AR15 velocity
- Thread starter muleman
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Re: AR15 velocity
That would depend on the powder. The right powder will push them to 2800fps in a 20" easily.
That would depend on the powder. The right powder will push them to 2800fps in a 20" easily.
Re: AR15 velocity
i can run 2800ish with 69snmk's out of a 16" tube using h4895. am getting ready to see if i can duplicate with imr 4895 without getting too hot.
i can run 2800ish with 69snmk's out of a 16" tube using h4895. am getting ready to see if i can duplicate with imr 4895 without getting too hot.
Re: AR15 velocity
How do you know whats to hot? Is there a spec from factory or a standard velocity that these are designed to shoot at, for best operation and barrel life? My book shows 2600-2700 maybe a little more, depending on powder, before getting into max loads with a 68gr BTHP.
How do you know whats to hot? Is there a spec from factory or a standard velocity that these are designed to shoot at, for best operation and barrel life? My book shows 2600-2700 maybe a little more, depending on powder, before getting into max loads with a 68gr BTHP.
Re: AR15 velocity
How much reloading experience do you have? Do you have experience "working up" loads and telling pressures signs?
Also, what reloading manual are you using? Finally, what powder do you plan on using?
Start here for some data on Sierra's 69gr SMK (a bit longer than the 68gr H, so you should be able to put a bit more powder behind the 68gr H)
http://accurateshooter.net/Downloads/sierra223ar.pdf
Note that this is for the 223 Rem, a cartridge that is designed to have lower pressures than 5.56mm NATO. If you are loading at 5.56mm NATO pressures, 3000 is doable with care working up a good powder - I gave you two good choices above.
There are some great loads on the 68gr H and 69gr SMK in reloading section of this website, especially here: http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=351023#Post351023
How much reloading experience do you have? Do you have experience "working up" loads and telling pressures signs?
Also, what reloading manual are you using? Finally, what powder do you plan on using?
Start here for some data on Sierra's 69gr SMK (a bit longer than the 68gr H, so you should be able to put a bit more powder behind the 68gr H)
http://accurateshooter.net/Downloads/sierra223ar.pdf
Note that this is for the 223 Rem, a cartridge that is designed to have lower pressures than 5.56mm NATO. If you are loading at 5.56mm NATO pressures, 3000 is doable with care working up a good powder - I gave you two good choices above.
There are some great loads on the 68gr H and 69gr SMK in reloading section of this website, especially here: http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=351023#Post351023
Re: AR15 velocity
I've used 25.5 gr W748 with 69 grain SMK's @2750fps. You can go higher but I don't like top end loads. IIRC Varget will get you at 2800 without using top loads.
I've used 25.5 gr W748 with 69 grain SMK's @2750fps. You can go higher but I don't like top end loads. IIRC Varget will get you at 2800 without using top loads.
Re: AR15 velocity
When it comes to approaching a max load (or slightly exceeding it), pressure signs & accuracy are more important to me than what the chronograph happens to say.
When it comes to approaching a max load (or slightly exceeding it), pressure signs & accuracy are more important to me than what the chronograph happens to say.
Re: AR15 velocity
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: J-Ham</div><div class="ubbcode-body">When it comes to approaching a max load (or slightly exceeding it), pressure signs & accuracy are more important to me than what the chronograph happens to say. </div></div>
Agreed.
Way too much speed chasin' for shooters and reloaders around here (everywhere else applicable too). I'm pretty sure that whatever target you shoot at whether it be game, paper or steel, doesn't care.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: J-Ham</div><div class="ubbcode-body">When it comes to approaching a max load (or slightly exceeding it), pressure signs & accuracy are more important to me than what the chronograph happens to say. </div></div>
Agreed.
Way too much speed chasin' for shooters and reloaders around here (everywhere else applicable too). I'm pretty sure that whatever target you shoot at whether it be game, paper or steel, doesn't care.
Re: AR15 velocity
usually not a good idea to try and match military spec velocities, they crimp the primer and only plan to use brass once, main reason to try for high end velocity is when you have a slower than ideal barrel twist for the bullet weight
usually not a good idea to try and match military spec velocities, they crimp the primer and only plan to use brass once, main reason to try for high end velocity is when you have a slower than ideal barrel twist for the bullet weight
Re: AR15 velocity
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JamesBailey</div><div class="ubbcode-body">How much reloading experience do you have? Do you have experience "working up" loads and telling pressures signs?
Also, what reloading manual are you using? Finally, what powder do you plan on using?
Start here for some data on Sierra's 69gr SMK (a bit longer than the 68gr H, so you should be able to put a bit more powder behind the 68gr H)
http://accurateshooter.net/Downloads/sierra223ar.pdf
Note that this is for the 223 Rem, a cartridge that is designed to have lower pressures than 5.56mm NATO. If you are loading at 5.56mm NATO pressures, 3000 is doable with care working up a good powder - I gave you two good choices above.
There are some great loads on the 68gr H and 69gr SMK in reloading section of this website, especially here: http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=351023#Post351023
</div></div>
Good point, I was just assuming he has a NATO chamber.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JamesBailey</div><div class="ubbcode-body">How much reloading experience do you have? Do you have experience "working up" loads and telling pressures signs?
Also, what reloading manual are you using? Finally, what powder do you plan on using?
Start here for some data on Sierra's 69gr SMK (a bit longer than the 68gr H, so you should be able to put a bit more powder behind the 68gr H)
http://accurateshooter.net/Downloads/sierra223ar.pdf
Note that this is for the 223 Rem, a cartridge that is designed to have lower pressures than 5.56mm NATO. If you are loading at 5.56mm NATO pressures, 3000 is doable with care working up a good powder - I gave you two good choices above.
There are some great loads on the 68gr H and 69gr SMK in reloading section of this website, especially here: http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=351023#Post351023
</div></div>
Good point, I was just assuming he has a NATO chamber.
Re: AR15 velocity
Sorry, I read the OP's question as what is the MAX recommended velocity, not as what is the recommended velocity. I would say the recommended velocity is the one that delivers the best accuracy at the desired range (this is assuming use is targets, as HPBT is not recommended for hunting). Remember, accuracy is different than precision (precision is measured by shooting groups and measuring how small they are). Accuracy is about hitting the desired target. And it is impacted by things like flatness of bullet flight path and wind deflection. Because the 68gr HPBT bullet is a poor ballistic projectile (it has low sectional density and crappy form factor), you need to overly rely on velocity for accuracy, at least compared to better ballistic projectiles (i.e. compared to a 142gr SMK in 6.5mm or a 175gr VLD in 7mm). Note this ballistic fact:
a 68gr HPBT doing 3000fps at the muzzle has 25% less drop and 15% less wind drift at 600yds than a 68gr HPBT doing 2700. Within these parameters, OP needs to select how much accuracy he wants. Of course, if he is shooting at all KNOWN ranges, drop is irrevelant. If he is shooting at short range, wind is irrevelant.
Now you may not get a precise load at 3000fps, which would reduce the ballistic advantage from the increased MV, but there is no reason why you would be more likely to get one at 2700 either. That is why we first test the load's precision and only later do we look at its down-range accuracy.
All this experimenting is part of the process that makes reloading fun, at least for some folks.
Sorry, I read the OP's question as what is the MAX recommended velocity, not as what is the recommended velocity. I would say the recommended velocity is the one that delivers the best accuracy at the desired range (this is assuming use is targets, as HPBT is not recommended for hunting). Remember, accuracy is different than precision (precision is measured by shooting groups and measuring how small they are). Accuracy is about hitting the desired target. And it is impacted by things like flatness of bullet flight path and wind deflection. Because the 68gr HPBT bullet is a poor ballistic projectile (it has low sectional density and crappy form factor), you need to overly rely on velocity for accuracy, at least compared to better ballistic projectiles (i.e. compared to a 142gr SMK in 6.5mm or a 175gr VLD in 7mm). Note this ballistic fact:
a 68gr HPBT doing 3000fps at the muzzle has 25% less drop and 15% less wind drift at 600yds than a 68gr HPBT doing 2700. Within these parameters, OP needs to select how much accuracy he wants. Of course, if he is shooting at all KNOWN ranges, drop is irrevelant. If he is shooting at short range, wind is irrevelant.
Now you may not get a precise load at 3000fps, which would reduce the ballistic advantage from the increased MV, but there is no reason why you would be more likely to get one at 2700 either. That is why we first test the load's precision and only later do we look at its down-range accuracy.
All this experimenting is part of the process that makes reloading fun, at least for some folks.
Re: AR15 velocity
You're correct. With regards to load development, I should have said that it is the "precision" of a given load that we are concerned with, not accuracy.
Ah, semantics.
You're correct. With regards to load development, I should have said that it is the "precision" of a given load that we are concerned with, not accuracy.
Ah, semantics.
