Was talking to the Hornady guys @ the Shot Show, they said, & I quote " that we as reloaders could not duplicate their velocities in the 7mm08 139 gr. SST's in Light Magnums because we can't do what they do to get their published velocities. Any Ideas what they do with brass, powders, etc? I think they claim 3150 fps.

I suspect that they have access to a powder that you don't have access to. I have a 26 inch TCR 7mm-08 barrel and accuracy not withstanding, the highest velocity that I can get is about 2950 with a 139 grain Hornady flat base and that is really pushing the max, not a load that I'd use often. 2900 is much safer and much more accurate.

graycg

One thing is they use thinner brass. I bought a box of hornady custom and a box of hornady light magnum in 7x57.

I weighed the fired cases Custom 192 grns Light Magnum 175 grns

It seems that we have given up on this too easily.

Years ago Keith and others were doing all sorts of things to increase performance.

Whats wrong with packing a case with a very slow burning high density powder with a drop tube and then compressing it some more with some device?

According to an account of an individual who disassembled one of the light magnum shells, the powder is actually a solid column of some sort. Whatever it is seems to have "cured" inside the case, as it would not dump out as conventional powder would do.

FWIW,

Dan

I have some once fired .270 LM brass, will find some other brand once fired brass & compare weights & specs.

It has been "reported" that Hornady is dumping powder in ther "magnum" loads as a liquid slurry...and then drying it...

Hmmm....solid fuel...

Sounds like rocket fuel to me!

Non-cannister grade powder combined with proprietary charging technique. Powder is dry inserted, and clumping is incidental. Powder technique allows greater volume than possible even with long drop tubes. Try reassembling a disassembled round.

Somewhat off topic, but (as I recall) when the British were still using Cordite, they charged the case blank before they formed the neck IOW the case was finish formed with the "powder" already inside.
Could Hornady be effectivly doing the same thing? That is final forming the brass around one large "kernel" of powder?

My understanding is that tailgunner has at least part of the technique. They dump their special powder into a cylindrical case, use a ram to compress it, then size the case to form the shoulder and neck, then seat the bullet.

Not something that a reloader can do easily without ruining his brass - even if you anneal the cases every time I bet you will still ruin many cases opening them back up to cylinder form.

I was using some Federal High Energy brass I had gotten for my 338wm, originally loaded with TBBC's. When I started working up loads using IMR 4831 and 250gr X bullets I noticed the regular Federal brass would top out about 200 fps slower than the HE brass would at the same load. I was able to push it up to over 3000 fps in the HE brass in my gun without much sign of psi. The brass only lasted 4 loadings before pockets were loose, so psi was probably up pretty high.

I never weighed the difference between the two types of Fed cases but they were obviously different. The loads were compressed ALOT. The loads in the normal Fed brass just flattened out in velocity, then suddenly dropped by almost 200 fps at the next grain increment. The load in the HE brass never did this but just kept climbing to 3050 fps where I stopped it at.

I got the same results with IMR 4350, but it took 2gr more powder and bullets bulged the cases if not seated VERY SLOWLY. I just switched to 4831 to minimize this a bit. When I ran out of these two boxes of brass I never got anymore, I imagine the psi was in the 70-75k psi range and just didn't want to weaken the action but running at that level continuesly. I wanted 3000 fps so I'm going to a bigger case to get it at the lower psi.

It would be interesting to compare the Hornady LM to the Fed HE brass, both in weight and a load for load velocity comparison. I might try this in the 308win sometime.

In developing loads for my wildcat 458, the fastest loads were with double-base ball powder.
On max compressed loads I had a shaker mounted
on side of press when seating bullets.Was able to get 5 extra grains in load.And the powder cakes together like Light Magnums do.Ed.

I recently chronographed hornadys 300 win 180 gr. heavy magnums. They averaged 2875FPS! I have no trouble exceding that velocity with reloads. regular old green box 180 gr. rem corelocs averaged averaged 3005FPS! All loads were chronographed in one afternoon in the same rifle.
Factory "ADVERTISED" ballistic's are usually
"VERY OPTIMISTIC". RAGHORN

I have used them in my 338 winchester, the 225 grains only went for 2800 not the 2900 they say on the box

I had a bad experience with Hornady's Light Magnum 7x57 load -- a squib round left the bullet stuck in the rifling. This was my first experience with a squib round and I am so thankful that the alarm bells went off in my head and I did not chamber/fire the second round. The recoil of the 7/57 is mild, and I was wearing earplugs and earmuffs, so the difference in recoil/sound was not as noticeable as one might think. Anyway, I notifed Hornady via email and promised myself I would stick to my own reloads from here on out. One can reload the 7x57 to a nice velocity, any additional velocity that the Light Magnum could give me would never be noticed in the field anyway. And I trust my reloads more!!

I'm told that you need a 24" barrel to achieve the higher velocities, because the peak of the pressure curve has been "moved" forward.

It has something to do with packing a special powder inside the case. I believe that they pack it in while the case is in some kind of die. When it first came out I worked the gun shop a guy came in saying that it would chamber in his 30/06. He bought in the ammo (and following safety guideline) I checked it and sur enough it wouldn't fit. I tryed the ammo in some other 30/06 on the shelf and it owuld fit any that I had. Called Hornady and they sent two new boxes for the customer. They told me about the reloading technique. The cases bulged out in some of the first production runs but has been corrected. What was intresting is that I got the rest of the box of shells from the customer some chambered and some didn't. If memory serves me right is was three shells didn't work out of a box of twenty.

Hcliff

I bought two boxes of Hornady Custom, 180gr and 190gr for 300Win Mag and best I could do with it was Foot-of-angle! I didn't have a Chrony at the time but who cares, my gun didn't like the stuff!