6 Creed build questions

[JD Jones]

I’ve looked and I have found conflicting information so I’m tossing the questions out here fellas.

1) I’m trying to determine the correct freebore to load 108 eldms. Is it safe to assume saami spec reamer is the right choice?

2) those who went 18” and reload id be curious what kind of velocity range you are seeing?

 

[sierracharlie338]

Since the 108 is a factory option you should have no issues running the 108 and SAAMI chamber. Im no help on velocity.

 

[waspocrew]

Hornady factory 108 match ammo is going about 2780 out of my 18” Bartlein.

 

[Gila]

I have looked high and low for the chamber info and have seen conflicting info for the same bullet. Might be a good question to ask over on the 6UM thread.

I have a barrel on order and went with the SAAMI reamer. The barrel maker lists as the “a” reamer. I want to shoot 103 to 115s. The free bore is .183 with a .277 neck (no-turn). If all you want to shoot is the 108s you can get a custom throat. Send in 3 dummy rounds and tell them where you plan on parking the leading edge of the ogive. I don’t hunt with suppressors so all of my barrels are 24”.

 

[wind gypsy]

I’d get the SAAMI throat if expecting to use elds. You can get into the 2800s with an 18” if you want. I’ve been more in the mid-upper 2700s with my 18”.

 

[TaperPin]

“Correct” throat depends on how much you want to seat the bullets off the lands. The saami throat is most likely sized for current, but also future bullets and might be a little overly long - here’s the chamber drawing off the saami website.

 

[JD Jones]

“Correct” throat depends on how much you want to seat the bullets off the lands. The saami throat is most likely sized for current, but also future bullets and might be a little overly long - here’s the chamber drawing off the saami website.View attachment 670374

Thanks for sharing the dims! On the topic of where I want to set the bullet relationship to the lands…I mean I’m not sure I would have final say? It’s really up to how the bullet performs. I’d seat it where it shot best

Am I overthinking/underthinking this?

 

[wind gypsy]

I was told the reamer was saami on my barrel and it wasn’t. That resulted in most factory ammo jamming in the lands. sAAMI is fine unless you’re an avid lands chaser.

Shorter is fine too. You’ll hit pressure a little quicker but no big deal.

 

[Article 4]

IME SAAMI spec reamers are fine for most people who don't hand load. I mean a guy can use a SAAMI spec reamer for handloads but my most successful builds and most accurate rifles perform best with specs designed for the bullet especially when running Match bullets. Most Match bullets like to be on or very close to the lands unless you run hybrids. .183 SAAMI freebore was set by hornady and will probably run most bullets up to 105 without losing much. I run 115 Bergers in mine and use a .190.
I recommend .190 freebore for most match bullets.

The other items to consider is getting the most performance out of your case. If you use longer bullets.
To your question about velocities, using SAAMI reamers you are going to potentially lose case capacity due to bullet length

I run a 24 inch 8 twist bbl and get 3009 with H4350. Tons of fast from a 6CM

 

[wind gypsy]

IME SAAMI spec reamers are fine for most people who don't hand load. I mean a guy can use a SAAMI spec reamer for handloads but my most successful builds and most accurate rifles perform best with specs designed for the bullet especially when running Match bullets. Most Match bullets like to be on or very close to the lands unless you run hybrids. .183 SAAMI freebore was set by hornady and will probably run most bullets up to 105 without losing much. I run 115 Bergers in mine and use a .190.
I recommend .190 freebore for most match bullets.

The other items to consider is getting the most performance out of your case. If you use longer bullets.
To your question about velocities, using SAAMI reamers you are going to potentially lose case capacity due to bullet length

I run a 24 inch 8 twist bbl and get 3009 with H4350. Tons of fast from a 6CM

True with most cases but with 6 creed all the non saami reamers I’ve seen have shorter throats rather than longer.

Stuff like this


came out and changed my thoughts about bullet jump. Never used to even try as much as 50 thou off the lands now I start with them there and never touch seating depth as long as it shoots acceptably.

 

[Article 4]

True with most cases but with 6 creed all the non saami reamers I’ve seen have shorter throats rather than longer.

Stuff like this

View attachment 670438
came out and changed my thoughts about bullet jump. Never used to even try as much as 50 thou off the lands now I start with them there and never touch seating depth as long as it shoots acceptably.

Staying on task with original question - If what they found is true, even more reason to have a custom reamer made with more freebore. Allows for more jump if that is what your bbl likes.

Dont know enough about that artilcle and the particulars in it to comment. Too many variables that are not listed - eg BBL specs, powders, other components. If you can send me a link to the full article? I would enjoy seeing how they set up a "Bomb Proof Test"

I agree with bullets that have both a Secant and Tangent ogives, generally like more jump. Some bullet designs are focused on ease of use and are engineered to be jumped. My personal shooting and build experience with Match style bullets is they like to be close or on the lands (.002 out to .009), especially Bergers. ABLRs usually like (.019 to .027)

Every bullet and rifle combination likes things differently. That is why you look at recommendations and shoot ladders - and then groups to true.

 

[wind gypsy]

Staying on task with original question - If what they found is true, even more reason to have a custom reamer made with more freebore. Allows for more jump if that is what your bbl likes.

Dont know enough about that artilcle and the particulars in it to comment. Too many variables that are not listed - eg BBL specs, powders, other components. If you can send me a link to the full article? I would enjoy seeing how they set up a "Bomb Proof Test"

I agree with bullets that have both a Secant and Tangent ogives, generally like more jump. Some bullet designs are focused on ease of use and are engineered to be jumped. My personal shooting and build experience with Match style bullets is they like to be close or on the lands (.002 out to .009), especially Bergers. ABLRs usually like (.019 to .027)

Every bullet and rifle combination likes things differently. That is why you look at recommendations and shoot ladders - and then groups to true.

Bullet Jump: Is Less Always Better?

About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...

precisionrifleblog.com

That’s a related article.

I don’t disagree that more freebore might be even better given these considerations. Really, if the freebore gives some breathing room for a bullet to be seated above the donut area without being jammed I’m happy. Cartridges like 6 creed are going to quickly erode the throat anyway.

 

[TaperPin]

Thanks for sharing the dims! On the topic of where I want to set the bullet relationship to the lands…I mean I’m not sure I would have final say? It’s really up to how the bullet performs. I’d seat it where it shot best

Am I overthinking/underthinking this?

Glad to help. It sounds like you are flexible and using similar bullets to factory rounds so you’re probably going to be happy with a normal chamber.

Some want a short jump to the lands and have a short magazine so they like a throat on the short end, others with a long magazine want a long throat to seat bullets way out and gain a little velocity.

All the saami dimensions are on their website - they break it down into rimfire, pistol, shotgun and centerfire rifle.

https://saami.org/wp-content/uploads/2023/11/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

I also have a long 4wt Clearwater nymphing rig and it is soft enough I wouldn’t suggest it.

 

[JD Jones]

Glad to help. It sounds like you are flexible and using similar bullets to factory rounds so you’re probably going to be happy with a normal chamber.

Some want a short jump to the lands and have a short magazine so they like a throat on the short end, others with a long magazine want a long throat to seat bullets way out and gain a little velocity.

All the saami dimensions are on their website - they break it down into rimfire, pistol, shotgun and centerfire rifle.

https://saami.org/wp-content/uploads/2023/11/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

I will place myself in the flexible camp but loading long is something I’m wanting to do so I can stuff more powder in there. Just not sure how much longer I will end up going. I’ll obviously be restricted by mag length at some point (no single feed)

 

[B_Reynolds_AK]

You might wanna call Josh at PVA. He’s very knowledgeable on the 6mm builds. His PVA Standard throat for 6CM is longer than any of the numbers listed previously on this thread. I have one and both factory 108’s and my new 112 hand loads are shooting awesome.

 

[Blackdog317]

My gunsmith offers a .120 freebore and a .183 (SAAMI) freebore for his 6 Creedmoor chambers. He said the .120 will not work with 80% of factory loads but is available for handloaders that want a short jump with specific bullets.

I'm leaning towards the .183 so I can load longer, stuff a little more powder in the case and pick up some velocity in a shorter barrel (20").

Good info in this thread as I am needing to make similar decisions soon...

 

[JD Jones]

I went .183 and barrels are getting worked now. Things are coming together fast … just need to decide which NF to throw on top

 

[JD Jones]

Action : BAT Vesper SA

Trigger: Triggertech Special

Barrel: Bartlein 6mm 7.5 twist SS Remington Varmint cut 20” and spiral flute.

Chassis: element magnesium 4.0

Optic: TBD nightforce

Suppressor: Sandman S

 

[Lawnboi]

Action : BAT Vesper SA

Trigger: Triggertech Special

Barrel: Bartlein 6mm 7.5 twist SS Remington Varmint cut 20” and spiral flute.

Chassis: element magnesium 4.0

Optic: TBD nightforce

Suppressor: Sandman S

I’d get to waiting on a lighter chunk of metal for the muzzle ASAP. Personally I can’t stand a super nose heavy rifle.

As for freebore, only way I would go shorter than saami is if I wanted to shoot Berger hybrids.

 

[JD Jones]

Wrap up: boring kitchen shot but today I got my barrels back, mounted a NX8 4-32 and got my new toy ready for some fun this weekend. Smith work done by Alamo (local).