reloading question

[AmbulanceDriver]

So gents, I know that some of us are members over at TFL - figured that I would ask the brain trust over here the same question that I posted over at TFL.  

http://thefiringline.com/forums/showthread.php?p=6336318#post6336318

So, admittedly, my methods were slightly crude in this experiment, but I wanted to share what I discovered today.

First, the backstory - I have two rifles chambered in .30-06. One is an M1 Garand I obtained from the CMP, the other is a Marlin XL-7.

After doing some load development for the Garand, I found a combination that it *really* liked. Sierra MatchKing 168gr HPBT, HXP brass, Winchester standard primers (what I could find at the time - prefer CCI, but whatever) and 45.5 grains of H4895. Sub 1.5MOA group at 100 yards off the bench, better than I have a right to ask of a 60+ year old rifle with iron sights

So I thought I would try the same cartridge in the Marlin..... Funny, the rounds won't chamber properly. Have to really reef on the bolt to get it to close... Well there's no way I'm pulling the trigger on that round, extracted just fine, no obvious scratches or anything that would make me think there's a burr in the chamber. Feeds factory ammo just fine, and getting 1 MOA groups at 100 yards with factory ammo - sweet. Long story short, the chamber on the Marlin is a little shorter than the Garand. No biggie, just means working up a different load entirely, but figured that would be the case anyways.

So I decided to make a poor man's OAL gauge by following the instructions here: http://www.larrywillis.com/OAL.html

The methodology:

After making the gauge from a sized .30-06 case, I randomly selected 3 bullets from each box of bullets, and measured each bullet 3 times. To attempt to maintain consistency, I squeezed the case mouth until the cut slits were touching (closed) between each measurement. I inserted the case/bullet into the chamber, then slowly closed the bolt by pushing it forward until I could just use the locking lugs to finish pushing the bolt forward as I levered the bolt down. Left the bolt closed for 1 second, then slowly opened the bolt and extracted the cartridge. I then measured it with a Lyman 6" dial caliper. The two data points I failed to obtain that I should have - bullet diameter, and bullet weight.

The results:

Sierra MatchKing 168gr HPBT (#2200)
Bullet 1) 3.247" 3.247" 3.246"
Bullet 2) 3.249" 3.249" 3.249"
Bullet 3) 3.260" 3.261" 3.261"

Hornady Match 168gr BTHP (#30501)
Bullet 1) 3.243" 3.244" 3.243"
Bullet 2) 3.240" 3.242" 3.241"
Bullet 3) 3.236" 3.236" 3.236"

Hornady 150gr FMJ/BT (#3037)
Bullet 1) 3.232" 3.233" 3.234"
Bullet 2) 3.236" 3.237" 3.235"
Bullet 3) 3.239" 3.237" 3.234"


The question:

I've heard for accuracy, you should seat the bullet (x) thousandths of an inch back from the rifling. With measurements like the above, how would you go about determining how far back you should set your bullet? Because as an example, even with the SMK's, the shortest measurement was 3.246", and the longest 3.261" - that's a difference of 15 thousandths of an inch. If I'm supposed to seat them 10 thousands off the rifling, as an example - well, how would I do that? If I go with 3.246", so I seat them at 3.236" - well the one that measured at 3.261" is gonna be jammed into the rifling. And if the distance from the rifling is so critical - well then if we go the other way, that means that instead of a 10 thousandths jump to the rifling, we're now at 25 thousandths - and from a non-benchrest rifle - is that difference *that* critical?



Oh, and just for reference, the Garand loads were set at 3.330 - 10 thousandths short of SAAMI Max OAL

[RoadKingLarry]

How are you resizing the cases?
Cases fired in one bolt rifle and fire formed to that chamber may be a poor fit in another rifle of the same caliber.

[AmbulanceDriver]

Full length sized with a Lee die

[AmbulanceDriver]

The problem though is that the Garand loads were almost a full tenth of an inch too long for the Marlin

[Scout26]

Full length sized with a Lee die

You'll have to work up loads for each gun.  (Especially when going from a semi- to bolt action.  The brass has been fire formed in the last gun they were fired in.  If that's the Garand, then they are not going to work in a bolt gun.  Full length sizer die from Lee is the only option.

The problem though is that the Garand loads were almost a full tenth of an inch too long for the Marlin

Due to throat erosion in the Garand.

He'll have to work up separate loads for each gun...

[HankB]

Keep gasgun reloads and brass separate from bolt action reloads and brass.

From what I've seen written by experts in service rifles is that even if the brass LOOKS good, gasgun reloads (M1, M1A, M14) should not reuse the brass more than 4 times due to internal stretching at the case head. Keep track of this!

Also - be aware of the overall case length; you may have to trim the cases at some point so the case head to case mouth distance doesn't exceed, IIRC, 2.494".

[brimic]

1: don't mix brass between 2 rifles. Headspace is different, As are other chamber dimensions. If you must, use a small base die when resizing. Try chavering an empty sized case, if there is resistance, there is something wrong with your resizing,
2: bullet seating- I've done it a few ways, but the bestest, easiest, most accurate way is with a  Stoney point guage(now Hornady, I think). You can make your own version for fairly cheap if you can thread tubing and d&t a case.(a friend of mine made one up for me for use in Schmidt-Rubins which Hornady doesn't make a case guage for. When you use these gauges, put the butt of the rifle on a bench or table and slowly push bullet until you feel resistance, then stop. You can pretty easily force the bullet to engave on the rifling and throw off your measurement if you push too hard. SMKs are tangent I give bullets and aren't usually too sensitive to seating length as secant or Vlds. Start 0.010 off the lands, and try increments 0.030"apart until you find a sweet spot then narrow down further if you like. You should use a bullet ogive comparator for measuring oal and setting up your seating die, but SMKs are pretty consistant and you can get away without one.
3. Resizing: do use a cartridge headspace guage to set up your resizing die for your M1(or AR-15, or M14), sizing the case too long can give you a slam fire, too short and you risk case head separation. My M1 has a tight headspace and isn't a problem, but I've also reloaded for AR-15s where the cases grew by 0.007"! You want to bump the case shoulder back 0.001" and make sure it chambers freely, if not, take it back another 0.001". I don't think lee has this issue with their instructions, but RCBS definitely does- never simply set a sizing die to 'cam over' per instructions and call it good enough.

Your load sounds about right- 45-46gr 4895 or 47-48gr of 4064 with a 168 SMK usually shoots great in all rifles, though you are limiting yourself to 'safe' M1 loads.
I would go with a slower powder like 4350 for the bolt rifle for more velocity. Just my humble opinion.

Source: my 20+years of reloading in 40+ different rifles.
Source:

[AmbulanceDriver]

Guys, were missing the point here. I already know I'm going to need different loads for the different rifles. Here's the actual question again:

Specifically for the Marlin

I've heard for accuracy, you should seat the bullet (x) thousandths of an inch back from the rifling. With measurements like the above, how would you go about determining how far back you should set your bullet? Because as an example, even with the SMK's, the shortest measurement was 3.246", and the longest 3.261" - that's a difference of 15 thousandths of an inch. If I'm supposed to seat them 10 thousands off the rifling, as an example - well, how would I do that? If I go with 3.246", so I seat them at 3.236" - well the one that measured at 3.261" is gonna be jammed into the rifling. And if the distance from the rifling is so critical - well then if we go the other way, that means that instead of a 10 thousandths jump to the rifling, we're now at 25 thousandths - and from a non-benchrest rifle - is that difference *that* critical?

[brimic]

Use a gizmo like this: (note top one is the home made version for the S-Rs)

Measure several times until you get consistent measurements- should only vary by a few thou.
Write this number down- whether you are measuring bullet tip to base or base to ogive using a bullet comparator.
Your case prep must be good- consistent headspace, necks trimmed/chamfered.

Start seating your bullet in an empty case.
If you are using a Lee die, you'll have a 18TPI adjustor which will give you about 0.055+/-" per turn or about 0.014" per 1/4 turn. measure, reseat, measure, reseat until you get the length you want, start out long, put this case aside.
Load a live round. seat it .010" deeper by turning your seater plug in <1/4 turn, measure, adjust, measure until you get it where you want it. Rinse, repeat for other seating depths you want to try.
That first dummy round you made? Size it to the eventual length that works best in your rifle, use it as a reference for setting up your seating die in the future- write the length, and rifle name on it with a sharpie.

[AmbulanceDriver]

Ok.   I have the data - the question is - how do I choose a seating length when the length is varying by as much as 15 thousandths from bullet to bullet within the same lot of bullets?

[brimic]

As far as seating length goes,don't get too wrapped up in it unless you are reloading for benchrest or F-class and are trying to eek a bit of extra accuracy out of the ammo.
I generally set .020" off the lands or magazine length (whichever is shorter) to start, and shoot a ladder in duplicate to get an idea of what my powder charge needs to be, tweak the powder charge, and I usually call it good enough.

[brimic]

Ok.   I have the data - the question is - how do I choose a seating length when the length is varying by as much as 15 thousandths from bullet to bullet within the same lot of bullets?

ok, I think I get the problem now...
A: are your measurements consistant? Can you use the sam ebullet and get the same measurement repeatably?
B: How are you measuring your OAL? tip to base or ogive to base?

[Jim147]

The bullets out of the same batch are not that far off each other so it has to be your method.
Take your shortest length and subtract from that.

[zxcvbob]

If you reload for the Marlin, using a powder that's also appropriate for the Garand, won't the loads work in both?  I don't see a problem.  Or have separate loads for each (you can use slower powders for the Marlin that way.)

[bedlamite]

I've seen some lots of bullets that vary by .020". Don't get too wrapped up in OAL, most of the variation is in the tip and the ogive is usually pretty consistent. Use something like this with a caliper to measure how deep the bullet is seated.

To find out where to seat the bullets, tun a test of 5 bullets each at .020, .030, .040, and .050 from the lands, just like you would with different powder charges and pick the one with the best group.

[AmbulanceDriver]

ok, I think I get the problem now...
A: are your measurements consistant? Can you use the sam ebullet and get the same measurement repeatably?
B: How are you measuring your OAL? tip to base or ogive to base?

A:  yes.   if you look at the data in the first post you'll see that all three measurements for each bullet are within a couple thousandths of each other.   
B:  base to tip.  I guess my concern is that, if I remember the shape of the bullet seating "plug" in the lee die, it sets the length off the tip.  I mean, maybe I'm overthinking it here, but if it does seat off the tip, then using the data from the SMK's we're looking at a difference from bullet 1 to bullet 3 of 15 thousandths.   So if the bullet depth on the lee die is set by the tip, then it's going to push the ogive off the rifling an additional 15 thousandths.   

[brimic]

Which lee die do you have- there are two completely different seating dies, their standard die and their dead length die.
their standard die has a cone shaped seater plug, its angled so that it shouldnt hit the tip, but maybe 1/8 inch back.
The DL die uses a hole to push against the ogive.

either way, its going to be more consistent than measurements taken from tip to base. The overall length, tip to base, doesn't matter for anything other than magazine function, the ogive to rifling distance is what matters.
If you are really worried about it, get the gizmo that bedlamite linked in his post. The same tool has sets of inserts for measuring cartridge headspace as well.

[AmbulanceDriver]

Yeah, I think I'm going to get the comparator he linked to.   That should be giving me a better idea of what I'm looking at.

[K Frame]

The problem though is that the Garand loads were almost a full tenth of an inch too long for the Marlin

The cases were a 1/10 of an inch longer, or the entire loaded cartridge?

If the cases, sounds to me like you've got a headspace problem with the Garand.

If the loaded cartridge, the Marlin has a tight chamber and leade.

[AmbulanceDriver]

The cases were a 1/10 of an inch longer, or the entire loaded cartridge?

If the cases, sounds to me like you've got a headspace problem with the Garand.

If the loaded cartridge, the Marlin has a tight chamber and leade.

The loaded cartridge.  And yeah, the leade on the Marlin is definitely shorter than on the Garand - decided to do the same measurement on the Garand that I did on the Marlin and found the OAL to be 3.370 - so the bullet on the Garand is jumping 40 thousandths.  I don't remember what the TE gauged at when I bought it (had a card attached that said what the MW and TE gauge readings were when I bought it from the CMP).  But this is a field grade rifle.  I'm not expecting it to be a sub-MOA gun.   

The Marlin, on the other hand, I know can produce sub-MOA results.  So I want to wring every bit of accuracy that I can out of that rifle.

[HankB]

2: bullet seating- I've done it a few ways, but the bestest, easiest, most accurate way is with a  Stoney point guage(now Hornady, I think). You can make your own version for fairly cheap if you can thread tubing and d&t a case.(a friend of mine made one up for me for use in Schmidt-Rubins which Hornady doesn't make a case guage for. When you use these gauges, put the butt of the rifle on a bench or table and slowly push bullet until you feel resistance, then stop. You can pretty easily force the bullet to engave on the rifling and throw off your measurement if you push too hard. SMKs are tangent I give bullets and aren't usually too sensitive to seating length as secant or Vlds. Start 0.010 off the lands, and try increments 0.030"apart until you find a sweet spot then narrow down further if you like. You should use a bullet ogive comparator for measuring oal and setting up your seating die, but SMKs are pretty consistant and you can get away without one.

I talked to the inventor of the Stoney Point gauge at an NRA convention quite a few years ago. He told me that he liked to set the bullet depth by putting the rifle in a horizontal cradle and using a lightweight dowel or ramrod down the muzzle as well as the rod at the back of the device. He said that by gently using your left and right forefingers to move the bullet back and forth by gently pushing on the muzzle and chamber end rods, you could feel where the bullet just barely touched the lands. Then you could tighten the device down and you'd be just as accurate as if it were set by a micrometer. (This is for a bolt action rifle.)

My .30/06 Garand is a service grade rifle, and my eyes aren't good enough to consistently shoot 1.5 MOA with iron sights. I have a scoped match-grade M1A (7.62 NATO, not .30/06 of course) which is a sub-MOA rifle, and I found 4064 powder gave better results than the usually recommended 4895. I've read that Federal uses non-cannister lots of 4064 for their Gold Medal Match ammo in both .30/06 and 7.62 NATO - or at least, they used to.

Here's an article about loading for the M14 - many of the same considerations apply to the M1. http://www.zediker.com/downloads/14_loading.pdf