New reloader / .308 load development questions

R

Red Doggy

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Data for questions

Savage 12FV .308 with Bell & Carlson Stock, Harris Swivel Bipod, Protektor Rear Bag, and Nightforce SHV 5-20x56 MOA reticle
1/10 Twist 18 Inch Barrel

Action Screws Torque: 40 Inch Pounds
Scope Screws Torque: 18 Inch Pounds
Case: Once Fire Formed Federal fgmm
Trim Case Length to: 2.01
Bullet: 175gr Tipped Sierra Matching SD:.264 BC: .545
COAL that touches Lands: 2.832
Powder: IMR 4064
Primer: CCI #200 Large Rifle Primer
Headspace: fire formed, Slightly stiff bolt

Initial Testing COAL 2.820 = .012 off lands/ 4 Shot Groups
Shot in 30-40 Degree Weather 4 MPH Steady wind

TESTING RESULTS
41.60 Gr-------------------------.560 4 shot group
41.80 Gr-------------------------1.386
42.00 Gr-------------------------1.084
42.30 Gr--------------------------1.016
42.60 Gr--------------------------.471 4 Shot Group
42.8 Gr----------------------------1.026

My Findings of Initial Testing:
focus on 41.5-41.6 & 42.5-42.6 Powder Charges at different seating depths

Focused Testing loads I have ready to go for next trip out:

COAL at 2.805:----------------COAL at 2.820: Retest--------COAL at 2.830:
41.5 Gr------------------------ 41.5 Gr-------------------------41.5 Gr
41.6 Gr-------------------------41.6 Gr-------------------------41.6 Gr
42.5 Gr-------------------------42.5 Gr-------------------------42.5 Gr
42.6 Gr-------------------------42.6 Gr-------------------------42.6 Gr

Questions:
1. Is a little bit of a stiff bolt (Tight Head space) dangerous or will it wear out my bolt prematurely? I have read it helps accuracy so I have left my fire formed brass a little tight in chamber when I resize it.

2. What’s your experience on group size in say 30-40-degree weather compared to 70-80-degree weather? Specifically, could my optimal load be different depending on temperature? If so how much different did your rifle perform in a 40-degree change of weather as far as group size. I want to know if I’m wasting my time because the shooting I will be doing will likely occur in 70-80-degree weather and not the 30-40 i'm testing in this winter.

3. Penny for your thoughts on seating depth and any other tips or suggestions you think might help me as I try to find the optimal hand load for my rifle.

4. Would you test further bullet jump to the lands then I am? Anybody an advocate of trying jamming here?

I am completely new to hand loading, (just got equipment couple weeks ago) this is my first attempt at it, and I don’t know anyone who does it well enough to ask them for help, so I’m reaching out here for any help or insight from experienced hand loaders. I have a Hornady reloading book, the internet, and hopefully you guys.

Any advice would be appreciated.

Thanks,
 
Personally, I don't go purely on group size. Find three groups that have a similar poi( point of impact) and go with the middle of the three.

How close to pressure signs are you at your current load? 40 degree swing may put you over pressure, although I don't know how temp sensitive your powder is.

The best thing to do is find a load that works harmonically with your rifle, and know that, let's say, at 30 degree ammo temp out shoots an inch lower at 100 than at 75 degree ammo temp. I prefer to do load testing me the summer. That eliminates finding out in the summer that my load is too hot.

That's about all the questions you asked that I have experience with.
 
I did notice that 41.6 gr poi was high 42.6 was in middle and 42.8 was low. So I think 42.6 is in middle of vibration. What u said makes sense. Is that like an example of a node? I see no pressure signs at 42.6.
 
That is more an example of the harmonics of the rifle.

What I would do it's load a set of your min to max in .3 grain increments. It seems you do two right next to each other then jump almost a whole grain and another set right next to each other.

Then print out an ocw target. You can then see where the groups hit, and how tight the groups are. Then you'll see a few different charges with a very similar poi (average impact point of all the shots). The harmonic "node" commonly referred to is when the bullet is leaving the barrel at its least deformed state. Barrels whip and move around a ton with all the vibrations that happen with the firing of the round.

What is your ultimate purpose of the rifle? Hunting? Plinking? F class? I know a few guys that run 6mmbr's for f class with insane jam. Having a little jump may be better for your application. Just gotta toy around

Also shoot round Robin style, not "batch" so one of each load at its target at a time. Eliminates weather changes affecting the overall group etc
 
I would not jump to any conclusions over a 4 shot group. If you used exactly the same load and shot 5 four shot groups you might see groups from .450 to 1.4 .

On your bolt lift/headspace issue,are you partial sizing with full length dies?
Thinking in terms of "Neck sizing"?

There is a problem with that.You still squeeze the case body dia down at the shoulder .This causes the shoulder to grow forward,with no contact wth the die to shape and control it.

I suggest you use a measuring tool such as the RCBS Precision mic,or a caliper attachment to set your shoulder back a known ,consistant,minimum amount. Full length size to a controlled degree.

If you choose to neck size,up to you,but get a neck size die.
 
Red Doggy said:
Some F-class and plinking.
Click to expand...
That opens a whole (very large) new can of worms.

Bushing dies are almost a must for f class reloading. You can set exactly what neck tension you want(essentially how much smaller the neck is than the bullet, giving the amount of squeeze holding the bullet)

Do you have a way to chronograph your loads? That will also tell you a lot.

The matches I go to stop in the end of September, so developing a load in the winter for that purpose is pretty useless. You can always load and plink whenever, but I'd work on/shoot your match loads in the season in which the matches are held.
 
I am using Hornady American Series 2 die set 308 Winchester.

It is a full length sizer to Saami Specs.

I turn it down so the die just touches. Then resize a test one. If it's real tight in chamber still i turn a little more to just push shoulder back.

I do this until i can cycle the unloaded bare case and have just barely a tight bolt and stop. I do not turn the Die in any more. That has been my process for sizing the fire formed cases.

As far as crimp. I trim all my cases. then i turn the bullet seating die down just until it touches case. I stop there. So basically no crimp.
 
I have no chronograph. I plan to move back to 300 yards and test groups as soon as i find something that's working at 100 yards.
 
The sizing adjustment technique is fine. The main limitation you will have with that economy die set is the issue of the expander in the sizing die pulling the case necks off-axis, as this video illustrates. All expanders can do that. You can mitigate it some by lubricating the inside of the case neck. A mix of alcohol and graphite powder can be swabbed around the inside of the neck and allowed to dry off.

For seating, nothing I've found beats the Redding Competition Seating Die, but it's expensive. It makes the bullet seat straighter and this has a measurable impact on group size. You can, however, make standard seaters do a better job if you can start your bullets into the seating die aligned straight up and down in the case mouth. Normally they tip and we let the seating die straighten them, which the Redding die will, but most miss getting them all the way straight without more help. The Lyman M die makes a little step in the case mouth that lets the bullet sit straight up in the case, so that would be a smaller investment you could make that clears a big portion of the bullet tilt issue up.

Take a read through this article. The first half is on shooting, while the second discusses reloading. Froggy's Lube is no longer available commercially, but I understand it was just graphite in alcohol, as I already described.

Anyway, see if you can do a little more to insure concentricity of the bullet position in the case and evaluate loads again. A good sweet spot load should be able to span a couple of those 0.3 grain steps, but yours didn't seem to. The fact the POI was dropping probably means you were not in the best barrel time spot for your rifle. You want a flat spot where a small load change doesn't move the POI much. If you can get the 300 yard range you can shoot an Audette ladder (described in lower half of this article), you may get a better idea where that is. Audette ladders are hard to interpret if fired at shorter ranges than that. Even the OCW method works better at 300 than at 100 because you are getting enough distance for bullet drop differences to begin to show. If I had 300 yards available near me, I would actually start there rather than at 100. Note that for an Audette ladder you have to keep track of which individual shot made which individual hole, so your scope or spotting scope needs to be able to see holes at 300. If they can't, you have a lot of walking back and forth to do. Here's an old thread on another board where I helped someone evaluate an Audette ladder.

The other thing to look at is seating depth. Especially since you are using the TMK's which are secant ogive bullets and secant ogives tend to be more sensitive to bullet jump. See this article on Berger's site about getting their secant ogive VLD's to shoot well.
 
Case length is too long at 2.010". Trim-to is 2.005". That's probably the cause of the slightly sticky bolt.
Fire forming has nothing whatever to do with headspace. The case has no headspace either.
It's really best to load to 2.800" OAL for load testing and forget about the off-the-lands thing. Eliminates one variable.
There is no absolutely written in stone OAL or formula for being off-the-lands. It's strictly a trial and error thing that is different for every rifle. Not really important anyway. It's a load tweaking technique that can be done after you've worked up the load.
It's also best to begin at the start load of 41.5, load a mag load(it 4 in your Savage?) or 5 for larger mags, and go up by half a grain to the max load of 45.6(c).
And shoot for group only off a solid rest.
 
Thanks for chiming in unclenick.

Is that a coax press? I really like that... And I'm Glad I got my whidden dies to replace my hornady dies. But they were able to take me to 1000. So hornady dies aren't awful, there are just better options out there.
 
Yes, that's a Co-ax in the video. Love mine. It makes very straight Ammo.


Per T. O'Heir's comments:
SAAMI and the US Military both have maximum case length at 2.015" and the chambers are actually longer a bit on standard reamers. So 2.010" is just fine. The reason for the hard fit is incomplete resizing. When you run a case into a sizing die, the first thing that happens is the case contacts the sides of the die, which squeeze it out longer than it was, pushing the shoulder further forward. If you don't resize enough, you never put the shoulder back, so you get an interference fit.

2.800" COL works well with most bullets that have close to the military 7 caliber tangent ogive, and it guarantees magazine fit, but the OP is shooting a secant ogive bullet. These can be funny about seating depth as the Berger article describes, likely owing to the large annular opening around the ogive in the throat, so he should run seating depth experiments.
 
Case length is too long at 2.010". Trim-to is 2.005". That's probably the cause of the slightly sticky bolt.
Click to expand...

Nothing wrong with it, max is 2.015 as long as its consistent and shorter than the maximum that's what counts.

I over trim, not by a lot but that's ok as well.
 
I've never heard of POI as a measure of accuracy since you can easily adjust the scope. A 5 round group will give you some idea and a 20 round group will give you an accurate measurement.

Last week, I had a sticky bolt with my cast loads but not my jacketed loads but they were about the same length. I think the cast ogive was the problem so need to back off on the seating. When I pulled the round out, it also pulled the bullet so need to really crank down on crimp for my cast rounds.

I've seen rifles that are more accurate when the bullet is close to the lands and others that doesn't matter. You can look up for each rifle or try it out and see what you get.

The temperature can effect the speed of sound which will effect your fpm but doubt it will make that much difference to accuracy.
https://www.nde-ed.org/EducationResources/HighSchool/Sound/tempandspeed.htm
 
Is there such a thing as the gun sounding different and feeling different when a good load is found?

I swore the 41.6 Gr Shots sounded and felt different. Kind of like a more in tune bang and they felt less violent and smooth.

Or it could have been because the powder charge was less. (that may explain it, and would be logical)

Maybe i'm crazy, i don't know.

It seems though that I was just left with the impression that the 41.6 felt and sounded better to me.
 
I think that's like asking if an A-sharp is better than a C-flat. You might be hearing the frequency of the rifle.

I shoot my 91/30 cast bullets at low loads 10 to 20 gn and my jacketed at 35 to 40 gn. The high loads make a crack and the low loads make a pop. I assumed it was the difference between subsonic and supersonic but others have told me can't tell without a chrono. I'm gonna try a faster burning powder (700x) and curious if it makes a difference.
 
I've also been told that need to zero at 50 yards instead of starting at 100 yards even with a scope due to flight ballistics. AFAIK, group size, consistency, and lack of fishtailing are measurements of desired bullet/powder combo. For hunting, bullet deformation and speed are important since you want the bullet to cause take down damage. I think the SD when measuring the speed with a chrono is a good measure of consistency (but others disagree).
 
RED DOGGY --
I too am trying to work up a load for 308, 175 S TMK
Mine is a 24 inch barrel
After 2 range trips and failure, I Emailed Sierra, his response was that
The TMK is finicky and try putting the bullet on the lands
( because it is a Secant and they are picky )
I have done some research and those using them are
using IMR 4064 in 24 inch and longer barrels
those with 20 inch and shorter barrels are using Varget
in their best loads

loads from good sources are
44.5 Varget 20 off
43.8 Varget 15 off

44.0 4064 touching lands
43.2 4064 touching lands

When you find your load let me know what it is
I am shure your 18 inch will be different than my 24 inch
but the info may help
 
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