Did I pick the wrong rifle to hand load for?

[Blue68f100]

Sierra's are 69gr HPBT-M where Hornady is 68gr BTHP-M and 0.090" longer than the SMK.

I would load to max mag length which is 2.260" that is where all of mine are so they fit the mags of my AR's. This is also what length most data books list. Using Varget they are by far my best load.

 

[ironworkerwill]

Hornady publishes the load data for many/most of their ammo right on the box of loaded ammunition. I very much appreciate that. Why would they bother if "their" Varget was all that much different to the Varget I buy at my LGS?

well like I said, I could be wrong. But, I haven't purchased factory in some while other than a few boxes of pistol ammo.
I didn't know they put the actual loads on the boxes now! It seems a bit counter productive, but OK.

 

[Bart B.]

Freebore is a fixed dimension from chamber mouth to the start of the rifling at a fixed diameter a few thousandths bigger than bullets. How far a bullet moves before touching the rifling is bullet jump distance. There's little, if any, accuracy difference in commercial rifles over a 1/10th spread in bullet jump. Commercial ammo shoots virtually the same accuracy with its fixed OAL as bullet jump increases 1/10th inch fron bore wear and erosion over a few thousand rounds. And very little with match ammo.

Whatever OAL that feeds from magazine and/or gives best accuracy is OK. SAAMI OAL specs typically mean a length that works in SAAMI spec chambers and rifle magazines. I wouldn't waste time and material trying to squeeze another 2/10ths MOA accuracy out by making small changes in cartridge OAL with over the counter rifles.

 

[bikemutt]

Thanks for the clarification/correction on freebore Bart B. I misinformed myself on that one.

 

[horsey300]

OK, I picked up a box of SMK 68 grain bullets and decided to check a few things out before I play around.

I used my Hornady OAL gauge to measure the length of the cartridge when the ogive touches the lands. Just for grins I compared a brand new Black Hills (BH) cartridge to this imaginary cartridge. The BH bullet is clearly seated well off the lands.

Measured length to lands of the SMK in the gauge is 1.995", measured length of the BH round is 1.897". If we believe the SMK bullets BH used are identical to the ones I bought at a LGS, that implies the BH is seated 0.098" off the lands.

Furthermore the COAL of the BH is 2.242", the imaginary (resting on the lands) is 2.378". In other words, the BH is within the maximum COAL of 2.260" whereas the imaginary round is 0.118" over the maximum COAL. If I backed off the lands by 0.005 that would still leave my hand load 0.113" longer than maximum. I don't know how important the maximum SAAMI COAL is in a bolt rifle, I'm guessing it might cause feeding problems in auto loaders.

In any event, the BH round clearly has a respectable amount of freebore in this particular rifle.

So, should I start with the SMKs seated similar to the BH, see how that goes and sneak up on less freebore? Or play the kiss-the-lands game and increase freebore to see if I can meet or beat the BH that way?

The bottom one is the BH cartridge.

I'd seat at bh length or Sierra book length and if it still ain't working try a new powder (tac was suggested or another you have been curious about and itching to try) after you get the groups close to what you're looking for, you could reduce the jump just a bit if you want, (I'd use a chronograph here to see how much you're affecting pressure as you go and add or reduce powder as needed to stay within your sweet spot zone) I agree with Bart that kissing the lands etc is not really something I worry about in an over the counter gun. For me I want the best accuracy I can get whilst feeding from the magazine and ejecting safely and reliably. Also would like to add (since I forgot to before) that while pushing for the best of the best is commendable, the groups you're getting are nothing to be ashamed of.

 

[bikemutt]

Thanks a lot for your encouraging words horsey300. I've learned so much just from this thread, I can't thank everyone enough.

My focus concerning bullet jump has come from a few fellow hand loaders for whom it seems like the holy grail. All but one of them shoot over-the-counter retail rifles. I'm really glad to learn that's not necessarily where I need to start, maybe it's something to try eventually. I'm going to spend more time on my case prep and loading consistency than obsessing about bullet jump.

 

[Captaingyro]

Sounds to me like you have a perfect rifle to hand load for and good baseline ammunition as well.

You have a chance to learn much more that you would with a rifle that shot nothing well. You are not going to see significant improvements in reduction of group size but your methods on reloading could benefit greatly.

I came here to say almost exactly this same thing; couldn't have said it better.

Do you have any idea how many shooters would love to have your problem?

 

[Bart B.]

The only case prep you really need to do is trim 'em to minimum length when they grow to maximum. Any where in between is ok. All that other case prep stuff is just an emotional improvement operation. Until your biggest groups are 1/3 MOA at 100 yards. Then you'll seldom, if ever, see any difference.

If more folks judge accuracy by at least 15 shots per test group for any change to the round, they might learn case and charge weight plus OAL have a wide range of excellent results. Commercial match ammo shoots very precise in most rifles with the same small numbers above zero for all components' spread in spite of a wide range of bore and chamber dimensions. That ammo's load consistency is not as good as most folks strive for and often do.

Arsenal 30 caliber match ammo at its best tested 10 to 12 inches extreme spread at 600 yards. Replacing its bullet with a Sierra 168, 175 or 180 grain match bullet resulted with 3 to 4 inch test groups; in spite of .003" spread in case headspace, .35 grain spread in charge weight, .006"'spread in case length, .003" spread in bullet runout and .060" spread in OAL. Go figure out why it shot so precise with all those sloppy measurements over a .070" spread in bullet jump to the rifling across several barrels.

 

[lightman]

As stated, Black Hills ammo has a good reputation for accuracy. Also, you are chasing your tail by trying to make a Hornady bullet shoot as well as a Sierra. Just my opinion, but its based on a lot of real life experience. Buy a box of Sierra's and give them a try.

 

[Wreck-n-Crew]

Freebore is a fixed dimension from chamber mouth to the start of the rifling at a fixed diameter a few thousandths bigger than bullets. How far a bullet moves before touching the rifling is bullet jump distance. There's little, if any, accuracy difference in commercial rifles over a 1/10th spread in bullet jump. Commercial ammo shoots virtually the same accuracy with its fixed OAL as bullet jump increases 1/10th inch fron bore wear and erosion over a few thousand rounds. And very little with match ammo.

Whatever OAL that feeds from magazine and/or gives best accuracy is OK. SAAMI OAL specs typically mean a length that works in SAAMI spec chambers and rifle magazines. I wouldn't waste time and material trying to squeeze another 2/10ths MOA accuracy out by making small changes in cartridge OAL with over the counter rifles.

If I am following along correctly, your point is working up a load should not include the bullet jump until you have an accurate load to begin with. Good point.

By taking out a factor that has a small effect on accuracy and a large effect on confusion (self doubt leading to rethinking materials used, or your own process and its accuracy) an accurate load can be achieved much quicker and with a lot less testing. Then one can attempt to fine tune a load by adjusting length..... if at all! Keeping in mind that the more one shoots the more that one load set for bullet jump changes due to erosion.

Great stuff and great advice!

 

[Bart B.]

Also, you are chasing your tail by trying to make a Hornady bullet shoot as well as a Sierra.

Here's an interesting fact. Hornady's accuracy standard for their match bullets is all 10-shot test groups shoot inside .95" in their 200 yard indoor test range. Sierra's is 1.00" in their 200 yard indoor range for their 10-shot groups. Is .050" difference really important at 200 yards?

 

[murf]

bikemutt,

suggest you start partial full sizing your cases and get rid of the crimp. neck sizing is holding you back, imo.

murf

 

[Walkalong]

Is .050" difference really important at 200 yards?

It depends. I lost an aggregate by .0012 once.

But the point is well taken, it wasn't the accuracy potential of the bullet(s) that got me.

 

[Bart B.]

suggest you start partial full sizing your cases and get rid of the crimp.

So you want him to raise the full length sizing die up a half turn or more so the fired case shoulder gets moved forward a little when sizing's done so when chambered, the bolt will bind a tiny bit very slightly crunching the case shoulder tight and well centered in the chamber shoulder?

That's what typically happens when bottleneck cases are partially full length sized; that's when part of the neck is sized, but not all of it.

 

[farmerboy78]

So you want him to raise the full length sizing die up a half turn or more so the fired case shoulder gets moved forward a little when sizing's done so when chambered, the bolt will bind a tiny bit very slightly crunching the case shoulder tight and well centered in the chamber shoulder?

That's what typically happens when bottleneck cases are partially full length sized; that's when part of the neck is sized, but not all of it.

This is exactly how I resize for my bolt guns. I bump the shoulders in my semi-autos

 

[murf]

bart b.,

partial full length resizing is using a full length resizing die and sizing the case just enough so the bolt closes on the case with no binding when closing the bolt. the idea is to have a minimum amount of delta headspace (difference between chamber headspace and case headspace (distance from case head to the point on the case shoulder that contacts the chamber)).

bikemutt is currently neck sizing with a bushing die.

murf

 

[Bart B.]

murf, that differs from the traditional meaning.

In talks with reloading industry folks who make the dies, partial full length sizing is setting the die to size part of the case neck and not touch the shoulder at all. That moves a fired case shoulder forward such that when rechambered, it binds the bolt a little satisfying the "snug fit" the reloader wants the case to fit the chamber. Any sizing that completely sizes the neck and keeps the case shoulder at its same place is called full length sizing. That's because the shoulder that's squished forward when most of the case going into the die that sizes down the body pushing it there, is set back to its original fired position.

This is also the meaning most reloaders have for that terminology. When I asked a SAAMI rep about this, he agreed with me. He also said that the SAAMI glossary doesn't mention "partial" sizing with a full length die, some people have suggested it be put in. But there's so many different interpretations of the term that SAAMI hasn't done so.

Your "delta headspace" term is covered in SAAMI's glossary as "head clearance." Your use of that term is the first I've noticed it. Most folks use "head clearance" to keep in step with the "industry standard" of SAAMI. Some still call it "head space" which it was originally when only rimmed cartridges were all that existed. But the industry changed that in the early 1900's when so many rimless cases were used.

farmerboy78, regarding your comment on partial full length sizing:

This is exactly how I resize for my bolt guns. I bump the shoulders in my semi-aut

Is there any other way the case shoulder can be pushed forward to center in the chamber shoulder before the round's fired?

 

[Walkalong]

In talks with reloading industry folks who make the dies, partial full length sizing is setting the die to size part of the case neck and not touch the shoulder at all.

Interesting, I have always considered it PFL if the neck is completely sized, and the body is sized, and the shoulder is merely moved a little compared to as much as the die will allow, but I never checked with reloading industry folks either. The way I figure it, it can't be FL if the shoulder isn't moved and the neck isn't fully sized. I guess I am wrong, but that is how I look at it. Neck sizing of course touches only the neck, whether one sizes it all or not (Partial neck sizing). If one tries to size only part of the neck with a FL sizer, the shoulder can get moved forward from the body being squeezed in and cause problems, so it doesn't make sense to me to try to partial neck size with a FL die. Instead, set the FL die to barely touch the shoulder and hold it where it is or maybe move it .001. So in my mind, I just full length sized, partially.

The better solution to FL sizing with partial neck sizing is a FL bushing style sizer. IMHO of course.

YMMV.

 

[murf]

bart b.,

yes, mass confusion on the different styles of case sizing. there is no universal agreement on what to call which (45 colt vs 45 long colt, etc.)!

i use "delta headspace" instead of "head clearance" because the end result of this sizing operation is to create a specific difference (a slop fit, if you will) between the case head/case shoulder (datum) distance and the chamber headspace distance (the number given in the saami cartridge drawing). head clearance is a misnomer imo.

anyway, there is total disagreement on what to call this thing.

and, i still think bikemutt should start sizing his cases this way (whatever we may call it).

"partial full length resizing" is what us old-timers called, what you (us) now call, "head clearance". more confusion added to the mix.

do you have a suggestion as to what we, here at thr, should call this thing? walkalong, your opinion as well?

murf

 

[Bart B.]

do you have a suggestion as to what we, here at thr, should call this thing?

Yes. Head clearance for the space between bolt face and case head. That's where clearance is when the round fires. Before then, it could be anywhere, which is why its firing position is the important constant.

That's what the industry standard has in their glossary which all companies suscribing to SAAMI standards agreed to. The reason is that when a round's fired, the firing pin has driven in as far forward into the chamber its dimensions will allow. That's the case shoulder against chamber shoulder, belt against chamber belt stop, rim against chamber rim stop; all depending on what type case there is. So, when the round fires, there's some space between the bolt/breech face and case head. Extractors don't hold case heads against bolt faces. So "head clearance" became the defacto standard decades ago.

Some don't. Hornady calls the space between bolt face and case head "head space" in their web site's FAQ section. When on tour of their plant, I asked them about that. The employee I asked got bent out of shape saying bad things to me, put politely so.

I think partial full length sizing should mean any way that the neck is not completely sized all the way to the shoulder and the shoulder's now forward from its fired position. If all the neck's sized but the shoulder's still at its fired position relative to the case head, that's still partial full length sizing because all of the case isn't sized. Only when all of the case outside dimensions forward of the extractor groove or belt or rim are reduced, is it just plain full length sizing.

The above's for rimless bottleneck cases. For belted and rimmed cases, they can have "shoulder clearance. If their size is such that when the headspacing part of the case is against its stop in the chamber, the case shoulder may not be touching the chamber shoulder. I've never seen "shoulder clearance" mentioned anywhere. But there sure is some with such cases when fired. Belted magnum new cases virtually always have some shoulder clearance when fired.

Hope I said what I mean; at my age, (one year short of four score) I'm often a smidgen or 3 short of perfect and well understood by others.

The better solution to FL sizing with partial neck sizing is a FL bushing style sizer.

They are typically much better. Sierra uses Redding full bushing dies on all cases they're made for testing their stuff for accuracy. Standard Redding full length dies for all the rest. On one tour through their plant, I was told I'd be asked to leave if I mentioned neck only sizing in any way.

My preference is a full length sizing die whose neck's honed out to the right size to size the neck down to the right mouth diameter so an expander ball isn't used. Case necks are straighter and better aligned with case shoulders and bodies because all three are kept in line during sizing. Bushings have a couple thousandths clearance to their chamber in the die so any variation in case neck wall thickness may or may not end up with the case neck perfectly in line with the case body and shoulder. It's the shoulder up front that centers the case neck and bullet in the bore. There's no centering at all by the chamber neck because it's always larger in diameter than the case neck.

I think it was Sierra Bullets' first ballistics man who resized then loaded cases to test all their bullets to shoot them for QC checks that proved all this. That was back in the 1950's.

 

[murf]

found it (head clearance) in the saami glossary. thx for the heads up (pun intended). still think it should be called "head/breech clearance", or some such, as there is no "head" in the chamber and "clearance" denotes a distance from something else, but i'm just whining. i'll relent and start calling it head clearance.

partial full length sizing could include sizing with a body die, so i'm still not with you on that. one can partially size a neck with either a neck die or a full length die, so "partial neck size" could also be used to describe this operation.

apparently, we need a new term for what we used to call "partial full length size". maybe call it "shoulder bump sizing"? who knows. in the mean time, when i say partial full length sizing, i mean bumping the shoulder back with a full length sizing die.

murf

 

[Bart B.]

Well, there's a case head in the chamber and that's at different places relative to the bolt face when the round's fired. The bolt face is always in the same place +/- .000003" so that 's why the head is clear of the bolt face by some amount. It varies by case headspace to the chamber headspace stop point.

The bolt/breech face is the standard reference for all length dimensions to chamber points, so, seems to me it should be the reference to where cartridges position themselves when fired.

 

[bikemutt]

I have a question about OAL for the Hornady 68 grain Match and the Sierra 69 grain Matchking bullets.

When I measure the factory Black Hills (BH) cartridge OAL, it's right at 2.250" average with SMK bullets. Looking at the Hornady reloading manual for their Match bullet, they recommend an OAL of 2.250", same as the BH cartridges measures.

Now, the Hornady bullet is a 0.082" longer than the SMK. If I seat the Hornday bullet to the same OAL as the SMK it's going to be 0.082" further into the case. So, should I seat the Hornday with the same OAL as the SMK, or seat it with an OAL of 2.332 so that the amount of bullet inside the case is identical to the SMK? As a followup, if I seat the Hornady to specification, should I be concerned about compressing the powder charge?

Thanks

 

[Bart B.]

As long as powder's not compressed, whatever length does best in your rifle is good enough.

Reloading data typically specifies an OAL for how they loaded their ammo with. It can vary a whole lot depending on the chamber it'll be used in as well as the magazine it'll be charged in. OAL is not carved in wood nor chipped in stone nor stamped in metal.

 

[bikemutt]

Good to know, I'll try seating some Hornady's to "spec", and some to the same internal depth as the SMKs. I guess that's the great thing about hand loading, I get to experiment within the bounds of safety.