Bullet sizing story / help request

[MRM]

Hello,

Fairly new to casting and just got my 2nd rifle caliber mold a few weeks ago. It took some searching, but I finally found a Lyman 280468 on the EE for my 270 Win.

Not having a lube sizer (yet) I opted for a Lee .278 sizing die. I expected it to produce a .278 bullet, but they come out at .2795.

I was about to load up my first batch of ammo tonight, but this was bugging me. I decided instead to slug my bore. Not sure why I did not do this a long time ago, but regardless it came out at .2755.

I don’t have a hardness tester, but have been casting the bullets pretty hard. Half are 1 WW to 1 Linotype, the rest are 2 WW to 1 Linotype. All are gas checked, some powder coated, some Alox, some both.

Questions:

1) Is it common for a sizing die to produce bullets not exactly to size?
2) Is the .004 oversize I’m dealing with a concern?
3) Does hardness make it more of a concern?
4) Could the hardness and cast size effect the sizing dies performance?

Thanks for the help

MRM

 

[yomomma]

First, why so hard?

Second, how do they shoot?

 

[shootnprep]

Second how are you measuring?

 

[Andy]

Second how are you measuring?

My first impression is that the measurements are not accurate.

My experience with Lee Lube-sizers is that there can be a bit of "bounce-back" (maybe 1/2 a thou), but that they're accurate.

I'd be very surprised to see a 270 Win barrel so small. When slugging, you need to be sure that the slug you used in large enough in diameter and long enough that it will provide enough area of full diameter to measure.

 

[Spawn-Inc]

1. yes
2. no
3. more of a concern for what?
4. no, unless you tried to use steel bullets through the sizing die. i have sized jacketed bullets that where .358 down to .229 in 1 pass with lube and it still sizes lead to .229, though i didn't do alot of them.

 

[pjs]

Hi MRM,
I doubt that your groove diameter is the .2755" that you measured. I does not matter anyway. Your throat size determines your bullet diameter. Obviously you can not load a bullet larger than your throat allows. At the same time you do not want to load a bullet smaller than your throat as you will have damage from gas leaking past the bullet. The old accepted practice of sizing .001" larger than groove diameter is true only because that typically is the throat size. On a factory gun chamber it may be larger than this but not less than .001". In your factory .270 the throat is probably .279 give or take a thou. Load some bullets and try it.
Pete

 

[jethunter]

Questions:

1) Is it common for a sizing die to produce bullets not exactly to size?
2) Is the .004 oversize I’m dealing with a concern?
3) Does hardness make it more of a concern?
4) Could the hardness and cast size effect the sizing dies performance?

Thanks for the help

MRM

1, Yes, Very seldom that sizer dies are spot on
2. Yes. That's quite a bit oversize but could still work.... i have shot .004" over but that was with somewhat softer bullets than you are using. I think it would be OK but it's your call - if they will even chamber they will likely work but no guarantee.
3. Yes
4. Possibly, with some alloys you can get a slight amount of "springback" but it's usally under .001"

 

[MRM]

First, why so hard?

Second, how do they shoot?

I have been casting them hard because the Lyman 4th addition says to use #2 alloy or Linotype for the 270. Was aiming to split the difference and powder coat. As its my first batch, I was going to start hard and work down from there. May not be right, but that was the plan.

 

[MRM]

Second how are you measuring?

Not formally measuring, but I have linotype and pure lead to gauge from. Thumbnail, or tap with a hammer. Not sure how hard they are, but they are hard.

 

[MRM]

My first impression is that the measurements are not accurate.

My experience with Lee Lube-sizers is that there can be a bit of "bounce-back" (maybe 1/2 a thou), but that they're accurate.

I'd be very surprised to see a 270 Win barrel so small. When slugging, you need to be sure that the slug you used in large enough in diameter and long enough that it will provide enough area of full diameter to measure.

Just realized Shootnprep was referring to measuring size as well. Measured with a digital caliper and just now double checked with a 4” dial caliber. Same result. I slugged the barrel with a 00 buck that I rolled to .283 before slugging. Looks really good, but I will redo it tonight with a larger slug.

 

[MRM]

1. yes
2. no
3. more of a concern for what?
4. no, unless you tried to use steel bullets through the sizing die. i have sized jacketed bullets that where .358 down to .229 in 1 pass with lube and it still sizes lead to .229, though i didn't do alot of them.

3. My concern is overpressure. Wondering if a bullet a bit too large and a bit too hard could compound into a bad deal.

 

[Papaclaude]

3. My concern is overpressure. Wondering if a bullet a bit too large and a bit too hard could compound into a bad deal.

Not unless it's wayyy oversize. And lead should not be an issue even if it were. People have shot such weird cases such as 30 cal. out of 7 mm's, etc. and, other than extreme recoil, they caused no harm.

 

[yomomma]

Thats what I said, shoot them and let us know how they shoot.

Generally cast bullets are supposed to be 2-3 thou over

 

[Spawn-Inc]

my mistake, i was thinking you meant is it a concern to put an oversized bullet into a sizing die for it to be sized down. Not sure i would shoot a .279 bullet down a .275 bore if you could even get it into the brass and chamber it.