New hand priming tool

[blackhawk8]

Im looking to get a new hand priming tool. The 2 im interested in are the Sinclair hand priming tool and the 21st Century hand priming tool. Do any of you guys have knowledge of these or own on what is your opinion ? Thanks for the help.

[Unclenick]

I own the Sinclair and it has great feel. I watched the 21st YouTube and is looks like it will go quicker than the Sinclair and if the feel is as good, that newer design may be better for priming by feel for that mode of operation. For fixed primer seating depth, I like the idea of the click adjustments, but wish they were 0.0010" instead of 0.0025". It also appears to me the tool relies on every case having an exactly equal rim thickness for that adjustment to actually control seating depth. The Sinclair can be adjusted, but you have to use shims, so you can't do it on the fly as you can with the 21st Century tool. But the Sinclair tool (and this is why it goes more slowly) has you tighten its collar on each case to force the case head down against the top surface and square to the priming ram and to fix its height above the ram so rim thickness is eliminated as a variable. At that point only the primer pocket depth variable is still in play, and you can get a depth uniforming cutter to make that dimension the same on all your cases.

I use the K&M Primer/Gauge tool for critical loads like test ammo or long range match loads, but it takes even more time as there is an extra step. It first measures the depth of each case's primer pocket and the height of the individual primer you plan to seat into it, so as to let you zero its dial indicator where the dial hand will be when when the primer anvil feet kiss the bottom of the primer pocket during seating. The second step is seating, in which you remove the case and remove the primer from its measuring platform, and then put that same primer into the seating ram sleeve and slip the same case back in again to seat the primer. When the zeroed gauge reads "zero" during seating, the primer anvil feet are just kissing the bottom of the primer pocket. You then seat the primer beyond that point by bumping it forward until light contact with it has the gauge reading exactly however far you want to compress the priming mix between the bottom of the primer cup and the anvil tip.

That compression is called setting the bridge or reconsolidating the primer and anvil. Federal recommends 0.002" reconsolidation for their small rifle primers and 0.003" for their large rifle primers. Remington and Winchester both recommend 0.002"-0.006" for both primer sizes, so I usually aim for 0.004" with them and use that as the default for other primers I don't have a recommendation for. My assumption is the manufacturers know their own products best. Since Federal is the only one I am aware of that uses basic rather than normal lead styphnate as their sensitizer, I speculate that may be responsible for the narrower range recommendation.

Controlling reconsolidation was the last topic the late Creighton Audette wrote about in Precision Shooting in 1994. He argued that primers were not digitial—that is, not just bang or no-bang—but analog in that how far the primer was reconsolidated affected ignition performance and consistency. There has been good anecdotal evidence to back that up in principle, though how exact it has to be is not as clear:

"There is some debate about how deeply primers should be seated. I don’t pretend to have all the answers about this, but I have experimented with seating primers to different depths and seeing what happens on the chronograph and target paper, and so far I’ve obtained my best results seating them hard, pushing them in past the point where the anvil can be felt hitting the bottom of the pocket. Doing this, I can almost always get velocity standard deviations of less than 10 feet per second, even with magnum cartridges and long-bodied standards on the ’06 case, and I haven’t been able to accomplish that seating primers to lesser depths."

Dan Hackett
Precision Shooting Reloading Guide, Precision Shooting Inc., Pub. (R.I.P.), Manchester, CT, 1995, p. 271.

[Bart B.]

Good post, Unclenick.

I've measured primers' seating in pockets uniformed to uniform depth. Those that gave the best results in shooting were all seated to where the cup bottomed out against the pocket bottom. There was a few thousandths compression of the anvil into the priming compound.

Russian primers (originally imported by PMC, then Wolf and now Tulammo) have been known to require full cup seating into primer pockets for their very consistant firing and they're a favorite these days. I found the same with RWS primers. USA commercial ones tend to be the same way in my use of them. One needs to easily sense the tactile feedback of the primer seating to do it right. I still use Lee's version; I'm on my fourth one as their soft metal camming parts wear out over time.

In a close second place of things your rifle and ammo has to do for repeatability is the impact of the firing pin on primers being the right amount to make them perform best. Hard smacks are typically best. Way too much means poor trigger and bolt operation, but factory specs on the spring or even 10 to 15 percent over is best. Weak springs cause inconsistant primer firing and is first noticed at long range when elevation shot stringing happens and previous zeros for a given load and range have to be moved up a few clicks.

[Unclenick]

Bart,

Glad to have your confirming experience with all the different primers, and it's interesting about the full cup insertion.

Hummer90 has gauges that resemble headspace gauges, except with a recess where a primer pocket would be, and calibrated copper slugs for them for evaluating firing pin impact by the indentation in the copper, as to whether it meets requirements or not. I've not used those, but am looking forward to trying them out at some point. He says he had a phone conversation with a design engineer at one of the major gun makers in which he learned the fellow wasn't even aware there was a specification for firing pins impact, much less that there was a gauge system for evaluating it. It leaves one scratching one's head.

[Bart B.]

Unclelnick,

Some years ago, a ammo rep at the Nationals mentioned that most primers need at least a .020" dent in them to make them fire consistantly. Deeper is not an issue as long as the cup isn't split before chamber pressure pushes the cup and firing pin back a ways. Measuring the dent depth can easily be done by firing primed, empty cases in the rifle then measuring the dent's depth.

Other dimensional issues are at hand doing this. One's the head clearance the case has. That's the space between the bolt face and case head when the case is hard against its headspace point being pushed there by the firing pin. An other is the firing pin has to stick out past the bolt face enough to dent the primer deep enough. The depth the primer's seated in the pocket matters; if it's not deep enough, the firing pin seats it deeper and that reduces the force it has to crush the primer pellet between the cup head and anvil that's between the primer pellet and pocket bottom. At least .055" pin protrusion from the bolt face is needed for most cartridges. Match rifles are often made with .060" to.065" pin protrusion if they'll ever use new cases. If a rimless bottleneck case has headspace a lot less than chamber headspace, the resulting head clearance will be greater and when coupled with little firing pin protrusion from the bolt face means primer firing irregularities.

A perfect half round tip on the firing pin reduces pierced primers. A tight fit of the pin's diameter to the hole in the bolt face ensures no cratering of the primer cup, or at least minimal with peak pressures. Too much clearance lets a lot of cratering show up that's often mistaken for pressures being way too high; especially with softer primer cups.

[Unclenick]

Yes. The firing pin indentation is what I've always looked at. What's different with the copper is that stopping the pin with its reaction force to deformation over a certain depth tells you the energy in the blow, which in turn can be related to the H test spec for primer sensitivity and tell you directly if your mainspring is failing to hit hard enough to meet that.

For primer seating, there's no doubt high primers are the single most common cause of failure to fire. It's amazing how much energy they can absorb as they are seated deeper by a firing pin. One problem, though, is there was a long period, certainly still true in the 80's, where many benchrest shooters and a lot of writers in magazines kept referring to seating primers just until they could feel the anvil feet stop on the bottom of the primer pocket, but no further. I still run into folk who remember that and don't realize you get better performance setting the bridge correctly. They are usually the same people who still think neck sizing-only produces the most accurate ammunition.