300WM load Question

[gahunter12]

I am currently at the range working up a load for my 300wm. I'm using 180gr AB's over RL-22. This is a continuation of my previous load work up, but just changed seating depth. I started at 73.7, 74.0, 74.2, 74.5, 74.7, and 75.0. My question is has anyone ever seen velocity drop off by going up .2gr? 73.7 gave me an average of 3016fps, up to 74.5 gave me an average of 3060fps with no sticky bolt or over pressure signs. I just shot 74.7, but it dropped off to 3020fps AV, ES 7, and SD 4. Seems odd that velocity dropped

 

[DrMike]

What you observed is not that unusual. The velocity changes roughly correspond to maximum chamber pressures. Gases are permitted to leak from the chamber as the bullet moves from the case neck to engage the lands, allowing for some slight differential in pressure. Am I correct in assuming that these were 3-shot groups? Statistical analysis would indicate that with that small of a sample, you are well within norms. How was accuracy?

 

[gahunter12]

Yes they were 3 shot groups. My accuracy went away at 74.5 opening up to 1.37". At 74.7 my groups were back to .95", and at 75.0gr they vertical string on me. My most accurate load was at 74.0gr. It gave me .79" 3 shot group at 3024fps av. I'm good with that velocity using less powder, and better groups.

 

[gahunter12]

BTW thanks for explaining that to me. I have never experienced it in the past.

 

[DrMike]

As you near maximum charge, the groups should be tighter, just as you observed.

 

[Dwh7271]

Dr mike is dead on (as usual :grin: )
Another thing that probably happened is you hit a node. Velocity flattens in nodes and accuracy tends to increase.

 

[Cleveland48]

I have saw this myself while I was working up a load. Where the velocity flattens out is where you wanna be[emoji106]


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[gahunter12]

Thanks! I went back, and revisited the load again yesterday. Here's my best 3 shot group @ 100yrds. I think I'm pretty happy with it. I plan to load up a few more, and check 200, and 300 yrd accuracy

 

[DrMike]

That'll do!

 

[OU812]

That'll do!

Couldn't have said it better myself Mike.

 

[emanon6]

It's a sweet thing hitting that node. I almost scrapped my cz550 in 7mm mag, until I worked up a ladder with RL 22 and hornady eldx 162gr. Noticed a leveling of velocities very similar to your situation. Wish I knew I could've just come to this forum. Instead I spent days trying to research what was going on.


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[DrMike]

Welcome aboard, emanon6. Glad you worked out the problem and pleased that you found this forum. You'll find good, knowledgeable people willing to help fellow shooters/hand loaders.

 

[emanon6]

Welcome aboard, emanon6. Glad you worked out the problem and pleased that you found this forum. You'll find good, knowledgeable people willing to help fellow shooters/hand loaders.

Thanks Drmike!

On kind of the same note, I've heard lots of stories about how temp. sensitive RL 22 is. Some say that Alliant stabilized the formula and it works great for them, while others have written it off. Any input?


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[DrMike]

I've used RL22 for many years. Admittedly, I don't use this powder (or any other) in temperatures above ~26C (79F), but I do a fair amount of shooting in temperatures dipping as low as -35C (-31F). I do not note pronounced sensitivity to an extent that my shots are hampered. Undoubtedly, for those engaging in shots exceeding ~450 meters, temperature sensitivity could be problematic. I seldom take a shot exceeding 300 meters, so accuracy has not been a significant problem for me.

 

[OU812]

I've used RL22 quite a bit but not in extreme temps and never seen any issue. That being said I have seen big LOT to LOT variations so when changing lots# drop back in charge weight and work back up. I shoot over a chrono when working up loads and when a new lot of powder is used I just shoot over a chrono with the different charge weights until I hit the same velocity as the old lot.

 

[DrMike]

I've used RL22 quite a bit but not in extreme temps and never seen any issue. That being said I have seen big LOT to LOT variations so when changing lots# drop back in charge weight and work back up. I shoot over a chrono when working up loads and when a new lot of powder is used I just shoot over a chrono with the different charge weights until I hit the same velocity as the old lot.

Excellent point, Bill. It can show quite a bit of variability lot-to-lot.

 

[emanon6]

I've used RL22 quite a bit but not in extreme temps and never seen any issue. That being said I have seen big LOT to LOT variations so when changing lots# drop back in charge weight and work back up. I shoot over a chrono when working up loads and when a new lot of powder is used I just shoot over a chrono with the different charge weights until I hit the same velocity as the old lot.

Excellent point, Bill. It can show quite a bit of variability lot-to-lot.

Thank you and noted. I guess it would be wise to find a five pound jug if I'll be shooting a bunch. Have 6" gongs at 250yds, 300yds and 400yds that I can shot at from the porch at camp, so I tend to shoot quite a bit. I'm also in central Texas, so high temps play a factor. Might have to constantly test loads.


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[OU812]

I've used RL22 quite a bit but not in extreme temps and never seen any issue. That being said I have seen big LOT to LOT variations so when changing lots# drop back in charge weight and work back up. I shoot over a chrono when working up loads and when a new lot of powder is used I just shoot over a chrono with the different charge weights until I hit the same velocity as the old lot.

Excellent point, Bill. It can show quite a bit of variability lot-to-lot.

Thank you and noted. I guess it would be wise to find a five pound jug if I'll be shooting a bunch. Have 6" gongs at 250yds, 300yds and 400yds that I can shot at from the porch at camp, so I tend to shoot quite a bit. I'm also in central Texas, so high temps play a factor. Might have to constantly test loads.


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When I find a power I like I buy 5 or 8 lb jugs. It would be interesting to see your results with higher temps. I don't shoot when it's real hot, mainly cause I don't like being out in the heat.

 

[DrMike]

That is my practice as well, Bill. If a larger size is not available, I'll try to pick up several one pound charges with the identical lot number. It saves a lot of trouble over the long run.

 

[OU812]

That is my practice as well, Bill. If a larger size is not available, I'll try to pick up several one pound charges with the identical lot number. It saves a lot of trouble over the long run.

Yes it does Mike, been down that road and didn't care for the ride.