Anyone running a 135 A-Tip, H4350, Lapua Brass Combination

[AllenOne1]

Looking for a real world load using the 135 A-Tip, H4350 and Lapua brass.

What I'm coming up with right now is 41 - 41.5 gr which should give me 2793-2827 fps (per Gordon's Reloading Tool). However I don't have an accurate COAL to use in the calculation so it could be off a bit. Need to measure jam length to get a starting point tonight.

I see a lot of loads using 42-43 gr but I suspect that they are using brass with a larger internal volume.

Any guidance would be appreciated.

 

[357Max]

Looking for a real world load using the 135 A-Tip, H4350 and Lapua brass.

What I'm coming up with right now is 41 - 41.5 gr which should give me 2793-2827 fps (per Gordon's Reloading Tool). However I don't have an accurate COAL to use in the calculation so it could be off a bit. Need to measure jam length to get a starting point tonight.

I see a lot of loads using 42-43 gr but I suspect that they are using brass with a larger internal volume.

Any guidance would be appreciated.

I think your in the right area to start.

For a reference with H4350
Lapua SRP
FGM 205 primers
41.6gr H4350
147 eldm COAL 2.830
2812fps SD 5.6
25" Barrel

This is important & it will make sense when comparing these 2 loads.
Per Gordon's that load above should only be 58,958psi. However.........it's outperforming Gordon's prediction for speed by 55fps. When I adjust powder charge to equal my speed it's right at the top end for pressure.


The 135 A-tips touched @2.937" in my chamber.

Sorry no H4350 data for the 135's. I tried RL 16 first & it shot so well I didn't bother trying 4350

My load is at the upper end, but shows no pressure. Gordon's shows this load is about 500psi over max, however it also predicts 2950fps, so in this case I'm under-performing predictions.
I always account for speed vs pressure when using Gordon's: i.e. 43.5 predicts my actual speed and that is 3kpsi under max. I also take into consideration the barrel. Mine is a Rock Creek & is not a slow barrel. A factory RPR would almost certainly hit pressure long before reaching 2900.

Lapua SRP
FGM 205
44.2gr RL 16
135 A-tip COAL 2.886"
2900fps SD's 1 - 2 on 5 round strings repeated several times.

25" barrel

This is also a very important note: Primers matter. I wish Gordon's had and input to account for primers. I inadvertently loaded the above in Lapua I'd already prepped and primed........accept they were primed with CCI#41 which is a magnum SRP. The speed jumped from 2900 with the FGM 205's to 2970 with the cci#41's Load went to shit, like 1.5moa shit & terrible SD's. Painful lesson learned on that one.

 

[AllenOne1]

Very interesting information. If I'm following you correctly I may be able to push a little harder than Gordon's is suggesting.

Here is my current load data:
Lapua SRP
CCI 400
H4350
140 ELD-M
BTO 2.270 (lately have increased BTO to 2.285 to decrease jump)
Touch length is 2.289 BTO and 2.908 COAL with the ELD-Ms
26" Bartlein 5R

Velocity @ 83 degrees
40.7 - 2751
40.8 - 2746
40.9 - 2762
41.0 - 2764
41.1 - 2770
41.2 - 2767
41.3 - 2779
41.6 - 2801

I think I'll try 41.1, 41.4, 41.7 & 42 and see how that goes. I need to measure touch length on the 135s so that may change the Gordon's enough to make me shift it a little bit.

 

[357Max]

Very interesting information. If I'm following you correctly I may be able to push a little harder than Gordon's is suggesting.

Here is my current load data:
Lapua SRP
CCI 400
H4350
140 ELD-M
BTO 2.270 (lately have increased BTO to 2.285 to decrease jump)
Touch length is 2.289 BTO and 2.908 COAL with the ELD-Ms
26" Bartlein 5R

Velocity @ 83 degrees
40.7 - 2751
40.8 - 2746
40.9 - 2762
41.0 - 2764
41.1 - 2770
41.2 - 2767
41.3 - 2779
41.6 - 2801

I think I'll try 41.1, 41.4, 41.7 & 42 and see how that goes. I need to measure touch length on the 135s so that may change the Gordon's enough to make me shift it a little bit.

Yep the short version is that if your speed is slower than predicted pressure should follow suit & vise versa.

-.052 jump was the happy spot for 135's in my Chamber (PVA cut).

 

[just browsing]

Obviously I’m going to use the caveat “work up” here but I was able to get into the 42s comfortably with this combo in my ATX.

Spreads were within 20fps of each other (as referenced by the same POI on all the groups) and the average speed was 2850 out of a factory 24” barrel.

Ignore the 3 on the right… fouling a removed/reinstalled/clean barrel. Adjusted zero and shot the 6 groups on the left.

 

[AllenOne1]

Obviously I’m going to use the caveat “work up” here but I was able to get into the 42s comfortably with this combo in my ATX.

Spreads were within 20fps of each other (as referenced by the same POI on all the groups) and the average speed was 2850 out of a factory 24” barrel.

Ignore the 3 on the right… fouling a removed/reinstalled/clean barrel. Adjusted zero and shot the 6 groups on the left.

View attachment 8221813

This sounds reasonable. Gordon's is estimating a velocity of 2855 @ 42 grains of H4350 out of a 26" barrel. Appreciate it.