Max powder compression?

[DaveA37]

I've been loading 165 grain Nozler "Partions" for my 300 win mag using 72 grains of IMR 4831 for a long time. That amount of powder fills the cases up to the base of the case neck. Thus far I haven't run into a problem with powder compression using that combination. To try and save some money and develop a load for "practice", I decided to switch the bullets to Nosler Ballistic Tips, also in 165 grain. Finished load case length should be at 3.326 OAL. Measuring the two different bullets, the ballistic tips are longer and therefore compress the powder more to get the OAL.

My question is, how much can one compress powder in a finsihed load?

 

[chet]

others will know more about this, but I'd like to throw my thoughts in.

#1 those two bullets differ greatly, they have a completly different ogive. which means you dont have to seat them to the same OAL, the BT can actually sit out farther as it has a sleeker design. However, the BT is a boat tail and that doesnt help your situation because the back end of the bullet does not provide you any neck tension. Also the bearing surface differs meaning more or less friction and different pressures, so you may want to back down a grain or to and work your way up.

#2 IMR4831 is an extruded powder, it can break into smaller odd shaped pieces when compressed. Personally I try not to compress any extruded powders as I feel it creates inconsistencies

#3 300 win mags have a very short neck, it's the only caliber that I turn the necks on because I feel it really helps concentricity for this caliber. I also feel that I need to use most all of that neck to hold the bullet. So if your powder is at the bottom of the neck a boat tail will definetly squash the powder, a little bit may be acceptable, but I'd prefer to just use less powder, especially if it's just a practice/target load.

clear as mud? :lol:

 

[chet]

another point.....
hodgdens list a 110 grain speer soft point load with as much as 81 grains of IMR4831 so the case will hold at least that much without spilling over.

I used to load for a friend, it's been ten years or so..... but if i remember correctly we used 72 grains of IMR4831 and 180 ballistic tips and I dont recall any compression.......

 

[rick smith]

You can compress powder in that round without a problem as long as the bullet isn't pushed out by the powder after you seat it. Nothing to worry about. You are not going to crush enough kernels to cause any pressure change. I unloaded some of the factory enhanced velocity loads, high energy, light mags, etc and couldn't get all the powder back in the case.

I load one round that I can hear the powder crunch when I seat a bullet. Never had a problem. Tried other powders in that particular round but none are as accurate as the compressed powder.Rick.

 

[Antelope_Sniper]

I've compressed powders to the point where I bulged the case.....and didn't have a problem until I bulged the case.

 

[RiverRider]

If you're going to compress a charge, extruded powders are the ones to do it with. I've seen admonitions against compressing charges of spherical powders, and it makes sense that they are already quite dense and do not afford a lot of air space to be taken up by compressing the powder.

 

[JD338]

I load a couple of compressed loads and have tried this trick which works well for me.
http://noslerreloading.com/phpBB2/viewt ... cker+mouse

JD338

 

[DaveA37]

Good idea. Definitely worth a try.

 

[kraky]

If you wanna have fun with "compression" take a 200 AccuBond and put it on top of 81-82 grains of retumbo in a 300 win mag. Surprisingly you don't hear much crunching. It does however make a "squeaking sound" that reminds me of my dentist packing a new filling in a tooth.
I once pulled some bullets with highly compressed retumbo and found that it had kind of packed into "globs" instead of running back out like many other powders.