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gschwertley
veteran member
Posts: 295
(2/4/05 11:56 pm)
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Problems with bullet pull in reloading
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After many years of practice and study, I feel safe in calling myself an experienced handloader. I cannot call myself a scientist, chemist, metallurgist or mathematician however. I am satisfied with the title of experienced handloader.
I still find it frustrating even with this experience to find that after I have seated bullets in charged cases, that these bullets can be pushed without too much trouble deeper into the case. When this happens, you have a problem with "bullet pull". This is just a technical term for how tight the bullet fits into the cartridge case. I have read somewhere that this is so-called because the ammunition makers use this term to describe the amount of force it takes to "pull" a seated bullet from a case during testing.
Reloaders need to be aware that this is a problem if the bullet is too loose (the more common problem) or too tight.
If too loose, the bullet might easily be driven farther into the case, reducing the amount of burning space the powder has. With some cartridges, this increases chamber pressure to a dangerous level. Some examples of where this is very critical are 9mm Parabellum and .40 S&W to name only two. With autoloaders, lever actions, or pump guns, the sharp edge of the case might easily catch on something before it gets into the chamber. Recoil in firing can cause loose bullets to work out of the cases and lock up actions, which is a common problem with the combination of heavy recoil and loose bullets in revolvers.
A situation with excessive bullet pull is not often encountered, but could be if the wrong sized bullet is used! More common would be the correct sized bullet seated into a rifle case neck that was too thick (such as might be encountered in cases reformed from a different caliber). In this situation, the bullet might be seated in the case without any noticeable problem. Once chambered, however, the overly thick brass neck would get squeezed down tighter against the bullet, then resulting in excessive pull. This is just one possiblity.
Two common threads that run through reloading are repetition and consistency. A reloader of even moderate experience knows when something doesn't feel right. When this happens, stop and check it out. Usually there is a reason something doesn't feel like it routinely has in previous similar procedures.
Let's back to the more common problem of insufficient bullet pull. The reasons are several, but three basic ones come to mind. One, problems with dies. Two, problems with brass. Three, problems with bullets. Of the three, I find that the last is by far the least common in my experience anyway.
With rifle dies, the problem is usually centered around the expander ball used in the sizing process. If too large, it will expand the case mouth too much and the bullet will be loose. With pistol dies, the same situation happens with the expander plug used in some die designs during the case mouth flaring process. Same deal, the plug makes the case too large where the bullet is to be gripped. With Lee dies, for example, an expander plug is not used; only a flare is made without expansion to a specificied diameter like with RCBS.
Sizing die bodies can also be over-sized, which will result in cases that are not sized down enough but I have found this to be less common than the problems mentioned above.
Ah, now the subject of brass. Whereas there is only so much goofing around to be done with dies, brass opens up almost limitless possibilities for problems. Ammo manufacturers in the US claim to adhere to SAAMI specifications, a set of specs set up to achieve commonality in the trade. In my experience, however, small differences can be found from one brand to the next. In the way of bullet pull, two main considerations rise to the top. The first is thickness and the second is hardness. Thick brass will size down smaller and will therefore hold a bullet better. Overly thick brass, however, causes other problems. Harder brass (but not to the point of being brittle!) will grip better than soft brass because it has more resistance to expansion. As you experiment, you will find this to be true and you will find brands of brass that you like better than others.
Aside from brand, brass also changes shape as it is fired. The more it is fired, the more it softens and lengthens. The softer it gets, the looser the grip on the bullet. The more it lengthens, and hopefully you are trimming it as necessary, the thinner it gets and the less it can be sized down to grip the bullet properly.
As to having problems with bullet size, as I said above, in my experience this is unusual. As it happens, it is also the easiest problem to check using a micrometer. I used to purchase Sierra factory seconds and I can't recall ever getting any that had problems with their diameter. Having said all of this doesn't mean that the bullet can't be the problem.
You all have done or can do your own experiments as to brands of brass. Just a few comments on my own experiences. I like PMC generally, as it is on the thick side, nicely annealed and stands a goodly number of firings. I have never bought any new; I don't think they sell it for reloaders, I just reload "pick-ups". With Remington brass, I have encountered over the years several examples of "thin brass" that gave bullet pull problems. I will never use any brass headstamped "Amerec" from the outfit in Florida; it is soft but thick, which has caused problems with chambering in pistol rounds. Makes me wonder, do they use slightly undersized bullets the first time around? With all of the new rifle ammo coming out of eastern Europe now, you discover some strange anomolies with the stuff that is boxer primed when you go to reload with it.
There is one band-aid that I have found for insufficient bullet pull. It is called the Lee Factory Crimp Die. Even if the bullet is loose, you can scrunch the case mouth into the sides of the bullet with one of these dies and it will usually hold it in okay. I don't like to do this; I would rather solve the problem the right way.
yockey5
Owner
Posts: 3922
(2/5/05 12:09 am)
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Re: Problems with bullet pull in reloading
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I had a problem with a small batch of 7x57 brass that I converted to 7.65x53. What I think I did was get the brass too soft when I annealed it, and on the 1st reloading it did not want to hold the bullet well. Thanks for the info GS, You made some clear, and great points.
Don
Yesterdays Weapons forums
http:pub151.ezboard.com/bsteyrmannlicher
txpete
veteran member
Posts: 59
(2/5/05 12:09 pm)
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Re: Problems with bullet pull in reloading
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excellent write up.I started off with the lee factory crimp die in 44-40 now I use in 45acp,9mm,7.7 jap,7.62X53R and all my lever rifles.it takes a extra step but well worth it.
pete
gschwertley
veteran member
Posts: 296
(2/6/05 3:57 am)
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Bullet pull
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Pete:
.44-40 is one of the cartridges that gave me fits for a while, and I too got the factory crimp for that one. .44-40 brass is so thin it doesn't tolerate variation in bullet diameter much. Most of my bullet pull problems with .44-40 went away when I got a .425 expander plug for the flaring die.
You might be better off to use the taper crimp on those pistol rounds that headspace on the mouth of the case like .45 ACP and 9mm.
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