In order to participate in the GunBroker Member forums, you must be logged in with your GunBroker.com account. Click the sign-in button at the top right of the forums page to get connected.
seating depth
colt100
Member Posts: 90 ✭✭
What are the tolerances of seating depth on reloaded rounds? I know that seating the bullet too deeply will cause excess pressure but how far could you seat a bullet and fire the round safely? When loading the 40 S&W, I will sometimes have bullets that seat + or - .01 from the C.O.L. Thanks in advance.
Comments
When in doubt...empty the magazine!!
The reloading data that I have showes a maximum length and a C.O.L. that the load was tested. I guess what I am asking is there a minimum length for every caliber? This info is more for my own knowledge and I do not wish to experimint. My first concern is safety.
Thanks again.
I have then taken the long round and re-inserted it into the seater plug. No change seems to take place. I will then seat another bullet and recieve the desired C.O.L. I can's seem to figure this out. This has been happinging with speer gold dot bullets. Speer sent me another seater plug (at no cost) and I have yet to try it.
I just want to know if the C.O.L. has some room for "error" and what that margin is. Thanks
I have not measured the bullets to see if there is a variation from one to the next. For the record, I have been using a volume charger for the powder and measure the charge every 8th round. Seems to be vary accurate.
What do you consider a serious under?
If you seat lead, you have to clean out the seating die. Lead shaves off and builds us with wax in the seater. Other than that, I just worry about the average cartridge being what it is supposed to be. It can't be too long to feed or operate in the magazine. The cartridge for the 40 cal needs the factory crimp die to eliminate jamming. The neck size has to be the right size or else. The 9mm doesn't seem to have that problem. As far as seating depth, factory specs have always worked out fine.
Also, I have been vexed by small variations in rifle ammo with overall length. Even with great ammunition like silvertip combined technology nosler, I get some variations in overall length. One or two thousanths.
Doesn't seem to hurt too much. I have been able to get my 1/2 inch group in spite of it. But I would still prefer them exactly the same.
At least with the powder, I can hand weigh and perfect every load.
As far as pistol loads go, I just try for 900 to 950 fps. That will get a great group and operate the weapon fine for any I have owned. For concealed carry of course, I use heavy duty factory loads.
Hope something in my comment helps. Happy shooting.
Eric
thats'me
First be aware that there are many documented KBs in the .40 Glock w/ reloads (in fact using reloads voids their warranty) and even some w/ factory loads. Links to sites detailing the problem have been posted here before, but I can't find them on my sys (too bloody many saved URLs!) now. You didn't indicate the firearm, but just in case . . . .
Second, I would consider a variation of .010" in seating or oveall length "serious" in any handgun cartridge. With the relatively small case capacities, that could cause a serious difference in pressure curves. I've used volumetric chargers for all but the fussiest loads for 30 years with consistently good results. I doubt like heck variations in powder charge are an issue given the consistency you've observed in that operation, but it wouldn't hurt to weigh some of the variants to verify that.
I'm not familiar w/ your use of the term "C.O.L." - do you mean the overall length of the cartridge? If so, you stumped this chump. I've had problems with lead buildup and loosening seating stems, but never something where the problem was intermittent and consistently repeatable. Grasping at straws, I'd check the belling operation. Possibly there's some variation there such that there's resistance to the seating? Logically this doesn't fly, but I'd put a lot more faith in factory tolerances than my own. Are your dies crimping simultaneous to, or after, seating the bullet (3 die or 4 die set)? I'd check that setting if they were the former. Again, not logical, but then the situation is not, either. I'd also try breaking down the variants and a few of the rounds of normal length and measuring everything I could - length & diameter of bullets, length, case mouth ID and wall thickness of the cases. I wouldn't hesitate to call the tooling and bullet manufacturers for ideas, either.
One thing for sure, at the very least, you need (1) to stay with very mild loads and (2) to check your individual rounds visually & dimensionally individually & even more carefully than usual until this is resolved, or you could, as others noted, end up "S.o.L."
Good luck!
dimension from top to ogive seems not all that controlled by bullet manufacturers.
Seating plugs that bear only on a bullet's side will deform it depending on the case resistance during seating. If the resistance is variable so will be the round to round variation in cartridge length. Soft, hollow point, plain or plated lead would be especially susceptable. A seating plug that also bears on the bullet nose will prevent this provided it is kept clean. If you're shaving lead because of soft bullets you need to flare/or deburr case mouths better.