I'm shooting Reminton .260, Lapua brass, 142 grain SMKs, with H414 powder. Hodgdon's max posted load for H414 is 43.5 grains @ 2734 ft/sec. At the published STARTING load of 41.0 grains I'm getting 2790 ft/sec, faster than Hodgdon says I should get with 2.5 grains more. My COL is longer than published because I'm seating .020" from the lands. That should lower the pressure, if anything. Spent brass looks okay, with slight flattening of the primer which I think is pretty normal. Does anyone know why I might be getting this kind of speed with a mild load? I'm reluctant to increase the load to search for best accuracy.
ft/sec too fast at low load
- Thread starter SavageLRP
- Start date
If I remember right Lapua brass was over a grain smaller on h20 capacity. 2 more inches of barrel different primers Speed difference between lots of powder and crony difference .
The speed difference is not abnormal.
Larry
The speed difference is not abnormal.
Larry
I'm measuring the distance to lands using a Hornady chamber gauge, and loading 2 hundredths short of that using a bullet comparator on my calipers which measures using the ogive. The 142 SMK bullets seem to be consistent. Given all that, and given that I'm getting fast speeds measured by a Magnetospeed crony, is it safe to increase my load staying short of the published max grain load? I'm just paranoid about the speeds I'm getting. (41.5 was clocking at 2820 ft/sec)
bdale
NRA Life Member
I'm measuring the distance to lands using a Hornady chamber gauge, and loading 2 hundredths short of that using a bullet comparator on my calipers which measures using the ogive. The 142 SMK bullets seem to be consistent. Given all that, and given that I'm getting fast speeds measured by a Magnetospeed crony, is it safe to increase my load staying short of the published max grain load? I'm just paranoid about the speeds I'm getting. (41.5 was clocking at 2820 ft/sec)[/QUOTE
Where is Hodgdon compared to where you are, sea level -mountains-cold-hot, what time of year was this published all these things will make a difference
First of all book reloading data is adjusted for sea level, standard temperature, humidity, and pressure. Altitude makes a big difference. Second book data is an average fired from a piticular rifle not your rifle. Third their is some misunderstanding when reading the book data. By this I mean the book says with XYZ components the velocity is 2650 as an example. This means the true velocity is faster than 2600 but slower than 2650. The numbers are rounded off. Know one is going to print a velocity of 2642 fps in a reloading book.
Info that's not been offered thus far....New or fireformed cases?
Starting loads should be safe in any rifle and it would seem yours will shoot quick, your 41.5 gr velocity increase shows you're above that scary range where low charges do silly things.
Where to next?
Cautiously move up in powder weights while carefully monitoring for pressure signs.
Get more reloading info and don't rely on 1 book or only manufacturers data....ever.
How fast can you go?
With the little data you've offered so far it hard to say, but maybe 200 fps faster than any published data is not unheard of for carefully worked up loads .....and suitable for ONLY ONE RIFLE.
I've been interested in getting a .260 but previous studies of velocities obtainable have left me unimpressed, your experience has me wondering again.
Keep us informed.
Starting loads should be safe in any rifle and it would seem yours will shoot quick, your 41.5 gr velocity increase shows you're above that scary range where low charges do silly things.
Where to next?
Cautiously move up in powder weights while carefully monitoring for pressure signs.
Get more reloading info and don't rely on 1 book or only manufacturers data....ever.
How fast can you go?
With the little data you've offered so far it hard to say, but maybe 200 fps faster than any published data is not unheard of for carefully worked up loads .....and suitable for ONLY ONE RIFLE.
I've been interested in getting a .260 but previous studies of velocities obtainable have left me unimpressed, your experience has me wondering again.
Keep us informed.
One thing about Lapua brass is if it is new it can give you too much neck tension which you should be able to tell by how much force it takes to seat your bullets. This in turn can give you significantly higher MV – I have seen as much as 100 fps.
Having shot .260 Rem with 140 Hybrids out of my 26” barrel and Lapua brass (H3450 powder),I do agree that you are starting to get to higher pressure although not dangerously so since my loads are safe and they are more at 2,850 fps with no pressure signs. I would agree that you can go higher but carefully.
Having shot .260 Rem with 140 Hybrids out of my 26” barrel and Lapua brass (H3450 powder),I do agree that you are starting to get to higher pressure although not dangerously so since my loads are safe and they are more at 2,850 fps with no pressure signs. I would agree that you can go higher but carefully.
SBS
Gold $$ Contributor
As mentioned earlier, lots of H414 vary on burning rate, particularly surplus lots which might be what Hodgdon used or perhaps you are using? If you have experience loading, I would use my normal workup method to develop a load, watching pressure signs and group size and watching the chronograph for signs of spikes or flattening of velocity.
A lot of the things that have been suggested so far have been valid but not for the large velocity discrepancy you are seeing, I would look for something more significant. I will give you and example of an experience I had recently where I had a 100 fps discrepancy. After several trips to the range to resolve the issue the short version of the story is I shot the wrong ammo. I was doing some velocity measurements of several different loads and when I got home and looked at the data there was one data point (ten shots) that did not make sense. After reshooting the data it was obvious that I had got the ammo mixed up, same color ammo box, same brass, etc. and I got distracted and shot load B thinking it was load A. I am not saying this is your problem but just giving you an example of a blunder that caused 100 fps discrepancy. In your case I would look for something big, not the small stuff.
Quickload shows....
260 Rem.
142 SMK
41.5gr H-414
26" barrel
2.850" coal
2,772 fps (48 fps slower than your load)
54,853 psi
This is well within powder lot variations. Not to mention Bullet variations, primers and cases.
Quickload also shows that 42.3gr makes 2,822 fps @ 58,207 psi.
I had the opposite problem.
I had a 243w load with 105amax & H-4831 that clocked 250 fps slower than Hodgdon's load with the same components. Except my barrel was 2" shorter than their test bbl, and my COAL was 0.010" longer.. But that doesn't explain the other 200 fps of lost velocity.
Hodgdon lists 41gr MAX for the 105amax & H-4831, while my rifle never showed signs of pressure at 45.8 gr which is as high as I tested.
260 Rem.
142 SMK
41.5gr H-414
26" barrel
2.850" coal
2,772 fps (48 fps slower than your load)
54,853 psi
This is well within powder lot variations. Not to mention Bullet variations, primers and cases.
Quickload also shows that 42.3gr makes 2,822 fps @ 58,207 psi.
I had the opposite problem.
I had a 243w load with 105amax & H-4831 that clocked 250 fps slower than Hodgdon's load with the same components. Except my barrel was 2" shorter than their test bbl, and my COAL was 0.010" longer.. But that doesn't explain the other 200 fps of lost velocity.
Hodgdon lists 41gr MAX for the 105amax & H-4831, while my rifle never showed signs of pressure at 45.8 gr which is as high as I tested.
Loading manuals are put together by the Powder and bullet manufacturing companies. (Plus a few others.) They are references. Many include a chapter in the front of the book about their test bed whether it be a fixture, actual firearm, etc. Every one of them tells you to start on the low end and work up. Not even one of them says to pick these certain components and you can start at the top end. Not even one.
I have many reloading manuals. Like several different Noslers, several Speer, several Hodgdon, VV, Lee, etc. When I go looking for a load, I do not go to one, I go to several, read thru all of the data and begin taking notes on my load preferences. I do not confirm all of my components until I have a positive correlation between data from several different manuals. I then work into my load carefully for my gun.
In looking thru your info I saw several things that quickly drew my attention. Remington vs CCI primers. 1:8 twist vs 1:9. Faster twist is going to raise pressure. Remington Primers, on average, are slightly hotter than CCI.....I do not have my H414 data handy, but if my memory is close, most Hodgdon loads with H414 use Remington or Winchester primers.
Not saying you didn't choose wisely, because you obviously did by choosing the lower end load. The differences I saw quickly were due to many years spent in the loading manuals and shooting my own loads. You have the perfect example of why it is important to read the manual, choose a load, but work up from the low end. You now know to see the difference between what is in the book, as reference material, and how you have to consider your true to life circumstance to make the safest decision in your reloads. What to me would have been obvious is now, in your new experience, a reference that you can look back on that will make you a safer reloader. You have to understand why the velocity and pressure in your ammo was greater than the book indicated tho. Just changing a primer can take a load from mild to wild...so can a different powder lot, different brand of brass, different bullet, etc. Starting to work from the low end, and learning to predict how changes you make will effect the ammo, will make you a better and more enjoyable shooter.
Have fun, but stay safe.
Steve
I have many reloading manuals. Like several different Noslers, several Speer, several Hodgdon, VV, Lee, etc. When I go looking for a load, I do not go to one, I go to several, read thru all of the data and begin taking notes on my load preferences. I do not confirm all of my components until I have a positive correlation between data from several different manuals. I then work into my load carefully for my gun.
In looking thru your info I saw several things that quickly drew my attention. Remington vs CCI primers. 1:8 twist vs 1:9. Faster twist is going to raise pressure. Remington Primers, on average, are slightly hotter than CCI.....I do not have my H414 data handy, but if my memory is close, most Hodgdon loads with H414 use Remington or Winchester primers.
Not saying you didn't choose wisely, because you obviously did by choosing the lower end load. The differences I saw quickly were due to many years spent in the loading manuals and shooting my own loads. You have the perfect example of why it is important to read the manual, choose a load, but work up from the low end. You now know to see the difference between what is in the book, as reference material, and how you have to consider your true to life circumstance to make the safest decision in your reloads. What to me would have been obvious is now, in your new experience, a reference that you can look back on that will make you a safer reloader. You have to understand why the velocity and pressure in your ammo was greater than the book indicated tho. Just changing a primer can take a load from mild to wild...so can a different powder lot, different brand of brass, different bullet, etc. Starting to work from the low end, and learning to predict how changes you make will effect the ammo, will make you a better and more enjoyable shooter.
Have fun, but stay safe.
Steve
As others have already stated book data is just that. I have always experienced higher than book velocities with my reloads, to the point that I really don't even look at their published velocities anymore. I pay attention to the primer, brass, bolt resistance and chronograph to determine whether a load is getting too hot. Anymore I find my self spending lots of time surfing the web to see others' experience with the same components to find a starting point for a load, instead of looking at books.
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