300 Winchester Magnum Velocity/drop Issues

[Awag1000]

I've been stewing over this issue I've been having with my drop table and the actual drop results from the range.
Im using a Savage 110 Tactical (300 Winchester Magnum)
SWFA 10x (MOA/MOA)
24" barrel
my handloads I'm using are:
SIG Sauer 300 Winchester Magnum Casings
CCI No. 250 Magnum Primers
67gr IMR 4350
Nosler 210gr RDF (.707g2)
COAL: 3.600 (.005 Jump)
I havent chronographed these rounds yet but they should be moving ~2800fps (on the Hot side)
with this being said, from a 100 yard zero my ballistic calculator (Strelok) shows they should drop 11.89" (3.78MOA) at 300 yards.
In actuality they are dropping 13.5" (4.5MOA) at 300 yards (I've tested this over 30 rounds and is consistent)
Im quite perplexed at these results and I have no answers. I'm fairly confident in my shooting ability and my equipment and can get 1/2MOA groups all day with this load. let me know what you think, thanks for your time.

 

[nn8734]

Sounds like you have a good load recipe for your win mag but not recording your MVs is probably the biggest driver behind your problem...using programs and apps to measure theoretical velocities has never worked for me; nothing beats the real thing.

that said, Don’t worry about what an app tells you after you stated shooting and gathering live dope. I also have a .300WM and use shooter to tell me where to start given my MVs. I shoot targets at 100 yard increments from 800-1500 yards, recording elevations that consistently resulted in hits at each distance. Eventually the drop chart builds itself. Takes several sessions over time (took me about 180 rounds before I got enough repeatedly reliable data). When live dope is compared to what shooter tells me, it’s always different. I largely ignore the differences until I go to another location with wildly different conditions. then I’ll use shooter again coupled with my dope for my home AO to come up with firing solutions for target engagement.

 

[Shootnwrench]

Never trust what a load should be for velocity, typically ammo boxes and load manuals don’t jive with actual.

Should be and is are two vastly different things.

 

[Huskydriver]

Sooooo your loads are going closer to 2700 fps... How does it group?

 

[plidenbrock]

I havent chronographed these rounds yet...

As already stated, without accurate MV data then you don't have a true framework for any expectations. What you're seeing is what you get.

The most likely explanation is your "expected" MV data is wrong. They are dropping more than your calculator says they should, which implies they are moving slower than you think they should.

An option would be to fiddle with the MV numbers until you get a match with that drop, and take that as your real MV for that temp. Another option is to beg/borrow/steal a chrono and get a few numbers. It's axiomatic that within supersonic range, inaccurate MV accounts for most drop errors.

One other question: are you dialing anything when you go to 300? Or are you just using holdover? Or simply aiming dead-on and measuring straight drop? In the last few years super chickens have become completely unreliable re: turret tracking in my experience, so if you're dialing any without having verified your scope's absolute tracking, that could also add to the problem.

 

[Punkur67]

Never trust what a load should be for velocity, typically ammo boxes and load manuals don’t jive with actual.

Should be and is are two vastly different things.

I broke my uncles heart when his 6.5 CM ammo was coming out of the tube about 175 fps slower than advertised on the box. I told him that box is cool and all but welcome to reality. It was driving him nuts that he was not getting higher velocities.

 

[Awag1000]

As already stated, without accurate MV data then you don't have a true framework for any expectations. What you're seeing is what you get.

The most likely explanation is your "expected" MV data is wrong. They are dropping more than your calculator says they should, which implies they are moving slower than you think they should.

An option would be to fiddle with the MV numbers until you get a match with that drop, and take that as your real MV for that temp. Another option is to beg/borrow/steal a chrono and get a few numbers. It's axiomatic that within supersonic range, inaccurate MV accounts for most drop errors.

One other question: are you dialing anything when you go to 300? Or are you just using holdover? Or simply aiming dead-on and measuring straight drop? In the last few years super chickens have become completely unreliable re: turret tracking in my experience, so if you're dialing any without having verified your scope's absolute tracking, that could also add to the problem.

I set up a large piece of cardboard at 300 slap a target sticker somewhere near the top of the cardboard and just keep my 100 yard zero dialed in my scope. I shoot at the target and measure center group (usually a 10 shot group) to the center point of the target sticker.
I have a Magnetospeed Sporter that I can use but I have nowhere to shoot due to the virus (I live in NJ, our governor (by unconstitutional executive order) shut down all the ranges)

 

[Shootnwrench]

I broke my uncles heart when his 6.5 CM ammo was coming out of the tube about 175 fps slower than advertised on the box. I told him that box is cool and all but welcome to reality. It was driving him nuts that he was not getting higher velocities.

I like to call chronos “heart breakers”

Quite a few guys have been sorely disappointed with their favorite load that’s shot well for years when they chrono it for the first time.

 

[Awag1000]

I like to call chronos “heart breakers”

Quite a few guys have been sorely disappointed with their favorite load that’s shot well for years when they chrono it for the first time.

I hear ya. The load I developed is very consistent (when it comes to group sizes) that's all that matters. As long as my velocities are consistent I'm happy. my expectations of the velocity should be lower though.

these are the last 2 rounds I tested at 100 yards. target is a 3" sticker

 

[GBMaryland]

For my 300 Winchester Magnum I weight the primers, The charge, the brass, and the bullets.

I then chronograph them and check the muzzle velocity, SD, and ES.

Super consistent rarely an issue...

 

[FatBoy]

@nn8734 Does exactly what I do. Nothing trumps real DOPE. If your scope height is a little off. Your internal adjustments off or you have a portions where the thread pitch is slight faster or slower, etc. It all throws the charts off. IMO program ballistic charts are a good starting point but that's it.

Once you have good, verifiable DOPE within say a 10° range, say 75°-85°, then work on cold and hot weather DOPE as well. Takes some time but you'll know your kit better than 99% of the people out there.

Hopefully you have enough of one lot or powder and bullets to burn out that barrel. If not, you get to start over when you change a variable. Since were not downrange, that data collection really becomes what this is all about.

Looks like you've got a shooter . Enjoy it.