Explain it to me like I'm 5

NZClaybuster

NZClaybuster

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Calgary, Alberta
Why does my rifle like to go slow.

Rem 700 heavy barrel
168 SMK
42.5 grains of IMR 4064


just shot a .393" group at 200 yards
Even 50 fps faster makes it measurably bigger...


Everyone wants to go fast , except my gun....
 
Let me guess; you're clocking about ~2,650 fps?
Every bullet has its sweet spot. Exceed that point & accuracy goes to #ELL, unless you can make it to the next higher accuracy node without exceeding max. pressure levels.
Given that you should be right around 100% loading density with 42.5 grs. of IMR4064 in a .308, with your bullet seated to give you a C.O.A.L. of ~2.800", in order to go faster, you'll need to switch powders.
'Sides, are others achieving higher velocity levels with IMR4064 & that bullet with your length of barrel? If not, WGAS, considering that you're getting 1/5th of MOA? It ain't a BR rifle.
My $0.02 Cdn.
 
SigWig said:
Brass? Too thick?
Barrel length?
Chrony speed?

Nice shooting
Click to expand...
Brass thickness was not measured, It was all Federal Premium Brass, purchased new, unloaded through this rifle and reloaded by me.
22" heavy barrel (stock barrel)
average speed on this group was 2542 fps measured with a Garmin Xero

Shot standing, gun on a calwell rest with a custom made rear bag..

Thanks for the compliment
 
jamesharrison said:
Let me guess; you're clocking about ~2,650 fps?
Every bullet has its sweet spot. Exceed that point & accuracy goes to #ELL, unless you can make it to the next higher accuracy node without exceeding max. pressure levels.
Given that you should be right around 100% loading density with 42.5 grs. of IMR4064 in a .308, with your bullet seated to give you a C.O.A.L. of ~2.800", in order to go faster, you'll need to switch powders.
'Sides, are others achieving higher velocity levels with IMR4064 & that bullet with your length of barrel? If not, WGAS, considering that you're getting 1/5th of MOA? It ain't a BR rifle.
My $0.02 Cdn.
Click to expand...
If i get to 2600 fps, the group opens up..
Here is the issue.. I am shooting a rifle set up that is under $2k. I am shooting alongside guys with rifles from 2x to 6x the money in them. As to OAL, i am using a comparator that measures of the ogive and 2.153 is the number that produces the best results. With my new Frankford Arsnenal micrometer seating die, i have been able to load to +/- .003 consistency.

I can get up to 44.5 grains in the case but the group opens up to 3.1 inches with speeds up to 2695 fps.

The speed for this group was 2542 fps
 
Rob 22 said:
REM 700 5R 155g SST and around 40.6g H4895 is its happiest at 300 m. This is below starting load. Slow and low pressure shoots well. Never really figured out why as next best load has close to 5g more powder
Click to expand...
I started with 4895 and was consistently smaller groups with 4064. the issue is replacing the powder now... I finished my first, on my second, third is in transit.. now the hunt is on..
 
NZClaybuster said:
shooting a rifle set up that is under $2k. I am shooting alongside guys with rifles from 2x to 6x the money in them.
Click to expand...
Seriously! Think of how many components you can buy with all the money you're saving compared to your buddies!

Nothing beats practice. Keep shooting until you can duplicate that sub 1/4 MOA group.

You might want to give some other bullets a try: Lapua 155, 167, 170 & 185 gr., Berger 155, 155.5, 168, 175, Nosler's HPBT competition line.

Powder too. I prefer Reloader 15, but good luck with that nowadays. Vihtavuouri N140, 540, or Hodgdon's Varget.

Maybe invest in some better brass, like Lapua, Alpha, Peterson, RWS, Norma.
 
Sounds like you are trying to get benchrest accuracy out of a factory rifle. You can only squeeze so much out of a factory barrel. Myself, I don't chase velocity and don't care what the numbers say. Accuracy is what you are after. Be happy with he groups that you are getting and forget about what the Chrony says.
I had one 30 inch long .308 barrel that shot very accurately with a velocity around 2950 fps. I used the same load in another barrel (same rifle) that produce 3015 fps average.
 
NZClaybuster said:
If i get to 2600 fps, the group opens up..
Here is the issue.. I am shooting a rifle set up that is under $2k. I am shooting alongside guys with rifles from 2x to 6x the money in them. As to OAL, i am using a comparator that measures of the ogive and 2.153 is the number that produces the best results. With my new Frankford Arsnenal micrometer seating die, i have been able to load to +/- .003 consistency.

I can get up to 44.5 grains in the case but the group opens up to 3.1 inches with speeds up to 2695 fps.

The speed for this group was 2542 fps
Click to expand...
You would have to keep adding powder in order to increase the speed so you can get to the next accuracy node. You may, or may not get there before pressure signs start showing up.

R.
 
NZClaybuster said:
I started with 4895 and was consistently smaller groups with 4064. the issue is replacing the powder now... I finished my first, on my second, third is in transit.. now the hunt is on..
Click to expand...
Varget will do everything IMR4064 does in the 308Win.

I believe IMR4064 is one of the powders which was discontinued??? I haven't seen it on shelves for quite awhile.

Every load change, will cause altered "harmonics"

Usually it's very gradual, rather than as drastic as you describe. IMR4064 is "old school" tech when it comes to propellants.

It's a great powder and it was one of my "go to" favorites for several cartridges, because it was "predictable"

My other "go to" powder in that burn rate is W748, again, because it's "predictable"

However, one thing about powders in this burn rate range, they have "definite sweet spots" where they are predictable and when the load densities are on one side or the other of those "sweet spots" they become unpredictable quickly.

If you're going to acquire more IMR4064, likely you won't be finding it in large quantities or from the same lot.

This happens when powders are hard to find or discontinued.

Because IMR4064 is "old tech" I would "blend" all of the containers you find, into one large lot. This will ensure a large lot of IMR4064 and you won't get any surprises when opening a new container.
 
Op,
Hodgdon bottled 4064 is faster burning than Dupont IMR 4064 powder.

Load to a jam to gain some velocity depending on your current pressure situation.

VV N135 would be a viable option.
H Varget is dirty schit.
WW ball powders won't get you the velocities that you seek.
 
maynard said:
Sounds like you are trying to get benchrest accuracy out of a factory rifle. You can only squeeze so much out of a factory barrel. Myself, I don't chase velocity and don't care what the numbers say. Accuracy is what you are after. Be happy with he groups that you are getting and forget about what the Chrony says.
I had one 30 inch long .308 barrel that shot very accurately with a velocity around 2950 fps. I used the same load in another barrel (same rifle) that produce 3015 fps average.
Click to expand...
I need chrony data so i can make longer shots.. gotta know the speed to calculate the clicks
 
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