So was contemplating the fact I do compressed loads with a few rifles, and I've never really thought much about it because it's a relative common practice. But I have to ask, are there any actual issues with using compressed loads beyond bullet seating problems? Does it affect burn dynamics drastically? Long term storage issues? Something else?
Compressed loads
- Thread starter Freyr_255
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Some powders are less tolerant of compression than are others.
Also, some spherical powders are not very compressible at all.
Most powders will work just fine as long as the compression is
not so much that the bullet is forced back out of the case. Then
it becomes a feeding/magazine issue, as Mark mentioned. Dave.
Also, some spherical powders are not very compressible at all.
Most powders will work just fine as long as the compression is
not so much that the bullet is forced back out of the case. Then
it becomes a feeding/magazine issue, as Mark mentioned. Dave.
At one time I would have sworn that compressed loads were no problem until they started pushing the bullets back out. I’d have bet my last dollar on it.
Jump ahead a few years and I was loading a couple Weatherbys in 257 and 300 with old style 7828 because I had a pallet of it. Speeds were great, accuracy plenty good enough, and compression was heavy. Lets just it would be hard to get more in there.
All was great because compression doesn’t matter.
Trouble was, after that ammo sat over the winter the first shot out of both rifles locked the bolts solid. Oops. My gunsmith shrugged on the first one but shot me a WTF look on the second.
I’m somewhat less confident in compressed loads now. How can you know what your loads are going to do in 6 months or six years? Its a sure bet that when they printed your reloading manual they never considered what would happen if your ammo sat 10 years. Hell in 10 years they will have several more manuals out.
Jump ahead a few years and I was loading a couple Weatherbys in 257 and 300 with old style 7828 because I had a pallet of it. Speeds were great, accuracy plenty good enough, and compression was heavy. Lets just it would be hard to get more in there.
All was great because compression doesn’t matter.Trouble was, after that ammo sat over the winter the first shot out of both rifles locked the bolts solid. Oops.
My gunsmith shrugged on the first one but shot me a WTF look on the second.I’m somewhat less confident in compressed loads now. How can you know what your loads are going to do in 6 months or six years? Its a sure bet that when they printed your reloading manual they never considered what would happen if your ammo sat 10 years. Hell in 10 years they will have several more manuals out.
I am sure that there are the religious hand loaders that swear by getting the mostested out of the powder by compression. It is more work but I am not saying it is wrong. At the end of the day some hand loaders are looking for the maximum velocity they can get out of that particular round that they use. Others hand loaders like myself are looking for the best accuracy that I can obtain from that particular round. As an example I have a couple 30-378 Sako TRGS rifles and they shoot better with reduced loads and I am talking about velocities that are comparable to a 300 Weatherby. When you are shooting 5 shots into sub half inch at 100 yards it is very hard to go ahead and change up that recipe even though it is no faster than the published data for the run of the mil 300 Weatherby. One rifle likes Hogdon 50 BMG and the other likes Hogdon US869 (go figure). I could probably get an additional 200 plus feet per second with compressed Retumbo but why ruin a good thing.
I'm OK with slightly compressed loads, with almost every type of extruded powder. SLIGHTLY. Reason I will go with slightly compressed, is exactly what Dogleg describes as well as consistency.
I don't always use up all of the loads I make up for hunting season or even target shooting and I have had very similar experiences with bullets being pushed out of the case mouths.
I do not crimp my hand loads. IMHO it's just one more thing that can go wrong when you least need it to happen.
Also, it may or may not solve the issue with the bullets creeping forward.
My perfect load is one that completely fills the case to the neck with either no compression or very slight compression, but not with BALL POWDER.
One of the reasons BALL POWDER was designed, was to be able to increase powder volume/density, WITHOUT COMPRESSING. Of course there were other reasons.
Still, the ideal load density with Ball type powders is a case full of powder up to the base of the neck, without being compressed. Of course, this isn't always possible.
I don't know of any powder that was purposely designed to work best when compressed. That being said, some do.
It's up to the personal likes or dislikes of the hand loader. Likely it won't hurt your rifle to run compressed charges through it and compression may even change the overall parameters of the burn rate, one way or another.
Whatever, it's always been my experience that heavily compressed loads could be better replaced with a slightly faster powder and usually get better consistencies in accuracy/velocity/dispersion/harmonics.
I don't always use up all of the loads I make up for hunting season or even target shooting and I have had very similar experiences with bullets being pushed out of the case mouths.
I do not crimp my hand loads. IMHO it's just one more thing that can go wrong when you least need it to happen.
Also, it may or may not solve the issue with the bullets creeping forward.
My perfect load is one that completely fills the case to the neck with either no compression or very slight compression, but not with BALL POWDER.
One of the reasons BALL POWDER was designed, was to be able to increase powder volume/density, WITHOUT COMPRESSING. Of course there were other reasons.
Still, the ideal load density with Ball type powders is a case full of powder up to the base of the neck, without being compressed. Of course, this isn't always possible.
I don't know of any powder that was purposely designed to work best when compressed. That being said, some do.
It's up to the personal likes or dislikes of the hand loader. Likely it won't hurt your rifle to run compressed charges through it and compression may even change the overall parameters of the burn rate, one way or another.
Whatever, it's always been my experience that heavily compressed loads could be better replaced with a slightly faster powder and usually get better consistencies in accuracy/velocity/dispersion/harmonics.
Thanks for the replies. Honestly the one I'm most concerned about is my 375 HH. I loaded 300 gr TSX's with 69gr of h4895 and it's a phenomenally accurate loading. But I'm noticing some bullets seated #### eyed because of the compression level and it got me wondering. I think I just need to tap the case to settle everything better to solve the issue but ya, thoughts got rolling as a result. 
Thanks for the replies. Honestly the one I'm most concerned about is my 375 HH. I loaded 300 gr TSX's with 69gr of h4895 and it's a phenomenally accurate loading. But I'm noticing some bullets seated #### eyed because of the compression level and it got me wondering. I think I just need to tap the case to settle everything better to solve the issue but ya, thoughts got rolling as a result.
If your bullets aren't seating straight I would say the accuracty of that load is not going to realize it's full potential. I don't compress powders too often, but when I do its only light compression. And I have found that using a drop tube (especially with extruded powders) can actually help the powder to settle enough that lightly compressed charges may actually no longer be compressed. After filling the case I'll often put my finger over the case mouth and tap it a few times on the reloading bench. Seems to help settle powder a little more.
At one time I would have sworn that compressed loads were no problem until they started pushing the bullets back out. I’d have bet my last dollar on it.
Jump ahead a few years and I was loading a couple Weatherbys in 257 and 300 with old style 7828 because I had a pallet of it. Speeds were great, accuracy plenty good enough, and compression was heavy. Lets just it would be hard to get more in there.
Trouble was, after that ammo sat over the winter the first shot out of both rifles locked the bolts solid. Oops.
I’m somewhat less confident in compressed loads now. How can you know what your loads are going to do in 6 months or six years? Its a sure bet that when they printed your reloading manual they never considered what would happen if your ammo sat 10 years. Hell in 10 years they will have several more manuals out.
So what caused the bolt to stick Dogleg? The bullet moved up enough to the point it engaged the lands, and the pressure spiked? Or do you think the powder burned faster after being compressed then decompressed?
All these loads were done some years ago. IIRC I tapped the case and seated the bullet. I can't remember how much compression there was exactly but it was there because the 300 tsx is a huge bullet. I just noticed this year that I got a deformed case neck on a couple I fired off that got me looking closer at that box of bullets, which is when I noticed a few of them were slightly #### eyed. It was making me wonder if I hadn't tilted the case and got a non flat surface that deflected the bullet base. I still need to pull them but it'd be impossible to tell if that was true.
If I had to guess the powder deformed over time and changed burn characteristics. Some powder I understand has a burn control coating that could be compromised. Or pushed the bullet out too far and it hit the lands. Really the only things that make sense given the variables.
Um, there may be another issue.
When you pull those bullets you may find that the granules are stuck together.
I've come across this often with old hand loaded and even old factory ammo. If and when I come across old ammo and after giving it a shake I don't feel any movement of the powder in the case, I set it all aside and pull the bullets later.
Often the powder has clumped and is no longer separated. It usually doesn't mean the powder has gone bad but I'll usually toss it anyway if it's a small quantity.
One thing about powder in this state is it doesn't ignite consistently and can give some serious spikes in pressure.
Well; being Weatherbys the bullets would never come close to the lands even if they moved which they never did. Or to be 100% accurate the remainder in the box never moved, which doesn't prove the fired cartridges didn't. Still; they fit in the magazine so if I was unlucky enough to pick the only one to grow twice in a row it still wouldn't have been much. Short answer, dumbed down is the powder in a compacted mass thinks its an over-sized bullet trying to go down the barrel.
Winchester had a bunch of trouble with compressed loads in the .458 back in the day. Some pushed the bullets out, some turned to squibs and some produced insane pressure spikes.
Agree with TB and Dave, a hunting round must be 100% reliable.
To that end I will only compress a charge up to about 105% load density and only with 'stick' powder. During load testing leave a loaded round in the bottom of the magazine, fire several rounds to see if the round that is in the magazine over the course of fire moves due to recoil, if it does, apply a light factory crimp and test again or go with a powder that performs well with out compression.
Ideally the load density should be 95%+ up to ~105%, at the same time avoiding 100% (some charges may or may not be compressed if loading at 100% due to variations in case volume and charge weight and how the powder settles in the case. (I use a 6" drop to tube to dispense powder).
