Help pick my load

[JA03]

48.5 and shoot.

 

[kevin11mee]

48.5 and adjust seating depth if you want more accuracy.

 

[Jeff_Gibbons]

I'm liking it as well especially if its not showing pressure like Rob already mentioned. Seat .0025 and .0045 off the lands and see if she'll really sing for you.

EDIT: keep in mind seating deeper will increase pressure so keep an eye on that if you think you are already approaching the top end.

Near my thoughts exactly. I’d repeat the original seat depth at same charge and move deeper 20 thou for 30 and 50 thou depths

 

[bmart2622]

I'm liking it as well especially if its not showing pressure like Rob already mentioned. Seat .0025 and .0045 off the lands and see if she'll really sing for you.

EDIT: keep in mind seating deeper will increase pressure so keep an eye on that if you think you are already approaching the top end.

Decrease pressure and speed with more jump

 

[kevlar88]

Decrease pressure and speed with more jump

If you are starting off in the lands and back off of them, yes you can decrease pressure. If not starting in the lands, the further you seat a bullet in to the case you are eating up case capacity, decreasing case volume and increasing your pressure.

 

[bmart2622]

Pressure and velocity increase and decrease together, higher velocity=higher pressure and vice versa

 

[kevlar88]

Pressure and velocity increase and decrease together, higher velocity=higher pressure and vice versa

Yes, What's your point?

My point is that if you seat a bullet deeper into a case you will decrease case volume and capacity and effectively increase starting pressure regardless of where you are in relation to the lands or how long the throat might be.

 

[bmart2622]

My point is that the closer to the lands the higher the velocity and higher the pressure and further from the lands the velocity decreases which means the pressure does also

 

[NW Hunt€r]

Yes, What's your point?

My point is that if you seat a bullet deeper into a case you will decrease case volume and capacity and effectively increase starting pressure regardless of where you are in relation to the lands or how long the throat might be.

This ^^^^

 

[kevlar88]

My point is that the closer to the lands the higher the velocity and higher the pressure and further from the lands the velocity decreases which means the pressure does also

How do you get a bullet further from the lands? You must seat the bullet deeper. When the bullet is seated deeper the case volume will be decreased. When case volume is decreased and powder charge remains unchanged pressure will increase even though you are moving further from the lands.

 

[bmart2622]

Load 5 bullets .030 off the lands and 5 .060 off the lands and tell me which one is faster

 

[kevlar88]

My apologies for the derailment @robtattoo. Also, in a previous post I meant to say try seating at .025 and .045 off the lands and not .00

 

[kevlar88]

Load 5 bullets .030 off the lands and 5 .060 off the lands and tell me which one is faster

I have many times in many different calibers and cartridges.

Seated Long


Seated short


Seated shorter is further from the lands and the velocity is higher. Just an illustration of what I have experienced in real life with every single one of the dozen plus rifles that I load for from 223 to 375 H&H.

 

[bmart2622]

Exact opposite of every load I have ever loaded and shot, longer bullets with less jump are always faster, which is why you find max charge weight with the bullet seated the longest you plan to shoot

 

[Mack84]

If you are starting off in the lands and back off of them, yes you can decrease pressure. If not starting in the lands, the further you seat a bullet in to the case you are eating up case capacity, decreasing case volume and increasing your pressure.

After about 100 thou or something, it’s a lot of jump to add pressure. .005 from the lands will have more pressure than .030 from the lands I think

 

[bmart2622]

^^^^^^100!!!!

 

[robtattoo]

So, having read & digested all this I've loaded up another 10 at 49gr & 10 at 49.2 (that might be pushing it, but I won't really know until I try) at the original 3.154 oal.
I also loaded 10 more at 48.5, but reduced OAL to 3.144"
I don't want to waste components, since this is purely a hunting rifle & good enough is really good enough, so I'm planning on shooting 5 of each through the chrono (magnetospeed.....) & 5 for grouping.

From previous loads in other Swedes, i know the 48.5s should be around 2750 +/- & the 49s real close to 2800. Either of which will be fine. The only time I've loaded 49.2 was with Berger 140s in a 32" target rifle (3080fps) so I'm not sure what they'll get in a 24" with a different bullet. I'm guessing they'll flatten primers though.

 

[EdP]

Brian Litz addresses the pressure vs jump correlation in his book Applied Ballistics for Long Range Shooting. Litz says that for a given powder charge and bullet combo, seating deeper into the case increases the pressure. Seating further out (longer) decreases pressure until you are almost into the lands at which point pressure can spike. I think "almost" meant .002 or closer.

 

[bmart2622]

Find pressure at the max length you would intend to shoot, back off 1-1.5 grains, load 10 and see what happens

 

[robtattoo]

Interesting day.....

The 48.6 @ 3.144 was no improvement over the initial 3.154. Slightly lower on the target but identical group sizing (tbc....) at 2735fps avg. SD of 9 over 5 shots

The 49gr load was, predictably, the same. Low & centered with very little vertical dispersion, an avg velocity of 2752 & SD of 16
The 49.2 however had very bad horizontal stringing. Velocity average was 2760 but the SD was 34.

So i drove back home & loaded up 20 at 48.5 with a 3.150 OAL. This centered the group nicely. Average of 10 shots over the chrono was 2732 but the SD dropped to 4!
10 shot group all fell into a neat little 1.25" circle & that's a good half inch better than I was hoping for!

Unfortunately i completely forgot to take my phone, so no photos, but I'm incredibly happy with this load. Yeah, another 100fps would been nice, but that still gives me better than 1000yds of performance window (2000fps) & if I'm shooting beyond 500, something has gone horribly wrong anyway!