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Posted: 9/24/2015 3:39:18 AM EDT
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I plan on working with a buddy to get him started on reloading since he has an interest in loading up some .223.
We have a large amount of LC brass and I would like to be able to prep it all in advance with him so it's ready to go when we need to load some rounds. I measured some fired brass from both his AR and my own, and the measurements differ enough that I'm wondering if I need to resize the brass differently for the two guns. His once fired brass measures on average 1.473" (from datum point) and mine measures on average 1.468". Do you guys think I can get away with resizing all the brass down to 1.465" and not have inconsistent primer ignition in his gun? |
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They're one tenth of an inch different? I hope that's a typo. If it is, 0.008" will stretch the brass and shorten the life, but it oughta fire. Personally, I use the Redding Competition Shell Holders. Start with the +0.010", size and chamber check with the lower ones until the case ejects without needing to mortar. |
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Quoted:
I plan on working with a buddy to get him started on reloading since he has an interest in loading up some .223. We have a large amount of LC brass and I would like to be able to prep it all in advance with him so it's ready to go when we need to load some rounds. I measured some fired brass from both his AR and my own, and the measurements differ enough that I'm wondering if I need to resize the brass differently for the two guns. His once fired brass measures on average 1.573" (from datum point) and mine measures on average 1.468". Do you guys think I can get away with resizing all the brass down to 1.465" and not have inconsistent primer ignition in his gun? What are you measuring? It can't be the COL. Do you have a reloading manual? If so, the COL should say something very close to, '1.760 inch'. What's the, 'datum point'? In 40 + years of reloading the only time I've ever encountered a term like that is in descriptions of the beginning of a rifle chamber's leade. Are you aware that the NRA offers training for new reloaders? They do! Call NRA Training @ 703-267-1500. They'll give you the name(s) of a local reloading trainer in your area. |
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I have found measuring fired brass is not very reliable. Cases spring back at different amounts. The only accurate way of measuring it with a tool like the Hornady tool is to size the case in incremental steps until it will chamber with light pressure. Then measure it.
Don't forget that the case will actually grow in length until shoulder contact is made and you begin to push it back. I believe in some instances the case even changes size while being extracted from the chamber of a semiautomatic. Motor |
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What measurement system are you using? Hornady's Lock-N-Load, RCBS's micrometer or Mo DeFina's micrometer give excellent results.
Resized brass will need to be trimmed to 1.750". Brass grows the most after the first firing and almost always requires trimming. It's impossible for your friends rifle to exhibit the fired size you posted. That much headspace would almost certainly cause ruptured case failure upon firing. I would resize your brass for your rifle. Let your friend resize his brass for his rifle. I use fired case size minus .003" to minus .004" for use in semi-auto rifles. I use minus .001" for bolt actions. Normally I use a SAAMI minimum headspace gage for any ammo destined for use in any rifle. This is a "tight" headspace clearance in new rifles, but will feed and function without issues. |
| I agree that fired brass dimensions vary too much to get exact chamber readings. Different brass spring back at different rates plus different load levels will show different readings. Some loads and the brass won't even show expansion. IF I were to need to presize a bunch of brass for different rifles I'd check factory ammo as most all the shoulder dimension is "zero" and I'd size all .002" longer than the factory rounds. Several AR's I've loaded for .002" longer than "zero" would allow all the rounds to chamber without problems with excessive case stretching. Only solution I see is to take your rifle and your buddies rifle and check your sized cases to make sure they will chamber. Barely size until the case will barely allow the bolt to close and lock, measure the shoulders and go from there. I'd bet both rifles have chambers very close to the same length. Like mentioned, trim all brass before checking chambers. |
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Whoops! That's what I get for typing this up before going to bed! I'll edit the original post but I typo'd the numbers...
His fired brass measures 1.473" and mine measures 1.468" It doesn't seem like a huge difference, but don't want to have any problems. I should've said, I already have loaded up quite a bit of ammo for my gun with Remington brass, but I'm trying to work up a new load with LC brass and some 55 FMJ's. The ammo that I already loaded I used a go/no go gauge to determine resizing. I must have lucked out because I measured a handful of them today and they are all around 1.465" +/- .001"`. I can definitely check to see if this ammo will chamber in his rifle, but don't really want to fire it from his without working up a new load. |
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Quoted:
Wow, recheck the numbers. I shoot multiple .223 rifles and I size .002 thousands of a inch under the shortest chamber. I edited the numbers in my original post....do you have any issues with rounds not firing from any of the rifles you reload for? Or does it go pretty smoothly as long as the brass is sized for the smallest chamber? |
| I would use his fired brass and check fit them to your chamber and bump the shoulder back .001 at a time and that may let you know what your chamber really is and how much spring back you are getting from your cases fired in your gun. Use that info to set up your die, if you are between bumping the shoulders back as saami spec that would work for both guns, his chamber would allow more stretch and wear but less than resizing to factory dimension each and every time. Others please chime in if this is correct. |
| I would use his fired brass and check fit them to your chamber and bump the shoulder back .001 at a time and that may let you know what your chamber really is and how much spring back you are getting from your cases fired in your gun. Use that info to set up your die, if you are between bumping the shoulders back as saami spec that would work for both guns, his chamber would allow more stretch and wear but less than resizing to factory dimension each and every time. Others please chime in if this is correct. |
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I would use his fired brass and check fit them to your chamber and bump the shoulder back .001 at a time and that may let you know what your chamber really is and how much spring back you are getting from your cases fired in your gun. Use that info to set up your die, if you are between bumping the shoulders back as saami spec that would work for both guns, his chamber would allow more stretch and wear but less than resizing to factory dimension each and every time. Others please chime in if this is correct. Okay cool, this sounds like a good idea. I'll give it a try tonight and see how closely the dimensions I get match up with my once fired brass |
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What are you measuring? It can't be the COL. Do you have a reloading manual? If so, the COL should say something very close to, '1.760 inch'. What's the, 'datum point'? In 40 + years of reloading the only time I've ever encountered a term like that is in descriptions of the beginning of a rifle chamber's leade. Are you aware that the NRA offers training for new reloaders? They do! Call NRA Training @ 703-267-1500. They'll give you the name(s) of a local reloading trainer in your area. Quoted:
Quoted:
I plan on working with a buddy to get him started on reloading since he has an interest in loading up some .223. We have a large amount of LC brass and I would like to be able to prep it all in advance with him so it's ready to go when we need to load some rounds. I measured some fired brass from both his AR and my own, and the measurements differ enough that I'm wondering if I need to resize the brass differently for the two guns. His once fired brass measures on average 1.573" (from datum point) and mine measures on average 1.468". Do you guys think I can get away with resizing all the brass down to 1.465" and not have inconsistent primer ignition in his gun? What are you measuring? It can't be the COL. Do you have a reloading manual? If so, the COL should say something very close to, '1.760 inch'. What's the, 'datum point'? In 40 + years of reloading the only time I've ever encountered a term like that is in descriptions of the beginning of a rifle chamber's leade. Are you aware that the NRA offers training for new reloaders? They do! Call NRA Training @ 703-267-1500. They'll give you the name(s) of a local reloading trainer in your area. By datum point, I meant I am measuring from the shoulder of the brass to the head of the case. That's cool to know about the NRA as well! |
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I don't know what type of equipment you load on and understand some will allow the shoulder to be pushed back a good bit.
The thing you have to consider is what your doing worth the effort. The "intended" benefit to limiting your sizing is to increase case life and possibly have a positive effect on accuracy. We already had a member do a case life study and besides split necks, which can be avoided by annealing, he was well into the teens on number of times reloaded and still hadn't had a case separation and he was sizing to full cam over effect. So that leaves us accuracy. I'll draw on my personal experience for this. I load on a single stage press using a Lee .223 standard die set.I set up for full-length sizing and good cam over. Less than MOA accuracy is easy with my Remington VTR-15 and my parts gun which is a PSA 20" A3 upper with chrome lined 1 in 7 barrel and standard hand guard and 5.56 chamber will shoot under 2MOA often closer to 1. Taking all of this into consideration I personally fill it's a total waist of time to try and size to a specific head space dimension for a semiautomatic that is going to be used for recreational shooting. I also have to question the reliability of basically short sizing. I guess enough people do it that it must be ok but caming over on a size die is done to remove all of the play in the press linkage. If you are relying on the sizing force to do this how can you be getting exact results? If you are using a different thickness shell holder to accomplish it and still caming over then that would be better. But you still have to leave enough room for the various amount of spring back that can occur. Think about it. Motor |
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Quoted:
I don't know what type of equipment you load on and understand some will allow the shoulder to be pushed back a good bit. The thing you have to consider is what your doing worth the effort. The "intended" benefit to limiting your sizing is to increase case life and possibly have a positive effect on accuracy. We already had a member do a case life study and besides split necks, which can be avoided by annealing, he was well into the teens on number of times reloaded and still hadn't had a case separation and he was sizing to full cam over effect. So that leaves us accuracy. I'll draw on my personal experience for this. I load on a single stage press using a Lee .223 standard die set.I set up for full-length sizing and good cam over. Less than MOA accuracy is easy with my Remington VTR-15 and my parts gun which is a PSA 20" A3 upper with chrome lined 1 in 7 barrel and standard hand guard and 5.56 chamber will shoot under 2MOA often closer to 1. Taking all of this into consideration I personally fill it's a total waist of time to try and size to a specific head space dimension for a semiautomatic that is going to be used for recreational shooting. I also have to question the reliability of basically short sizing. I guess enough people do it that it must be ok but caming over on a size die is done to remove all of the play in the press linkage. If you are relying on the sizing force to do this how can you be getting exact results? If you are using a different thickness shell holder to accomplish it and still caming over then that would be better. But you still have to leave enough room for the various amount of spring back that can occur. Think about it. Motor Thanks for the info! Sounds like I may be over thinking this....The numbers seem close enough that I'll prep like normal for my other loads and see what happens |
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I edited the numbers in my original post....do you have any issues with rounds not firing from any of the rifles you reload for? Or does it go pretty smoothly as long as the brass is sized for the smallest chamber? Quoted:
Quoted:
Wow, recheck the numbers. I shoot multiple .223 rifles and I size .002 thousands of a inch under the shortest chamber. I edited the numbers in my original post....do you have any issues with rounds not firing from any of the rifles you reload for? Or does it go pretty smoothly as long as the brass is sized for the smallest chamber? No. |
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Quoted: Thanks for the info! Sounds like I may be over thinking this....The numbers seem close enough that I'll prep like normal for my other loads and see what happens Quoted: Quoted: I don't know what type of equipment you load on and understand some will allow the shoulder to be pushed back a good bit. The thing you have to consider is what your doing worth the effort. The "intended" benefit to limiting your sizing is to increase case life and possibly have a positive effect on accuracy. We already had a member do a case life study and besides split necks, which can be avoided by annealing, he was well into the teens on number of times reloaded and still hadn't had a case separation and he was sizing to full cam over effect. So that leaves us accuracy. I'll draw on my personal experience for this. I load on a single stage press using a Lee .223 standard die set.I set up for full-length sizing and good cam over. Less than MOA accuracy is easy with my Remington VTR-15 and my parts gun which is a PSA 20" A3 upper with chrome lined 1 in 7 barrel and standard hand guard and 5.56 chamber will shoot under 2MOA often closer to 1. Taking all of this into consideration I personally fill it's a total waist of time to try and size to a specific head space dimension for a semiautomatic that is going to be used for recreational shooting. I also have to question the reliability of basically short sizing. I guess enough people do it that it must be ok but caming over on a size die is done to remove all of the play in the press linkage. If you are relying on the sizing force to do this how can you be getting exact results? If you are using a different thickness shell holder to accomplish it and still caming over then that would be better. But you still have to leave enough room for the various amount of spring back that can occur. Think about it. Motor Thanks for the info! Sounds like I may be over thinking this....The numbers seem close enough that I'll prep like normal for my other loads and see what happens Be sure to have buddy bring over his rifle when you start to size cases. Have him chamber/eject sized cases. Better to find out immediately there is a problem, than size a batch and have to do them over. Or best to find every thing is fine. But it gives piece of mind to test early on. |
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Agreed, you would be well served to have both rifles at hand with cleaned chambers to start your checks.
I use a hornady tool and my 6" dial mitotoyo to measure the brass. Other than fixed steel headspace gages there are tools that fit in the gun and have a slip fit to try to measure the inside of the chamber dimension. I never got the warm and fuzzies from such a tool that slips. You could of course and should of course take numerous measurements of the same rifle before settling on a number with such a tool. You could use actual headspace gages and a layer of scotch tape on the base for a relatively good idea but you need to have a consistent feel of pressure when you start to make contact. That would get you pretty damn close. You could also do the same with a piece of brass, size it with long with the shoulders forward and keep check fitting the chambers feeling for the point of the loss of contact/compression. Size the brass farther and farther down in small increments and keep checking at each size interval. The rifles should be close and I would expect them to be within 2 or 3 thousandths and not as wide as your two fired brass samples. I have fired brass sized 8 thousandths under the chamber size and I saw split necks and shoulders in a couple firings. IIRC it was with Rem brass, not LC. For an auto loading gas gun I would try to be about two to four thousandths. Any tighter and your variance will creep you to no headspace at times. For plinking fodder, a full die cam over crush can be achieved with my RCBS dies. I set up my die years ago for full cam over and that's where I got the 8 thou headspace before learning more, buying more measuring tools, and refining what I wanted. That full cam over works for different things like where a 3 gunner will put more weight on 100% operation with less chance of stoppages versus a bench shooter or a highpower shooter tweeking an 800 yard load with minimal slop in his headspace. Knowing what you want and making a call is part of the reloading choices. I have another die, a Redding FL .260 that barely does it for my custom tight chambered .260 Rem. With un annealed cases I can get spring back after sizing where the case has some binding on chambering. One of those situations that put me at the edge of where I wanted to be by a gunsmith that likes a chamber on the tight side and a die that just barely gets there. just my thoughts on the matter. |
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Teach him the correct way to set his die ( if he choses to do otherwise, that is his choice ) RCBS says to size max. of 2 thou. smaller than chamber you are loading for ( measurement at datum point ) ( They will have no problem chambering in that a semi auto rifle ) ( in this case you would size for each rifle )( otherwise you will have shortened case life ) If one rifle has an oversized chamber, it may be a simple repair ( as simple as replacing a worn bolt head ) and that would eliminate your dilemma ( I use an RCBS Precision Mic. set, and they use a different system, + or - from Sami 0 for that chamber, so I am not familiar with the numbers you have given ) |
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Quoted:
What are you measuring? It can't be the COL. Do you have a reloading manual? If so, the COL should say something very close to, '1.760 inch'. What's the, 'datum point'? In 40 + years of reloading the only time I've ever encountered a term like that is in descriptions of the beginning of a rifle chamber's leade. Are you aware that the NRA offers training for new reloaders? They do! Call NRA Training @ 703-267-1500. They'll give you the name(s) of a local reloading trainer in your area. Quoted:
Quoted:
I plan on working with a buddy to get him started on reloading since he has an interest in loading up some .223. We have a large amount of LC brass and I would like to be able to prep it all in advance with him so it's ready to go when we need to load some rounds. I measured some fired brass from both his AR and my own, and the measurements differ enough that I'm wondering if I need to resize the brass differently for the two guns. His once fired brass measures on average 1.573" (from datum point) and mine measures on average 1.468". Do you guys think I can get away with resizing all the brass down to 1.465" and not have inconsistent primer ignition in his gun? What are you measuring? It can't be the COL. Do you have a reloading manual? If so, the COL should say something very close to, '1.760 inch'. What's the, 'datum point'? In 40 + years of reloading the only time I've ever encountered a term like that is in descriptions of the beginning of a rifle chamber's leade. Are you aware that the NRA offers training for new reloaders? They do! Call NRA Training @ 703-267-1500. They'll give you the name(s) of a local reloading trainer in your area. Raven- On Non-belted bottleneck cartridges, headspace is measured from the base of the cartridge to a DATUM point on the shoulder. On 308 it is the point at which the shoulder is .400 diameter, on .223 it is the point at which it is .330. You can look up some SAAMI cartidge dimension pictures to see this, or call the NRA Training @ 703-267-1500 for further info. OP- I don't know the port pressure of an AR-15, but on an M-14 it is about 14,000 PSI- This means the brass is still under some pretty good pressure while being extracted. This results in brass ballooning out somewhat, to the point that it is larger than the chamber it came from. This is why you have to Full-length resize for an auto. This means that brass thickness, alloy, and hardness affect the fired dimensions, as well as the chamber and load parameters. |
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