yoteblaster
Active member
Why does bolt gun load data appear to be higher than the AR-15 platform. If I have an adjustable gas block can I use bolt gun loading data?
Bolt loading data compared to AR-15 data
- Thread starter yoteblaster
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BubbaChicken
New member
I think it has to do with potential for slamfires from the feeding operation, along with COAL considerations in feeding/throat length. Someone can probably tell you more, I am just about to start loading for the AR and will be interested myself to see if I heard/read correctly..
Originally Posted By: yoteblasterWhy does bolt gun load data appear to be higher than the AR-15 platform. If I have an adjustable gas block can I use bolt gun loading data?
I've been told it is because of pressure differences in the two rifles you mentioned. I personally would NOT be relying on the guide given for a bolt gun and using it to reload on a gas gun. The result could be catestrophic and you could end up with a blow-up gun. Just my thoughts.
I've been told it is because of pressure differences in the two rifles you mentioned. I personally would NOT be relying on the guide given for a bolt gun and using it to reload on a gas gun. The result could be catestrophic and you could end up with a blow-up gun. Just my thoughts.
CatShooter
New member
Originally Posted By: yoteblasterWhy does bolt gun load data appear to be higher than the AR-15 platform. If I have an adjustable gas block can I use bolt gun loading data?
I compared the 223 bolt loads with the 2223 AR-15 loads, in the Sierra manual, an some of the AR loads are higher.
But the difference between the two on either side were miniscule, and not worthy of any attention. Another manual will give different numbers.
It has NOTHING to do with blowing up your gun, and cannot cause slamfires - that is a primer caused problem, not a pressure issue. (... and we wonder where wive's tales come from???).
The difference between the two loads comes from how the tester reads pressure signs, the size of the bolt's firing pin hole, and what he had for breakfast, and how beetchie his wife has been.
There is no actual difference in the pressure that either gun type can handle.
.
I compared the 223 bolt loads with the 2223 AR-15 loads, in the Sierra manual, an some of the AR loads are higher.
But the difference between the two on either side were miniscule, and not worthy of any attention. Another manual will give different numbers.
It has NOTHING to do with blowing up your gun, and cannot cause slamfires - that is a primer caused problem, not a pressure issue. (... and we wonder where wive's tales come from???).
The difference between the two loads comes from how the tester reads pressure signs, the size of the bolt's firing pin hole, and what he had for breakfast, and how beetchie his wife has been.
There is no actual difference in the pressure that either gun type can handle.
.
Darkker
New member
Cat has it right-on.
The only potential consideration is port pressure, since you have an adjustable GB; you to can take advantage of a slightly wider array of powders like the bolt guns.
The slower twist of many bolt guns, along with a longer barrel CAN provide you with some more total velocity. Nothing that will be earth shattering, but some.
The only potential consideration is port pressure, since you have an adjustable GB; you to can take advantage of a slightly wider array of powders like the bolt guns.
The slower twist of many bolt guns, along with a longer barrel CAN provide you with some more total velocity. Nothing that will be earth shattering, but some.
When I read the section on Gas guns in the Sierra manual I came away with what they were saying is that their loads and powder choice for an AR 15 had to do with the pressure at the gas port needed to be within certain parameters to work effectively and not make the bolt slam back to hard and damage the AR. Sounds logical to me. This is just what I thought they were saying
I my self use the Sierra loading section for the AR15 when loading for my AR 15. I don't have any fancy equipment to check pressure or anything else so I will go with what is printed in the AR section. They know a lot more than I do.
DAB
I my self use the Sierra loading section for the AR15 when loading for my AR 15. I don't have any fancy equipment to check pressure or anything else so I will go with what is printed in the AR section. They know a lot more than I do.
DAB
doggin coyotes
Well-known member
Originally Posted By: CatShooter(... and we wonder where wive's tales come from???).
I wonder why they are called wives tales. Could very well be cousin, sister, brother, uncle, aunt tales.
Maybe I'll ask my wife. On second thought, naw.
I wonder why they are called wives tales. Could very well be cousin, sister, brother, uncle, aunt tales.
Maybe I'll ask my wife. On second thought, naw.
yoteblaster
Active member
Heres what I am talking about, Sierra reloading data out of the Complete Reloading Manual For The 223 Remington
AR-15 load data
Sierra 55 grain SBT #1365
25.7 H335 max load
Bolt action
Sierra 55 grain SBT #1365
27.5 H335 max load in 223 chamber
It shoots great with 27.2 grains of H335 but it shows some pressure signs, flat primers but functions fine. It does have a 5.56 chamber. It shoots the best at all of the top loads but as stated it shows some pressure signs.
AR-15 load data
Sierra 55 grain SBT #1365
25.7 H335 max load
Bolt action
Sierra 55 grain SBT #1365
27.5 H335 max load in 223 chamber
It shoots great with 27.2 grains of H335 but it shows some pressure signs, flat primers but functions fine. It does have a 5.56 chamber. It shoots the best at all of the top loads but as stated it shows some pressure signs.
Smokeless
New member
Originally Posted By: yoteblasterHeres what I am talking about, Sierra reloading data out of the Complete Reloading Manual For The 223 Remington
AR-15 load data
Sierra 55 grain SBT #1365
25.7 H335 max load
Bolt action
Sierra 55 grain SBT #1365
27.5 H335 max load in 223 chamber
It shoots great with 27.2 grains of H335 but it shows some pressure signs, flat primers but functions fine. It does have a 5.56 chamber. It shoots the best at all of the top loads but as stated it shows some pressure signs.
But the book says 27.5 as max. Why are you showing pressure at 27.2?
Manuals are not Bibles. They are a guide, based on the equipment and components tested at the time. The test does not simulate what is happening in your gun, only what they tested. Therefore they are all guides. They give you a "safe" place to start, and then they show you where they found Max, but that may differ from your specific application.
AR-15 load data
Sierra 55 grain SBT #1365
25.7 H335 max load
Bolt action
Sierra 55 grain SBT #1365
27.5 H335 max load in 223 chamber
It shoots great with 27.2 grains of H335 but it shows some pressure signs, flat primers but functions fine. It does have a 5.56 chamber. It shoots the best at all of the top loads but as stated it shows some pressure signs.
But the book says 27.5 as max. Why are you showing pressure at 27.2?
Manuals are not Bibles. They are a guide, based on the equipment and components tested at the time. The test does not simulate what is happening in your gun, only what they tested. Therefore they are all guides. They give you a "safe" place to start, and then they show you where they found Max, but that may differ from your specific application.
Originally Posted By: yoteblasterHeres what I am talking about, Sierra reloading data out of the Complete Reloading Manual For The 223 Remington
AR-15 load data
Sierra 55 grain SBT #1365
25.7 H335 max load
Bolt action
Sierra 55 grain SBT #1365
27.5 H335 max load in 223 chamber
It shoots great with 27.2 grains of H335 but it shows some pressure signs, flat primers but functions fine. It does have a 5.56 chamber. It shoots the best at all of the top loads but as stated it shows some pressure signs.
If it is showing pressure signs then you should back off the load a bit. No sense in punishing a rifle when the load is showing signs of pressure.
DAB
AR-15 load data
Sierra 55 grain SBT #1365
25.7 H335 max load
Bolt action
Sierra 55 grain SBT #1365
27.5 H335 max load in 223 chamber
It shoots great with 27.2 grains of H335 but it shows some pressure signs, flat primers but functions fine. It does have a 5.56 chamber. It shoots the best at all of the top loads but as stated it shows some pressure signs.
If it is showing pressure signs then you should back off the load a bit. No sense in punishing a rifle when the load is showing signs of pressure.
DAB
Darkker
New member
The reason for the "pressure difference" is in the gun/powder.
First the powder, are you shooting the same lot of powder that they tested? No, so the burning rate may be somewhat different.
Next the gun.
The bolt gun in their data has a 14-twist, what is your AR?
Probably a 9-twist, but very well could be a 7-twist; just like the Sierra data.
The faster twists generate more pressure. An over-simplified explanation goes like this:
In the 14-twist the bullet leaves the case and engages the rifling. It slightly slows forward momentum, as the rifling begins the bullet rotating. With a faster twist, the bullet slows more, or the "dwell" time is increased as it must spin faster for the same distance traveled. The acceleration in the direction of spin cannot be instantaneous, so the forward movement is ever so slightly slowed, causeing the propellant to generate more pressure at that point(compared to the slower twist rifle).
First the powder, are you shooting the same lot of powder that they tested? No, so the burning rate may be somewhat different.
Next the gun.
The bolt gun in their data has a 14-twist, what is your AR?
Probably a 9-twist, but very well could be a 7-twist; just like the Sierra data.
The faster twists generate more pressure. An over-simplified explanation goes like this:
In the 14-twist the bullet leaves the case and engages the rifling. It slightly slows forward momentum, as the rifling begins the bullet rotating. With a faster twist, the bullet slows more, or the "dwell" time is increased as it must spin faster for the same distance traveled. The acceleration in the direction of spin cannot be instantaneous, so the forward movement is ever so slightly slowed, causeing the propellant to generate more pressure at that point(compared to the slower twist rifle).
yoteblaster
Active member
The twist difference makes sense.
Hooked
New member
Interesting over-simplified explanation regarding twist rate and pressure.
I had looked and compared the differences in load data before, bolt vs AR and just figured the BA could handle a little more due to the mode of operation (bolt locked and remains that way untill the burn..er.`deflagration`..lol is complete). I like that new word.
I had looked and compared the differences in load data before, bolt vs AR and just figured the BA could handle a little more due to the mode of operation (bolt locked and remains that way untill the burn..er.`deflagration`..lol is complete). I like that new word.
yoteblaster
Active member
Thats funny, I was just looking at that. I will try it tomorrow. Hoping for better velocity than. I want a load that shoots 3200 without pressure signs.
BubbaChicken
New member
I have been toying with this particular thought and something has come to mind. Generally full power loads for the AR in 5.56 are considered to be a little hot in milsurp ammo, and full pressure commercial ammo on the shelf is safe to fire in any AR chambered for it. Therefore, why would one gun that uses the same loads be less safe than the other if both are in good repair? Overloading the ammo would be indicated as the only variable that would cause a problem if the ammunition is correctly loaded, as it should be able to function in ANY correctly chambered weapon that is in good repair!
CatShooter
New member
Originally Posted By: BubbaChickenI have been toying with this particular thought and something has come to mind. Generally full power loads for the AR in 5.56 are considered to be a little hot in milsurp ammo, and full pressure commercial ammo on the shelf is safe to fire in any AR chambered for it. Therefore, why would one gun that uses the same loads be less safe than the other if both are in good repair? Overloading the ammo would be indicated as the only variable that would cause a problem if the ammunition is correctly loaded, as it should be able to function in ANY correctly chambered weapon that is in good repair!
Mil-surp ammunition is not hot.
They are both loaded to the same pressures - it's just that they measure the presures differently.
Military 5.56 and commercial 223 are interchangeable in bolt and gas guns, with no problems - about a eleventy billion rounds fired are proof of this.
Mil-surp ammunition is not hot.
They are both loaded to the same pressures - it's just that they measure the presures differently.
Military 5.56 and commercial 223 are interchangeable in bolt and gas guns, with no problems - about a eleventy billion rounds fired are proof of this.
yoteblaster
Active member
I am confused a bit catshooter. Why does Ramshot provide load data for Tac that is way over the max that anyone lists for 223 if they are leaded at the same pressure?
CatShooter
New member
Originally Posted By: yoteblasterI am confused a bit catshooter. Why does Ramshot provide load data for Tac that is way over the max that anyone lists for 223 if they are loaded at the same pressure?
Because the "art" of pressure measurement is just that, an art... NOT a science.
So you read pressure signs in one gun until they say stop, and you write it down as max.
Then you read signs in another gun until they say stop, and you write it down as max - you get two different numbers, cuz you used two different guns.
Now it gets more worser - you give the same gun, same can of powder, same box of bullets and same box of primers... to five different labs and you will get five different max loads.
You load 1,000 rounds of ammo with the same lot of weighed brass, same everything, and break it up into 10 bunches of 100 rounds, and send them to ten labs, and you will get back 10 different pressure measurements.
Don't fight it, and don't whine and don't cry about it - it is what it is, and there is nothing the industry can do about it. It is an imperfect science, (on a good day!!).
That is why ANYONE in the ammunition business will tell you that the manuals are just guide books - ALL of the manuals have different numbers for max loads - which is why we tell you to start low and work up.
The listed max might be over max and dangerous in your gun, or your gun might take 3 grains more and still be safe!!!
Make sense now?
No?? I know it doesn't
Because the "art" of pressure measurement is just that, an art... NOT a science.
So you read pressure signs in one gun until they say stop, and you write it down as max.
Then you read signs in another gun until they say stop, and you write it down as max - you get two different numbers, cuz you used two different guns.
Now it gets more worser - you give the same gun, same can of powder, same box of bullets and same box of primers... to five different labs and you will get five different max loads.
You load 1,000 rounds of ammo with the same lot of weighed brass, same everything, and break it up into 10 bunches of 100 rounds, and send them to ten labs, and you will get back 10 different pressure measurements.
Don't fight it, and don't whine and don't cry about it - it is what it is, and there is nothing the industry can do about it. It is an imperfect science, (on a good day!!).
That is why ANYONE in the ammunition business will tell you that the manuals are just guide books - ALL of the manuals have different numbers for max loads - which is why we tell you to start low and work up.
The listed max might be over max and dangerous in your gun, or your gun might take 3 grains more and still be safe!!!
Make sense now?
No?? I know it doesn't
yoteblaster
Active member
yep, makes sense.