Cam Over

[TAMU20]

I was rethinking my reloading process to get SD and ES down and was wondering how many of you guys have cam over when resizing your brass with a FL die getting 2 thousandths shoulder bump. I have a pretty heavy cam over. Could this be giving me my higher ES and SD or is it more of a factor of the die, brass, and press I'm using.

I am using:
Lapua 308 Brass
Redding Type S Bushing FL Die
Hornady Single Stage Press
Redding Competition Shell Holder

Thanks for the input!

 

[antithesis]

If you call Redding they are going to tell you this -> If the brass has not been fired a few times before you started doing that then it did not stretch enough to be setting the should back with setting the die off the shell holder. It takes 2-3 firings.

Before I bought the stuff to get consistent should bump measurements (I went with L.E. Wilson) would push new fired cases into the chamber with my finger and then close the bolt. I did not try to set the shoulder back until I started getting a noticeable increase in resistance closing the bolt when working with new batches of brass. Even with doing that, it took a few firings before all the cases had stretched enough to where I could get a firmer bolt close without trying several pieces of brass. YMMV.

 

[supercorndogs]

The cam over helps assure frame flex in your press is not effecting shoulder bump. The only reason most don't cam over, is because their chamber is too long for the die to be set up that way.

High SD and ES could be a factor of lots of things.

 

[Deleted member 10043]

Ah,, just set the die a little at a time until you can see it is touching the juncture of the widest part of the shoulder and case. There should be a visible ring around that juncture. One firing of the brass is enough. When it comes to bumping this is the section that frustrates people. Depending on the die and other factoring you may have to settle with .003 +/- .001. The difference is immaterial.

 

[ShtrRdy]

I don't necessarily have "cam-over" on my press when pushing back the shoulder 0.002".

There are many things that can mess with SD / ES. One of the more recent topics is sticky bullet to neck interface. Are you doing a deep clean of your brass?

 

[MtnCreek]

Heavy cam over = wearing out your press linkage prematurely. I don't see why it would effect velocities.

 

[skatz11]

I think powder charge and neck tension have the largest influence on ES and SD. As long as cases are consistently sized (and chambering easily) I would look for other variables to help improve consistency l.

 

[TAMU20]

Thanks for the input. I didn’t think the cam over would have a huge impact on SD and ES, but trying to minimize those started me thinking about my reloading process as a whole.

I think I might try to readjust my die to eliminate some if not all of the cam over.

I don’t deep clean my brass. I just use a vibratory cleaner.

 

[RegionRat]

The Redding Incremental shellholder set can be used to control the bump size while still using a mild camover, assuming a single stage press like a RockChucker or similar.

Before we found the Redding shellholder sets, we had made our own shellholders to custom dimensions based on the amount of bump we wanted. Now you can just buy them in a set where they step them in 0.002” increments.

By preloading the press against the die by camover, you just insure that the stiffness of the press doesn’t cause some cases to be less than fully sized.

I’m sure if you run a life test on a RockChucker with one being cammed-over versus one that isn’t, it might show a slight difference, but RockChuckers run with camover have outlived their owners more than I care to talk about, and those guys run them plenty hard. Mine has been run that way for close to 40 years and it will likely be something my wife has to deal with when I’m gone.

The general idea is to insure your sizing the body bump with as little dispersion as possible and to target only enough bump to insure reliable feeding to avoid wearing the brass and adding variability to case size. Neck tension and neck friction is a whole other discussion...

 

[wpgk58]

I follow a consistent reloading program, which yield me mid single digit SD's in .308 and low single digit SD's in 6.0 / 6.5 CM.
Details:
1. De-prime - I use a Mighty Armory Universal De-Priming Die
2. Wipe Clean with clean rag
3. Anneal - I use an AMP annealer for the most consistent results
4. Lube - lite spray with Lanolin and Alcohol mix
5. Resize and Set Neck Tension - I use Redding T7 press with Redding Type S Neck Bushing Full Size Die (de-priming stem and ball removed) / Mild cam-over used to insure consistent performance. Set neck tension to .0015" and Bump Shoulders .002". Use Redding Competition Shell Holders to control shoulder bump. Annealing insure that the brass is consistent softness to make the brass hold .002" bump and minimize the change of metal spring back.
6. Wet Tumble Clean - In order to fully clean brass. I use Frankford Arsenal tumblers with SS pins and Southern Shine Chips (50/50 ratio), 2-3 hours
7. Rinse / Rinse - I double rinse to make sure all chemical residue is removed.
8. Dry - I use a cheap dehydrator. 1-2 hours.
9. Inspection - I do a close inspection of each case. Any abnormalities are discarded.
10. Trim/Debur/Chamfer - I use a Giraud trimmer, which in one action does all, with extremely accurate cutting.
11. Prime - I prime on my Redding T7. Any soft or hard pressures on the press handle indicate primer pocket inconsistencies. These are marked and used as foulers or practice rounds.
12. Powder Charge - I use a A&D FX120i scale with Autoloader and Autotrickler and Area 419 enhancements. Scale is accurate to .02 grain (one kernel of H4350 / Varget). I do batches of 50 with flashlight checks before seating.
13. Bullet Seating - On Redding T7 using Redding Competition Seating die with custom honed seating stem (Seating Stem honed with Flitz on a bullet (Hornady ELD-M) to minimize friction between bullet and stem.
14. Record Batch - record all specs of batch

This is my approach and seems to work pretty well for me.

 

[ilmonster]

Some of the presses such as my Lee Classic Cast don't cam over. Would have to use something like Redding's Competition Shellholder set to get more bump.

 

[clcustom1911]

In my Dillon I have just a hair of cam-over to take the slack out of everything. For consistency. You don't need heavy or hard cam-over on anything.

 

[clcustom1911]

Some of the presses such as my Lee Classic Cast don't cam over. Would have to use something like Redding's Competition Shellholder set to get more bump.

With my Lee presses, I always set them up to where the shell holder would contact the bottom of the die, then turn the die down another 1/8-1/4 of a turn.

 

[Jimmy V]

The Redding Incremental shellholder set can be used to control the bump size while still using a mild camover, assuming a single stage press like a RockChucker or similar.

Before we found the Redding shellholder sets, we had made our own shellholders to custom dimensions based on the amount of bump we wanted. Now you can just buy them in a set where they step them in 0.002” increments.

By preloading the press against the die by camover, you just insure that the stiffness of the press doesn’t cause some cases to be less than fully sized.

I’m sure if you run a life test on a RockChucker with one being cammed-over versus one that isn’t, it might show a slight difference, but RockChuckers run with camover have outlived their owners more than I care to talk about, and those guys run them plenty hard. Mine has been run that way for close to 40 years and it will likely be something my wife has to deal with when I’m gone.

The general idea is to insure your sizing the body bump with as little dispersion as possible and to target only enough bump to insure reliable feeding to avoid wearing the brass and adding variability to case size. Neck tension and neck friction is a whole other discussion...

....the Redding shell holder set combined with the body die makes it possible for me to have a very consistent shoulder from one handloading session to the next without having to fiddle with die adjustments.... I have several conventional FL dies collecting dust as a result..

 

[TAMU20]

I readjusted my die and I still have cam over just not as much. I noticed by shoulder bump was more consistent but that could also be because my annealing process was also refine.