Chamber OAL

[Rickc]

Thanks! That is a good read ... And he put in a huge amunt tof time to collect the source material and to write it up.

His pressure traces are remarkably clean, which means he either cherry picked or did an excellent job of controlling wire runs and preventing interference. The picture of his test setup suggests the latter.

I thought so too!

I used to work hard with the .223 AR15 finding a load for.my precision rifle. I have probably tried every match bullet out there from jammed to .120 jump. 6 or 8 different powders. When I found the 6mm AR turbo 40 I gave my brother in law my precision .223 and all the dies and brass. Now I am learning what the grendel will do. Why waste time with the .223 when there are better options out there.

[Rickc]

... And we also have the ongoing PRVI brass and cartridge discussion.

Just buy lapua brass and be done with it.

[JASmith]

Just buy lapua brass and be done with it.

That is the practical consumer answer, although for cost reasons, I am very happy with Hornady and I get pretty good case life with it.

The issue with PRVI is related to your OP in that length is an issue. In this case it appears that the body length is a tad short for most chambers. The surprise is that the issue did not surface in this forum before the PRVI announcement.

Further, rickOshay measured a bunch of Lapua brass to better inform our discussion and found that the body lengths were much the same as what folks measure for PRVI brass.

There seems to be more to this story but it is being discussed in other threads.

[Rickc]

That is the practical consumer answer, although for cost reasons, I am very happy with Hornady and I get pretty good case life with it.

The issue with PRVI is related to your OP in that length is an issue. In this case it appears that the body length is a tad short for most chambers. The surprise is that the issue did not surface in this forum before the PRVI announcement.

Further, rickOshay measured a bunch of Lapua brass to better inform our discussion and found that the body lengths were much the same as what folks measure for PRVI brass.

There seems to be more to this story but it is being discussed in other threads.

I opened a brand new box of lapua 6.5 Grendel brass and after sizing I checked the trim length with the max and trim to length in the hornady manual. Can't remember the numbers off the top of my head but I know it was somewhere between the two. Closer to the trim to length if I remember right. Always check 10 or 12 out of 100 and they were consistent. None were short. I hate that when that happens trimming. But really what I have found is short brass works just fine. Now long is another story. but I don't trim until I have to and then I trim a whole group together.

How many out there measure the headspace on fired brass and then only bump the shoulder 3 to 5 thousands?

[Rickc]

Just checked the new lapua brass.

Hornady Manual max length 1.520 trim to length 1.510

Lapua brass is 1.515 give or take a thousandth

[diddlyv]

For years I was a member of a set the shoulder back to what ever the die in contact with the shell holder was as I was shooting a M1A in high power matches. 4 or 5 loadings was the cost of doing business and one did not want failures to chamber. OAL was not much of a problem, rounds had to fit in the magazine Sierra Match king hollow points are pretty much all over the place if you measure true OAL to the tip of the bullet probably at least .005 variation.

I tried the old technique to 6.5 grendel brass and ended up trimming approx .010 after the first sizing. In my book that is setting the shoulder way to far back. I have just ordered the OAL and Headspace bushings from midway for all my current calibers. I have been dragged kicking and screaming into the 21st century.

I did have issues with brand new hornady brass binding in the chamber if I did not put a bit of a crimp ( sized the new brass, was shorter than max length ) After firing and resizing and triming to 1.510 -0.000 plus .002 the crimp was not necessary to eliminate the binding in my chamber.

Saturday the bushings arrive and I can get real info on my chamber and throat.

[diddlyv]

My Hornady manual lists the max of CFE as 31.7. Just as a point of reference, I measured several cartridges from a box of factory Amax loads, lot #3152506. They varied from 2.249 to 2.253. This is longer than a box I check around a year ago. Those seems to run right at 2.240.

The tip on the bullet can vary causing variations of OAL. If you are using a bullet comparator it would be interesting to know what the variation on length to the Ogive