Savage 12FV in 223 Rem Accuracy Experiences

[SlowSqueeze]

FINDING THE 12FV’S LANDS (THE WRONG WAY)

Back when I started reloading the ammo I used in early 2016 I was specifically interested in getting the 69gr SMKs to 0.20” off the lands. Much of the reloading advice that I found online and in manuals suggested this was a good starting point for handloads. In order to get 0.020” off the lands however, I needed to know where the lands were in the chamber (DUH!).

Rather than spending money and purchasing a gauge, I figured I’d cheap out and make my own. I bought a $0.99 wooden dowel rod, and cut a slot in one of my spent cases (you can see the slot in the case below) and drilled out the primer pocket of the case to fit the dowel. I figured I won’t be measuring the lands very often, so spending $45 on a tool (and required case) didn’t make a lot of sense.



My solution works okay from a mechanical perspective, but the brass is a little tight around the bullet which makes it hard to find the lands by touch. Making matters worse, the tension on my homemade case was sufficiently high that it gave enough force to the bullet against the lands to bind- at least to bind enough to pull the bullet from the neck of the case. At that point I’d have to push my wooden dowel through the muzzle to dislodge the bullet, and then repeat the process all over with no reading (since I was relying on the neck to hold the bullet for the reading).

I also tried two different ways to measure things with this setup (and the next one):

1. Seat the bullet (it was hand tight) really long, and chamber the blank-round using the bolt to compress the bullet into the neck on the lands. Basically I’d push nice and slow into the lands and (hopefully) let the bullet seat deeper. Do that enough times and you should find a point where the bullet is never longer than X (the point where the lands are in theory).
   
   
2. The second approach was to seat the bullet way short and push the bullet forward using the dowel until it hit the lands. This is the method I alluded to above. The problem was the neck tension on the bullet was high enough that pushing the bullet forward with the dowel from behind was hard- when the bullet did contact the lands it was usually INTO the lands and got pulled from the case (i.e. start over).

Of the two methods closing the bolt down and compressing the bullet back tended to work a little more often.

NOTE: I DO NOT recommend using a homemade tool to measure the lands! This method turned out to be VERY inaccurate, and dangerous.

 

[SlowSqueeze]

FINDING THE 12FV’S LANDS (THE SECOND WRONG, BUT BETTER, WAY)

When I measured by lands way back in 2015 I didn’t have the OAL comparator and measured the length to the end of the SMKs. If you use SMKs of that vintage you know the tips aren’t straight or regular, meaning the tip of the bullet introduced error to the readings. These days Sierra also has tipped versions of the SMKs that have polymer tips on the bullets, so this is less of a problem with that variety.

I remedied the issue of error from irregular tips very quickly in early 2016- there’s no point measuring your lands if you aren’t going to measure bullets on the ogive. The solution was the Hornady Bullet Comparator and Insert Set. It's easy to use and eliminates any messy reading due to bullet tip shape.



Furthermore, my homemade method was laborious to use and seemed to have a wide spread in measurements. That’s not to say that my dowel concoction couldn’t work, but I’m not confident that I’ve got good readings. [Refer back to the sidebar conversation I had with Mozella about the role of ‘state of mind’ and confidence play in getting good groups.]

 

[SlowSqueeze]

FINDING THE RIFLE LANDS THE RIGHT WAY

Rehashing all that mess above got me thinking, it’s probably time I grew up and got a tool that would give me the precise readings I’m looking for. I checked my Cabela’s points, and pleasantly found that I had enough points to get a Hornady OAL Gauge and a 223 cartridge for the gauge with NO CASH out of pocket. That fact turned the tides a bit and flipped the question to:

You: “Why wouldn’t you take a free gauge Slow?”
SlowSqueeze: “Okay, okay, it's for a good cause.”



So there you go- if I had to do it over again, I’d just have bought this tool from the start. As a side bar, before you spend your money, I just got my RCBS Precision Mic for 223 Rem that also has a tool to measure the lands. I’ll post more details shortly, but the mic enables you to measure OAL, headspace, and the lands for a lower price than all three of the Hornady tools I’ve mentioned- it’s worth a look!

 

[SlowSqueeze]

SAFETY NOTE: MEASURE YOUR LANDS EFFECTIVELY

Here’s the data I gathered using the various methods of measuring my lands, starting with my homemade tool to those funky SMK tips (the wrong way), then two methods with my homemade tool and the Hornady Bullet Comparator and Insert Set (the second wrong way), then today with the Hornady OAL Gauge and the Hornady Bullet Comparator and Insert Set (an accurate and acceptable way). The results are pretty telling.



The information that I got from measuring my lands with the Hornady tool was certainly not what I was expecting. In fact, the information in the above table is quite alarming- I was cramming bullets WAY into the lands of my rifle and thereby increasing chamber pressures pretty dramatically. Given that I was loading my rounds to 2.180”, and that my lands start at 1.866”, that means I was pushing the bullet in over 5/16” of an inch, or 0.314”! Thankfully I was intentionally staying away from the heavy side of the IMR4064 charge weights- otherwise I could have been a candidate for the annual Darwin awards!

So take a note from SlowSqueeze- if you are going to be serious about loading ammunition to close tolerances of your rifle lands, get an accurate tool to measure them and don’t cheap out like I initially did.

Next up, HEADSPACE round two! It's at least a 3 round fight...

 

[SlowSqueeze]

HEADSPACE REVISITED (ROUND 2)

After discovering the issues I was having above with measuring my headspace (not just comparing it), I bought a RCBS Precision Mic set in 223. It was on sale on Midway for under $40, and was a good deal at that price. It finally arrived in the mail yesterday and I couldn’t wait to crack it open!

Here’s a picture of what you get in the case- it’s more than I was expecting since I didn’t really do a ton of research before buying it… That was a pleasant surprise!


I had to read the directions carefully to figure out what this thing was all about- and MAN do I hate HAVING to read directions to figure things out. In a nutshell, the mic is setup to provide readings from a relative standard, not an absolute measurement (i.e. 0.005” less than standard). What you really have to know to use the mic is the STANDARD that it’s set to. For 223 we know that the headspace minimum is 1.4636”, and that is what the RCBS Precision Mic ‘headspace nut’ is setup to measure from. There are two calibrated mic heads- the short one is for headspace, and the long one is for Overall Length (OAL) to the ogive. The bullet-looking thing is used to measure the leade and tells you where the lands are on your chamber (I’ll try that out soon and compare it to the Hornady measurements). Now, on to using the mic...

Slowsqueeze: “Oh, okay, I get it. That seems simple enough… So I put the case in here, and screw the headspace nut down, gently wiggle, and apply the slightest pressure and…?”

I got a reading 0.004” LESS than the minimum SAAMI headspace spec.

Slowsqueeze: “Huh, what did I miss…?” (reading directions) “Blah, blah, yep, okay… Hm, let’s try a new fire-formed case.”

This time I got a reading of, ready for this, 0.004” LESS than the SAAMI min headspace spec. COME ON! I was expecting something like 0.004” OVER the min spec, definitely not UNDER. So I got an idea- let’s measure the factory PMC Bronze ammo and see what the headspace is there. I’m expecting it to be just under the min SAAMI chamber headspace spec, or around 1.462”. That means my mic should be at the -0.001” mark on the gauge.

I got a -0.002”. Now, that’s not bad, and generally matches with my expectations that the ammo should be slightly less than the min SAAMI chamber headspace spec. The problem is the factory ammo headspace is BIGGER than my fire-formed brass headspace:

…. meaning my PMC brass headspace got SHORTER after firing;
…. meaning my 12FV chamber headspace is SMALLER than the SAAMI min spec??
…. (strongly doubt it!!)

 

[SlowSqueeze]

HEADSPACE ROUND 3 (DING!)

I vehemently dislike when things don’t add up or make sense. Like a dog licking a wound I just can’t leave things alone- and I’ve been licking this headspace wound for a while now. At this point I was left to twiddling the gauge and thinking, measuring a few cases, measuring some factory ammo, and thinking some more. Then I had a thought (something that tends to happen when thinking)- what if the mic wasn’t calibrated correctly? That would not explain why my fire-formed cases are shorter than the factory cases, but if things were off by, say 0.003” it would make a little more sense.

Now, I happen to have a 223 AI NO GO gauge around for another project (that fancy Savage 12 VLP is getting a new barrel soon). As it turns out, Mr. Ackley set things up so the NO GO gauge for an AI chamber has the same exact headspace as the GO gauge of that caliber (see this PDF from Pacific Tool and Gauge for more detail). So, my 223 AI NO GO gauge, from Pacific Tool and Gauge no less, is exactly 1.4636” (ok, maybe not to the 1/10,000 of an inch) and I can use that to verify the calibration of my new RCBS Precision Mic. Here’s a pic of the stuff, just ‘cause we all like pictures, right!?




I loaded up the gauge into the mic and then took a picture so you can see the reading. One of my beefs with the RCBS Precision Mic, besides the fact that it’s not calibrated correctly is the base (part you put the case into, on the left of the following picture) has really SMALL calibration marks that are wicked hard to read. I touched up the picture to make it a bit more obvious for you- hopefully you can see where the gauge indicates (where the 47.5 mark would be).




It turns out that my RCBS Precision Mic is 0.002” (strong) short on it’s calibration. Perhaps that’s the reason RCBS calls it the “Precision Mic” and not the “Accurate Mic”? (<- that’s some serious engineering geek humor there!)

I found this thread, near and dear to my heart with gory details, over at thefiringline.com that provides some really good information about what happens with headspace when you fire a cartridge. I’m not a metallurgist, but I can tell you at the level these guys are talking you have be aware of the difference between ‘plastic’ and ‘elastic’ flow in metals. For something more at my level, check out these articles on headspace:

1. Cartridge Headspace — Understanding the Basics on our own Accurateshooter
2. Gauging Success - Minimum Headspace and Maximum COL over at Brownells.com

#1 is a pretty direct and brief overview- as the title indicates with the “Basic” term. The second article, well, that’s simply an outstanding write up with what you’ll need for two critical topics- it’s worth the read!

 

[SlowSqueeze]

HEADSPACE, ROUND 4

So what am I to do when things don’t measure up (literally)? Take more measurements and investigate of course! I gathered up a sample of 1 box of factory PMC Bronze ammo (20 rounds per box), and 20 random fired cases from the garage to measure. It’s important to note, now that it’s getting cold, that I let the cases warm up to room temperature (~70 degrees) before I measured them. That prevents error from the cases warming up during the readings, stretching a bit from warmer temperatures, and causing the readings to be skewed over the measurements.

And here’s a bit of pay dirt for all the thinking I did- once I measured the fire-formed cases I sized them in the Lee full-length sizing die. I realized that some of my cases (most in fact) are 2 & 3 times fired- between firings there is sizing! At the time I was mostly using my basic Lee dies. There is no adjustment to the Lee die- it just does what it does across the whole case, and I’m sure the dimensions are conservative as well, so it will likely bump the shoulder back quite a bit.

NOTE: The data in the following table is corrected to adjust for the 0.002” in calibration error of my RCBS Precision Mic as measured above. In other words, these are my most accurate actual readings.

 

[SlowSqueeze]

HEADSPACE, 5th AND FINAL ROUND! (FOR NOW…)

In order to put this to rest, here’s what I will take from all this headspace nonsense.

1. My Savage 12FV in 223 chamber is headspaced to the SAAMI Minimum of 1.4636” (unsure about the 1/10,000” precision however, so rounding to 1.464” is probably in order).
2. The factory PMC Bronze ammunition is headspaced to 1.464”, meaning there is, on average, no headspace. Technically the headspace is below my instruments ability to read- in the 1/10,000” scale.
3. My Lee sizing die (which I used for most of the study) sizes the headspace UP to 1.4653”, leaving 0.002” of NEGATIVE headspace.

Therefore, I assume that, the elasticity of my full-length sized brass leaves 0.0002” (yes, 2/10,000”) of headspace AFTER fire-forming.

I guess it’s worth a swing at why the Lee die INCREASES headspace during sizing: I surmise that the die excessively sizes the case body, and forces the neck forward as a result (think of squeezing a water balloon and watching the ends pop out on the top and bottom of your clenched fist). I would also assume the die pushes the shoulder back down a bit to result in only 0.002” of negative headspace. That’s all me guessing though, so take it as such- I might be totally wrong...

 

[SlowSqueeze]

MEASURING BARREL TWIST (REALLY? MAN, I HAVE ISSUES!)

When I was getting heavily into the JBM ballistics calculator and the Powley Computer I began to notice how important barrel twist is when determining the weight of bullets that you can use in a specific rifle. The 12FV is published with a twist of 1:9, or 1 bullet rotation every 9”. If you play with the calculations you’ll see that a 1:8.5 vs a 1:9.5 twist change has quite an impact on projectile stabilization. So, in another feat of ‘get myself wrapped around the axle’ (or should we say ‘twisted in the barrel’?) I decided to measure my barrel twist to see how close it really is to 1:9.

But before I do, is this really necessary (should you do it)? Short answer, no. If you want to push the boundaries though, at try bullets above 70 gr (with a 1:9 twist), then yes. The barrel on my Savage 12FV, at a published 1:9” twist, can stabilize a 69-70gr bullet well, and mathematically a little heavier. If you want to shoot a 75gr bullet, well, that's pushing it, probably too far. Measuring your twist will tell you definitively where the line is on your barrel.

To accomplish this I took my cleaning rod, with the 223 bronze cleaning brush installed, and started it in my barrel from the muzzle end. This is a little hard to explain, but I took a piece of tape about 1.5” long and put in on the rod near the handle so the ends stuck together and ‘pointed’ away from the rod- in other words I didn’t wrap the tape around the rod in a spiral. I used this piece of tape to point up and show me when I’ve made 1 turn on the rod.

Next I slowly pushed the rod in until the tape was pointed up. At this point I marked the rod with a ‘Gold Metallic” sharpie right at the muzzle. I’m not thrilled to decorate the crown of my barrel with gold sharpie, but it’s the only color that would show on my gloss black cleaning rod- besides, it wipes off pretty quickly. After getting my base mark it was a pretty simple matter of gently pushing the brush down the bore and watching the tape until it rotated 360 degrees and was pointing back up and again marked the rod at the muzzle with my gold sharpie. The following picture shows the rod after I was done- it’s long and little hard to see, but the tape on the left is the pointer, and you can just make out the gold bands from the sharpie (annotated to help).




Now, this next part is REALLY important- I pushed the rod all the way through the action to make sure the brush was out of the barrel before reversing direction and pulling the rod out. This avoids the bristles on the bronze brush from gouging the bore when being reversed mid stroke.

Once the rod was out of the rifle I used a tape measure to carefully get a reading on the distance between my two marks. And the winner is…

 

[SlowSqueeze]

SLOWSQUEEZE USES BRONZE CLEANING BRUSHES

I’m not looking for a holy war, please, but I use bronze cleaning brushes in my barrels.

I subscribe to Ryan Cleckner’s point about metallic brushes not harming a rifle barrel. I don’t remember which video by number it was, but it was in the “How to clean your rifle” episode. If you have a top of the line barrel and don’t want to use a brass brush, more power to you. It just seems that a single bullet going down the bore does a lot more wear and tear than a bronze brush.

Here’s a little science to back it up. The following table includes the Brinell Hardness of a few common metals we come across in the shooting world.




From these numbers can can conclude that copper is the softest of these metals, so copper jackets on bullets don’t really stand much of a chance against any of the above- they will yield the fastest. More specific to the topic at hand, my bronze brushes (assumed to be common bronze) are softer than carbon steel in general, though it’s much closer. Pound for pound (given similar shapes) the steel would win the day, BUT, the bristles on my bronze brushes are much, MUCH smaller and thinner than the steel barrel (shape really matters on this point as well). Hence, while they likely do leave some very small marks on the barrel, I believe the bristle bending and creating a more favorable angle, and then contacting the steel takes more of a toll on the bristle end than the barrel.

For the record however, a set of similar nylon brushes sells for about $20. The only number I could find for nylon on the Brinell scale is around 20 (hard to compare ‘plastic’ to metals when it comes to being hard). So, when it is time to replace my brushes I’ll probably buy a set of nylon brushes- they’ll likely do the same job and I won’t even have to worry any damage from bristles.

 

[beemanjohn]

Wow. Just Wow! When you get finished with this project you should buy a target shotgun and start trying to figure out which high dollar choke makes the best pattern!

 

[SlowSqueeze]

CONCLUSIONS ABOUT MY 12FV 223 CHAMBER/BARREL

So, there you have it- I’ve measured up just about everything I can on my Savage 12FV, which I have included in the following table. You need to verify any of these measurements before using them for your 12FV in 223 however, so use the data at your own risk.

 

[SlowSqueeze]

SUMMARIZING CASE PREPARATION MEASURES AND SPECS

Given the above measurements for my chamber, the following table shows how I would have prepared my brass. It’s hard telling how much better my results would have been if I had this information before and wasn't doing 'basic' reloading. Here’s the summary, which might be useful for you to compare your measurements against. As always, use this information at your own risk.

 

[243winxb]

The Sierra 69 and Hornady 68 gr match bullets did well also in this stock 6 lb trigger Savage.

 

[Ned Ludd]

View attachment 1028582

1.866" - 0.020" = 1.666"

Better check your math before you start seating bullets.

 

[SlowSqueeze]

The Sierra 69 and Hornady 68 gr match bullets did well also in this stock 6 lb trigger Savage.

You have a few good groups there 243winxb. I would have anticipated the top row, and then the bottom row, having something in common since they are both pretty tight. The top row also looks similar… Hmmmm.

That’s exactly the reason I ended throwing up my hands and doing a way down in the weeds experiment- to get statistical results. Thanks for sharing!

1.866" - 0.020" = 1.666"
Better check your math before you start seating bullets.

DOH! It’s always the easy math that’ll get ya! Thanks for pointing that out! I’ve fixed all the points where I reference the OAL.

 

[SlowSqueeze]

EXCEPTIONAL HANDLOADING PRIMER ARTICLE

I’ll be posting my brass preparation process shortly, but wanted to let you know it is largely based on this EXCEPTIONAL article on our very own AccurateShooter.com by by Jacob Gottfredson. I must have read this article, word for word, about 15 times. And I’m not joking- I poured over it for many, many hours many, many times. The result, put simply, is I’m a changed man in terms of hand-loading.

If you know me, you’ll know I tend to take things to extremes (as shown above), and I’ve likely done that with my new process as well, which goes beyond what Jacob talks about. I don’t know if all this extra work (beyond Jacob’s write-up) will matter, but I don’t intent to leave it to speculation, which is a big part of why I’m doing all this work! I want to know what really drives accuracy and precision, and why. I’ll come back to the process in detail later on, but wanted to give you a chance to read up before I post my (sufficiently over thought) process in a little while.

 

[SlowSqueeze]

FINDING NECK SIZING REQUIREMENTS (PMC BRONZE EXAMPLE)

Note: The following only applies to the PMC brass cases that I have been studying in this thread. More accurately, it only applies to brass cases with a neck wall thickness of 0.011” and measured standard deviation of about 0.0005”. I will measure new case necks to determine the exact neck thickness and sizing needs for those cases. If you are following along, you will need to measure your case neck thickness as well- DO NOT take these numbers blindly.

From Jacob’s hand loading article above, in Step 9 we have the basic math to figure out the neck sizing requirements for the PMC brass IF I was going to turn the PMC brass on my lathe (I’m not though). To lay it all out, I’m using the table below.


So, per the article I would order 3 bushings that are 0.001”, 0.002”, and 0.003” less than 0.245”. In short I’d order bushings that are sized to 0.244”, 0.243”, and 0.242”. Like I said above, we’ll verify those measurements when we get to the shiny new Lapua brass that’s waiting in my garage!

 

[SlowSqueeze]

ACCURACY VS PRECISION

On a slight tangent, I think it's important to have a brief discussion about accuracy and precision. While I titled this article to be about accuracy, I'm really looking for BOTH accuracy AND precision. I guess I can sum it up by assuming the common statement that Savage rifles are 'accurate' to mean the rifles are both accurate and precise. If you want more information about accuracy and precision in simple technical terms, take a look at this site: http://celebrating200years.noaa.gov/magazine/tct/tct_side1.html.




Most of my time spent studying brass and loads has focused on PRECISION (bottom left target in the pic), not accuracy. My feelings are, if I can get 0.2” MOA precision, accuracy is simply a matter of adjusting my scope. In other words, as long as my groups are small, I’m not particularly concerned with where they land on the target for now- once I get my peak precision load I’ll make adjustments for accuracy (with high confidence).

Elite shooters (I'm not one) are likely less concerned with precision when they compete because they have already solved that part of the equation- they are concerned with the accuracy of each and every shot. Perhaps better stated, they care about how bad their worst shots (extremes) are. These folks understand enough about what’s going on that they can study the outliers/extremes- that means most of what I’m doing statistically right now in this thread isn’t as interesting because it’s defining the ‘normal’ case so I can effectively identify outliers and figure out what made them outliers...

 

[SlowSqueeze]

NOTE ABOUT STANDARD DEVIATION VS SPREAD/RANGE & VARIATION

I’m not going to go into super detail here, but through some PMs with a few folks on the site (namely Boyd Allen) it became obvious to me that my use of Standard Deviation may be misunderstood, and humbly, a little misguided. Furthermore, once you have established your stable methods for loading and shooting (whatever your precision and accuracy expectations), you’ll likely only care about the individual extremes.

I use Standard Deviation (St Dev, or SD) because I want to know the range in which most of samples (mostly brass) fall. One SD (34.1%) on either side of the average/mean (the zero point in the middle of the following figure) tells me where 68.2% of samples are (the dark blue area). Range and extreme spread do not tell me what I can ‘usually expect’ about the rest of my population (i.e. cases)- they only tell me how far out the edges are, which is what becomes more important once I (and perhaps you) figure out the basics.



I should disclose that I am, technically, not using SD appropriately because SD assumes a normal distribution or ‘bell curve’ in the sample just like the above figure. I know some of my samples are NOT bell curves, but I’m still using SD as a rough gauge. The above picture was snipped from the Standard_Deviation Wiki and does a pretty good job of showing you want I mean. If you want to know more, the Wiki is a pretty good overview…

Going forward I’m not going to be using SD as much and will instead, take the advice of others, and focus on the extremes- so I’ll be sharing the range in most cases with histogram plots when a visual would be helpful.