Primer Performance

[McLernon]

Is there anyone out there that can answer a question on primer performance. I'm experiencing some difficulties with my hand loads and I think it may be an ignition related problem. I'm shooting a .223 NEF Handi break- barrel rifle that has a transfer bar system that is prone to problems if the trigger isn't pulled all the way back on firing. From time to time a shot will hit way low, and there is no apparent reason for it.

My question is this:

If primers are impacted by the firing pin with varying degrees of impact such that they still always goes off, can this result in varying performance of the primers leading to significant variations in muzzle velocity?

Thanks

McL

[Questor]

What kind of problems occur when the trigger isn't pulled back all the way?  The symptom sounds more like a side effect of your anticipating recoil than a problem with the detonation of the primers.  If the trigger is creepy or inconsistent in some way, then it's harder to adjust our trigger pull technique to accommodate it.

I don't know the answer to your question, but I reckon that detonation is detonation and it shouldn't make much difference in the point of impact.  

I'm most suspicious of the trigger, and after that maybe the way the action locks up and whether the sights are tight. Are you using a scope? If it's a real cheapie you may want to try another scope to see if that corrects the problem.  I know the NEF triggers can be very good. I've tried a few that I suspect the owners had tuned by a gunsmith, but they were really good triggers.  The guns were really good too. Very accurate.

[KN]

I agree with Questor,I could see maybe a small variation from a primer but nothing major. I would think you could hear differences in your rounds if it varied that much.  KN

[McLernon]

If the trigger is not pulled all the way back the transfer bar that transfers the impact from hammer to firing pin starts to drop. The transfer bar then may get grazed by the hammer instead of getting the full whack and thus the firing pin gets less than the full whack.

Thanks for your comments

McL

[ricciardelli]

In theory, if the mechanical process and timing of your NEF is off, the chemical process will also be off.

Also, if the trigger/transfer bar timing is that sloppy, then it is also possible that your barrel lock-up is just as sloppy.

Now, that being said, I have a couple of questions for you:

What do you mean by "way low"?

Do you have the same problem with factory loads?

[McLernon]

By 'way low' I mean as much as 6 inches which is easily called. I have not had the trouble with Winchester White Box ammo. I plan some more tests tomorrow. ( total of 3 primer types will have been tested to eliminate faulty primers as the source). Barrel lock-up is as tight as a bank vault as advertised. Scope/mounts have been checked. The transfer bar system seems normal, that is 'not sloppy' it is the design I think that is the potential problem. I may be making things worse by employing a hammer extension thus increasing lock time. This I will also check tomorrow by removing it..

McL

[Questor]

I know that some users of T/C Contender single shot pistols have complained of weak primer strikes when using a hammer extension.  Most have no trouble though. It seems like those that do have modified their springs, and the modification caused the problem.

[McLernon]

Questor

Your comment regarding weak primer strikes on the T/C's seems to imply that they encountered ignition problems. Can you tell me if it was misfires or were they of the type that I have been thinking.(ie. lowered muzzle velocity)?

Or is it as simple as a "detonation is a detonation' and 'misfire is a misfire' and there is nothing in between???

Thanks for your comments

[Questor]

From what I've heard and read the light strikes on Contenders only affected performance in that the cartridge did not fire. Some have said this was a cold weather phenomenon, others reported the problem during summer. I can't recall ever reading anything on the effect of light primer strikes.  Maybe somebody with a lot of back issues of American Rifleman can recall whether anything has been published.  You might also try contacting your gun manufacturer about it. They may have encountered the problem before and have a fix for it.

[McLernon]

Good idea. I think I will contact NEF. Thanks for your response.

[McLernon]

Hello Questor

I talked to NEF/HR today as you suggested about primer performance as affected by trigger pull. They told me that if the trigger pull doesn't leave the transfer bar right up so that the hammer grazes the transfer bar instead of whacking hard, primer performance will be adversely affected. According to them this could result in a misfire OR reduced performance resulting in lower muzzle velocity. Of course this would be made worse or more likely if you had the hammer extension attached as this would increase lock time and give the transfer bar more time to slide down.

McL