Someone Check My Neck Measurement Math For Bushings

[sawacs]

I am trying to dive into the world of sizing case necks with bushings and wanted to make sure I am ordering the correct bushing. The bushing die is the Redding Bushing Neck Die #56415

I am using the KM expand mandrel/die with the window that measures 0.264. After expanding the neck and immediately loading with a 139 grain scenar,140 Vmax, or 120 and 123 scenars, my case neck measures 0.294.

Would it be safe to order a .293 and .292 bushings to get started? I also have a KM neck turning setup coming in and plan on turning the necks just enough to make them uniform and no more. Lets say I turned the necks and took 0.0125 off, would I need to subtract this from the .293 and .292 bushings and go with .292 and .291 bushings?

Edit: I should probably run a case through the expander, turn the necks, load the dummy round then measure to get the correct size bushing correct?

I hope all of this made sense..

Thanks,

Shawn

 

[22BRGUY]

I think if you took off 0.125 from a .293 or .292 you'd be changing calibers.

 

[sawacs]

I think if you took off 0.125 from a .293 or .292 you'd be changing calibers.

Yup, you are correct.. That should have read 0.0125. I think I will just buy in the .288-.294 range and take it from there.

 

[ballistic64]

Are you fitting for a tight neck chamber or just turning to clean up the necks? Either way I usually go -.003 to -.004 from the bullet dia. + case neck thickness x 2. In other words .308 bullet dia. + .014 case neck thickness + .014 case neck thickness = .336 So probably the first bushing I'd try would be .333 and go from there. Its personal preference and desired neck tension and what your gun wants from there.

 

[sawacs]

Are you fitting for a tight neck chamber or just turning to clean up the necks? Either way I usually go -.003 to -.004 from the bullet dia. + case neck thickness x 2. In other words .308 bullet dia. + .014 case neck thickness + .014 case neck thickness = .336 So probably the first bushing I'd try would be .333 and go from there. Its personal preference and desired neck tension and what your gun wants from there.

I am simply fitting for a Shilen Select Match Savage pre-fit barrel from Northland Shooters: small shank varmint contour. I am also hoping to clean up the necks and take the minimal amount of brass off to do so.

This is the road I think I should follow.
1. Redding body die
2. KM neck expand mandrel
3. Trim cases uniform
4. KM neck turn
5. Chamfer case mouth
6. Seat dummy round
7. Measure neck
8. Order bushing .002 and .003 sizes under the neck measurement.

Those Redding titanium bushings are expensive so I am trying to make the most educated guess I can before ordering two bushings.

Thanks for the advice!

Shawn

 

[fdshuster]

Shawn: I have a few of the titanium or carbide bushings at about $30 each, and seldom use them. The sizes are just not what I need. I now buy nothing but the plain steel at about $12 each and that equals a larger selection of sizes at less cost.

 

[sawacs]

Shawn: I have a few of the titanium or carbide bushings at about $30 each, and seldom use them. The sizes are just not what I need. I now buy nothing but the plain steel at about $12 each and that equals a larger selection of sizes at less cost.

From reading on the forums, I was under the impression that the steel bushings can scratch the necks up pretty good? I don't mind using the steel bushings providing they don't leave scratches. Getting two bushings for the price of one is a much better deal imho

Thanks!

Shawn

 

[fdshuster]

Shawn: Nope, not on my Lapua (or any other) brass. No scratches, nothing, zip, nada !

But I do keep my case necks clean and use a minimal amount of Imperial die wax.

 

[sawacs]

Shawn: Nope, not on my Lapua (or any other) brass. No scratches, nothing, zip, nada !

But I do keep my case necks clean and use a minimal amount of Imperial die wax.

Copy that and thanks. You just saved me some buckaroos!

I'll give the steel bushings a try and go from there.

Off topic but when using the KM expand mandrel and expanding the necks, I noticed they are still not perfectly straight. I suppose the bushing would probably solve this issue wouldn't it? I am wondering if maybe I should use the bushing die first then run the expand mandrel through before neck turning?

Thanks again,

Shawn

 

[kolar55]

As an example: take chamber neck dia.-.002 clearance. This should be the loaded neck dia. Get bushings .003, .004, and .005 less than that dimension and you should have it covered. Neck thickness =chamber neck dia.-.002-bullet dia.(including pressure ring if flat base) /2.
If you clean the residue from the necks and use imperial sizing die wax on them they will not scratch.

 

[fdshuster]

Shawn: If you're talking about the case necks being a little crooked, on new, unfired brass, before outside neck turning, that is common 'til the case is fired in the chamber. Then all but a few will straighten. Once in a while all will be straight. Depends on the quality of the brass.

I mark the ones that remain "crooked" after initial firing and if they do not straighten out after 3 or 4 firings, they are kept for close range, barrel fouling, basic scope sight-in and informal, not match, shooting.

 

[sawacs]

As an example: take chamber neck dia.-.002 clearance. This should be the loaded neck dia. Get bushings .003, .004, and .005 less than that dimension and you should have it covered. Neck thickness =chamber neck dia.-.002-bullet dia.(including pressure ring if flat base) /2.
If you clean the residue from the necks and use imperial sizing die wax on them they will not scratch.

I am not sure how to go about measuring the chamber neck diameter: fire a round and then immediately measure the neck? Wouldn't there be some spring back in the brass right after firing? I suppose I could call Shilen and ask them what the reamer dimensions were. My cases necks with unturned necks and 120,123's, and 139 scenars were .294 so if I subtract .002 from that I should come out needing bushings in .292, .291, and .290 to be safe. If I turn the necks, I should probably get a few more bushings smaller than these to be on the safe side also? I should probably grab bushings from .288 all the way through .292 and that should cover all the bases.

Thanks everyone for the advice. This is the most technical I have ever gotten with regards to reloading. Its easier to use a regular full length sizing die and load a round up but this is a lot more fun ;D

 

[DCRYDER]

Just doing a clean up job on the necks won't remove a lot of brass. If your chamber is a no - turn neck it is probably around .299" (if this is a 6.5-284), another reason not to remove more brass than necessary.

 

[sawacs]

Just doing a clean up job on the necks won't remove a lot of brass. If your chamber is a no - turn neck it is probably around .299" (if this is a 6.5-284), another reason not to remove more brass than necessary.

Thanks for the feedback..

I am assuming the Shilen chamber on the Savage pre-fit barrel has to be a no neck turn chamber or Jim from NSS would have mentioned it to me. Just for giggles, I took the Savage 116 in 6.5-284 (purchased for the action only) and loaded up a dummy 140 Amax. I managed to touch the lands at 3.146 oal with the stock barrel which kinda suprised me. I am hoping the chamber on the Shilen barrel is a little tighter.

After banging my head into the keyboard trying to find a Redding FL bushing die for the 6.5-284, I finally gave up and purchased a standard Redding full length sizing die to get started with sizing the new brass. This way I can at least get some rounds loaded up and the barrel broken in before going crazy with reloading accuracy. Besides, by then someone might actually have all the bushings in stock that are needed for this cartridge :

Cheers!

Shawn

 

[fdshuster]

Shawn: In every instance where I have measured my case neck diameters (as fired & after cleaning), using a micrometer, the as fired diameter is always .001" smaller than the actual chamber neck diameter.
That's the common amount of springback.

This has also been proven with all my PTG chambering reamers: Reamer is marked showing neck diameter, with the same diameter on the reamer print drawing. Example: Chamber is .269", fired case is .268". Works each and everytime.

 

[22BRGUY]

Just doing a clean up job on the necks won't remove a lot of brass. If your chamber is a no - turn neck it is probably around .299" (if this is a 6.5-284), another reason not to remove more brass than necessary.

Thanks for the feedback..

I am assuming the Shilen chamber on the Savage pre-fit barrel has to be a no neck turn chamber or Jim from NSS would have mentioned it to me. Just for giggles, I took the Savage 116 in 6.5-284 (purchased for the action only) and loaded up a dummy 140 Amax. I managed to touch the lands at 3.146 oal with the stock barrel which kinda suprised me. I am hoping the chamber on the Shilen barrel is a little tighter.

After banging my head into the keyboard trying to find a Redding FL bushing die for the 6.5-284, I finally gave up and purchased a standard Redding full length sizing die to get started with sizing the new brass. This way I can at least get some rounds loaded up and the barrel broken in before going crazy with reloading accuracy. Besides, by then someone might actually have all the bushings in stock that are needed for this cartridge :

Cheers!

Shawn

I personally do NOT like to ASSUME anything.....maybe a little more skeptical or too skeptical but when it comes to personal safety...
Anyway, just to be on the safe side, I'd suggest checking with NSS or better yet, perhaps cerrosafe cast the chamber. Although the risk is small in terms of there being a very tight neck chamber, the risk is great in terms of personal safety.....JMHO

 

[sawacs]

Shawn: In every instance where I have measured my case neck diameters (as fired & after cleaning), using a micrometer, the as fired diameter is always .001" smaller than the actual chamber neck diameter.
That's the common amount of springback.

This has also been proven with all my PTG chambering reamers: Reamer is marked showing neck diameter, with the same diameter on the reamer print drawing. Example: Chamber is .269", fired case is .268". Works each and everytime.

Thanks FD..

I wish I had of thought of that before trying to order all these different size bushings :-[ If I could start over with the 6.5-284, I would have ordered a simple full length die set, loaded some rounds and then began working on the accurate reloading part.

On another note, I do have the KM neck turning complete kit coming in with the steel cutter. Roger had mentioned the the steel cutter is a little more forgiving and would be better having never turned necks before.

Thanks everyone for the advice!

Shawn