Thread: My first load development

You can lose 30fps average per inch loss of barrel. But it varies and can be more or less. A chrono is the best way as too many variables in play between the book and your rifle/shooting circumstances.

Originally Posted by Remmodel7

Yes realize one group is not definitive but I have to start somewhere. Plan on loading a few more, Checking velocity and looking for pressure signs at that load.
How do people calculate velocity change compared to book data from a 26" barrel in the load data to my 20” barrel?

Greetings Remmodel7,
I have not found ejector hole marks all that reliable as an indicator of pressure. There can be a slightly rough edge around the hole that makes a mark at normal velocities. Another rifle may show no mark, or any of the other "pressure signs" but expand the case head beyond further use with one shot. I've seen both. In the second case the claim was really good velocity with no pressure signs. Old data that had not been pressure tested was a culprit here as well. Velocity is easily the best indication of pressure that can be used by handloaders. Actual tests of velocity loss v barrel length reduction have shown 20 to 30 fps loss per inch for standard calibres with the smallest cases losing the least. I would figure on 20 fps per inch for your Grendel. Hodgdon/ADI book data for the Grendel is for a 24" barrel so 80 fps would be right.
Regards Grandpamac.

Originally Posted by Remmodel7

Yes realize one group is not definitive but I have to start somewhere. Plan on loading a few more, Checking velocity and looking for pressure signs at that load.
How do people calculate velocity change compared to book data from a 26" barrel in the load data to my 20” barrel?

Don't get me wrong, you've made a good start.
What projectile are you using?

If you're willing to divulge your load I'll run the numbers thru Quickload.

@Remmodel7 - you better change you name to "Alice" cause you just fell down the rabbit hole! lots of us down here, we even have our own song: "who the fuck is Alice" (points for getting the reference)

Originally Posted by zimmer

Don't get me wrong, you've made a good start.
What projectile are you using?

If you're willing to divulge your load I'll run the numbers thru Quickload.

@zimmer that would be choice. All data is on the first page half way down. 20” barrel.

Originally Posted by grandpamac

Greetings Remmodel7,
I have not found ejector hole marks all that reliable as an indicator of pressure. There can be a slightly rough edge around the hole that makes a mark at normal velocities. Another rifle may show no mark, or any of the other "pressure signs" but expand the case head beyond further use with one shot. I've seen both. In the second case the claim was really good velocity with no pressure signs. Old data that had not been pressure tested was a culprit here as well. Velocity is easily the best indication of pressure that can be used by handloaders. Actual tests of velocity loss v barrel length reduction have shown 20 to 30 fps loss per inch for standard calibres with the smallest cases losing the least. I would figure on 20 fps per inch for your Grendel. Hodgdon/ADI book data for the Grendel is for a 24" barrel so 80 fps would be right.
Regards Grandpamac.

@grandpamac.
Yes sorry 24” from adi book. From the top of my head I think max load was 2460fps so I'm guessing I should be in the high 2300?
Was hoping for better then that.
I had read that the Grendel being such a short case burns all it's powder and Max velocities can be reached from as little as a 14" barrel.
Ideally I want to use 8208 as my powder but as you will all know it's bloody hard to find anything at the moment. Or if you do in the car of powder get it to you.

Originally Posted by Remmodel7

@zimmer that would be choice. All data is on the first page half way down. 20” barrel.

Doh, apologies, missed that.

Originally Posted by Remmodel7

@grandpamac.
Yes sorry 24” from adi book. From the top of my head I think max load was 2460fps so I'm guessing I should be in the high 2300?
Was hoping for better then that.
I had read that the Grendel being such a short case burns all it's powder and Max velocities can be reached from as little as a 14" barrel.
Ideally I want to use 8208 as my powder but as you will all know it's bloody hard to find anything at the moment. Or if you do in the car of powder get it to you.

Greetings Again Remmodel7,
Max was 27.5 grains of Benchmark for 2,460 fps. You are 0.5 grains below that. Calculating the velocity per grain using the start and max loads gives 94 fps per grain gives 47 fps loss. About the only cartridge that gives max velocity with a 14 inch barrel is the .22 Long Rifle RF so you will loose velocity from the 20 inch barrel. 4 inches at 20 fps per inch (a conservative estimate) gives another 80 fps loss gives a corrected velocity of around 2,330 fps for 27 grains and around 2,380 fps for 27.5 grains. Whoever said max velocities could be achieved in a 14 inch barrel must have a degree in wish full thinking. Only a chronograph will tell you the truth. If you want more velocity a lighter projectile would be needed. Around 2,400 fps with a 123 grain pill is a pretty decent load though.
Regards Grandpamac.

You can borrow my chrony if you want

@Remmodel7 Unfortunately my version of Quickload doesn't have the 123 ELD-M, only 123 gr A-Max and 123 gr SST.
I don't have a Hornady manual so didn't know the expected velocity.
Hodgdon and ADI only list loads for the 123 gr Sierra HPBT. When I tried to replicate their loads in Quickload it gave much higher velocities than either the Hodgdon or ADI data.
That's unfortunately the nature of Quickload. Sometimes its spot on other times you have to frig with it to match your real world results with the results displayed in QL.

Using the 123 gr A-Max (SST gave very similar results) the pressure for a 26 gr load of BM2 is predicted to be 48923 psi versus the Pmax for the cartridge of 52000 psi. Again, because I have no Hornady manual the predicted velocity was not able to be compared to the manual velocity.

The calculated velocity drop for a 20" barrel over a 24" barrel is 86 fps (123 gr A-Max).

Originally Posted by grandpamac

Greetings Again Remmodel7,
Around 2,400 fps with a 123 grain pill is a pretty decent load though.
Regards Grandpamac.

yes its right up there with a 7.62x39mm LMFAO.......

Don't forget the forum has chronographs for use in both North and South Islands. I have the SI one waiting to go to whoever needs it. I think @EFriz was hoping to collect it from me.

Originally Posted by Remmodel7

@grandpamac.
Yes sorry 24” from adi book. From the top of my head I think max load was 2460fps so I'm guessing I should be in the high 2300?
Was hoping for better then that.
I had read that the Grendel being such a short case burns all it's powder and Max velocities can be reached from as little as a 14" barrel.
Ideally I want to use 8208 as my powder but as you will all know it's bloody hard to find anything at the moment. Or if you do in the car of powder get it to you.

The Hornady Manual Edition Ten has 27.1 of Benchmark max at 2450fps in a 18"barrel the top velocity is 31.2 CFE223
This from the Hodgdons site,https://www.hodgdonreloading.com/rel...2C9694%2C10068

So I went out for a bit of a quick sight in yesterday as there was a possibility of a hunt today.
Only had a brief time during lunch so got myself zeroed

Black tape was aiming point.
Next put in 2400 as velocity and shot at 300yards.

A bit low so used applied ballistics to calculate velocity.
Came out at 2389fps.
Shot out to 400

There was a slight cross wind that I didn't allow for.
Pretty happy with the results so far.

Originally Posted by Magnetite

Beg, borrow, or buy a chronograph. Without it you’re loading in the dark. As far as I’m aware velocity is the closest approximation to pressure we have. With traditional pressure signs you won’t know if you’re actually over pressure or it’s something else. And when you do see them you’ll could be in excess of 70kpsi. Even with traditional load data you won’t know if you rifle is running under/over pressure or the burn rate on the powder has changed from when the data was published.

Agreed. Compared to your overall investment in reloading equipment, a budget model chrony is not an expensive addition to your setup, but one of the most essential. I’m not alone in the opinion that you can’t safely load to maximum without comparing actual velocities alongside reloading manual information and other available data, such as brass inspection.
https://www.brownells.com/shooting-a...rod122616.aspx