Primer for lowest ES

[Guest]

From the board's experience which brand small rifle primer and also large rifle primers give the lowest Extreme Spread?
I am after the experience from those who have compared various brands over good chronographs for low ES and LR work.
APB

 

[abinok]

Ive got great results from Federal primers, and CCIBR2, and RWS... I think that there is a bit of magic to the mix in terms of a particular powder liking one primer over another. Don't get me wrong, there are definately good and bad lots in all makes and models, but I think that powder compatability as more to do with it than anything else.

For selecting primers for LR use, I typically get a couple of different lot#s of a given primer that I know performs well with the powder, then seat them in FL sized 308win brass necked down to 243 without an expander ball. I seat one of the heavier 6mm plastic bbs into the case (12gram... 14gram... I forget which), then shoot it across the chrony. This will give you a comparison as to which lot is most or least mild, as well as the most consistant. I will often buy 100 of a given lot, burn 20 primers in testing, shoot a ladder to find the load, then go back and buy however many I think im going to need for the given load, or to layback stocks for the forseeable future. That way I know im using a primer than has a known level of performance and consistancy.

 

[goodgrouper]

I am in total agreement with Abinok.
All primers are capable of producing low extreme spreads and standard deviations with the right combo of powder and powder column. All primers will probably also yeild different velocities with same powder charges compared.
That being said, it is my experience that some cartridges will never give great extreme spreads no matter what you try, and then some cartridges will do nothing but give small spreads. It also is my experience that the smaller and faster the bullet, the harder it is to get the standard deviations small. Heavy bullets being propelled at sufficient velocities often give good sd's with just about any load. In other words, you might have a hell of a time getting 40 grain ballistic tips in a 220 swift to get an sd of 25 or less and it might be a piece of cake to get a 338 win mag to shoot an sd of 8 with a 225 grain Accubond. It might even produce sd's in the single digits straight across the board.

I have a 6 br improved set up to shoot 105 grain and 95 grain vld's. In load testing, I tried 3 different primers, and 4 different powders for an eventual combo of 27 different loads. Of those 27 loads, 25 ended up having sd's in the single digits! The two that were out were 10 and 11!! THis cartridge used just about any primer to get a low sd.

 

[Bart B]

Competitive highpower (fullbore) rifle shooters who've properly tested primers find the PMC primers made in Russia to produce SD's about 3 or 4 fps. Plus they don't deteriorate over time (~ 5 - 6 months from when made) and start producing much higher SD's like virtually all others do.

Other things to do to reduce muzzle velocity spread are:
* firing pin should protrude from bolt face .055- .060-inch.
* replace firing pin spring every year.
* use firing pin spring about 20% stronger than stock.
* light neck tension on bullets = low spread in release resistance.
* seat bullets so lands push 'em back a few thousandths so starting resistance is uniformed.