Armory Sponsor
Posted: 5/21/2016 11:19:06 PM EDT
|
I've been messing around for a little bit checking the length of a new chamber in the process of load development and have some questions. I've done this several times with other rifles and have had good luck and accurate measurements. Basically I think I'm being too OCD in checking my measurements and need to hear from you guys.
I've got the Hornady tools to do OAL with the modified cases and with the comparator to check the ogive length. This is for my precision match rifle in .260 for reference. I'm checking 139 Scenars and the new 140 ELDs. The Hornady modified case doesn't fit my chamber to my liking and I don't like the measurements I'm getting because I think the case isn't fitting right. I should do a fire formed case to get dead nuts but I just haven't had time to, and Hornady uses a weird thread pitch for the gauge and I havent gotten a tap yet. I guess what I am asking is, I have a fire formed case that still has a decent amount of neck tension (enough to hold the bullet snug) can I not just put the bullet in the case, leave it long and carefully chamber the case and remove it? Wouldn't that essentially give me the same measurement to the lands by letting the bullet index off the lands and just insert back into the case? |
|
Just so you know, there is a Precision Reloading forum under the Precision Rifle tab. Here is a link http://www.ar15.com/forums/f_16/10_.html And that's all the help I can be. |
|
Quoted:
I guess what I am asking is, I have a fire formed case that still has a decent amount of neck tension (enough to hold the bullet snug) can I not just put the bullet in the case, leave it long and carefully chamber the case and remove it? Wouldn't that essentially give me the same measurement to the lands by letting the bullet index off the lands and just insert back into the case? I did this with my 6mm Rem. I made a case that would hold a bullet tight but not so tight that it couldn't be pushed in. Carefully chambered and removed. I measured the length and then did it several more times for an average. Each time was nearly the same so I figured I had a good measure to the lands. |
|
Quoted:
Just so you know, there is a Precision Reloading forum under the Precision Rifle tab. Here is a link http://www.ar15.com/forums/f_16/10_.html And that's all the help I can be. Thanks Dryflash, I didn't crosspost over there. I just figured it may get more traffic over here in the big section. |
|
Quoted: Thanks Dryflash, I didn't crosspost over there. I just figured it may get more traffic over here in the big section. Quoted: Quoted: Just so you know, there is a Precision Reloading forum under the Precision Rifle tab. Here is a link http://www.ar15.com/forums/f_16/10_.html And that's all the help I can be. Thanks Dryflash, I didn't crosspost over there. I just figured it may get more traffic over here in the big section. Your post is certainly welcomed here. First time I've seen you post, so just plugging the other forum.  |
|
Quoted:
I guess what I am asking is, I have a fire formed case that still has a decent amount of neck tension (enough to hold the bullet snug) can I not just put the bullet in the case, leave it long and carefully chamber the case and remove it? Wouldn't that essentially give me the same measurement to the lands by letting the bullet index off the lands and just insert back into the case? If you do it that way, the trick is to remove the ejector and extractor or carefully slide the dummy cartridge under the extractor and into the chamber. You don't want the ejector/extractor interfering with the measurement. You want the case dead flat against the bolt face during chambering. Alternatively, as long as the Hornady case is smaller than a fired case, it will work. Measure the headspace of the gage case and a fired case. The difference has to be added to the fired cases to get the proper OAL on loaded ammo. |
|
Quoted:
The trick is to remove the ejector and extractor or carefully slide the dummy cartridge under the extractor and into the chamber. You don't want the ejector/extractor interfering with the measurement. You want the case dead flat against the bolt face during chambering. As long as the Hornady case is smaller than a fired case, it will work. Measure the headspace of the gage case and a fired case. The difference has to be added to the fired cases to get the proper OAL on loaded ammo. Just to clarify, the proper way to measure OAL is with a fireformed piece of brass or brass at maximum expansion? Vs a full resized/ new factory dimension/undersized case, which I assume hornady's modified cases are? Assuming I am not using neck sizing dies and I were just setting back the shoulder 0.001-0.002", would I still used the fireformed case or the case that had been shoulder bumped? |
|
You may try one of these |
|
Quoted:
I guess what I am asking is, I have a fire formed case that still has a decent amount of neck tension (enough to hold the bullet snug) can I not just put the bullet in the case, leave it long and carefully chamber the case and remove it? Wouldn't that essentially give me the same measurement to the lands by letting the bullet index off the lands and just insert back into the case? This is exactly what I do. I take a case that I've bump-sized for my chamber, then with a hack saw blade, cut a slot straight down the case mouth down to the shoulder, and remove any burs. You can also drill out the flash hole so you can push the bullet back out (optional). Next, I start the bullet I want measured, and simply push the case into the chamber by hand as far as it'll go. Call me lazy, but this is easier than taking the bolt apart, etc., and since I know my headspace to a reasonable accuracy, I can determine how much slack is in the chamber when the bolt is closed, and add that to the measurement. Carefully take them back out, measure, and repeat several times until I'm satisfied the measurement is correct. |
|
I've seen people mention that process before but never really paid close attention to it. That seems really simple and effective. I'll pick up some dowel rods tonight at Lowe's and give that a whirl. It would also be a good way to keep an eye on throat erosion as a barrel shoots in as long as you know what it was to start with.
Thanks again guys! |
| I just stuff the loaded round into the chamber w/ my thumb. Tip the muzzle up. If the ctg falls out on it's own, then it's not touching the rifling. So if you want to find the lands, seat it long then shorten in small increments till it drops out. Simple and repeatable. |
|
I use Hornady's Lock-N-Load system and actually did it last night. You can make the cases at home using once fired brass from your rifle. The internal threads on Hornady's custom cases is an oddball size and you may have to order it, most hardware stores and even machining supply houses don't usually stock it.
I run Hornady's custom cases in a neck sizing die only 1/16th" to no more than 1/8" to center the bullet and supply very light grip. You could do this with your once fired cases should you make them at home. For what it's worth, I never seat Sierra Match Kings all the way into the rifling. I normally jump them around .030" +/-. VLD's work better actually into the rifling, but SMK's just need to be close. |
|
Quoted:
What don't you like about the fit of the Hornady case? I measure the headspace of the Hornady case vs. my cases and seat accordingly. I have the tap but found it to be too much trouble to hold the case without damaging it. The case just doesn't want to fit the chamber correctly. It's fairly snug and not repeatable taking it in and out. The headspace is good compared to a fired case of mine, shoulders are bumped about .006 and taking measurements at the base and up its in spec with my fire formed stuff. I've got a .308 and a .223 Hornady modified case that will just drop in several different chambers and theres been no fit issues at all with either of those. Makes me wonder if maybe the threads weren't cut straight and its ever so slightly binding up in the chamber. Its scratching the case up at the head some. I've got a small base .308 die, I may try to just pull the expander ball and stem out and just run it through to see if that helps any. I got my wooden dowel rod the other night and am gonna try that and see how it goes. |
|
Quoted:
The case just doesn't want to fit the chamber correctly. It's fairly snug and not repeatable taking it in and out. The headspace is good compared to a fired case of mine, shoulders are bumped about .006 and taking measurements at the base and up its in spec with my fire formed stuff. I've got a .308 and a .223 Hornady modified case that will just drop in several different chambers and theres been no fit issues at all with either of those. Makes me wonder if maybe the threads weren't cut straight and its ever so slightly binding up in the chamber. Its scratching the case up at the head some. I've got a small base .308 die, I may try to just pull the expander ball and stem out and just run it through to see if that helps any. I got my wooden dowel rod the other night and am gonna try that and see how it goes. You really need a body die, or you will never get the bullet to drop into the neck even if you keept the expander in the die. |
Armory Sponsor