Choosing my Redding FL bushing size

[MeasureOnceCutTwice]

I've read a lot and watched a lot and I've still got questions.

I'm loading 6.5 Creedmoor, a buddy that got me started loaned me a .288 bushing, said that's generally what most people end up with, it's what he's used, etc. I ran my cases through with that and did my load development, happy with charge volume, seating depth, now want to finalize with the bushing.

If I measure the wall thickness of the neck with a spherical anvil micrometer, I've got .014" thick walls. Double that up, add .264, subtract one thou, I need a .291 bushing.
If I measure a loaded round after sizing with the loaner .288 bushing, I'm getting .289.

Which method is "appropriate"? I can buy both and test but good lord have I not spent enough already just building the bench?

 

[omgtkk]

Your methodology is sound but, personally, I think 0ne thousands is not enough. I know several people who promote that, but a lot of others suggest that the brass will spring back a thousands, so to go 2-3 thousands smaller on your bushing.

I just got done neck turning 200 pieces of Peterson 6.5 brass. The neck thickness measures a consistent .014. Added to the .264 gives me .292. I'm going to go three thousands smaller on my bushing for a .289.

Your .288 bushing seems a bit tight, but a .291 may not give you any neck tension if the brass springs back or you have case neck thickness variables of as little a one thousands. And if you don't neck turn, it's pretty certain you have that much variation.

Keep up the good work

 

[ShtrRdy]

I like to measure the outside neck diameter with a bullet seated. Then subtract 2 thou from that numbber.

 

[LA260]

I like to measure the outside neck diameter with a bullet seated. Then subtract 2 thou from that numbber.

This is how I do it too.
6.5CM Hornady Brass - 0.287
6.5x47 - 0.288
260REM Lapua Brass - 0.292

Lately I've started using the expander mandrel so I use smaller bushing than what's listed above.

 

[MeasureOnceCutTwice]

I like to measure the outside neck diameter with a bullet seated. Then subtract 2 thou from that numbber.

This is my inexperience showing, just not knowing what to expect. Once the case is fired and you can manually slip a bullet in and out pretty easily, how accurate is that measurement for this application? I mean, there's obviously a spectrum of neck OD measurements, as I can manually slip a bullet in and out on some and then there's the tighter ones that I used for finding the lands. I guess I should measure both and see what the variance on the neck OD is before I make a decision. I imagine there's something measurable there, but maybe not. Or, even if I overdid it on the neck with say a .280 bushing and I cram the bullet in with some effort, is it going to stretch the neck brass enough that the OD will still be similar to if I'd used a .290.

Time to experiment, and then I"ll report back. I could easily be overthinking it but this is a game of thousandths too, so...maybe not?

Your methodology is sound but, personally, I think 0ne thousands is not enough. I know several people who promote that, but a lot of others suggest that the brass will spring back a thousands, so to go 2-3 thousands smaller on your bushing.

I just got done neck turning 200 pieces of Peterson 6.5 brass. The neck thickness measures a consistent .014. Added to the .264 gives me .292. I'm going to go three thousands smaller on my bushing for a .289.

Your .288 bushing seems a bit tight, but a .291 may not give you any neck tension if the brass springs back or you have case neck thickness variables of as little a one thousands. And if you don't neck turn, it's pretty certain you have that much variation.

Keep up the good work

Good point about variables. I've not looked into neck turning yet, so yeah that may well affect me. Thanks for the suggestion!

 

[MeasureOnceCutTwice]

This is how I do it too.
6.5CM Hornady Brass - 0.287
6.5x47 - 0.288
260REM Lapua Brass - 0.292

Lately I've started using the expander mandrel so I use smaller bushing than what's listed above.

I'm using Hornady right now as well, and that's what I measure .289" when loaded. But, if I measure the walls alone the number adds up a few thou larger, so which way do I go?!?! I guess $15 isn't going to kill me if I get a .290 and compare with my buddies .288 and .287 and find out that one of those groups better. How far do I want to chase it though,

I just bought 500 pieces of Starline as well, it measures the same wall thickness, which is nice. I'll be ready to replace this barrel before it's a year old though...

 

[LA260]

I'm using Hornady right now as well, and that's what I measure .289" when loaded. But, if I measure the walls alone the number adds up a few thou larger, so which way do I go?!?! I guess $15 isn't going to kill me if I get a .290 and compare with my buddies .288 and .287 and find out that one of those groups better. How far do I want to chase it though,

I just bought 500 pieces of Starline as well, it measures the same wall thickness, which is nice. I'll be ready to replace this barrel before it's a year old though...

I dont think 0.001 here or there is going to make a difference. The reason I was using 0.287 for the 6.5CM is because it's for a semi. If it was a bolt gun I would go with 0.288.

 

[JimLee]

Get a .288 .289 and .290 for 6.5 CM. With different brass thickness' for different manufacturers the number you need is going to change. It's nice to have the one you need on hand. I used to use .289 on my starline brass until I took real good measurements and realized how inconsistent the neck walls were so I turned them, now I use a .288, it was nice to switch without having to wait for a new bushing in the mail. It's also nice to be able to experiment with different seating tensions to see how it affects your accuracy. My rifle likes 1 thou of tension, but the high angle from my mag to my chamber was pushing some bullets off center on the feed ramp so I had to move up to 3 thou. Some guys find their bullets get pushed in from recoil in the mag if their tension is too light. These are things you have to experiment with and figure out what works best for your rifle, that's why it's nice to have options if you want to make a change.

Edit: I also saw a video where a guy was begging an RO to let him shoot a chambered round after he timed out in a match. He was setting his bullet tension so light that he was afraid that if he ejected the unfired round the bullet would stay in the barrel as he was also seating them into the lands.

 

[MeasureOnceCutTwice]

Get a .288 .289 and .290 for 6.5 CM. With different brass thickness' for different manufacturers the number you need is going to change. It's nice to have the one you need on hand. I used to use .289 on my starline brass until I took real good measurements and realized how inconsistent the neck walls were so I turned them, now I use a .288, it was nice to switch without having to wait for a new bushing in the mail. It's also nice to be able to experiment with different seating tensions to see how it affects your accuracy. My rifle likes 1 thou of tension, but the high angle from my mag to my chamber was pushing some bullets off center on the feed ramp so I had to move up to 3 thou. Some guys find their bullets get pushed in from recoil in the mag if their tension is too light. These are things you have to experiment with and figure out what works best for your rifle, that's why it's nice to have options if you want to make a change.

Edit: I also saw a video where a guy was begging an RO to let him shoot a chambered round after he timed out in a match. He was setting his bullet tension so light that he was afraid that if he ejected the unfired round the bullet would stay in the barrel as he was also seating them into the lands.

Well cool, that sounds like a plan to me. Thanks everyone!