Quick question about "Fill Percentage" ...

[rustyinbend]

I have a good reference load for my 338-LM using MagPro, but just got some Retumbo and pondering info from the Berger Load Data as I think about building a ladder test ... Berger 250's and Retumbo ... that shows a fill ratio as 108% for the max charge (94gr). My QuickLoad software lists that charge at 106% of fill rate. My question is ... Is it a bad idea to go over 100%, and should I look for Bullet/Powder options that keep me at or under 100%? Should I just compress it and head for the range? (Or not?)

This question is slightly complicated by the fact that I'm magazine-limited on my Barrett MRAD and end up with a seating depth that's pretty big ... .6895" on a bullet that is 1.6405" in total length.

Any advice from the "big bore guys" out there on over-filling a case?

 

[Isaiah's Blacksmith]

Berger shows it is max load. QL shows it is just about 10% below dangerous load. So, you have enough information to know that you should work up to that load in increments looking for pressure signs on your way up. If you start to see pressure signs than back off .5 grains and that is YOUR max load. No different than any other load work up. It's fundamental.

 

[rustyinbend]

Berger shows it is max load. QL shows it is just about 10% below dangerous load. So, you have enough information to know that you should work up to that load in increments looking for pressure signs on your way up. If you start to see pressure signs than back off .5 grains and that is YOUR max load. No different than any other load work up. It's fundamental.

Thank you ... no great surprises there for me regarding start-low and pressure awareness ... but excellent reminders on "process". My question was more about "Fill Percentage" and whether there are any issues (generically) going over 100%.

 

[Steel head]

It means depending on seating depth or case volume you may get compressed loads of varying levels.
I don’t like compressed loads as it causes seating issues and or bullets getting pushed back out changing your seating depth.
People have buggered their seating dies and creased bullets from compressed loads.

A tiny bit of powder crunch isn’t a bad thing though.

It doesn’t necessarily mean you’ll get pressure issues.

 

[Holliday]

I have run compressed loads and as @Steel head stated it can cause things like dented bullets and and cracked seating stems. Redding makes it clear they don’t like or warranty for compressed loads.

I try to stay under 104% myself. My personal opinion is a slight compressed load is best but that’s purely anecdotal on my part……

 

[Steel head]

I have run compressed loads and as @Steel head stated it can cause things like dented bullets and and cracked seating stems. Redding makes it clear they don’t like or warranty for compressed loads.

I try to stay under 104% myself. My personal opinion is a slight compressed load is best but that’s purely anecdotal on my part……

I’ve had some of my best ES’s with slightly compressed loads.
Like when you barely feel the powder shift a bit at the end of the seating.

 

[rustyinbend]

So all this brings me to a self-question (no answer required from the masses) ... "What good is a slow-burning magnum big-bore-specific powder like Retumbo, if you can't use it because it takes up too much room in the case to get the velocities that make it useful?" Things to ponder ... I'll probably load a ladder from "start" to "max", and be ready to deconstruct at whatever point I see RWS happening.

 

[Steel head]

So all this brings me to a self-question (no answer required from the masses) ... "What good is a slow-burning magnum big-bore-specific powder like Retumbo, if you can't use it because it takes up too much room in the case to get the velocities that make it useful?" Things to ponder ... I'll probably load a ladder from "start" to "max", and be ready to deconstruct at whatever point I see RWS happening.

Generally retumbo is phenomenal in 338 lapua, Norma and Edge.
Getting good speed and case fill.
Try H1000 or retumbo in something like 7 saum and you get crunchy before you get full speed, that’s why R26 is so great in short magnum as it gets the speed and fill like retumbo in the bigger magnums.

My 338 edge load with 265 badlands and N570 is a 99% fill

 

[rustyinbend]

I usually shoot for 99% fill and 100% burn ... but the Retumbo recipe for my 338-LM doesn't get me there, at least not with reasonably high velocity for ELR work. More noodling required ... thanks all.

 

[Steel head]

I usually shoot for 99% fill and 100% burn ... but the Retumbo recipe for my 338-LM doesn't get me there, at least not with reasonably high velocity for ELR work. More noodling required ... thanks all.

You’ve already tried it?
Just because some computer program says it might be a bit crunchy doesn’t mean it will or that it will be too much.

It doesn’t have your chamber measurements, density of new lots of powder and probably a perfect case volume.

If the program says I’ll be maybe at 104% I’d 100% be trying it.
If it predicted 120% I might think otherwise.

Retumbo is famous in 338 lapua for a good reason, it’s like H4350 in 260, well known performer.

If you want speed look into N565 for the 250’s
It’s a more energetic and dense powder but if it was me I’d 100% also consider retumbo.

 

[Halfnutz]

Academic question... How much (if any) can you gain with a drop tube to relieve some of the compression?

 

[Steel head]

I never bother with them as I always can find a powder that works without one.

You can also vibrate the case a bit with a toothbrush before or during seating, I played that game with varget in 223 till I learned the wonderful quality’s of 8208XBR

 

[Choid]

So all this brings me to a self-question (no answer required from the masses) ... "What good is a slow-burning magnum big-bore-specific powder like Retumbo, if you can't use it because it takes up too much room in the case to get the velocities that make it useful?" Things to ponder ... I'll probably load a ladder from "start" to "max", and be ready to deconstruct at whatever point I see RWS happening.

I don't think Retumbo was developed for 338 Lapua like some others, like RL33, MRP2 and N570, were. So I am not sure why you are complaining about what Retumbo is, which is a great powder, but maybe not the best one for this application. It isn't a bad powder because it doesn't offer you exactly what you want. I'd much rather look to something like RL33 which will give you more speed at lower pressure, and keep your fill around 103% or so, which is just about ideal.

 

[Holliday]

I don't think Retumbo was developed for 338 Lapua like some others, like RL33, MRP2 and N570, were. So I am not sure why you are complaining about what Retumbo is, which is a great powder, but maybe not the best one for this application. It isn't a bad powder because it doesn't offer you exactly what you want. I'd much rather look to something like RL33 which will give you more speed at lower pressure, and keep your fill around 103% or so, which is just about ideal.

As an aside, retumbo seems very popular how is it’s temperature sensitivity?

 

[orkan]

Take care not to run too compressed when close to the lands. Those heavily compressed charges will push bullets out over time, all by themselves.

 

[Choid]

As an aside, retumbo seems very popular how is it’s temperature sensitivity?

I have never had a problem with it, and we get pretty good temperature swings here throughout the year. It's honestly my least favorite powder among that speed class. I sold off my last 16 lbs to a guy on here a few months ago for cheap.

 

[Cascade Hemi]

I generally think 105% on QL is when compressed loads begin.