I recently had someone work up a bunch of handloads for a 7mm rem mag. My question is what should be the normal variance of muzzle velocity on handloaded ammo? If all other variables are consistent, how much effect will different brass have on mv? I have not been pleased with results but was looking for some input before contacting the gunsmith.
Handload MV consistency
- Thread starter derquhart
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RELH
Long Time Member
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using different brands of brass can have a big effect on velocity due to low to high variance in internal pressure.
If you are looking for the least amount of variance in velocity for a string of shots, everything must be consistant for each cartridge.
I am assuming you are not pleased with the accuracy after a gunsmith worked on the rifle? If that is the case, you need to try other ammo before you complain to the gunsmith. I would get a box of Federal Premium 7mm mag. ammo and see what groups you get with that. For good accuracy, I have always had good luck with the Federal Premium line of ammo.
RELH
If you are looking for the least amount of variance in velocity for a string of shots, everything must be consistant for each cartridge.
I am assuming you are not pleased with the accuracy after a gunsmith worked on the rifle? If that is the case, you need to try other ammo before you complain to the gunsmith. I would get a box of Federal Premium 7mm mag. ammo and see what groups you get with that. For good accuracy, I have always had good luck with the Federal Premium line of ammo.
RELH
Thanks for the reply---- I would clarify I am unhappy with this batch of hand loaded ammunition. I have had good success with previous handloads (1 hole at 100 yard) For starters, I would have assumed a gunsmith that reloads would know that the different brass would have a different MV and not use varying brands. I had an assumption that was the cause so I made sure to separate the 3 brands used to shoot them all separate. Shooting the same brass, I am getting variances form 70 FPS all the way to 120 FPS on 3 types of brass. This is what I was trying to get input on, what should the normal variance be? 100 FPS is about a full MOA off at 500 yards. The overall high to low MV of the 3 brass types combined was 230 FPS!
RELH
Long Time Member
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LAST EDITED ON Oct-24-15 AT 09:44PM (MST)[p]Just because he is a gunsmith, does not make him a expert in reloading as you found out. You need to find a better source of ammo. You might start with those loads that gave you such great results in the past.
RELH
The neck variances mentioned above can be a direct result of using different brands of brass. Remington has a reputation of having thinner wall brass then some other brands that will throw off neck tension and internal volume with less pressure.
RELH
The neck variances mentioned above can be a direct result of using different brands of brass. Remington has a reputation of having thinner wall brass then some other brands that will throw off neck tension and internal volume with less pressure.
>LAST EDITED ON Oct-24-15
>AT 09:44?PM (MST)
>
>Just because he is a gunsmith,
>does not make him a
>expert in reloading as you
>found out. You need to
>find a better source of
>ammo. You might start with
>those loads that gave you
>such great results in the
>past.
>
The same guy loaded the stuff that shot great in the past! Maybe just got sloppy.
>AT 09:44?PM (MST)
>
>Just because he is a gunsmith,
>does not make him a
>expert in reloading as you
>found out. You need to
>find a better source of
>ammo. You might start with
>those loads that gave you
>such great results in the
>past.
>
The same guy loaded the stuff that shot great in the past! Maybe just got sloppy.
My advice, get some new brass and load a dozen rounds of 150 gr Ballistic tips a couple grains under max. powder and promer don't matter.
If the gun won't shoot this well then it's the gun, the scope or you. I've found lots of loads guns don't like, but if they don't like this one you're peeing in the wind. make it someone elses gun.
Stay Thirsty My Friends
If the gun won't shoot this well then it's the gun, the scope or you. I've found lots of loads guns don't like, but if they don't like this one you're peeing in the wind. make it someone elses gun.
Stay Thirsty My Friends
>I hope for 30fps variance.
>I usually get about 90 fps
>variance on factor loads.
>
>I have had great luck getting
>consistent loads.
>I try to really always use
>the same kind of brass,
>the same age of brass,
>the same primer....
>
>Good luck
Just the input I was looking for. Appreciate it.
>I usually get about 90 fps
>variance on factor loads.
>
>I have had great luck getting
>consistent loads.
>I try to really always use
>the same kind of brass,
>the same age of brass,
>the same primer....
>
>Good luck
Just the input I was looking for. Appreciate it.
That's way too much. Possibly using a powder that is temperature sensitive???? Agree the ES/ should be no more than 20-30fps, especially with the extensive list of powders from Hodgdon or IMR (with Enduron) with low temperature sensitivity. Had good luck with H1000, H4831, Retumbo in that caliber. One of those and possibly try different primers. Have been able to occasionally knock off another 5-10fps changing there.
What do you pay this guy to do your loads for you? Its a time consuming process, I least it is for me. Is this guy hand weighing every load or just throwing loads using a powder measure? If he's just throwing loads that could be your differences right there.
Utah400Elk
Very Active Member
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I average less than 10 fps between my shots. I am very meticulous with my re-loading and weigh out every round.
llamapacker
Moderator
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- 1,068
Lots of factors. Probably most important is powder selection. Some powders regularly produce loads with a SD of 20 fps or less. Other powders you are lucky to get a SD less than 50 fps.
Another factor could be your chrony. Cheaper models and certain bullet profiles / tip styles give pretty irregular readings. The ammo may be better than your chrony indicates. Of course if you are using an Oehler or other high end chrony you can probably disregard this.
Aside from the data, how does it shoot? (accuracy). While I like to have ammo with as small an SD as possible, it is surprising to see how average looking SD data can ocassionally produce really tight groups. You just never know....
Bill
Another factor could be your chrony. Cheaper models and certain bullet profiles / tip styles give pretty irregular readings. The ammo may be better than your chrony indicates. Of course if you are using an Oehler or other high end chrony you can probably disregard this.
Aside from the data, how does it shoot? (accuracy). While I like to have ammo with as small an SD as possible, it is surprising to see how average looking SD data can ocassionally produce really tight groups. You just never know....
Bill
