How important is primer pocket/flash hole prep?

[338 dude]

Thank You for clarifying about the lapua brass being punched to save money and speed production. It only confirms that they all need to be checked, prepped, and deburred regardless of brand or price. You do have a very nice bench and set-up as well. Dave

Thank you Dave

 

[bushmotornv]

Sacriledge!!
Seriously though, I've always deburred mine, then stopped and saw great groups without. Lately watched the video where Gavin is interviewing Bryan litz and Bryan said that he doesnt based on testing showing it doesn't do any good. He is a x ring guy though, not a BR guy. Try 10 rounds of each for yourself and see if it helps

I wonder if Litz's results are based on brass that is already "prepped" out of the box,so to speak.

 

[338 dude]

I wonder if Litz's results are based on brass that is already "prepped" out of the box,so to speak.

 

[Lee Goodwin]

I use a small screwdriver and twist it once, and check for blockage in the hole...next. those military crimp primer pockets need work sometimes, but, I try to avoid that brass.

 

[SteveBurton]

IMHO it depends on the brass. If you are using Remington, Winchester, etc, then I think it is worthwhile. I have seen lots of primer pockets and flash holes that are different sizes, depths, diameters, etc.
If you are using Lapua, Norma or even the newer Hornady brass, I don't see a need to do it. I always check but the brass has been pretty good.

 

[MoaFlat]

Hunting you are spot on....match and BR entirely different matter. Every brass prep is necessary.... flash hole reaming and OD sizing Lapua and Norma have their differences too and require uniformity and consistency or it will be that 2 or 3 out of a box of 50 that loose the match. You decide.

 

[RD57]

I prefer to uniform the primer pockets for all my brass. The primary reason is to have all my primers seated at the same depth in the primer pocket, which equates to the same amount of movement during the priming process. I like having all my primers below flush for my semi-autos. I haven't seen any detrimental results on targets for not doing it, but I'm not a BR competitor or work in a ballistics lab.

 

[pony doctor]

In my reloading experiences thus far I've never messed around with deburring flash holes, specially cleaning or uniforming or in any way correcting primer pockets or flash holes...

Am I missing out on a very important practice? How big of a difference does this make for es numbers and accuracy? Please share if you do this, and please I'd love to see some "before and after" data regarding consistency of performance.

thanks.

My limited experience with attention to flash hole de-burring and pocket uniforming in developing a load for my AR 15, using once fired Lake City 5.56 brass has made a believer out of me. There are many details for improving consistency in patterns and it just depends on how much consistency you are looking for. Using military brass, it is imperative to "expand" the primer pocket to remove the primer crimp and then uniformed the pocket. My best "load development" 5 shot grouping was 1/2 moa at 100 yards with a standard deviation of 33 fps using a Lab Radar.

I decided to experiment at this stage by de-burring the flash holes just to see if this would improve the standard deviation of my rounds and thus the accuracy. After tumbling the brass and resizing, I was surprised to find most all cases had a significant burr! I discovered amazing results, as this was my first attempt at paying attention to the flash hole uniformity. All 5 rounds were stacked inside a 1/4 MOA with a std. deviation of 11 fps! I am convinced that for this caliber, this case, this powder charge, and this seating depth, plus detailed primer pocket attention has yeilded a very improved accuracy. Just my 2 cents worth!

 

[Swiftkill]

You only have to do it once, why not hedge your bets? Cleaning the pockets is a PITA!

 

[BoomWop]

I use peterson in the 6.5 creed Lapua and LC118lr in the 308 for matches or when I need to make a point in a class. These are all uniformed to produce the same result. I neck turn to make sure each piece is round not for a tight neck but round as close as possible to .015 thickness.
To me if I have uniform primer depth no matter the brass used I shoot better. I concentrate more and make the shots count. I wish I could say that with virgin brass but I'd be lying. I will look for seating depth and pressure while shooting virgin brass and then prep and finalize my load or look for a different bullet powder or primer if it's a common load with a good reputation.
In domestic brass of the past if you didn't uniform the brass to the nth degree at a shoot you were an also-ran. As far as tuning the firing pin protrusion spring weight and loaded spring height. Imho there is not one single thing after bedding that will contribute to better vertical control and wider loading nodes than this. My 308 with several different powders and bullets will shoot well at. slow newbee low recoil, medium competition and top pressure hunting speeds. The savage in 6.5 went from 1-1/2" at 300 to a hole. That took me 6 different springs to accomplish. Also I am now running .048 vs .042 with the heavier spring it came with. Vertical is less than a bullet width at 650 vs 3/4" at 300 in the stock configuration.
Does it work? In my mind YES. However, I can shoot FGMM and Hornady match in 308 and Hornady match in 140 and 147 in the creed almost as well because I know it shoots.
Shooting is a mental game if you think you can or think you can't your right

Which tool do you use for the Peterson brass? I've had mine for 20 some odd years so I don't remember the brand but it's anodized blue so I think it's either k&m or a Russ Hayden's. Anyway the pockets on my Peterson 6xc brass are way too tight for it and I'd like to find a tool to mill the pockets. I'm like you and like to remove all variables if possible.

 

[340PR]

A lot of good sound practices listed above. Consistency is also mentioned.
I strive for that with a capital C:
New (quality) brass is sorted into weight classes, flash holes deburred, pockets uniformed. After fire form; anneal, trim, scrape carbon from pocket, brush inside of neck. I do all cases the same after every firing, all in the name of consistency..
Before I started following these practices, my average ES was 22. since, it is 13. For me, that is a big deal.

I am currently identifying "anomaly" cases with very high or low velocity (often, but not always show as "fliers") and segregating them. This a work in progress, but so far, my ES has come down an additional 4 fps on average.

Full disclosure, I address all aspects of loading and shooting with the same degree of obsession (insanity), but it works for me. Doing so eliminates as many variables as possible, leaving the shooter solely responsible for results..

 

[Capt RB]

Which tool do you use for the Peterson brass? I've had mine for 20 some odd years so I don't remember the brand but it's anodized blue so I think it's either k&m or a Russ Hayden's. Anyway the pockets on my Peterson 6xc brass are way too tight for it and I'd like to find a tool to mill the pockets. I'm like you and like to remove all variables if possible.

Its carbide so either he or my dad made it

 

[340PR]

Which tool do you use for the Peterson brass? I've had mine for 20 some odd years so I don't remember the brand but it's anodized blue so I think it's either k&m or a Russ Hayden's. Anyway the pockets on my Peterson 6xc brass are way too tight for it and I'd like to find a tool to mill the pockets. I'm like you and like to remove all variables if possible.

I have both .062", and .080" made by K&M. they have carbide inserts, and the handles come off so you can chuck them up in a drill/driver. both Peterson 6.5CM, and 338 Lapua use the 080".

 

[BoomWop]

I have both .062", and .080" made by K&M. they have carbide inserts, and the handles come off so you can chuck them up in a drill/driver. both Peterson 6.5CM, and 338 Lapua use the 080".

Sorry for the confusion, I was talking about my pocket uniformer. My flash hole deburring tool works fine.