33xc powder charge test idea

[AlanX]

I'm working on a 33xc load with a velocity greater than 3000f/s for a 34'' barrel, using H50 BMG, 300 gr CE laser bullets, and Federal 215 primers. I will do a powder charge test to find the plateau with the fewest rounds. I wonder if the following strategy would work.

1. Using a 0.3 gr interval, load from 120 to 123.9 gr one round each (14 rounds).

2. Locate the first plateau that produces over 3000f/s mv by charting the velocity.

3. Confirm the plateau with three groups, each with three rounds (9 rounds).

For all rounds above, I will set the seating depth at 20/1000 from the jam.

Please advise. Thanks!

 

[John Glidewell]

In a large case like that .3 is a waste of time and $$. I would go in 1 grain increments until I see mild pressure, then back off a couple grains (prob 2.5) and play in that area.

 

[Sigma]

In a large case like that .3 is a waste of time and $$. I would go in 1 grain increments until I see mild pressure, then back off a couple grains (prob 2.5) and play in that area.

i did 5 grain increments of h50 in my 338-408 cheytac with no issues…….but would not recommend it to someone who is aprehensive.

if you aren’t afraid to shoot up ammo, then do what John said, no less than 1 grain increments to find your pressure. if you want to fart around with 0.5 grain increments after that then so be it, but you will find these large capacity cartridges to be much less sensitive and much more forgiving trying to obtain a good mv variation.

 

[AlanX]

i did 5 grain increments of h50 in my 338-408 cheytac with no issues…….but would not recommend it to someone who is aprehensive.

if you aren’t afraid to shoot up ammo, then do what John said, no less than 1 grain increments to find your pressure. if you want to fart around with 0.5 grain increments after that then so be it, but you will find these large capacity cartridges to be much less sensitive and much more forgiving trying to obtain a good mv variation.

Did you end up fine tuning the charge in smaller increments?

 

[Sigma]

Did you end up fine tuning the charge in smaller increments?

i actually happened to find a good “node” when jumping the large increments and am probably just going to stick with it.

this is a 338-408 cheytac just to reiterate. bullet is a 300 smk.

I used 125.0 for fireforming which yielded 3,000
130.0 - 3150
135.0 - 3220
140.0 - 3300 (clicker at top of bolt and slight cratering)

same 3 cases for each load. 130 jumped out at me, for 3 shots i had an es of 4. the rest of the loads had an es of like 10-15. after i finished finding my max pressure i decided to revisit the 130 load again. 3 shots, and again with an es of 5 and sub 1/2 moa at 300.

i have some 300 a tips sitting here, and when running the numbers on the kestrel, the gains past a mile is very impressive. decided to take the same 130 load, but just direct swap to the 300 a tip.

recoil felt noticeably harder, lost 40 fps, es went to poop, accuracy was barely sub moa if even.

idk, it was cold as crap that day and my head wasn’t entirely in the game……and i am doing all my testing off my tailgate at the moment until i get my picc rail installed with a proper rear bag which doesn’t help for consistency….

im going to revisit the atips but haven’t had the chance to test for a few weeks and kinda been scratching my head ever since, mostly at why the recoil felt so different (because same weight).

 

[AlanX]

i actually happened to find a good “node” when jumping the large increments and am probably just going to stick with it.

this is a 338-408 cheytac just to reiterate. bullet is a 300 smk.

I used 125.0 for fireforming which yielded 3,000
130.0 - 3150
135.0 - 3220
140.0 - 3300 (clicker at top of bolt and slight cratering)

same 3 cases for each load. 130 jumped out at me, for 3 shots i had an es of 4. the rest of the loads had an es of like 10-15. after i finished finding my max pressure i decided to revisit the 130 load again. 3 shots, and again with an es of 5 and sub 1/2 moa at 300.

i have some 300 a tips sitting here, and when running the numbers on the kestrel, the gains past a mile is very impressive. decided to take the same 130 load, but just direct swap to the 300 a tip.

recoil felt noticeably harder, lost 40 fps, es went to poop, accuracy was barely sub moa if even.

idk, it was cold as crap that day and my head wasn’t entirely in the game……and i am doing all my testing off my tailgate at the moment until i get my picc rail installed with a proper rear bag which doesn’t help for consistency….

im going to revisit the atips but haven’t had the chance to test for a few weeks and kinda been scratching my head ever since, mostly at why the recoil felt so different (because same weight).

Losing 40 fps is particularly interesting... I am going to stick with my plan and see how it turns out since I've already loaded the first 14 rounds.

A side question, any recommendations for a good bullet puller? I have a cheap impact puller but it can barely fit in the 33xc case.

 

[John Glidewell]

RCBS puller with caliber specific collet.

RCBS Collet Bullet Puller

The RCBS Collet Bullet Puller is designed so the reloader can easily pull jacketed bullets from brass cases without damaging either. The puller utilizes...

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[Sigma]

Losing 40 fps is particularly interesting... I am going to stick with my plan and see how it turns out since I've already loaded the first 14 rounds.

A side question, any recommendations for a good bullet puller? I have a cheap impact puller but it can barely fit in the 33xc case.

check out the the hornady cam-lock one

 

[AlanX]

Just got back from the range and have the data below. Labradar missed two data points (somehow it didn't pick up the signal) but it doesn't seem to matter. There seems to be an outlier at 122.1 gr. No pressure sign for all loads. It looks like 123.0 gr is the winner.

 

[Sigma]

Just got back from the range and have the data below. Labradar missed two data points (somehow it didn't pick up the signal) but it doesn't seem to matter. There seems to be an outlier at 122.1 gr. No pressure sign for all loads. It looks like 123.0 gr is the winner.

the barrel on my cheytac is 34”

3150ish is my node too for now, just seems thats where its happy velocity and accuracy wise.

i know theres alot more variables to it than that, but just seems coincidental that both of our 34” barrels are happy at 3150ish with a 300 grain bullet