Reloads travelling way lower then anticipated!!!

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Bwb2709

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Hi guys,

I was out last weekend testing some hand loads for my Sako 85 Long Range and found the velocity to be 200-250 FPS slower then I was expecting. I was shooting 178gr Hornady ELDX bullets over 75 grs of IMR 7977 with CCI large rifle mag no.250 primers. Bullets were seated about 2 thou off the lands. I expected to achieve between 2900 - 2950 FPS or more as that’s what’s advertised on hodgdons site, with a 24” 1:10 twist barrel. My Sako has a 26” 1:11 twist, so naturally I expected them to be a little faster. I should mention it was a sunny day with a few clouds rolling by, temp was about 6 degrees. From what I could tell the lenses on the chrono looked clean, free from dust. Just wondering if it could be that the battery is almost depleted, could it have been the sunny conditions. I wish I had access to a magnetospeed to check. Any insight or info you could provide would certainly be appreciated.

Cheers
 
Your reloading manual has drop tables. Sight in at 100 yards, dead on. Then shoot a group at 300 yards and measure drop below point of aim. Refer to table to see approximate muzzle velocity to get that amount of drop at 300. If can't shoot to at least 300 yards, doesn't really matter much anyway.
 
Bwb2709 said:
Hi guys,

I was out last weekend testing some hand loads for my Sako 85 Long Range and found the velocity to be 200-250 FPS slower then I was expecting. I was shooting 178gr Hornady ELDX bullets over 75 grs of IMR 7977 with CCI large rifle mag no.250 primers. Bullets were seated about 2 thou off the lands. I expected to achieve between 2900 - 2950 FPS or more as that’s what’s advertised on hodgdons site, with a 24” 1:10 twist barrel. My Sako has a 26” 1:11 twist, so naturally I expected them to be a little faster. I should mention it was a sunny day with a few clouds rolling by, temp was about 6 degrees. From what I could tell the lenses on the chrono looked clean, free from dust. Just wondering if it could be that the battery is almost depleted, could it have been the sunny conditions. I wish I had access to a magnetospeed to check. Any insight or info you could provide would certainly be appreciated.

Cheers
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Hey there - the first thing I would look at is measurement error. 200FPS / 2900FPS is about 7% error.

Many reloading manuals quote muzzle velocity as measured right at the muzzle, where many chrono users place their cronographs 10-20 feet in front of the muzzle, so this can be a source of error.

If you can find someone with a LabRadar chrono, this is a great device that can provide velocities corrected back to the muzzle.

Second, ammo temp of 6 degrees C is lower than the 15-20C that many tests assume, colder ammo = slower velocities, especially if the ammo is outside long enough to get cold - another source of error.

Third, every gun/bullet combination is different, so this could also contribute to error.

Do keep in mind that you can increase powder charge in conservative increments if you want to see higher velocities, but always being very carefully aware of pressure signs - and do not use velocity data as your sole source of information when determining your final load.

Keep going!
 
I used to buy my barrels 3 at a time for the 3 shooters in the house.

When I developed loads for the "identical" rifles and barrels, each was quite different and with the same load a difference of 150 fps was not unusual.

So a 200 fps difference between their very different rifle is quite possible. And the speed difference between lot numbers of powder, and fresh vs stale powder can make a big difference, too.


Start low and work up and find the accuracy.
 
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Why does it need to go 2900-2950 fps? Is it not shooting good at the lower velocities? Rather then chasing an arbitrary number, you should be doing what the rifle likes, the target and Chrono will tell you what that is.

Reloading manufacturers are notoriously out to lunch with their numbers, but usually on the conservative end due to liability and whatnot. Regardless, I never look at those numbers.

Every gun, every barrel, every lot of powder, primers, etc behaves differently from one to another.

IF you want to chase velocity, you need to do a ladder test to see where you start seeing pressure. Then start testing some prospective loads that are safely under the pressure zone. Using your preferred and proven load development method.

You're bound to be disappointed if you are going about this process blindly, expecting identical numbers from a manufacturer.

Also, if it's a new barrel, it's going to speed up as you break it in. Gaining ~200 fps while the barrel is breaking in is not unheard of.
 
OP seems to be looking for a way to verify if numbers he got on his chronograph are correct - he seems to doubt that they are. So adding powder is not a solution - I took his post to mean he was looking for a way to know if his numbers from his chronograph were real, or distorted from something. I can only think to shoot and measure longer range drop as a way to verify. Else getting at least one or more other chronographs and see if they all agree?
 
Potashminer said:
OP seems to be looking for a way to verify if numbers he got on his chronograph are correct - he seems to doubt that they are. So adding powder is not a solution - I took his post to mean he was looking for a way to know if his numbers from his chronograph were real, or distorted from something. I can only think to shoot and measure longer range drop as a way to verify. Else getting at least one or more other chronographs and see if they all agree?
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His post is pretty convulated, but re-reading it I think you are right.

What chronograph is the OP using?

Also, my comment above still stands. Is your barrel new? You will gain 80+ fps just from it breaking in. Your lot of powder could be slow. Have you done a ladder test to test velocities per charge weight, and see where pressure starts?

Right now I feel like the OP is just shooting from the hip, and disappointed because he is not seeing some arbitrary number.
 
todbartell said:
why have a 300 win mag to get 308 win speeds? Add more powder
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My experience with IMR 7797 is that it is noticeably slower burning in the 308 Norma Mag/300 Win Mag than is IMR 7828.
I do not believe that 75 grains behind a 178 grain bullet with a fairly short bearing surface is near max at all.

For example, in one of my custom barrelled 308 Norma Mags, with a 180 flat based bullet, I am at 78.5 grains for 3020 fps.

I would be working up cautiously [.5 grains at a time] to approach the 2900 or so he is wanting to see. That being said,
some barrels are simply "slower", and will not reach the velocity expected, even when pressure signs appear. Dave.
 
I’ve really been meaning to get back to this post ha ha. Life gets way too busy with two kids and being one of two working parents. I switched to RL22 after and picked up some ADG brass. Velocity jumped up almost 300 fps with that combo with no pressure signs. Ending up settling with 205 Berger elite hunter bullets and pushed them at 2900, which was just what the rifle liked. Could easily maintain 1/2 MOA out to 600 yards, with the occasional 1/4 MOA group.
 
Bwb2709 said:
Hi guys,

I was out last weekend testing some hand loads for my Sako 85 Long Range and found the velocity to be 200-250 FPS slower then I was expecting. I was shooting 178gr Hornady ELDX bullets over 75 grs of IMR 7977 with CCI large rifle mag no.250 primers. Bullets were seated about 2 thou off the lands. I expected to achieve between 2900 - 2950 FPS or more as that’s what’s advertised on hodgdons site, with a 24” 1:10 twist barrel. My Sako has a 26” 1:11 twist, so naturally I expected them to be a little faster. I should mention it was a sunny day with a few clouds rolling by, temp was about 6 degrees. From what I could tell the lenses on the chrono looked clean, free from dust. Just wondering if it could be that the battery is almost depleted, could it have been the sunny conditions. I wish I had access to a magnetospeed to check. Any insight or info you could provide would certainly be appreciated.

Cheers
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I have a Sako 85 finnlight in 300wm, I shoot Barnes 175 LRX using 79gr of H1000 seated 40thou off lands, getting 08 ES for an average speed of 3031fps cronographed over my Labradar, I Have shot it out to 985 yards farther kill shot spring Bear 563 yards! You should try other powders as for the twist rate it works but would be nice if it was faster for heavier bullets.
 
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accumark said:
I have a Sako 85 finnlight in 300wm, I shoot Barnes 175 LRX using 79gr of H1000 seated 40thou off lands, getting 08 ES for an average speed of 3031fps cronographed over my Labradar, I Have shot it out to 985 yards farther kill shot spring Bear 563 yards! You should try other powders as for the twist rate it works but would be nice if it was faster for heavier bullets.
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Thats a NICE Load - Giving Good Velocity ! Nice shot on the Yogi - how did that LRX perform ? Where did you hit the bear and how was the penetration ? Thxs RJ
 
remington jim said:
Thats a NICE Load - Giving Good Velocity ! Nice shot on the Yogi - how did that LRX perform ? Where did you hit the bear and how was the penetration ? Thxs RJ
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Shot was quartering away bullet went in ahead of right hind quarter smashed its way thru existed left front shoulder, Bear went 30-35 yards into the timber found him 8 yards in bear down! Good load could get more speed but group opening up once I got over 3100fps so backed it off shots 1/2 moa it i do my part.
 
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accumark said:
Shot was quartering away bullet went in ahead of right hind quarter smashed its way thru existed left front shoulder, Bear went 30-35 yards into the timber found him 8 yards in bear down! Good load could get more speed but group opening up once I got over 3100fps so backed it off shots 1/2 moa it i do my part.
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WOW...nice bullet performance !!
 
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