300 Win Mag: Proper Neck Tension - Surprising Results!
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- เผยแพร่เมื่อ 30 ก.ย. 2024
- In this video I try to find the optimal SAC bushing to set proper Neck Tension in 300 Win Mag. I find so much more than consistent Neck Tension.
SAC Bushings in 223 Rem - • Testing Neck Tension i...
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More 300WM please.
I've a bit of logic, and a hypothesis. Maybe someone can find fault with it.
I've noticed;
- Expander mandrel has bad SD regardless of what else it's used with
- Stock without mandrel is somewhat better
- SAC SD is very low compared to the other options tested
> you mentioned specifically that the SAC bushing has given you best runout numbers
I'm assuming;
- Expander mandrel is as good as one can be
- You lube but don't neck turn, based on your last video
So I figure that;
- Bushings, assuming high quality (in this case, SAC), create a near-perfect cylindrical outer diameter of the case neck
- Mandrels, assuming high quality, create a near-perfect cylindrical inner diameter
- It stands to reason that variations in wall thickness have to go somewhere
> With bushings, the variation is pushed inwards, leading to imperfect inner cylindricity
> With mandrels, the variation is pushed outwards, leading to imperfect outer cylindricity
- Because neck tension measurements are averages of the way a case clamps onto a bullet, imperfect inner cylindricity goes largely unnoticed in this particular measurement, thus leading to better results if neck tension is your only criterion.
- Given how you also saw better results in grouping with the SAC bushing, I theorize that centering the cartridge in the chamber is more important than even clamping of the bullet, likely as a result from more even expansion of the case neck into the chamber
So I predict;
- Brass that is neck turned AFTER sizing with quality mandrel will have both good inner and outer cylindricity and uniform wall thickness, resulting in best possible SD and grouping.
> Material must be removed from the full circumference of the neck to ensure uniform wall thickness, there may be no spots untouched by the turning process.
> Cases should still be lubed
What could be tested;
- Whether mandrel + turning (in that order) gets same or better seating force SD and grouping
> Hypothesis: slightly better
- Maximize inner runout with perfect outer runout VS the opposite VS minimized inner and outer runout, all with similarly good seating force SD and same powder charge, test for grouping
> Hypothesis: mandrel + turned slightly better than bad inner runout, much better than bad outer runout.
- See if lube still makes the same difference if turned after the use of expander mandrel
> I couldn't tell from your previous video if you expand before turning, in which cases this is already tested and last video results apply and we have our answer.
> If not, I hypothesize that the difference lube makes will be less than shown in said video, but still make a difference of some significance
Man please keep this series going!! Ide love to see more videos on the 300WM with more comparison of sizing methods. Ive been chasing my tail with my neck tension on reloads with bushing first then mandrel sizing.
Would definitely love some ol 300 Win Mag videos... see if you can finally get it to shoot with this new data you got now.
Have you tried the Lee Collet Die? My 300WM groups .42 with HDY 225gn and 75.4 of h1000 3.497 COL GW Brass 26" barrel
As a avid 300 win mag shooter I will confirm that more neck tension is good. I size down to .007 below loaded round and expand back up to .004 below loaded round.
Stop thinking about neck size she said lube the neck case and put your mandrel in!!!
They get less spring back, the more you do it
I have a Remington in .300 Winchester Magnum and the information you put out on this is gold. Please keep it up.
Definitely keen to see more on the 300.
My 300WM likes 190 SMKs at 2800-2850. Have you tried a different powder for more speed? I used IMR-4530, and IMR-4831.
Would like to see a comparison of turning mandrel and these bushings I thought the mandrel would be more consistent since it sizes from the inside. But I'm also kinda new to reloading.
My experience with fill length sizing (bumping the shoulder 0.0020) with bushings only in .300WM is that after 3-4 sizing the case mouth started have an inward bend. I had to start following up with an expander mandrel to flatten out the inside of the necks so that there was a larger and more consistent surface area making contact with the bullet. Not sure this applies to this video… but just providing a warning for others to look out for.
In case the data point helps someone, in use a Hornady 0.332 bushing and a 0.3070 expander mandrel. I average slightly under 1” for 5-shot groups with Hornady ELD-M 225gr bullets.
I'm interested in more info. I'm loading for a browning xbolt in 300wm- and getting close to half moa with the sac bushing 2 thou under. I'm novice reloader and stubbled on it but not going to mess with success.
Never reloaded anything, but this is good information for if i ever am able to. This isnt a good time to start getting into handloading and i would really like to.
I just got setup a couple of weeks ago besides primers and some powders most everything is readily available to me but BOY IS IT EXPENSIVE!lol
@@wheelzandgillz Thats the problem, to darn expensive! I messed up and should have started 30 years ago.
@@Longtrailside same here, I shoulda spent my money stock piling components rather than ammo lol
It's totally unnecessary to go to these lengths to produce accurate ammunition. If someone enjoys hair splitting like that more power to them. A good set of dies and maybe a competition seating die will get you sub moa groups if your rifle is capable.
So you have 2thou neck tension at the best group?
I have not had a problem with accuracy under sub 1/2 moa, shoulder 2thou and standard custom grade die already sets neck tension to 2 thou. Case length trimmed to keep all cases even all the time.
It does seem the common neck tension value of 2thousands is the best place to start.
Thanks for the video.
Definitely would like to see more testing on the 300.
Thanks for the update brother and enjoyed it.👍😀
This method goes hand-in-hand with annealing.
I'd like to see the process using these neckbushings (-0.002, plastic deformation) plus mandrel (+0.001 only elastic? ) and some lube on the bullets. At least this is the way Keith (winning in the wind) once told. Last week I tested it this way and instantly had a SD of 5 and 15fps on 12 shots with my Creedmoor. 300WM is still pending cause I got no fireformed brass. But I'd be interested to see if this process could be copied for 300WM, cause the truth is most somewhere between...
(Video: "getting consistent neck tension")
It would be interesting to see how the smallest grouping load and largest grouping load would compete in a 20 shot group. (Via 3 shots cooling intervals) With a sample that big, would we see the supposed best group load continue to produce smaller groups, or would the best and worst batches produce the same size larger group with that many shots? Blind test too. Mark the bottom of matching ammo boxes with "A" & "B". Don't identify the loads until after the test.
More 300 win mag!!
I have this same issue with a CA 300WM (3” groups@ 100yd😢). I have off the shelf Remington that shoots smaller groups. Sad that a $2k+ rifle shoots worse than a $700 rifle. Will defiantly give this a try….. Now if only I can get my hands on some H1000
Exceptional narration
Good information
SAC always tells me when I say I want 2 thou neck tension, they recommend 3 thou smaller due to spring back in the brass. I don’t question, I just buy and it works.
yes more 300 mag. I switched to vihtavuori N565 for my Berger 208's
When you necksize, are you still using the standard expander ball or still using the expander mandrel before loading?
Any idea how these might perform when reloading 308?
So is using a SAC bushing, then mandrel, then neolube the best way to get consistent neck tension?
Have you tried LE Wilson bushings?
I would have to see if the results are repeatable. Does make one say "hmmm".
Although you are using SAC neck bushings to size down case neck, are you still going back through and using expander mandrel as finishing piece before seating bullet?
Hi Ethan, I have not shot anything yet sized with these bushings and then with the expander. (I loaded some and showed the force chart toward the end) the initial information with velocity and groups are simply with the bushings only.
BAR
Yes please in .224valkyrie:-)
Great video
Do you think this improvement would transfer to a 300 Rum?
HI J M, I can't make any promises but it may be worth a try. I have no idea what the particular situation is sometimes magnums are just harder to deal with. Brian Litz has some interesting theories on this in his new book. He relates accuracy to rifle to weight of the platform vs projectile with some other factors.
I miss your load development videos
Also voting more on .300 WM.
Theory: the smaller the bushing, the more the bullet functions like an expander mandrel upon seating. I've have been using a Redding .334 bushing and a standard expander mandrel with my .300 Win Mag for years. I have been extremely happy with both accuracy and SDs.
I use 334 as well but for 300 prc.
I use .334 for .308 for most brass including Lapua.
@@ironDsteele I tried 334 on Norma brass for 308 win, but the bullet slipped right though. Had to wait on my reloads and get 333 and 332's shipped to me. It surprised me, because I reloaded Starline brass in 308 just fine with 334.
@@thelittledetailscr7231 In order for your bullets to slip right through after sizing with a .334 bushing, your brass neck thickness would have to be less than .013". In my experience, that's not consistent with Norma brass, which is on the beefy end of the scale. Did you or someone else neck turn that brass?
@@njgrplr2007 No, it is once fired Norma. I guess it is possible that I had the wrong sizing ring in there, but I am 95% sure it was 334.
I noticed the chart at 6:50 shows the lubricated version with the 332 bushing was higher in force then the one without? Is it possible those are flipped or was the seating force with lube actually higher?
I would guess your next move would be to re-test your hypothesis, that is, were the SAC bushing groups a fluke or does something about using this brass prep with the SAC bushings actually improve the group size compared to the previous prep method?
Hi Dino, At 6:50 in the chart there is no mention of lube. There is a version with and without a Expander mandrel. The chart is correct. I will certainly be retesting with the bushings.
@@BoltActionReloading gotcha, I thought that might mean they were lubed. Hope you get the chance to run your follow up tests. It would be something to take a less than mediocre rig and turn it into a performer!
So that's amazing, but it doesn't quite answer the question yet, right? Why are the groups better? Because the seating forces using the SAC bushings were more consistent. But why were the seating forces using those bushing more consistent? Aren't your expander mandrels also SAC?