Help deciphering load data and FPS to make IDPA PF

[JMPhotog]

OK, So I have a load that I like for IDPA, but I am still trying to finalize the powder charge for IDPA PF in CDP which is 165,000.

I am loading Bullseye on 200gr RN Hi-Tek coated from Bayou with an OAL of 1.260

Here is my Chrono data:

4.8gr Bullseye 200gr RN

Chrono:

Hi 838

Lo 823

Avg 829

4.9gr Bullseye 200gr RN

Chrono:

Hi 838

Lo 803

Avg 824

Chrono string 2:

Hi 836

Lo 812

Avg 822

I had been loading 4.7 gr of Bullseye on a SWC and getting an average of 837 fps. But I switched to a RN because I had a couple SWC's not feed.

It seems like the higher gr in the RN does not go as fast. Am I missing something or is this normal?

[TDA]

It could be that the 200gr RN bullets are shorter in length than the 200gr SWC, which is what I have found.

This means that at the same COAL the case volume is a bit more with the RN and needs a bit more powder to compensate.

I can't say for sure because I am shooting coated LSWC and plated RN, so there is a velocity difference right there with the same powder charge.

YMMV

Edited September 27, 2015 by TDA

[JMPhotog]

Thanks. It just seemed as I increased the grains it decreased the FPS, ever so slightly, but lower

[TDA]

That could be the max velocity that you are going to get from that powder.

From what I understand, a powder can peak and then start falling off on velocity as the load increases. (for that particular bullet)

When that happens it's time to go to a bit slower powder.

You may also be using a temp sensitive powder.

Edited September 27, 2015 by TDA

[JMPhotog]

OK, so I did some reloading last night and went and tested them this morning:

5.0 gr Bullseye 200gr RN
Hi 848 Lo 827 Avg 841 gives a PF that passes, but not by much (168)

5.2 gr Bullseye 200gr RN
Hi 897 Lo 851 Avg 872 gives a PF of 174

Then I did some 230gr RN Hi-Tek coated from Bayou

4.2 gr Bullseye 230gr RN
Hi 723 Lo 690 Avg 715 does not put me in PF

4.4 gr Bullseye 230gr RN
Hi 763 Lo 740 Avg 745 gives me a PF of 171

I used a 14# recoil spring in my gun and I really liked the softer feel of the 230's. Both rounds grouped real nice, the 230's grouping a little tighter. The 200's felt a little snappier and a little more muzzle flip. With the 230's and the 14# spring I felt I could get back on target much quicker.

I think I am going to load a bunch of the 230gr with 4.4 of BE for the local match this weekend.