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Can undersized brass cause light primer strikes?

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Thank you for your interest in my post - am committed to providing factual information - please allow me to comment


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It would appear the key word in my post was, "type", small words like this can be easily overlooked and might be a reason to create a separate post having a separate heading. Yes, primers of the same manufacturer commonly have different thicknesses. But in this particular thread we are concerned with the mighty high pressure .338 Lapua Magnum.

For Boyd & Matt, to direct this post to a more certain outcome I might ask what kind or type primer might be used in the .338 Lapua magnum. A CCI 300? no! wrong type because this is a pistol primer intended for pistols. The .338 Lapua uses large rifle primers, a different type of primer.

check this out

www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

I am not a primer expert and apparently my knowledge is open to a general critique on the particular subject being type of primer in this case large rifle then more particularly a CCI 250 primer. I see a common thickness of .027 for all primers of the same type being large rifle.

For Boyd & Matt, actual measurements of the same type of primer used in the .338 Lapua magnum might be offered as a response. In fact I did look and discovered that all large rifle primers, same type, were of the same cup thickness.

All I can say is read stuff real careful.
All I can say is there have been dozens and dozens of threads talking about primers not going off or with hangfires. Most all have been CCI primers. I know lots of competitors that will not use them because of the not firing.

It just seems everything including seating depth, firing pin weight, strength of strike, headspace and maybe a few other issues are causes.

I have a 338 Lapua IMP and I use Federal 215. Never had a misfire. In fact almost every competitor and hunter I know uses Federal for hunting and competition. Matt
 
Then again, I've gone thru at least 10,000 + CCI primers (BR and Mil Spec) and only had two FTF and that was because they got oil contaminated.
Just blame it on the CCI primers and never find out the REAL PROBLEM.
Probably brass length issue.
 
If the Perterson brass had the shoulder pushed just a tiny bit to far, or if the chamber in the rifle were a slighty out of spec, could that result in light primer strikes?
No. IMO.

The extractor should stop the cartridges forward movement , allowing the primers to fire. I tested this in a Savage Axis, using brass with no shoulder. Fired all 3 times.

If the bullet is seated into the rifling, the firing pin strike may seat the bullet deeper into the case. This absorbs the firing pins energy, before contact is made with the extractor.

The velocity of the firing pin should be considered first. Is something slowing iit?

Is pin protrusion correct?HeadClearance.JPG
 
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No. IMO.

The extractor should stop the cartridges forward movement , allowing the primers to fire. I tested this in a Savage Axis, using brass with no shoulder. Fired all 3 times.

If the bullet is seated into the rifling, the firing pin strike may seat the bullet deeper into the case. This absorbs the firing pins energy, before contact is made with the extractor.

The velocity of the firing pin should be considered first. Is something slowing iit?

Is pin protrusion correct?View attachment 1033308

Actually that's backwards seating the bullet into the rifling pushes the head against the bolt face causing a better fire form.
 
I have used probably 100 hundred thousand CCI primers over the last 51 years and have only had less than 5 fire without some good reason. Some reasons are contamination with either oil or water, excessive head-space, weak firing pin tension and obstruction of firing pin hole in bolt face. I keep my stuff clean and up to spec - especially triggers, safeties, and bolt innards. Primers are seated by feel, slightly below flush with compression of anvils.

Of possible consideration is the term, "sweet spot" that CCI uses to describe their primers - this alludes to the top of the anvil configuration being positioned to be under a firing pin dent. Should an off center firing pin strike at some distance from the top of the anvil detonation might not occur.

My last CCI fail to fire occurred with a CCI 41 primer (mil spec small rifle) - no good reason was determined, the previous 750 of a brick of 1000 went off just fine with 2 rifles. Nothing inside the fail to fire primer indicated a problem. Possibly some water or oil contamination caused the problem.

Nothing is perfect and the OP states that he had a 20% fail to fire and that should indicate some serious problem. Possibly, mass contamination during storage or shipment. Load the others in a different rifle & see what happens.

This link should please Fed 215 fans

www.btgresearch.org/High-speed%20measurement%20of%20rifle%20primer%20blast%20waves.pdf

Possibly the OP should check out his Peterson .338 Lapua brass & switch to Fed 215 having a substantial increase in blast wave pressure over CCI 250's - lots of powder in the huge .338 Lapua mag case. Observe the Fed 215's had a lower SD for blast wave psi.
 
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Primer depth is the most likely culprit in my opinion. If some work and others don't, then the variable is most likely proud primers/deep primers.
 
Recently had to fire-form some Winchester .300WM brass that was criminally undersized from the factory. The shoulder was blowing forward 15-20 thou... and yet every single one went 'bang'. I'm not sure the long-range accuracy would be all that great, but they did go off reliably.
 
**********



Thank you for your interest in my post - am committed to providing factual information - please allow me to comment


***********

It would appear the key word in my post was, "type", small words like this can be easily overlooked and might be a reason to create a separate post having a separate heading. Yes, primers of the same manufacturer commonly have different thicknesses. But in this particular thread we are concerned with the mighty high pressure .338 Lapua Magnum.

For Boyd & Matt, to direct this post to a more certain outcome I might ask what kind or type primer might be used in the .338 Lapua magnum. A CCI 300? no! wrong type because this is a pistol primer intended for pistols. The .338 Lapua uses large rifle primers, a different type of primer.

check this out

www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

I am not a primer expert and apparently my knowledge is open to a general critique on the particular subject being type of primer in this case large rifle then more particularly a CCI 250 primer. I see a common thickness of .027 for all primers of the same type being large rifle.

For Boyd & Matt, actual measurements of the same type of primer used in the .338 Lapua magnum might be offered as a response. In fact I did look and discovered that all large rifle primers, same type, were of the same cup thickness.

All I can say is read stuff real careful.
I was replying to your last post that said that all primers of the same type are assumed to have cups of the same thickness. In that post, you spoke in more general terms. If you had said all large rifle primers, I probably would have looked for the table before responding, but you did not. Many times we post not so much for the OP but for the benefit of those who are lurking and may be led astray. In this case, as you are aware, all primers of the same type do not have cups of the same thickness, but yes all large primers do. Before you caution someone to read more carefully....
 
But in this particular thread we are concerned with the mighty high pressure .338 Lapua Magnum.
Why is its pressure mighty high?

I don't think it has mighty high pressure. Many people load their non-magnum cartridges to the same pressure it has.

The 338 Lapua Mag is SAAMI spec'd at 65,000 psi max average pressure. Same as many belted or rimless "magnum" cartridges.

Regarding light primer strikes, I've seen some instances of weak firing pin springs causing more muzzle velocity spreads. Vertical shot stringing at long range is an indicator. Primers need smacked consistently hard to produce repeatable flame output. Some striker springs weaken with age.
 
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Recently had to fire-form some Winchester .300WM brass that was criminally undersized from the factory. The shoulder was blowing forward 15-20 thou... and yet every single one went 'bang'. I'm not sure the long-range accuracy would be all that great, but they did go off reliably.
Normal for all belted mags to be short..... Head spacing off the belt not the shoulder, and yep they will all go bang.
 
Recently had to fire-form some Winchester .300WM brass that was criminally undersized from the factory. The shoulder was blowing forward 15-20 thou... and yet every single one went 'bang'. I'm not sure the long-range accuracy would be all that great, but they did go off reliably.
I've not seen any significant accuracy problems with belted cases stopped against the chamber belt ridge and several thousandths shoulder clearance in the chamber. Such cases well center their neck in the chamber neck because the belt is quite square with the case body shoulder and neck axis. The bullet is therefore well aligned to the bore. There's a tiny clearance around the case to the chamber.

Why else would new belted cases be used to win long range matches and set records? Such cases in my 30 caliber belted magnums easily tested sub MOA at 1000 yards.
 
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Normal for all belted mags to be short..... Head spacing off the belt not the shoulder, and yep they will all go bang.

Don't shoot belted magnums....However....my understanding (?) is the first firing is headspaced off the belt. Then (maybe 2 or 3 firings later) the headspacing is off the shoulder as it (the shoulder) moves forward. This could be rubbish as I am referring to something I read somewhere. But I can understand this being true. Now of course 'bumping' the shoulder back with each resizing...I guess can revert it back to the belt. I'd be interested if what I said is indeed what is happening.
 
I've not seen any significant accuracy problems with belted cases stopped against the chamber belt ridge and several thousandths shoulder clearance in the chamber. Such cases well center their neck in the chamber neck because the bells is quite square with the case body shoulder and neck axis. The bullet is therefore well aligned to the bore. There's a tiny clearance around the case to the chamber.

Why else would new belted cases be used to win long range matches and set records? Such cases in my 30 caliber belted magnums easily tested sub MOA at 1000 yards.
I dont know of hardly any long range matches being won with belted cases. They disappeared a few years ago in 1000 yard BR. The case winning and setting records are the little 6mm IMP versions and the 300 WSM. They just are easier to get to shoot smaller and the brass is better. Matt
 
Recently had to fire-form some Winchester .300WM brass that was criminally undersized from the factory. The shoulder was blowing forward 15-20 thou... and yet every single one went 'bang'. I'm not sure the long-range accuracy would be all that great, but they did go off reliably.
New belted cases are stopped form going forward in the chamber by their belts. after that, if properly sized, by their shoulders. There is nothing criminal about their when new shoulder location, but rather they take into account the wide variations in chambers' bolt face to shoulder dimensions. The problem is die manufacturers' instructions about how to set their FL dies. I have never seen any problem caused by one of these cases having its shoulder blown forward during its initial firing, but I have seen many cases that split because reloaders were unaware of the proper procedure for setting their belted case FL dies. The dies are made intentionally so that they can size cases from rifles with the shortest shoulder to head dimension, which of course means that if yours is more typical that the bump will be way too much if the die is set to touch the shell holder. Knowing this, knowledgeable shooters treat fired belted cases as if they were rimless when setting their FL dies.
 
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Of course the belted cases disappeared. Rimless ones are easier to reload and smaller caliber rimless ones now have more accurate heavy bullets. They're easier to shoot accurately.

But the best of them are no more accurate. All test shots under 5 to 6 inches at 1000. Belted cases have done that for decades. But only when full length sized all the way to the belt with a body die.

1000 yard NBRSA benchrest three 10-shot agg record is 5.11 inch average. How big was the largest group? Same for the PA 1K yard club's ten 10-shot group agg record of 5.8954 inch for light gun, 6.1149 inch for heavy gun.

I'm not infatuated by single, tiny few-shot groups. They're more luck than anything else. So are the largest ones, but they represent what can be counted on most of the time. Both happen just as often; once.
 
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Of course the belted cases disappeared. Rimless ones are easier to reload and smaller caliber rimless ones now have more accurate heavy bullets. They're easier to shoot accurately.

But the best of them are no more accurate. All test shots under 5 to 6 inches at 1000. Belted cases have done that for decades. But only when full length sized all the way to the belt with a body die.

1000 yard NBRSA benchrest three 10-shot agg record is 5.11 inch average. How big was the largest group? Same for the PA 1K yard club's ten 10-shot group agg record of 5.8954 inch for light gun, 6.1149 inch for heavy gun.

I'm not infatuated by single, tiny few-shot groups. They're more luck than anything else. So are the largest ones, but they represent what can be counted on most of the time. Both happen just as often; once.

Have you shot NBRSA match or any group match?
 
Strip and clean any factory gunge from inside the bolt.
Had the same problems with a Tikka recently and cleaning of the bolt fixed it.

I had the exact same issue recently with my Surgeon action. I removed the firing pin/spring assembly from the bolt and cleaned it as well as the interior of the bolt body. It fixed my problem.

I don't know if the bolt on my rifle came from surgeon heavily greased, or if the gunsmith that barreled the action heavily greased it. Removing all of the grease and lightly lubing it with regular gun oil resolved my problem.
 
I had the exact same issue recently with my Surgeon action. I removed the firing pin/spring assembly from the bolt and cleaned it as well as the interior of the bolt body. It fixed my problem.

I don't know if the bolt on my rifle came from surgeon heavily greased, or if the gunsmith that barreled the action heavily greased it. Removing all of the grease and lightly lubing it with regular gun oil resolved my problem.
I suspect it's climate related and the tacky corrosion prevention used by some manufacturers is migrating inside the bolt to where it's causing a hydraulic'ing issue and as this stuff is tacky and thick it's not being displaced by the firing pin.
Yes, a regular gun oil would be a better choice providing it doesn't dry and give the same issue further down the track.
 

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