How much velocity difference have you seen from changing primers, and nothing else?

B

Boyd Allen

Active member
There have some recent posts, in various threads, discussing ignition, and what difference it makes. I think that we can divide this subject into several areas: what sets the primer off, what primer, how it is seated, flash hole configuration, ambient conditions, type of propellant, etc. Differences in all of these areas may be evaluated by pressure, velocity, and ultimately, accuracy. When discussing tuning for accuracy, we talk of nodes, at various velocities, and it is pretty well accepted that accuracy, for a given rifle, and bullet, is directly linked to velocity. Velocity can be adjusted by various means, seating depth, neck tension(?), powder charge, and primer selection. This brings me to my main questions. First, what is the total range of velocities that are available by using different primers? Secondly, could changing primers take a load out of tune? Finally, if primers can move us out of tune, why do shooters test primers without adjusting the powder charge to a velocity that has been shown to be accurate?
 
About 3-4 years ago I did a test of 5 different primers. Using the same load and bullet each time. All small rifle primers in a 6ppc. I used the Fed 205M, Remington, CCI standard, CCI magnum, CCI BR. I shot all (5 each) over a chronograph. I didn't notice a lot of difference in velocity in the whole lot, but the CCI standard gave the lowest ES and SD of all. I just shoot mostly what I can get now. That being the standard Fed 205 for the most part. I also did not see any measureable difference in accuracy. But that small number of shots doesn't prove much, if anything. Just my observation.

Donald
 
Last year when Dad and I got down to 25K prmers during the primer crunch I bought a bunch of CCI small rifle BR (forget the number) to try against the Federal GM 205M's that we use. Interestingly the CCI's shot 50 shots 4 fps faster Avg, but a 7 SD rather than the 5.8 SD thet we had with the Federals. I'd give up the 4 fps for SD. both were decent on paper at 100 yds.
Paul
 
Several weeks ago I helped a mate sort out a load for his 6BR. Using AR2206H, Federal Match Primers and Sierra 70gr Match Kings the velocity spread over 5 shots was 67ftps, with no alterations other than changing to Remington 7 ½ Primers the velocity spread dropped to 7ftps

Cheers
 
German,
Excellent article! I have noticed some posts about misfires with Russian SRM primers. The thought has been that the cups may be too hard, possibly due to the plating. A friend who shoots BATs (short range Benchrest, 6PPC, hot loads) which I believe have .068 firing pin tips, and a reputation for good fit, has been shooting the Russian SR primers, with no problems, and excellent accuracy. Since my Viper has an .062 firing pin, and I have some of these primers, I am going to give them a try next time out. It may be that the whole thing about the Russian SR cups may be specific to hot loads with an .072 pin that is a sloppy fit. We shall see. Do you think that their .223 SR primers' unplated brass cups might be not quite as hard as the plated SRMs, and the same heat? If this is the case, these may be the ones to buy, hard enough, but not too hard.
Boyd
 
Boyd Allen said:
German,
Excellent article! I have noticed some posts about misfires with Russian SRM primers. The thought has been that the cups may be too hard, possibly due to the plating. A friend who shoots BATs (short range Benchrest, 6PPC, hot loads) which I believe have .068 firing pin tips, and a reputation for good fit, has been shooting the Russian SR primers, with no problems, and excellent accuracy. Since my Viper has an .062 firing pin, and I have some of these primers, I am going to give them a try next time out. It may be that the whole thing about the Russian SR cups may be specific to hot loads with an .072 pin that is a sloppy fit. We shall see. Do you think that their .223 SR primers' unplated brass cups might be not quite as hard as the plated SRMs, and the same heat? If this is the case, these may be the ones to buy, hard enough, but not too hard.
Boyd
Click to expand...

Boyd, at Wideners they explain the types of Wolf primers... Good info.
http://www.wideners.com/itemdetail.cfm?item_id=7277&dir=278|284|737

Myself, the one thing I like is a definate ES reduction compared to ANY other primer. Really like this primer in the 6PPC.
Ya got a gun that fires them reliably.... You'll love them.

Heard the TULA primers are Wolfs, just sold a tad cheaper "OEM" product.

I suggest those shooting slowish Ball (double base powders) get the " small rifle .223" primers.... As the SR and SRM primers use the same mild primer cake and do have a more difficult time lighting slowish Ball powders. No issues with most all single based powders.

cale
 
German, I deleted a post because I thought it misplaced here. But with your comment, I'll redo it.

I have a 6.5" Bat action, early mini port. Firing pin protrusion was checked and is good. Firing pin fit is good. I did not check the spring. A 6.5-inch action would have a slightly lighter firing pin that a longer action, but we're getting down into hair-splitting country here. Best I can tell, f still equals ma.

Cases are Lapua "6mm Norma BR" necked up to .30. (Chambering was .30-BR.) Load was 34.2 grains H4198. Cases were several times fired, and neck sized only. i.e., they fit the chamber, the load was not too hot. It is true that the primer pocket depth in Lapua is a bit deep, but after several firings, I had reamed these with a Whitetail primer pocket tool (Dick Wright's old tool, and I've not reset the cut). It was picking up brass at the bottom of the pocket.

Using Wolf Small Rifle magnum primers, Lot number 1-09, I had 9 failures to fire out of 50 rounds. Shot indoors, temperature about 70F. Re-cocking the bolt and hitting them again did not result in firing.


[Edit: forgot to add:] Primers seated with K&M tool. When I seat primers, I seat the primer, rotate the case 180-degrees, and seat again. The little "flat" on the Wolf primer gets a bit bigger. With the K&M tool, you can set it so as to feel everything bottom out and gauge the applied force [end edit]

I disassembled the rounds, pressing out the primer with a Wilson de-priming rod using an arbor press. Best "feel" I can get. Most of the primers came out with the anvil separated from the primer. Well, de-priming does stress them. I have no idea if this is a clue. The anvil is far less robust than other primers I've used.

I have since fired two matches with this rifle, same cases, same load, but with 205M primers No FTFs.

To pass off such experiences lightly (which you don't do, others have) strikes me as inappropriate.

If 1-09 is in fact a lot number, has any one else with FTF used that lot? Or used that lot with no FTF?

BTW, according to some old-timers, the best priming system is the Berdan system. Wish we could get them, and the cases that use them. No anvil problems, and two small flash holes.
 
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German you mentioned in your small primer study "All primers were seated with the Sinclair tool which has proven to be the best tool for this purpose".. Can you you provide a basis for this?

I would like to have seen the test done at the same primer crush and with firing pin strikes adjusted optimum for each.
As implied in your seating pressure article, Creighton Audette determined that optimum primer seating was not too much - not too little - but JUST RIGHT. His tool(offered by K&M) consistently sets crush. The Sinclair does not, as can be demonstrated by K&M measurement before/after seating with a Sinclair.
You might also understand & correct the article w/resp to the K&M seating prerequisite of uniformed pocket depths. This is false, the K&M accounts for both pocket depth and primer height during it's zeroing operation (prior to actual seating).
But of course pockets should be uniformed for consistent firing pin strike..
Speaking of which, I find that a different firing pin strike can change the whole ballgame between these primers. That the chasm between sufficient to excess for ignition can play havoc with long range loads.

Your articles are fantastic German. Thank you.
But there is a great deal to be explored with ignition still.
 
German Salazar said:
best for me in terms of seating the primers to a "just right" crush by feel
Click to expand...
There is no just right crush 'by feel'. You cannot feel 2thou or 3, or 4 of crush +/- 0thou...

I can only assume that you haven't used your K&M -per design.
I'm sure 20 minutes of correct use with one, followed by comparison measurements with any other, would have cleared your mind of it's present notions.

Anyway, I wish I had time to approach ignition with a scientific method. I have only been forced to resolve a related 'situation' recently with one of my guns.
To summarize:
A solid 3/8moa Cooper intermittantly opened +1/2moa(wait, don't walk away).
Took awhile to find, but the root cause was a failed cocking piece setscrew.
This allowed variance in striking force that did not show on fired primers. It was cold, and I had no reason to setup the chrono really as this load has always been tolerant to temps. If I had, I would have seen the problem right off the bat(and ordered a BAT).
Simple deal to fix right? Not a chance....
2 months of testing(here & there) it took to reach a final setting that performed as before, even better, but with a different primer. Never could get the gun back shooting with a primer I had determined early in load development to produce lowest SDs.
Two things I took from it unofficially; For each primer brand there is potentially a different optimum crush, and optimum firing pin strike. I believe it's an abstract that leads to us swapping primers during load development, with scarcely a trend(trial & error).

My next custom action will have an externally adjustable firing pin w/detent settings. And I will revisit every other load settled on specifically in this regard.
 
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