a couple years ago for a better bullet in the wind. It's a bit better, but not head and shoulders better.

I'm using 40.1 of H4350 under a 139 Scenar. I get about 2710 fps from a 24" barrel. Brass lasts a long time if you anneal, and so does the barrel. Accuracy is good. It has about 2000 rounds through it at this point.

I try playing with seat depth in 5 thou increments, any larger and I might miss the sweet spot. The 139 Lapuas work best about 15 thou off the lands in my rifle. I start at 20 thou off and work in both directions. If your load is hot to begin with, be careful with close to the lands or seated deeply in the case. Both will increase pressure.

Nothing wrong with Sierra bullets if you can get them. Berger makes a good bullet but in my experience the Sierras are no slouches.
Noslers are largely made of unobtainium in Canada these days, and expensive when you DO find them.

Once I think I've got a load ironed out, I load a dozen rounds and fire them into one group and see what it looks like. Based on 2 sighters and 10 on score in an F-class match. If I can live with the results, I go with it until something changes.

Just my opinions, as usual.

 

[Mark71]

I shot a bracket group Friday of 41.6, 41.7 & 41.8 (5 shots each charge).



Based on the groups I got I settled on a charge of 41.7 gr and moved on to trying some different seating depths, increasing depth by 0.003" and this is what I got.



I was a little surprised to see the velocities decrease slightly with each slightly deeper seating depth. I was expecting them to increase slightly?? I may try going another 0.003" deeper to see if it tightens up a little more or starts to fall apart, but I'm just slightly compressed already on the depth shown in group 4, so not sure I want to go deeper. Shots felt good, but who knows, shot #2 on the last target being slightly left could have been me too. I may just load 10 at this seating depth and see what that looks like.

Thanks again for all the advice!

 

[Mark71]

The guys are right about several things.

One being the new barrel. Once it gets about 300 rounds on it, or at least 200 it will speed up somewhat. Probably 50, maybe as much as 100 fps.
Yours being a lapped Kreiger, that number may differ a bit.

I think I'd work around the 40.6 load for a bit to see how wide that node is, and even if it'll repeat. It may not.

Second, you're going to end up doing this process all over again for the match bullets you want to use. Using the Ballistic Tips will get your barrel broken in and somewhat "settled", but keep in mind the 6.5 doesn't have stellar barrel life. Probably 3000 rounds with a moderate load for match accuracy. That number will decrease considerably if it's pushed hard.

I used Sierra 123 match kings in my 6.5 CM for a couple years at about 2930 if I remember right, they're good bullets. Last time I checked, Hirsch Precision in NS had lots of them left. They ship.
I switched to the Lapua 139 Scenar a couple years ago for a better bullet in the wind. It's a bit better, but not head and shoulders better.

I'm using 40.1 of H4350 under a 139 Scenar. I get about 2710 fps from a 24" barrel. Brass lasts a long time if you anneal, and so does the barrel. Accuracy is good. It has about 2000 rounds through it at this point.

I try playing with seat depth in 5 thou increments, any larger and I might miss the sweet spot. The 139 Lapuas work best about 15 thou off the lands in my rifle. I start at 20 thou off and work in both directions. If your load is hot to begin with, be careful with close to the lands or seated deeply in the case. Both will increase pressure.

Nothing wrong with Sierra bullets if you can get them. Berger makes a good bullet but in my experience the Sierras are no slouches.
Noslers are largely made of unobtainium in Canada these days, and expensive when you DO find them.

Once I think I've got a load ironed out, I load a dozen rounds and fire them into one group and see what it looks like. Based on 2 sighters and 10 on score in an F-class match. If I can live with the results, I go with it until something changes.

Just my opinions, as usual.

Thanks for the feedback.

If I hadn't inherited about 6 boxes of the ballistic tips I never even would have considered using them in this rifle and would have started with a Sierra or Berger, but with the cost of components, free bullets won me over. LOL

40.6 definitely looked tempting, but I wanted to run a hair faster. Being a 26" barrel I figure I'm not running to hot as I would likely be right around 2700 if it was 24". I am definitely wanting to try and baby this thing and make it last as long as absolutely possible.

As a side note, this chamber must not have much free bore because even at jam (2.261") I am seated well into the case with the bullet (0.523"), but I am no gunsmith or 6.5CM expert, so maybe this is the norm for this cartridge...If I do move forward with the seating depth noted in my previous post (CBTO 2.229") I'm 0.555" into the case. The few rounds I have shot at this charge weight (41.7) I averaged 2743 fps.

 

[Mark71]

1 last thing...
Never ever try H-4831sc between 44-45gr "brass dependent" 140gr'sh in your 6five, you'll have a hard time keeping a grin of your face.

Bc'z, thanks for the seating depth tips...seems to be paying off.

I have some H4831SC...may have to give it a try too.