RPR bullet jump

[swiftdood]

I have a factory RPR in 6.5 Creedmoor and I’m building a load using 140gn Nosler RDF bullets. Using Tres Mons load building pages, I’m now at the stage where I’m going to start ladder testing. Crushed into the lands .010” my COAL is 2.883”. I know there is a pressure test involved here too. But.....the RPR magazine appears to restrict me to loads with a max COAL to 2.830”.
Even if I backed bullet seating off 0.010” to 2.873.....that is a jump of 0.030”. Is this too big a jump for great accuracy?

 

[Chernobyl]

I have the same rifle and ran into mag restriction issues as well. I soon realized my best bet was to replace the factory mag. I went with the American rifle co. 6.5 with no binder plate. It has an inside cartridge length of 2.920 or so. I now can run any bullet at any distance during load development and find what my rpr truly shoots the best. I have not completed load developement on the 140 rdf yet so not sure on seating depth. Also just about any aftermarket mag you buy will feed much smoother than factory mag. I tried multiple before settling on the American rifle co.

 

[Doc68]

Get the Magpul aics pattern mags. I have no issues with mine.

 

[Hawk in WY]

The 140 RDF went from one MOA to one hole in my rifle with shorter COAL.

I usually develop loads .02 off the lands and have not needed to test different COAL before.

Will now go back and test other 0.5 MOA loads with more jump.

I’m not sure if the bullet likes more jump or if lowering case capacity with the bullet seated deeper fine tuned the velocity, but I do know it made an amazing difference.

 

[swiftdood]

I have the same rifle and ran into mag restriction issues as well. I soon realized my best bet was to replace the factory mag. I went with the American rifle co. 6.5 with no binder plate. It has an inside cartridge length of 2.920 or so. I now can run any bullet at any distance during load development and find what my rpr truly shoots the best. I have not completed load developement on the 140 rdf yet so not sure on seating depth. Also just about any aftermarket mag you buy will feed much smoother than factory mag. I tried multiple before settling on the American rifle co.

Thanks Chernobyl....I looked on the AMerican Rifle site and can’t find the mag you’re talking about. Can you shoot me the url for it?

 

[swiftdood]

The 140 RDF went from one MOA to one hole in my rifle with shorter COAL.

I usually develop loads .02 off the lands and have not needed to test different COAL before.

Will now go back and test other 0.5 MOA loads with more jump.

I’m not sure if the bullet likes more jump or if lowering case capacity with the bullet seated deeper fine tuned the velocity, but I do know it made an amazing difference.

Thanks Hawk for the input. I’ve still got to run my ladder test...14 rounds starting at 36gns of H4350 out to 42.5. RDFs are seated to crush .010. In this ladder test I’m ‘supposed’ to find a group that I then have to fine tune. Then mess with seating depth. I’m encouraged that your loads show the RDFs like a little jump. The Hornady 140gn Match ammo is giving me solid .7s @100 and that is with a jump of .067”. That’s quite a jump in my book. How far off your lands are you jumping to get one holers?

 

[Huskydriver]

Some bullets prefer to be jumped in particular barrels. I have a Berger vld load that groups like a blunderbuss seated to the lands but one ragged hole seated .12 off the lands. Just gotta play around with it

 

[Chernobyl]

Thanks Chernobyl....I looked on the AMerican Rifle site and can’t find the mag you’re talking about. Can you shoot me the url for it?

Sorry brother I was incorrect. The one I settled on is accurate mag not ARC. Here is the url.

6.5 Creedmoor DSSF Magazine

The Accurate-Mag 6.5 Creedmoor box magazine is a standard AICS type magazine that will fit any AICS type bottom metal or chassis system. It is nearly identical to the standard .308 mag with the exception of the stamp and the exclusion of the blinder plate to allow for cartridge length up to...

accurate-mag.com

 

[918v]

You don’t need to be close to the lands, necessarily, for great accuracy.

 

[Howland]

RPR .338LM here. Loading to mag length is a .080" jump. I don't know if there is an aftermarket mag that will let me seat to the lands.

 

[Hawk in WY]

Thanks Hawk for the input. I’ve still got to run my ladder test...14 rounds starting at 36gns of H4350 out to 42.5. RDFs are seated to crush .010. In this ladder test I’m ‘supposed’ to find a group that I then have to fine tune. Then mess with seating depth. I’m encouraged that your loads show the RDFs like a little jump. The Hornady 140gn Match ammo is giving me solid .7s @100 and that is with a jump of .067”. That’s quite a jump in my book. How far off your lands are you jumping to get one holers?

50 thou off seems to be the sweet spot.

I plan to test even shorter. Still well over SAAMI 2.80 and Nosler recommended 2.775.