I am working up some loads for my 7.62X39 with 150gr Sierra Pro Hunter. Hodgdon lists 28.5gr of H322 as max, Sierra list 27.7gr as max. I started at 25.0gr and worked up from there. I stopped at 28gr. I am a little concerned about the amout of compression that is being placed on the powder. 28gr of H322 dam near fills the case to the top of the neck. When I seat the 150gr bullet to an OAL of 2.20 I have to put quite a bit of force to seat the bullet. Is there such a thing as too much compression? Am I asking for trouble loading with a heavily compressed load such as this?

Thanks


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Steve, Know what you're talking about, had the same thing with 51grs. H380 with the 308Win. under 165 Hornady. You could do a swirl charge where you slowly pour the powder into the case by hitting the outer edge of the funnel which might arrange the powder better in the case. Or, do what I'd do and use RE7 or H4198 which only uses upwards of 24.8 and 24.5grs respectively. J

FWIW,Compressing some ball powders is like compressing a liquid. It ain't gonna happen to much. you will some times back out a primer or swell a case so the brass starts to fill the seating die. you may not kill yourself but you may have a chore closing that bolt handle. Extruded powders give you a wide birth when compressing. roger

There is certainly such a thing as too much compression. The cases you're using may have a little less volume than those used for the loads in the manual. I would only compress to the extent that there is a little "crunch" when seating the bullet but definitely not so much that a lot of force is required to seat the bullet or the case bulges.

If your magazine is long enough to accomodate longer cartridges maybe you should not seat the bullets quite so deeply.

Also, maximum loads should be approached with caution. I've found on many occasions that what is listed as maximum in the manual will give excess pressure signs and/or poor accuracy. I always load for best accuracy and when testing a series of powder charges the groups start opening up, I don't push the load further.

quote:

Originally posted by bartsche:
FWIW,Compressing some ball powders is like compressing a liquid. It ain't gonna happen to much. you will some times back out a primer or swell a case so the brass starts to fill the seating die. you may not kill yourself but you may have a chore closing that bolt handle. Extruded powders give you a wide birth when compressing. roger

H322 is a fine extruded(Rat Turd) powder. Does that mean I may not kill myself less??

In the case of "too much compression" what can go wrong besides backed out primers or swelled cases? I mean, can a heavily compressed load be dangerous, even if the load is not over pressure?

I've fought such things, and had lot's of half empty can's on the shelf I'd never use again.

Flat got tired of it. I never load to the max in anything anyway. To me Best is what can be used in anything I load for with good results.

That's reason enough to use only one powder for everything I load. From .223, to .375H&H. That's 4895.

It's a good average velocity powder and will nearly fill any case but, don't have to be crush fit either. You can find it anyplace that sells powder too. Anywhere in the world.

Can you beat that????

George

quote:

Originally posted by steve4102:
[QUOTE]Originally posted by bartsche:
H322 is a fine extruded(Rat Turd)FLY TURD ,Steve powder. Does that mean I may not kill myself less??This will require serious thought.

roger

quote:

Originally posted by steve4102:
In the case of "too much compression" what can go wrong besides backed out primers or swelled cases? I mean, can a heavily compressed load be dangerous, even if the load is not over pressure?

I'm not sure I understand the "if it's not over pressure" part of the question. Some powders under compression have a jackrabit increase in their burning rate that sky rockets the chamber pressure to deadly levels. Case in point IMR7383. roger

Did it not occur to you that there might be a good reason why Sierra lists a max of 27.7 with their bullet? Hodgedon may list 28.5, but likely it was with different brass, primer, and firearm. Are you duplicating Hodgdon's firearm and components, or just winging it to see what happens?

"...even if the load is not overpressure..." Just because you see none of the obvious signs, it may still be overpressure (and likely is). Have you measured the case webs? Tiny differences in components, ambient tempertures, compression, and OAL can cause big pressure spikes and you are already over max.

If you want to push the envelope, buy a .308. You only have one head, why risk it? There are too few shooters today as it is. Be safe, live long, and pass along the tradition.

Steve,

in my son's 223, our favourite (carefully worked up, and below 'book value') load is easily contained by the case, when poured from the pan of a loading scale... That same load, when filling the case from the powder measure, overfills the case to the extent that powder goes everywhere.

Someone suggested 'swirling' the powder into the funnel, IIRC, there are also 'drop tubes' that make the powder fall further.. hence slightly compresing the load..

One hazard of highly compressed loads is the bullet being pushed forward after the bullet is seated and contacting the lands when chambering - that will DEFINITELY raise pressures unpredictably!!!

Steve 4102 is his ususal amiable self.
Why answer the jerk?

quote:

Originally posted by steve4102:
I am working up some loads for my 7.62X39 with 150gr Sierra Pro Hunter. Hodgdon lists 28.5gr of H322 as max, Sierra list 27.7gr as max. I started at 25.0gr and worked up from there. I stopped at 28gr. I am a little concerned about the amout of compression that is being placed on the powder. 28gr of H322 dam near fills the case to the top of the neck. When I seat the 150gr bullet to an OAL of 2.20 I have to put quite a bit of force to seat the bullet. Is there such a thing as too much compression? Am I asking for trouble loading with a heavily compressed load such as this?

Thanks.

Well, there is a point where compression of a powder charge bewcomes excessive. In my experience, that point is reached when compressing the charge results in expansion (buldging) of the case shoulder, preventing you from chambering the round, OR when compression causes the bullet to "ooze back out" of the case!

I have been using compressed charges for 50 years, and have yet to experience anything like excessive pressures resulting from a compressed charge of smokeless powder, but I guess it could happen.

For example, I use a compressed charge of 54 grains of RE22 with 175-grain Nosler Partition bullets in my 7X57mm Mauser caliber rifles, and have to load the powder in two increments, settling each by tapping the case, in order to have any space at all in the case mouth to start the bullet. This charge is, obviously, heavily compressed! Yet it shows no signs of excessive pressures in the least.

In my 7.62X39mm CZ carbine, I get extreme accuracy with Sierra .308" 150-grain spitzer flatbase bullets and 31.5 grains of H335, WW cases, F210 primers. This is a compressed load as well, but is safe IN MY RIFLE, as is 28.5 grains of H335 with the Speer .311 180-grain RN, another accurate compressed load. The 150-grain load shoots like this:


at 2300 FPS, 10' from the muzzle.

Stick powders will stand compression better than ball powders, which pretty much fill up all available space in the case when you pour it in.

Steve, Like I said before try this powder instead and save the H322 for something else.


H4198 This Extreme Extruded propellant has gone through some changes since its inception, all the time maintaining the same important burning speed of the past. The kernels were shortened for improved metering and necessary elements were added to make it extremely insensitive to hot/cold temperatures. H4198 is outstanding in cartridges like the 222 Remington, 444 Marlin and the 7.62 X 39.

J

I agree with El D.. compression works best with the extuded powders, less well with ball powders. I routinely compress Re25 - even after tapping it in. I can get 71 grs. of Re25 in a '06 AI Lapua case, without bullet extrusion or case expansion. Indeed, problems can occur when the bullet pushes out, and this may occur insidiously over months. Hence, you must chamber the round before hunting to be certain you won't pull the bullet after it gets jammed into the rifling. The latter could ruin a hunt, as you watch the trophy-of-a-lifetime walk over the hill. Also, bullet seating depth can change accuracy and PSI. Thus, compression is safe, but know what you're doing.

There is nothing wrong with compressing powder. I like my loads to compress 1/8" or so. I hate powder to slosh around inside the case.

My load component selection, therefore, calls for 100% load density and an appropriate powder to match.

All of my compressed loads, It was suggested to me so I tried and made different length drop tubes from aluminum arrows, helped a lot.

I've started loading 7.62x39 with Reloder 7 using a Hornady 123 SP bullet.

30 grains fill the case. I loaded 5 round batches of 27, 28 and a 10 round batch at 29 grains. It a small case.

Now if I can just add that scope to that 527 carbine and go to the range.

steve4102

Compressing the charge won't have an effect on pressure, other than the obvious if your charge is too high. That said, I don't like to compress anything very heavily, would try using a long drop tube first and secondly change powders. Sooner or later you will get a bulge just below where the base of the bullet is and have a cartridge that won't chmaber, etc. It's just not worth the headaches.

Thanks everyone. If I understand correctly, compressed loads are OK and in some cases desired as long as I take steps to not over compress. Over compressed loads can result in a backed out bullet or bulged case,Yes? If the compressed load does not buldge the case or back the bullet out , I am good to go, yes?

Over compression is not good and there is a rule of thumb at what is considered max compression. It is measured in % IIRC, but I don't recall the number.

There is a very easy method that has been used for years to test/measure your compression to verify you are w/in limits. Load your powder (but do not use a drop tube, shake the case, tamp the case, etc.) and seat the bullet to your measured OAL but w/ out a crimp. Wait 24 hours and remeasure the OAL. If you have compression beyond max, it will translate into an increased OAL measured in .001"s. It may be .008" (the compressed charge pushing the seated bullet out more than this measurement is considered over max) but I am unsure off the top of my head. I'll look thru my load notes as I have the numbers noted as well as reference info for the technique.