loading for semi auto help
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MikeMcCasland
Team Texas F-T/R
I suppose we'd need to know what you're doing for your bolt guns before we advised you what you should/shouldn't be doing differently.
That said, in general you'll just want to FL size, and bump the shoulders .004-.005 (vs. .002-.003 for a bolt gun). If you're running a bushing die, you may want to use a .001 smaller bushing to add a little more neck tension. Otherwise, should be close to the same process.
Don't mess with crimping if you're using .002-.003 of neck tension.
As far as seating/OAL, just stay away from trying to jam bullets in a semi (if that's even possible with the chamber/mag length restrictions). In mag fed weapons, you're typically ok with just seating to mag length -.005; be sure to measure your mags as some will give you a little more room to work out towards the lands.
That said, in general you'll just want to FL size, and bump the shoulders .004-.005 (vs. .002-.003 for a bolt gun). If you're running a bushing die, you may want to use a .001 smaller bushing to add a little more neck tension. Otherwise, should be close to the same process.
Don't mess with crimping if you're using .002-.003 of neck tension.
As far as seating/OAL, just stay away from trying to jam bullets in a semi (if that's even possible with the chamber/mag length restrictions). In mag fed weapons, you're typically ok with just seating to mag length -.005; be sure to measure your mags as some will give you a little more room to work out towards the lands.
Dusty Stevens
Shiner
Call wilson and get a case gage is my main suggestion. You cant check your headspace in the chamber
Well, the answers depend on the rifle you’re going to load these cartridges for. But in general
Full length size setting the shoulder back to the MINIMUM cartridge as gaged in a Wilson Case Gage. This ensures reliable chambering. This means you get to trim more often, generally, and I recommend trimming to .005 below the “suggested trim length”.
Using a bushing die or a seperate body and neck die combo can lead to trouble so don’t use those until you understand how reloaded ammunition work is in your rifle. Whether you use a standard FL size die or a “Small Base” die will depend on your rifle, your cases, and perhaps your sizing die.
Use powders in the middle of the cartridge appropriate “burn rate”. Too fast and the gun may not cycle, too slow and the gun may cycle too harshly and could damage the rifle’s operating components.
To be more specific, you’ll need to tell us the rifle and cartridge.
Full length size setting the shoulder back to the MINIMUM cartridge as gaged in a Wilson Case Gage. This ensures reliable chambering. This means you get to trim more often, generally, and I recommend trimming to .005 below the “suggested trim length”.
Using a bushing die or a seperate body and neck die combo can lead to trouble so don’t use those until you understand how reloaded ammunition work is in your rifle. Whether you use a standard FL size die or a “Small Base” die will depend on your rifle, your cases, and perhaps your sizing die.
Use powders in the middle of the cartridge appropriate “burn rate”. Too fast and the gun may not cycle, too slow and the gun may cycle too harshly and could damage the rifle’s operating components.
To be more specific, you’ll need to tell us the rifle and cartridge.
Good advice already abounding on this thread, and yes, reloading for auto loaders is a different world. If you want to get some good insights, I’d r commend any of several books by Glen Zediker. He has one called “Handloading for Competition: Making the Target Bigger” that is excellent. While the focus is on turning out match ammo, it’s geared primarily towards the Gas Guns. Tons of very useful info that will save you an untold amount of troubles that you’d otherwise have to learn the hard way.
Service Rifles (and autos in general) are a very different platform than bolt guns, and they really do need a very different approach.
Service Rifles (and autos in general) are a very different platform than bolt guns, and they really do need a very different approach.
I’ve never loaded for an AR in 308, but I have loaded for ARs in 223, 7.62 x 39 and 308 and 30-06 for M1A and M1s respectively. So that said, I offer the following:
Set your sizing die so that you size your brass to the same height as the groove in the Wilson case gage. You can have your case head up to .002 below to .001 higher than that groove and still get good function. Case life will be hit somewhat but cases don’t last very long with autoloaders anyway. You can check chambering by taking a sized case putting it in the chamber and closing the bolt by pushing on the rear of the carrier. A light tap from the heel of the hand is acceptable. When you extract the case by using the charging handle, it should just pull out without any tugging at all.
I suggest using CCI #34 “military” primers to start with. I’ve used Remington, CCI (regular), Winchester, and, occasionally, Federal primers to load for the M1A but I knew how to mitigate the exposure to slamfire. So use the CCI #34 until you know how your rifle reacts to dropping the bolt on a chambered round.
Use powders and load data like 4895, 4064, Varget, RL 15, VV 135 & 140, WW748, BLC2. Do not load with slow powders like 4350.
All of these instructions are to provide you with techniques to develop reliable & safe ammo for your rifle. In a semi auto, Accuracy is important but safety and reliability is higher.
Set your sizing die so that you size your brass to the same height as the groove in the Wilson case gage. You can have your case head up to .002 below to .001 higher than that groove and still get good function. Case life will be hit somewhat but cases don’t last very long with autoloaders anyway. You can check chambering by taking a sized case putting it in the chamber and closing the bolt by pushing on the rear of the carrier. A light tap from the heel of the hand is acceptable. When you extract the case by using the charging handle, it should just pull out without any tugging at all.
I suggest using CCI #34 “military” primers to start with. I’ve used Remington, CCI (regular), Winchester, and, occasionally, Federal primers to load for the M1A but I knew how to mitigate the exposure to slamfire. So use the CCI #34 until you know how your rifle reacts to dropping the bolt on a chambered round.
Use powders and load data like 4895, 4064, Varget, RL 15, VV 135 & 140, WW748, BLC2. Do not load with slow powders like 4350.
All of these instructions are to provide you with techniques to develop reliable & safe ammo for your rifle. In a semi auto, Accuracy is important but safety and reliability is higher.
Thanks Riflewoman!
Kevin, ++ on Zedikers books
Kevin, ++ on Zedikers books
It does help to size using a small base die. This gives you a little more insurance that rounds will chamber easily.
@riflewoman- why not use slower burning powders? Just curious. TIA, lg
Dusty Stevens
Shiner
Since its a 308 id recommend the rcbs full length small base die set. I use them for 223 and 308 and they work perfect
jepp2
Gold $$ Contributor
I load for a variety of gas guns (20 and 224 cals). Just to add my experiences:
- On shoulder bump, some folks get pretty heavy handed on the amount of shoulder set back. Realize that brass is not normally formed to the chamber on a single firing. So unless you know the length that is max for your chamber, setting the shoulder back as much that is quoted is excessive in my experience. If I only know fired dimensions, I set the shoulder back 0.001" on a bolt gun and 0.002-0.003" on a gas gun.
- Small base dies, I have an unused set. Never have found the need to use them. Not saying some don't need them, but I wouldn't use them until I found I needed to use them.
- Case life. I had "read" where folks tossed their brass after say 5 firings in an AR. So I ran a case life test to see how long the cases would last, and how they would fail. Using range pickup up single fired LC brass, I got up to 35 firings before I retired them. And none failed due to incipient case head separation (which is what I expected). So yes, gas guns are harder on brass, but you can still get some outstanding case life.
- Powder burn rate. I mostly run rifle length gas systems, so on AR's I don't let burn rate dictate my powder selection.
- A brass catcher will be convenient for you, and a blessing for those you shoot next to at the range. .308 brass stays hot for a while after ejection. Doesn't take long to learn that. The catcher will save your brass from a lot of dings, and you will be amazed how quickly that brass can disappear.
I find how to properly clean, maintain, and lube a gas gun to be more of a learning than the loading process to feed it.
I’ll agree with jepp2 here, with the minor exception of the S/B dies. While most ARs will function just fine with standard F/L dies, the S/B dies do provide just that much more insurance that everything will flow smoothly, and that’s always a good thing. One thing the do offer is reduced extraction force, which of course we don’t notice in operation. But certain parts may well wear a bit longer, not tend to break as frequently and just be happier all the way around. The S/B dies don’t cause any problems, give you that added insurance, and may help extend the longevity of your rifle, so it seems eminently worthwhile to me.
As for his commentary on case life, I agree completely with one proviso: the comments apply to ARs, and not autos in general. As long as the headspace is good, and you’re not bumping the shoulder back to any stupid degree, case life in these guns is very good. But others, such as th Garland, can be brutal on cases. And if the Garland is bad, the M14/M1A is far worse. Three reloading there, and the cases should be tossed, whether they still seem good or not. Two eyes, ten fingers. That’s what you’re issued, no replacements on tap,so it behooves one to make sure they stay functional and attached. Trying to get additional case life in these guns is false economy and is a genuinely bad idea.
As for his commentary on case life, I agree completely with one proviso: the comments apply to ARs, and not autos in general. As long as the headspace is good, and you’re not bumping the shoulder back to any stupid degree, case life in these guns is very good. But others, such as th Garland, can be brutal on cases. And if the Garland is bad, the M14/M1A is far worse. Three reloading there, and the cases should be tossed, whether they still seem good or not. Two eyes, ten fingers. That’s what you’re issued, no replacements on tap,so it behooves one to make sure they stay functional and attached. Trying to get additional case life in these guns is false economy and is a genuinely bad idea.
Chambers and dies vary in size and in Zedikers book “Handloading for Competition: Making the Target Bigger” Zediker tells you the following. The full length resized case should be .003 to .005 smaller in diameter than its fired diameter. This ensures the case springs back from the chamber walls and extracts reliably.
I have small base dies and use them but I also have a "standard" Lee full length .223 die that reduces the case body diameter more than by RCBS small base die.
So do you need a small base die? Measure your fired and resized cases at three points along the case body and find out.
Below a once fired Lake City 7.62 case in a Dillon case gauge.
Below the same case in a JP Enterprise case gauge.
Chambers and dies vary in size and so do case gauges and the majority of drop in case gauges only check headspace length. And the JP Enterprise gauge also checks case diameter, meaning if the passes a plop test in the JP Enterprise gauge the cartridge will chamber in any rifle.
Semi-Auto Case Gauge .308
https://www.jprifles.com/buy.php?item=JPCG-308
"Optimized for semi-automatic rifles, the second generation JP Case Gauge guarantees function of your ammo. If it fits our gauge, it will fit even a minimum-depth SAAMI chamber without interference.
Take comfort that your ammo will never hold you back."
Features:
AR, Garand, M1A — Six Rules for Gas Gun Reloading
http://bulletin.accurateshooter.com/2018/01/ar-garand-m1a-six-rules-for-gas-gun-reloading/
The U.S. Army Marksmanship Unit (USAMU) has published a great series of reloading “how-to” articles on its Facebook Page. This post covers key factors to consider when loading ammunition for Match Rifles and Service Rifles, with a particular focus on self-loading “gas guns”. Visit the USAMU Facebook Page each Wednesday for other, helpful “Handloading Hump-Day” tips.
I have small base dies and use them but I also have a "standard" Lee full length .223 die that reduces the case body diameter more than by RCBS small base die.
So do you need a small base die? Measure your fired and resized cases at three points along the case body and find out.
Below a once fired Lake City 7.62 case in a Dillon case gauge.
Below the same case in a JP Enterprise case gauge.
Chambers and dies vary in size and so do case gauges and the majority of drop in case gauges only check headspace length. And the JP Enterprise gauge also checks case diameter, meaning if the passes a plop test in the JP Enterprise gauge the cartridge will chamber in any rifle.
Semi-Auto Case Gauge .308
https://www.jprifles.com/buy.php?item=JPCG-308
"Optimized for semi-automatic rifles, the second generation JP Case Gauge guarantees function of your ammo. If it fits our gauge, it will fit even a minimum-depth SAAMI chamber without interference.
Take comfort that your ammo will never hold you back."
Features:
- Specially calibrated to ensure function in semi-auto rifles
- Guarantees ammo fit in a minimum-spec SAAMI chamber
- 416 stainless steel construction for wear resistance and greater longevity
- Also gauges all features of .260 Rem. short of concentricity runout
AR, Garand, M1A — Six Rules for Gas Gun Reloading
http://bulletin.accurateshooter.com/2018/01/ar-garand-m1a-six-rules-for-gas-gun-reloading/
The U.S. Army Marksmanship Unit (USAMU) has published a great series of reloading “how-to” articles on its Facebook Page. This post covers key factors to consider when loading ammunition for Match Rifles and Service Rifles, with a particular focus on self-loading “gas guns”. Visit the USAMU Facebook Page each Wednesday for other, helpful “Handloading Hump-Day” tips.
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Because of the gas system. With slower powders the pressure at the gas port is higher. Autoloaders are designed with a specific port pressure in mind.
The FAL military rifle was designed with an adjustable gas system that allowed for variations in port pressure. The M14 rifle and M60 machine gun were designed with a cutoff-expansion gas system for the same purpose. The cutoff-expansion theory was that higher pressure gas would flow in faster and the first movement of the gas piston would cutoff this higher pressure and the residual gas would expand. And it worked, sort of...ish. But now, by NATO STANAG agreements, port pressures for NATO ammo is controlled by agreement.
The only way to do this is by limiting powder selection to that commonly loaded (in military ammo). For 308 those powders are in the range previously identified.
I never felt that the M1A had a worse effect on case life than the M1 but I did have to trim just about every load. There’s an old rule of thumb to scrap cases after the fifth trimming. So the magic number for me was 5 loads. After 4 I was asking the military shooters if they were willing to swap a can of OF LC brass for a can of my old brass.
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