INSIDE NECK SCRATCHES - EFFECT

[quest450]

who's erik cortina ?

 

[muleystalker]

On my .30's, I've done a lot of inner neck work. This started when I was shooting a .165 short 308W on Lapua cases in Hunter class Benchrest. The best solution I found was to cut the inner necks to make them round and remove the funnel shape before neck turning the outside. Elzie Scott from Wilson Tool and Die made me a series of reamers from .3060 to .3090 in .0005 increments. I made a flanged pilot bushing for them and used them in the standard Wilson case trimmer....very gently and by hand.

It took a bit of work to come up with a finish that would let the carbon stay on the inner necks and not come off when I ran a nylon brush in there after firing.

There was a definite accuracy improvement as the gun was more responsive to neck tension changes. I was the test mule for this. I was making cases for two other competitors with the same chambering and then did new cases for both of them. Both picked up accuracy and the scores reflected this.

The 30BRs don't need quite this level of work....though I've done it from time to time with no detrimental effects, either. The rounder and straighter the (inner) necks are before you start...the better.

I still 'condition' the inner necks on the 30BR cases before firing them the first time. I feel it helps. But like Tim Wilson says, I could be wrong.

Al, when making your 30BR cases these days do you use a carbide cutter pilot to cut the donut out of the neck? I'm knew to the 30BR and am getting ready to make some brass soon so just bring to get a good handle on it so I don't ruin a Buch of new brass. My thoughts are to neck up with the K&M 6mm-.30 expanding mandrel, then turn the necks with a 21st Century lathe with a K&M Carbide neck cutting pilot that fits the 21st century neck cutting tool head. What are your thoughts? You can PM me if you feel this is getting off topic of the OP.

Thanks,
Dave

 

[AlNyhus]

Dave, I don't use the K&M cutter mandrel. Pals of mine do and have good results. -Al

 

[muleystalker]

Dave, I don't use the K&M cutter mandrel. Pals of mine do and have good results. -Al

Thanks Al

 

[abosely]

I made a wildcat cartridge based on necked up 220 Russian case.

I’m forming cases from Lapua 220 Russian brass, necking up from 22 to 6mm then to .308 dia, to be easier on brass.

I lightly use inside & outside neck chamfer tool to just make sure no burr on necks.
About half a turn with chamfer tools.

Then I use 6mm tapered felt bobs liberally coated with Flitz polish chucked in cordless drill.
It really smooths and polishes the inside of necks. And only takes few minutes to to polish inside 100 case necks.

Put cases in sink with full hot tap water and dawn dish soap, stirred them around a bit, drained water & rinsed couple of times.
Completely removed any residue of Flitz.

I’m using PMA Tools neck expanding and neck turning mandrels with Redding Imperial sizing wax, applied to inside of necks with Q-Tip for expanding necks and Lucas Extreme Duty Gun oil for turning necks.

I got Flirz, 8000 grit diamond polish & Lucas Gun Oil from Amazon.

I chucked the mandrels in cordless drill and polished them few minutes with Flitz on a cloth, then cleaned them with rag & alcohol and polished them again with 8000 grit diamond polish.

They were nice originally, but after few minutes of polishing they were mirror smooth.
Only need to polish them once.

Was noticeable reduction in force to expand necks and when turning necks didn’t get any galling on mandrel or inside case necks.

Sounds like a lot of work, but really didn’t take long polish mandrels and case necks.

Cheers, Allen

 

[searcher]

guess what erik cortina uses on his brass

Yes - have seen his vidoes.

 

[searcher]

Then I use 6mm tapered felt bobs liberally coated with Flitz polish chucked in cordless drill.
It really smooths and polishes the inside of necks. And only takes few minutes to to polish inside 100 case necks.

I have done that too, with varying results - probably because I was using some not-so-great fitting felt polishing tips from my moto-tool kit. Where do you get your felt bobs? Thanks for posting. Good tips
Found some on Amazon that will work better than what I was using. They have the diamond polish as well - I had been using a different compound which was also a bit sketchy for the purpose.

 

[abosely]

I have done that too, with varying results - probably because I was using some not-so-great fitting felt polishing tips from my moto-tool kit. Where do you get your felt bobs? Thanks for posting. Good tips

I got an assortment of sizes from Amazon. After using the hard felt bob on several cases they compress down and or wear down a bit and don't fit as snuggly. Only took 5 or 6 seconds for each case. Biggest reason I polished inside necks is I was expanding necks from 22 cal up to .308, so wanted to be sure inside necks were nice and smooth to help reduce friction on expander mandrel.

After polishing expander mandrels and neck turning mandrels could definitely tell difference in force needed to expand necks and when turning neck there was less gripping on mandrel, just felt smoother.
Haven't hade any galling when turning necks at all after polishing.

 

[Benchrest Braxton]

Yes - have seen his vidoes.

do you think he would use it if it put him at any disadvantage?

 

[searcher]

do you think he would use it if it put him at any disadvantage?

No, I don't. He is one guy that does what he feels works for him and I'm sure he would want to continue doing what he feels works for him. I like his videos and he seems like a real nice guy. I like to get a feel for what as many guys are doing as I can. I don't view all of his methods as you might. With certainty, there are many guys on this site that can print teeny groups not using "his" methods - so it is nice to hear different perspectives. Eric didn't come up with all of his knowledge on his own. No doubt, he gleaned much of it from learning from other knowledgeable people (such as those people telling him what to do in all his vidoes). That all I'm doing here. Like Eric, I listen to a lot of folks that know what they are doing and try to learn from them.

 

[searcher]

I got an assortment of sizes from Amazon. After using the hard felt bob on several cases they compress down and or wear down a bit and don't fit as snuggly. Only took 5 or 6 seconds for each case. Biggest reason I polished inside necks is I was expanding necks from 22 cal up to .308, so wanted to be sure inside necks were nice and smooth to help reduce friction on expander mandrel.

After polishing expander mandrels and neck turning mandrels could definitely tell difference in force needed to expand necks and when turning neck there was less gripping on mandrel, just felt smoother.
Haven't hade any galling when turning necks at all after polishing.

I looked on Amazon and saw the bobs that are securely attached to the shaft. When I had experimented polishing mine a long time ago, I was using those little suckers that screw onto a moto-tool screw shaft. They were good for about ten seconds before flying off. These newer bobs are pretty nice. I'm going to mess with those again. Thanks!

 

[abosely]

I looked on Amazon and saw the bobs that are securely attached to the shaft. When I had experimented polishing mine a long time ago, I was using those little suckers that screw onto a moto-tool screw shaft. They were good for about ten seconds before flying off. These newer bobs are pretty nice. I'm going to mess with those again. Thanks!

Yes the ones with the compressed felt bobs last good while, they are cheap enough that can get selection of different sizes and shapes for different purposes.
I got the quart can of Flitz and have used it for smoothing and polishing Mini 30 action and commonest of custom Mini 30 with Kreiger SS 5R .308 1:12 18" .750 dia barrel, chambered in my wilscat 30-220 Russian.
Reamer from Manson will be finished April 3.

 

[Benchrest Braxton]

No, I don't. He is one guy that does what he feels works for him and I'm sure he would want to continue doing what he feels works for him. I like his videos and he seems like a real nice guy. I like to get a feel for what as many guys are doing as I can. I don't view all of his methods as you might. With certainty, there are many guys on this site that can print teeny groups not using "his" methods - so it is nice to hear different perspectives. Eric didn't come up with all of his knowledge on his own. No doubt, he gleaned much of it from learning from other knowledgeable people (such as those people telling him what to do in all his vidoes). That all I'm doing here. Like Eric, I listen to a lot of folks that know what they are doing and try to learn from them.

so does greg at primal rights, and he is super anal about interior neck surface. way more than warranted IMO

 

[searcher]

Yes the ones with the compressed felt bobs last good while, they are cheap enough that can get selection of different sizes and shapes for different purposes.
I got the quart can of Flitz and have used it for smoothing and polishing Mini 30 action and commonest of custom Mini 30 with Kreiger SS 5R .308 1:12 18" .750 dia barrel, chambered in my wilscat 30-220 Russian.
Reamer from Manson will be finished April 3.

Good to know. I'm always polishing the sharp edges off feed ramps, ejectors, etc. on A/R's and such. Those hard felt bobs will help a lot.