Working up a load on a necked down case????

[rsbhunter]

Need to tap into the experts knowledge here....building an ar15 in 22 arc for a club match. I have a rifle (ar) that is in 243 lbc, Same parent case (6.5 grendel) , same dimensions except neck diameter. So , if a given load that used 27.0gr of a given powder was 100% safe with a 105gr .243 bullet , what happens when the cases necked to .224 with a 85.5gr bullet ? Not looking for definitive answer, but a "general" rule of a starting point. Thanks for any input....rsbhunter

 

[CJ6]

Treat it as a new cartridge (it is). Start low and work up.......You wouldn't use 30-06 loads in a 270 would you....

 

[Bill Norris]

^^^^^^^ I would definitely start low and work it back up. Almost impossible to guess at where the load would need to be.

 

[rsbhunter]

C J6, you are correct, except I'm asking about doing a 270 load in a 30/06. NOT saying that it would work or be safe, but a totally different direction...thanks for the input though....rsbhunter

 

[rsbhunter]

Bill, very true. The reason I ask, there is a video of a gunsmith/builder , that took Hornady 6mm ARC, pulls the pulled, necks down the neck, and seats a Berger 85.5gr bullet. In the video, shot without any pressure signs. I understand the apples to oranges comparison, I am just curious as to the pressure differences from changing the neck diameter. I guess I need to look at cartridges like the 30/06 to 270 , and 308 to 7/08. Maybe then I can get an idea of the load proportions. rsbhunter

 

[rsbhunter]

Ok, looked at Hodgdon data on the 308 with Varget and 180gr bullet, and the 7/08 with 150gr and varget as a comparison... the charges are not comparable..... I'm going to research 22 grendel loads as load data. Thanks for the responses, they made me look at it from a different angle...Thanks to you both..rsbhunter

 

[TTE]

Most of the loading advise here includes "Be Safe".
I'm pretty sure you have included those words in one of your posts.

Although you are an experienced reloader, it's wise to return to the basics of reloading.

JMO

 

[rsbhunter]

SO TRUE!!!

 

[RegionRat]

I'm probably being slow.... but why not just use the 22 ARC data for a 22 ARC?

It would be different if there weren't any, but now that there has been such a splash for this new cartridge, there is data available.... what am I missing?

Even if you don't run QL or GRT, you can see how this cartridge responds in the table below.
You didn't name the powder, but these will give you a good idea.

 

[RegionRat]

Bill, very true. The reason I ask, there is a video of a gunsmith/builder , that took Hornady 6mm ARC, pulls the pulled, necks down the neck, and seats a Berger 85.5gr bullet. In the video, shot without any pressure signs. I understand the apples to oranges comparison, I am just curious as to the pressure differences from changing the neck diameter. I guess I need to look at cartridges like the 30/06 to 270 , and 308 to 7/08. Maybe then I can get an idea of the load proportions. rsbhunter

If you really want to study this, then your approach plus GRT or QL will be a good way to estimate pressure.
Keep in mind, just about every day on here, folks take their pressure above the CIP/SAAMI limits of the cartridge. Just because there appears to be no pressure signs, doesn't mean they are not at higher than desired pressure.

Weird things can happen when the barrel diameter is smaller and all other things are equal.

 

[rsbhunter]

RegionRat, yes, there is some great info out there , I am going to do some load development with RL16 and H4895.... with the cost and availability of both powders, was just hoping that there were some safe load data for 80.5 to 95gr . But the Hodgdon charts are fantastic... Thanks, rsbhunter

 

[RegionRat]

Of those two, study the H4350 data for a similarity to RL16. The H4895 is much faster.

 

[chop house]

Just because there appears to be no pressure signs, doesn't mean they are not at higher than desired pressure.

amen. question might be 'how long can you get away with it'...