How much free bore

[homefrontsniper]

I have a shilen select match 28" 8 twist 6.5 creedmoor barrel with .200" free bore.
I think that's to much FB
Plan on shooting 140 grn. Bullets. I want to get it re-chambered with less free bore.
Any ideas ?
0" free bore

.100 free bore

Thx

[RC20]

I picked this off on the discussion of free bore. I need to chew on it as well. Seems to be someone who knows his stuff and does the work

"
Obviously you know something about chambering and I just wanted to share my experiences having also shot completion at the state and national level and also built lots of rifles for myself and others.

The reason that I don't recommend chambers that have a tight neck is they can cause higher pressures without velocities reaching the desired/possible levels if the necks are not turned.

I like to keep the necks as thick as possible as long as they are true and uniform.

No throat is another way to limit the possible velocity of a cartridge. If you short throat a chamber
you will not be able to reach designed velocities without excessive pressure.

The 6.5 x 47 is not a large capacity case and needs the free bore to achieve the designed velocities
for a given bullet weight.

I re chambered a 6.5 x 47 for a friend that had pressure issues with minimum loads and extraction was very hard. after taking a chamber cast to see if I could figure out what the problem was and
discovered it had no throat and a tight neck (Turning the necks would not have solved the problem)

This was a pre-chambered and threaded barrel and it was for a savage and my friend installed it himself. (The head space was correct when I checked it).

I have seen this problem on other rifles with no free bore and tight necks.

Some think that you have to seat the bullet against the lands to get accuracy, with the better dies
chamber reamers and powders we have today this is no longer true.

I personally have 5 rifles and one pistol that will shoot under 1/10th of a minute and they all have
free bore and SAMMI neck diameters.

All of the "New" high velocity/pressure cartridges have Plenty of free bore in order to reach there intended velocities.

I just thought I would explain the reasons for my recommendations.

I hope you don't have any problems and good luck on your build, you will like the 6,5x47."

[homefrontsniper]

Thanks for that information.^

[homefrontsniper]

Is it true that gunsmith would have to take an inch off to re chamber ?

[gbflyer]

Is it true that gunsmith would have to take an inch off to re chamber ?

No. Wouldn't have to take off any more than the length of the new shorter throat. Would need a reamer ground to your specs or a reamer with no throat then use a throating reamer to your spec.

I'd shoot it before I did anything if you haven't already. Might be that you'll like it.

[Deadshot2]

No. Wouldn't have to take off any more than the length of the new shorter throat. Would need a reamer ground to your specs or a reamer with no throat then use a throating reamer to your spec.

I'd shoot it before I did anything if you haven't already. Might be that you'll like it.

Barrel shortening is usually done in multiples of thread pitch. If you have a 16 thread per inch "pitch" changes in chambers are made by moving barrel back One, Two, or more turns so any engraving on the barrel still lines up. Especially in cases when there are front sights attached to the barrel. Most of the 'smiths I know only remove the minimum amount to accomplish what they are looking for. For example, if he wanted to reduce the freebore to .100" from .200", he would probably move the barrel back two turns and re-chamber. This would move the throat back .125", more than needed but then he'd fix that with the chamber reamer, etc. There are other considerations but severe barrel shortening is not necessary unless re-chambering for a different caliber.

[deerhunter99]

How is the gun shooting, or do you want to change the free bore before you shoot, some calibers need that jump my 6.5x284norma likes .150 of free bore but that's my gun !!!

[Rob01]

.199 freebore is the SAAMI spec chamber so you aren't overly long. Both my custom Creedmoors have that chamber. Loading the 140 ELD-M at .020" off the lands I am at 2.850" OAL and it works great in AICS mags. I wouldn't go to .100 freebore. Too tight and you will have to push that bullet too deep in the case. Go with a .169" if you want shorter as that will put them at 2,820" at about .020" off the lands but I would try to shoot what you have now first.

[homefrontsniper]

.199 freebore is the SAAMI spec chamber so you aren't overly long. Both my custom Creedmoors have that chamber. Loading the 140 ELD-M at .020" off the lands I am at 2.850" OAL and it works great in AICS mags. I wouldn't go to .100 freebore. Too tight and you will have to push that bullet too deep in the case. Go with a .169" if you want shorter as that will put them at 2,820" at about .020" off the lands but I would try to shoot what you have now first.

Haven't put barrel on yet. Still shooting M12 LRP
Just getting as much information ad I can before I switch barrels.

Rob01 hows come you're not shooting 147 eldm?
Could they be just a little heavy for the creedmoor?

Thanks

[Rob01]

Haven't put barrel on yet. Still shooting M12 LRP
Just getting as much information ad I can before I switch barrels.

Rob01 hows come you're not shooting 147 eldm?
Could they be just a little heavy for the creedmoor?

Thanks

Funny you mention the 147s. Not too heavy at all for the Creedmoor. I was just out on Friday testing them from 600-1020 yards. They shot great and I had no problem keeping them all on a 10" plate at 1020 yards. I am getting them going 2820fps with H4350 in my 27" barrel. I load them .030" off the lands and they re 2.860" OAL.

[homefrontsniper]

Funny you mention the 147s. Not too heavy at all for the Creedmoor. I was just out on Friday testing them from 600-1020 yards. They shot great and I had no problem keeping them all on a 10" plate at 1020 yards. I am getting them going 2820fps with H4350 in my 27" barrel. I load them .030" off the lands and they re 2.860" OAL.


Thanks...i am ordering 147 tomorrow!
Maybe I will leave chamber @ .200"