223 Nosler 77 RDF with N540

[nicknewt]

Hey guys,
70gn RDFs worked great with N140 for my first PRS match... but I can only get the 77s now.. great!
I'm happy to go with the higher BC and a little less velocity but I have to work up a load again..

So.. has anyone loaded the 77RDF/N540 combo and with what results?
Or with different powder.amd with what results?

What fps
What's the seating depth COAL or BTO?

I've been told RDFs like a it if dancing room so a reasonable jump if preferable. Can anyone confirm or disagree in your experience?

My rig:
Tikka Tac A1, 223, 24 inch, 8 twist barrel

Thanks, Nick

 

[Jeff Porter]

What is your max mag length in the magazines ? I may be confusing with another bullet but thought the profile of the 77 RDF was set up for single loading over 2.250”.

 

[Laurie]

What is your max mag length in the magazines ? I may be confusing with another bullet but thought the profile of the 77 RDF was set up for single loading over 2.250”.

Yes, you're correct - all of the 'traditional' 77gn 0.224s (Sierra, Berger, Nosler Custom Competition, and Lapua) are very similar designs meant to be loaded to magazine length, and perform well there irrespective of jump distance. They all have relatively short and blunt nose sections in consequence. This shape makes them all very well behaved and position tolerant, albeit deeply positioned in the 223 Rem case which is often the limiting factor on charge weights when using slower burning powders such as N140/540.

The 77gn RDF though? The OP doesn't say which of Nosler's two 77gn models he is moving to. On the face of it, the RDF design is generally longer nose and hence OAL which makes it less suitable for magazine feed in the 223. The short / blunt designs like the 77 Nosler CC are seated very deeply at 2.25-2.26" COAL, so the RDF design will suffer even more in this respect

My rig:
Tikka Tac A1, 223, 24 inch, 8 twist barrel

Depending on the chamber throat in the Tikka you may be able to seat them to longer COALs for single-loading and increase charges, but as you're into PRS, I'm assuming you're stuck with the longest COAL that the magazine will accept and feed reliably with.

I'm happy to go with the higher BC and a little less velocity but I have to work up a load again..

According to Bryan Litz's field tests, the 70gn RDF and 77gn Nosler CC have near identical BCs (G7 0.197 / 0.193). As your MVs will be lower with the 77s, you'll see a less flat trajectory and more wind induced movement. The same weight RDF?

 

[nicknewt]

What is your max mag length in the magazines ? I may be confusing with another bullet but thought the profile of the 77 RDF was set up for single loading over 2.250”.

I'm picking them up tomorrow so I'll give more detail once I get my hands on them

 

[nicknewt]

I wasn't aware there were different versions but here is what I have.
Part number 54612

 

[Dgd6mm]

I believe Laurie is referring to the Nosler 77 Custom Competition bullet as the othe 77.

 

[Laurie]

Nosler lists the 77gn RDF as being 1.070" OAL which is a tenth inch plus a little longer than for the 70gn model so the bullet base will be the same amount deeper at the usual 2.25-2.26". It's a similar amount longer than the 'other' Nosler 77, the Custom Competition, or the Sierra MK. As you only have a half-inch of bullet nose allowed outside of the case (2.26" COAL - 1.76" max case OAL), it means you have 0.57" of bullet sitting inside the case and taking a lot of room up that would be better utilised in holding powder.

This set-up will work, but it remains a major limitation on charges and MVs in this little capacity-constrained cartridge. In this context, N540 is a good choice, better than N140, as it's a more dense powder and you can literally get a heavier charge into a limited powder space. It works fine with the 223 and 77-90gn bullets. It is a very 'hot' powder though affecting barrel life, although that is largely determined by the pressures it's producing, and you might not get enough into the case at 2.26" to really stretch it in this respect.

 

[SecondsCount]

I have had good success with the 70 and 77RDF, but found that they like to be on the closer side to the lands compared to the Custom Competition.

 

[Tireguy]

From my years of shooting N540, when developing loads, it tends to perform(groups shrink) at the higher end of the loading spectrum.