Compressed loads?

J

jski

New member
This relates to another posting of mine. What are the effects of compressing the charge in a case?

I use 14-15 gr. of H110 in my .30 Carbine loads. This puts the powder close enough to the case mouth that you're compressing the charge. With heavier bullets this becomes even more of an issue because they're inserted further into the case.

So are compression loads problematic?
 
Last edited:
If it is a compressed load out of a manual? NOTHING, and maybe be very accurate.
Charge weight goes down as bullet weight goes up.
 
There used to be a 'rule' to not compress more than 10 %.
Me ?I'd prefer not to compress .But if you find it in a reloading book give it a try if you want.
 
14.5 gr IMR 4227, with 15 gr being max, is a standard load for the .30 carbine and 110 gr bullet. This loading fills the case to about 1/16th or maybe even 1/32nd of an inch below the case mouth. So you get more compression there than with H110 powder. Proper compression with the .30 is nothing to be concerned about.
 
Max H110 loads are not compressed. Max loads of IMR4227 are though. Anyway, compressed loads are nothing to worry about.
The only heavier bullet data available is for cast bullets for handguns. 130's with a 1.680" OAL. Do not use cast bullet data for jacketed bullets. Any heavier jacketed bullet will be too long anyway.
14.5 grains of IMR4227 is the current max. Wasn't when I worked up the load either though. 14.5 grains of IMR4227 with a 110 grain bullet is exceptionally accurate(moreso than the H110 loads I tried long ago) and it gives a very satisfying BARK!!! sound.
 
Compressed loads are a sign that the powder might be to slow for what your loading. I also see over 100% loads now and then in manual's, I never use them. I've heard some guy's swear by them, never an over charge. That's true, case is to small and the slow powder keep's you out of trouble. I use powder's in Jacketed loads that come out around 80% capacity and above. 90% is fine with me. Compress to much and I've read where the powder may actually start de-compressing itself and move the bullet forward, the more compression you get the more likely it might happen. Those thing's alone kept me from using compressed loads. In cast loads I use awfully light loads. With some powder's in a big case, that can really jump pressure. I experienced that one time years ago with a 7mm mag I wanted to blow some dent's out of. The jump in pressure was really really obvious! But by pointing the gun up before shooting and then leveling it out slowly, the problem went away. In cast rifle bullet's regardless of the powder I never get over 50% capacity so every one of them get a quarter sheet of toilet paper to hold the powder against the flash hole. Is that needed? Shoot I don't know but not willing the not do it just to find out. I had a load here a while back I pulled a cast bullet form for my 308. Using the inertia puller I expected the paper and powder to come out with the bullet, didn't happen! The paper and the powder looked to be right where I'd set it at. Had to dig the paper out with a pick to get the powder out. If I remember the problem with my 7mm mag was created because it was a small load of hard to ignite powder, N205.
 
Compressed loads are not a problem within reason. I regularly use compressed loads in pistols of up to 120% (vvN105-amazing pistol powder)

If you go to a faster burning powder, you will generally have less compression but you will also lose a lot of performance. FWIW, Nosler lists compressed loads in their load data exceeding 110%

I regularly load a 116% compressed vvN105 under a 125g bullet in the 357 SIG for 1500 feet and a 110% load of vvN105 under a 230 HC WFNGC in the 10mm for 1100 feet.

Don't worry about a little compression.
 
I have been loading and shooting compressed loads since the mid 60s and I'm still here.

Of course you gotta do your research as some powders are not to be compressed.
 
I have been loading compressed loads since I started reloading. I prefer compressed loads in my precision rifles. If it is compressed, it will not affect the ignition no matter how the cartridge was oriented before chambering.
My most accurate rifle loads, and most consistent velocities are all achieved with compressed loads. I try not to go much above 107-110% . But I usually try and pick a powder that fills the case to at least 95% or more.

In my model 70 Super Grade .300wm I am using a load that is 108.7%. velocity with H1000, ES 7 fps, using 200 gr Nosler Accubond.
Similar results with H 4831 long graines in my .270.

A case with too little space filled by powder is probably more of a danger than a case being too full ( assuming you worked up to that and you can seat a bullet)
 
I guess this boils down to: does powder behave differently when it's compressed? If yes (and assume it does), is it a function of how compressed it is?
 
jski said: ↑
does powder behave differently when it's compressed?
Click to expand...
Yes. But H110 is a flattened ball powder. Its already been rolled/smashed. This is why its not easy to compress or at all.

Stick powder like IMR 4350 types can be compressed. If the powder changes shape, smaller, the burn rate may change. Depending on how much its smashed.


http://www.firearmsid.com/Feature%20Articles/McCord_gunpowder/

Shape and size have a profound effect on the burning rate and power generation of a powder (Meyer 1987). Common particle shapes of smokeless propellants include balls, discs, perforated discs, tubes, perforated tubes, and aggregates
Click to expand...
Many photo of powders and types. http://www.ilrc.ucf.edu/powders/sample_detail.php?powder_id=80
 
Yes, as an example Hodgdon reports that compressing Trail Boss can result in erratic accuracy even though the compressed load is entirely safe. Trail Boss does have a "formula" for a max load which is just short of compression but exceeding that by compressing can result in loss of accuracy.
 
I would say that if you find a load MARKED as a compressed load in the manual then it is likely a safe load. If you find a ball powder or double base powder load that is compressed in a manual get a different manual. There were warnings back in the 1960's that compressing double base powders could result in detonations or (get this) squib loads.
So if if you are lucky the powder doesn't ignite and leaves you with a mess of unburned powder and a bullet stuck in your bore. If your luck ran out you get a few days in the hospital, a busted gun, and a lot of pain.
 
I would say that if you find a load MARKED as a compressed load in the manual then it is likely a safe load. If you find a ball powder or double base powder load that is compressed in a manual get a different manual. There were warnings back in the 1960's that compressing double base powders could result in detonations or (get this) squib loads.
So if if you are lucky the powder doesn't ignite and leaves you with a mess of unburned powder and a bullet stuck in your bore. If your luck ran out you get a few days in the hospital, a busted gun, and a lot of pain.
Click to expand...

No offense, but that is a little bit dated wouldn't you say?

For example, EVERY max load for Ramshot BIGGAME is compressed in the 308 Winchester straight from the Western Powders reloading manual.

As do MANY other sources.

Just sayin.....
 
There were warnings back in the 1960's that compressing double base powders could result in detonations or (get this) squib loads.
Click to expand...

I too am wondering where these warnings came from as I have been stuffing cases since before the mid-60s and I compress H110. I have NEVER had any issues with it.

I also compress Lil'Gun and AA #9 among many others.

As I said before, before you do it, do your research for your own safety and so it does not go unsaid, what one feller does, does not mean for you to do it blindly.
 
No offense, but that is a little bit dated wouldn't you say?
Click to expand...

You would have had to be there. It went something like there is no way you an get too much powder in the case and all you have to do is dip the case into the powder to fill it and then? seat the bullet.

I always thought there were too many chances for misunderstanding and then there is that chance of transposing numbers.

F. Guffey
 
The warnings came from the fact that there can be up to 50% nitroglycerin by weight. It was not a good idea to compress powders like H414, H110, WW296, WW760, WW748 and WW785. Dated information, yes. After a quick look at Western powders I see that Western Powders limit the nitroglycerin content to <25% and they must have found buffers that negate the effects of compression. At Hodgdon I found 3 loads in one caliber, 450 Extreme, that were listed as compressed with Lil'gun. It is still not a good idea in my mind although I will admit that it seems to be a growing practice with the newer double base powders. I still remember the results that Alfred Nobel had trying to use buffered nitroglycerin in naval artillery guns. Trying to find a safe way to use nitroglycerin as a propellant didn't work out but he did invent dynamite along the way. Nitrocellulose was finally and successfully invented and began the wide use of smokeless propellant.
Back in the 60s again, there was also a warning about using double base powders at temperatures below -35F (or -40F) because the nitroglycerin could be in a frozen state and detonate catastrophically. I haven't heard anything on that subject in a long time either so, maybe it no longer applies either. Anyone up north use double base powders in the winter?
 
You would have had to be there. It went something like there is no way you an get too much powder in the case and all you have to do is dip the case into the powder to fill it and then? seat the bullet.

I always thought there were too many chances for misunderstanding and then there is that chance of transposing numbers.

F. Guffey
Click to expand...

Like you, I would never personally advocate such a careless loading technique. While it may be applicable under certain conditions, it promotes an overly simplistic view of a serious topic.

The warnings came from the fact that there can be up to 50% nitroglycerin by weight. It was not a good idea to compress powders like H414, H110, WW296, WW760, WW748 and WW785. Dated information, yes. After a quick look at Western powders I see that Western Powders limit the nitroglycerin content to <25% and they must have found buffers that negate the effects of compression. At Hodgdon I found 3 loads in one caliber, 450 Extreme, that were listed as compressed with Lil'gun. It is still not a good idea in my mind although I will admit that it seems to be a growing practice with the newer double base powders. I still remember the results that Alfred Nobel had trying to use buffered nitroglycerin in naval artillery guns. Trying to find a safe way to use nitroglycerin as a propellant didn't work out but he did invent dynamite along the way. Nitrocellulose was finally and successfully invented and began the wide use of smokeless propellant.
Back in the 60s again, there was also a warning about using double base powders at temperatures below -35F (or -40F) because the nitroglycerin could be in a frozen state and detonate catastrophically. I haven't heard anything on that subject in a long time either so, maybe it no longer applies either. Anyone up north use double base powders in the winter?
Click to expand...

Maybe the combination of reducing the nitro content in addition to the stabilizing agents you mention are what make compressed loads safer? Perhaps they are some of the same reasons powders, especially double based, are becoming more temperature resistant as well.

H414 and W760 are the same powder (nowadays), browsing Hodgdon's data, I don't see any compressed loads in the calibers I load so your information may be right on those. I also use H110 and W296 (same powders again) and I just looked and none of my loads are compressed. Some of my Lil'Gun loads are 100% but no more.

Maybe this would suggest that one should only compress loads that the powder people say to compress.

I do wish there was a more definitive answer though.
 
For a while I did use 14.5 gr H-110 for the .30 since the H seemed to be so popular, but gave it up since the extra fine granules of H would become wedged between the sliding surfaces of the 550 powder measure and would require cleaning to restore proper activation. Then immediately returned to 14.5 IMR 4227. That loading can be observed at the bullet seating station and of course is compressed. I don't think the 14.5 gr of H is compressed and the powder level cannot be observed at the seating station.
 
You must log in or register to reply here.
Back
Top