I have a problem.

At issue is blown primers in a .204 Savage FCV rifle. It is a twin of my own rifle (it's serial number is 1 higher than my rifle).

For background:

The rifle is about 5 years old. It is very accurate with 39 gr Sierra BKs (27.5 gr Varget, Hornady cases, and Federal primers). That load has killed hundreds of squeaks out to 400 yards.

My shooting buddy, the rifle's owner, has been reloading for 10-12 years and is very careful in assembling his loads.

Yesterday (Friday), we were at the range trying out some 26 gr Barnes bullets. He was testing 2 loads: one was using Benchmark (27.0 Gr), the other was Varget (27.0 Gr). (Max Benchmark is listed at 28.7 gr., Max Varget is 30.0 Compressed.) The COL of 2.31 was the same as my loads.

He was exceptionally careful because a week earlier he had blown a primer. He didn't like that . . .

But yesterday, again, both the Varget and Benchmark loaded rounds blew a primer.

I was playing with 3 different loads, each 0.5 grain below maximum with no signs of pressure.

He shot 5 rounds of each of my loads and they showed no sign of pressure whatsoever, and he actually shot quite a nice group with the 5 loaded with IMR 4198.

SUMMARY SO FAR: His "starting loads" blew primers, my slightly below Max loads were fine when shot in his rifle.

I took one of his loaded rounds (Varget) home and disassembled it.

I calibrated my scale using check-weights and weighed the powder (27 grains) but threw it away because I couldn't verify it was Varget.

I left the primer in the case and confirmed that the case fit properly into my Wilson "Head Space" gauge. But the case was close to being at SAAMI maximum length.

The bullet measured .204 in and weighed 26.05 grains (as best I could tell).

Okay! Got it, I thought. Wrong or contaminated powder, and/or case neck entered the leade and wouldn't release the bullet.

I trimmed his case back to the length I use (from near-max 1.849 to below-min 1.835) and partially neck-sized it (⅛ in) to increase the grip of the case neck on the bullet.

I calibrated my scale using check-weights (again) and broke out my own jug of Varget. I measured 27 grains and dumped it into that case and seated the bullet to 2.31 in. (Remember: this is the starting load at Hodgdon's site.)

Then I loaded 11 identical rounds using my Nosler brass and Tula primers and today we again went to the range.

The Hornady brass round I had disassembled and reassembled blew its primer!

He also shot several 39 gr. Sierra's with 27.5 gr Varget and had no signs of pressure!

The 11 rounds that I loaded using my Nosler brass and Tula primers, the same batch of Varget (27 grains), the same case length, and the same COL of 2.31 in.

They functioned flawlessly and he produced a 5 shot 0.5 inch group (100 yds) and accounted for 2 ground squirrels who had the misfortune to run in front of his bullets.

My question is: What on earth, is going on here??

Is the primer pocket opening up and the primer blowing or is the FP indent blowing out?

quote:

Originally posted by Bobster:
Is the primer pocket opening up and the primer blowing or is the FP indent blowing out?

The primers were blown out, found in the magazine. The case heads are blackened(!).

UPDATE: Yeah, the primer pockets were bigly opened.

The only time I have blown a primer was in a Savage 22/250. I was shooting a proven and accurate load, killing prairie dogs in SW Kansas. The afternoon became miserably hot and my ammo heated up and then the primer blew. I packed up and went home. The only reason I know for a gun with correct chamber dimensions to blow a primer is the load was too hot, whether it was overcharged or heated up in the heat of the day as was my scenario. In the 204Ruger, my go-to load was a 40 grain Hornady Vmax over 27.1 grains of H4895 and WSRP primers in Win. brass. I never had problems with this load but the SW Kansas gale force winds blew the little pills all over and I sold my TC Encore after a short love affair with that cartridge. Your bud needs to find a load that shoots well and stick to it, at least that is what has worked for me for many years.

quote:

Originally posted by Luckyducker:
The only time I have blown a primer was in a Savage 22/250. I was shooting a proven and accurate load, killing prairie dogs in SW Kansas. The afternoon became miserably hot and my ammo heated up and then the primer blew. I packed up and went home. The only reason I know for a gun with correct chamber dimensions to blow a primer is the load was too hot, whether it was overcharged or heated up in the heat of the day as was my scenario. In the 204Ruger, my go-to load was a 40 grain Hornady Vmax over 27.1 grains of H4895 and WSRP primers in Win. brass. I never had problems with this load but the SW Kansas gale force winds blew the little pills all over and I sold my TC Encore after a short love affair with that cartridge. Your bud needs to find a load that shoots well and stick to it, at least that is what has worked for me for many years.

I understand the practical solution. That's not the problem.

What baffles me is why he can shoot my 26 grain Barnes loads in his rifle just fine, but the identical load (except the brass and primer), loaded by me, blow primers.

What about a "starting load" of Varget in a properly-sized Hornady case with a Federal Primer blows primers, but a "starting load" charge of Varget would NOT cause a properly-sized Nosler case with a Tula primer to blow primers, when they are identically loaded?

I want to know because I don't want to walk into whatever conditions caused this in the future, with different calibers or components.

Also, I'm trying to protect not only myself and my friend, but also folks who read this forum.

Too long to read; but any time you change any component in a system and expect identical results to any other load combination, you are dreaming.
Start over, develop loads with and for, one set of components and rifle. Only one. Looks like you changed the brass and primer; and maybe rifles, so the loads, in reality, are not the same at all.
Can't always mix and match components and expect the same results.

What dpcd said.......plus.....

Since no one has mentioned it......I'd clean, clean, and CLEAN the bore again. Then, if possible, borescope it.

Small calibers, at 3800fps plus velocities, can foul like crazy......especially in the pd fields.

Hope this helps.

Friend Of The 17.....and 20
Kevin

quote:

Originally posted by dpcd:
Too long to read; but any time you change any component in a system and expect identical results to any other load combination, you are dreaming.
Start over, develop loads with and for, one set of components and rifle. Only one. Looks like you changed the brass and primer; and maybe rifles, so the loads, in reality, are not the same at all.
Can't always mix and match components and expect the same results.

I apologize for the length of my post and am sorry you didn't read it. But in 50+ years of reloading I've never seen anything remotely like this.

I understand about working up loads when one changes components and that safe loads are rifle-specific. Honestly. I do.

But it seems to me (and maybe others) that if the "starting load" - where primers blow with Hornady cases and Federal primers but not with Nosler cases and Tula primers - the cause of this event might be of use to others. If there's something I'm unaware of, maybe others are as well.

Our starting load of 27 grains of Varget was 3 grains below Hodgdon's Max [and 0.5 grains below Hodgdon's "starting load"]. Case brand and primer brand were the only variables.

Have you seen or heard of any instance where subtracting 10% of a "Maximum Load" could blow primers because of brass-brand and primer brand differences?

weigh the cases.

Your buddy got a batch of soft brass

Make sure there are no "do-nuts" in the case necks. This can cause pressure should the bullet base go pass the "do-nut". Foster makes a nice reamer which you can use before sizing. It works excellent. You can test for 'do-nuts" by inserting a bullet in the case neck after firing. Should feel resistance once the bullet pass the shoulder/neck junction, there is definitely a "do-nut". Not sure if the 204 is prone to "do-nuts" forming like the 243 for instance.

quote:

weigh the cases.

THIS!

Several good ideas offered already. A friend wrecked a Rem 700 action. Problem turned out to be some fast burning powder got dumped into a can of slower burning powder. Things went south real quick after that

quote:

Originally posted by snowman:
Several good ideas offered already. A friend wrecked a Rem 700 action. Problem turned out to be some fast burning powder got dumped into a can of slower burning powder. Things went south real quick after that

That was my very first thought. But I pulled the bullet from one of his cartridges from our Friday outing, tossed the powder, trimmed the case 0.015, neck-sized about ⅛ of the neck (to hold the very short bullet a bit better), and used Varget from my stash (measured by on my carefully-calibrated scale). The load was 27 grains, which was 3 grains below max., 0.5 grains below "starting load" recommendation.

That primer blew yesterday (Saturday).

Without prompting, he mentioned that after Friday's episode, he had inspected and cleaned the gun especially carefully (he's a former career Marine and by habit he cleans his weapon after every range or shooting session). His barrel was clean.

So far, the "soft brass" suggestion seems the most plausible, and I sent him a note asking if the case was virgin or had been previously fired with a normal load (which for him is typically 1.0-1.5 grain below max.)

I have only one of his cases, but will compare its volume with one a few of my cases by trimming both to same length and weighing each filled with water.

Thanks for all the suggestions. Please keep them coming and I'll report any results I can "rule in" or "rule out."

Just weigh the case. You already know it is the same shape on the outside.
The solution is obvious and simple; he has to reduce the load to suit his components. Whether it is soft, or thick, doesn't matter; you have already proven it is not the same as your brass. Now that you have shown it is not just his rifle, you can remove that from the list of possible variables.
These sub small bore cartridges are very sensitive to changes of any kind. Expansion ratio is high.

Again, thanks.

First, I learned that this was the 4th time the Hornady case with blown primer had been fired. So I don't think soft brass is the issue.

Second, I weighed the cases.

I have only 2 of the Hornady cases he shot in his rifle, but including fired primers they average 99.3 grains.

1. One of those was a case with a 27.5 grains of Varget pushing a 39 grain Sierra, and the primer was perfectly normal.

2. The second case was the one with the blown primer (I weighed the primer and the case together). This is the case that used 27 grains of Varget pushing a 26 grain Barnes.

I weighed 6 Nosler cases that were shot in my friend's rifle with the same load that had blown the primer, and their average with primers is 101.74 grains.

Since the Nosler cases average is greater than the Hornady's, am I right to conclude that it's volume was less than the Hornady? If so, wouldn't that mean that the pressure would be greater in Nosler case?

Again, I really want to thank you all for your suggestions.

Yes, you are correct.

quote:

Originally posted by dpcd:
Yes, you are correct.

Thanks. I appreciate your guidance.

FWIW . . . here's Barnes load data page for their 26 grain bullet.

Did you measure the diameter of the bullets?

God Bless, Louis

The ogive of the two bullets is different, and the one that's blowing primers probably is closer to the lands, increasing pressure. Reduce your overall length of the loaded rounds to reduce the pressure.

I'm kind of stumped.
but I have heard of some recent batches of Hornady cases stretching the primer pockets prematurely.

What Whelenite said: Bullet too close to or into the lands.
Have you checked seating depth as compared to distance to the lands? This is where the Hornady tool works well.

Have you checked the neck diameter of a loaded round? I ran into a similar problem once and after much head scratching I found that the necks had thickened just enough to not allow any expansion on firing. Also make sure your cases are not too long for the chamber.
C.G.B.

What kind of primers were used?

Young outdoors

quote:

Did you measure the diameter of the primers?

No. But they are the same Federal primers that work just great when shooting the longer, heavier (39 gr. Sierra BK) with more powder (27 gr Varget for 26 grain, 27.5 grain Varget with Sierras).

Whelenite

quote:

The ogive of the two bullets is different, and the one that's blowing primers probably is closer to the lands, increasing pressure. Reduce your overall length of the loaded rounds to reduce the pressure.

I've (provisionally) ruled it out on indirect evidence: His rifle shoots my Nosler-cased 26 grains bullets just fine and both COLs measure 2.31.

Also, the COL of our cartridges loaded with the Sierra 39 grain bullet are longer and they shoot fine.

But your point is well-taken and I'll be ordering an insert for my comparator. Direct evidence beats indirect evidence every time.

Lamar

quote:

I'm kind of stumped.
but I have heard of some recent batches of Hornady cases stretching the primer pockets prematurely.

That's certainly plausible, but that would mean that the primers blow with a very mild load and light bullet and don't do it with a stiffer load with a heavier bullet. (27 gr Varget for 26 gr bullet, 27.5 gr. Varget for 39 gr bullet.)

BC3

quote:

What Whelenite said: Bullet too close to or into the lands.
Have you checked seating depth as compared to distance to the lands? This is where the Hornady tool works well.

Please see above.

cgbach

quote:

Have you checked the neck diameter of a loaded round? I ran into a similar problem once and after much head scratching I found that the necks had thickened just enough to not allow any expansion on firing. Also make sure your cases are not too long for the chamber.

Loaded round neck diameter, no. I'll see if I can get that info. (But his 39 grain Sierras [27.5 Gr. Varg] shoot just fine using the same brass.)

Case length. After the initial episode, I disassembled one of his rounds and measured it: it was near max length (it was 1.848 with SAAMI max of 1.85) so I trimed it back to 1.835, neck sized it minimally so the case would grip the bullet and reassembled using my powder to COL of 2.31. And that primer blew.

I've just measured the blown case for length (2.43) and I measured the thickness of its neck brass and the thickness of one of his Hornady cases from which he'd shot the more robustly loaded 39 Sierra. Both thicknesses are the same (0.011) +/— .004 depending where on the circumference or length of the neck I measure.

Pegleg

quote:

What kind of primers were used?

Federal SR.

I thought it might be useful to see an image of the case heads. The one on the left is (obviously) the blown head. The load was 27 gr Varget pushing a 26 grain Barnes.

The right case was loaded with 27.5 grains of Varget pushing a 39 grain Sierra.

JFWIW.

Looks like a pretty hot load with the cratering that the primer shows. Benchresters did some testing of primers in the 80's and found CCI had the hardest primer cups. You might try them if you can find any.

That primer looks to have been extruded back into the firing pin recess in the bolt.
It sure doesn't look like all the "good" primer pictures in the reloading manuals.

Yes, the picture shows extrusion which is accentuated by the photo's shadows. (I can feel it easily with my finger nail, but it's hard to feel with the finger tip.)

My rifle had the same problem but worse: I punctured a few primers with loads that I thought should have been safe.

I stopped shooting it and went on-line to look for help.

I read that Savage rifles sometimes have that problem because of - what? - "tolerance mismatch(?)". Same thread 2. Same thread 3.. (Small diameter firing pin, larg diameter firing pin hole, both within specs.)

I sent my bolt to Greg Tannel to have the firing pin turned and the opening bushed. Problem gone. I like what he did so well I sent 2 other Savage bolts to him for the same process.

But my friend's rifle hasn't had a pierced primer in the thousands of rounds he's shot, and I'd hate for the discussion to focus on cratering rather than the fact that the blown primer is from a low powder charge behind a light bullet, while the intact primer is from a greater charge behind a heavier bullet.

Another question: would 0.5 grain below "starting load" reduce the charge enough to cause detonation?

I don't think so because he fired a bunch of my loads (Nosler cases were the only difference) and they worked find.

First of all, thanks to all who gave their time and thoughts to my friend's problem.

He just called to say that he thinks he's tracked down the source of his blown primers.

He thinks he substituted Small Rifle Magum primers for Small Rifle primers.

He didn't know he even had any SR-Mags much less even purchasing them.

Thanks especially to dpcd, whose identification of the operative principle was spot-on:

quote:

These sub small bore cartridges are very sensitive to changes of any kind. Expansion ratio is high.

UPDATE: Also an apology to Pegleg. I was mistaken.

no no no no no.
a start load and a magnum primer is not going to open up a primer pocket like that.
look at the flash hole size too.

that is high pressure not sorta kinda a little bit higher pressure.

What Lamar said.

I still lean toward a batch of soft brass.

quote:

Originally posted by Lamar:
no no no no no.
a start load and a magnum primer is not going to open up a primer pocket like that.
look at the flash hole size too.

that is high pressure not sorta kinda a little bit higher pressure.

We'll find out this Thursday. My friend is going to duplicate the load with SR primers.

I'd be less than honest if I didn't say you've fanned an ember of doubt in me.

I once ran a small experiment to compare LR and LRM primers with my .270 (58 gr RL 22, I believe), and the only difference I saw was in the extreme spread of the velocities.

The LRM spread was less than the garden variety LR primers. Go figure.

In any event, we'll see Thursday. Thank you.

Sub-caliber cartridges are pretty much a world unto themselves.

Shooting small sectional density bullets at around 4000fps have their problems....as dpcd alluded to. I've long thought that sub-calibers impart a more focused pressure spike to the case flashole.

Small powder changes.....primer cratering/blanking(due to a too large boltface firing pin hole, for the application).....and, sooner or later, severe bore fouling(cleaning a 223 ain't nothing compared to fixing a coppered 17 or 20 caliber bore)....are commonplace. These are everyday topics over on the small caliber board(Saubier dot com).

BTW.....I once wore out 3 brushes, cleaning a neglected 17-223 barrel.

I guess one could say......assume NOTHING when dealing with sub-calibers.

Hope this helps.....again.

Kevin

quote:

Originally posted by Kevin Gullette:
Sub-caliber cartridges are pretty much a world unto themselves.

Shooting small sectional density bullets at around 4000fps have their problems....as dpcd alluded to. I've long thought that sub-calibers impart a more focused pressure spike to the case flashole.

Small powder changes.....primer cratering/blanking(due to a too large boltface firing pin hole, for the application).....and, sooner or later, severe bore fouling(cleaning a 223 ain't nothing compared to fixing a coppered 17 or 20 caliber bore)....are commonplace. These are everyday topics over on the small caliber board(Saubier dot com).

BTW.....I once wore out 3 brushes, cleaning a neglected 17-223 barrel.

I guess one could say......assume NOTHING when dealing with sub-calibers.

Hope this helps.....again.

Kevin

It does help. I think we'll know more on Thursday. But the point that's gradually sinking in to me is your comment that:

quote:

Sub-caliber cartridges are pretty much a world unto themselves.

So thank you.

If we had pressure gauges there would be a lot less guess work and tea leave reading.

One assumption I see in this thread is that different lots of Varget produce exactly the same pressure curves. That is a bad assumption.

People are generally unaware of the number of products that are blended. Ketchup, mustard, olive oil, whiskey, wine are all blended. Branded items are blended to a specific flavor, though many scotch drinkers will deny that single malt scotches are blended, but they are.

The master distiller will rotate barrels during aging, recask in a different barrel, sample mixes from different barrels, and finally blend to achieve the brand taste.

Gunpowder is blended. It does not have to be, if you had your own pressure gauge you could load it up, measure the pressure and velocity, and there you would have your load. Unfortunately, the process of making gun powder is still imprecise enough that for each different lot, the pressure curve is different for the same charge weight.

The stuff we get is blended, and according to Accurate Arms, the industry standard was plus or minus 10% about a mean pressure.

So, lets say your powder lot was the upper 10%, and your bud's was the lower ten percent. I know the math is difficult,




but there could be a 20% difference in pressures, for the same powder charge, just due to variances in powder lots.

When shooters are loading maximum loads, things can get out of hand very quickly.

quote:

Originally posted by SlamFire:
The stuff we get is blended, and according to Accurate Arms, the industry standard was plus or minus 10% about a mean pressure.

So, lets say your powder lot was the upper 10%, and your bud's was the lower ten percent. I know the math is difficult,

but there could be a 20% difference in pressures, for the same powder charge, just due to variances in powder lots.

When shooters are loading maximum loads, things can get out of hand very quickly.

If there's anyone who is worse than you in math, it would be me.

And you make a very smart point: If I've been using a powder that is at one end of a +/- range of 10%, and I change to the same powder at the other end of that range, it's a 20% difference.

However, our problem isn't with maximum loads. It is quite the opposite.

The load that's blowing primers is 0.5 grain below the "starting load" of 27.5 grains recommended on the page for the combination of Varget plus their 26 grain bullet (Barnes Reloading Data). One would expect shooting a load of 27 grains would be perfectly safe, but twarn't so!

Thanks for making the point about the meaning of lot variations. That's a very important point.

It not an unusual problem..Individual rifles have tight chambers and less than snug chambers, tight barrels and less than snug barrels..

A tight barrel or chamber is the difference in the two guns in question in all likelyhood, but brass thickness can be the culprit as can a hot primer as opposed to a mild primer, mag primer or std..just a few of the problems that can crop up..

Bottom line is if you deal in max or max plus loads then you must work up a usable load for your rifle and your rifle only...What someone else loads is not of your concern, and problems such as you post will occur from time to time..

If you deal in mild loads, less than max it is seldom a problem, but still can happen or rare ocassions. Its the guns fault and the reloader. Max loads on a hot day with rifle cooking over the hood of a pickup is common denomenator for blown primers..

Bottom line is a blown primer is too much powder, end of story, and it may not happen with the first few rounds but as the gun and barrel heat up it blows the primers..cut two grains, better yet drop a gr. or two below max to start with as it gets you nothing as a rule, but can get you accuracy in some cases, so use a different powder to compensate for that. I think it best to slowly work up a sho nuff max load then cut two grs. MOst problems develope with squeezing that last drop of velocity out of ones gun, but you should know where max is on all your guns and stay behind that.

quote:

Originally posted by Atkinson:
It not an unusual problem..Individual rifles have tight chambers and less than snug chambers, tight barrels and less than snug barrels..

A tight barrel or chamber is the difference in the two guns in question in all likelyhood, but brass thickness can be the culprit as can a hot primer as opposed to a mild primer, mag primer or std..just a few of the problems that can crop up..

Bottom line is if you deal in max or max plus loads then you must work up a usable load for your rifle and your rifle only...What someone else loads is not of your concern, and problems such as you post will occur from time to time..

If you deal in mild loads, less than max it is seldom a problem, but still can happen or rare ocassions. Its the guns fault and the reloader. Max loads on a hot day with rifle cooking over the hood of a pickup is common denomenator for blown primers..

Bottom line is a blown primer is too much powder, end of story, and it may not happen with the first few rounds but as the gun and barrel heat up it blows the primers..cut two grains, better yet drop a gr. or two below max to start with as it gets you nothing as a rule, but can get you accuracy in some cases, so use a different powder to compensate for that. I think it best to slowly work up a sho nuff max load then cut two grs. MOst problems develope with squeezing that last drop of velocity out of ones gun, but you should know where max is on all your guns and stay behind that.

Thanks, Ray, excessive pressure certainly is the problem, but we are looking for the cause of the blown primers in a sub-"starting load" charge of Varget.

We may now have identified the problem: he had unknowingly used SR Mag. primers rather than SR primers. The issue is, as you say, likely human error.

Apporeciate the thoughts.

quote:

Originally posted by B L O'Connor:
Thanks, Ray, excessive pressure certainly is the problem, but we are looking for the cause of the blown primers in a sub-"starting load" charge of Varget.

We may now have identified the problem: he had unknowingly used SR Mag. primers rather than SR primers. The issue is, as you say, likely human error.

Apporeciate the thoughts.

Something else, a primer is not a primer is a primer. They are as individual as any other product. They are made within tolerances. Since I don't have a pressure gauge, and don't make primer cake, I don't have data on how primers vary, and how their variance affects the pressure curve.

Understand, primer cake is a mixture, hand stirred by humans. The components in primer cake vary in purity, have plus or minus percentages, and since it is a mix, will have homogeneity issues.

I am aware primers have different flame temperatures, different dwells, different amount of mass ejected, and there is probably more, which I don't know about. All of these are controlled parameters which tells me, they have an effect on the ignition and combustion of gunpowder. And therefore, have an affect on the pressure curve.

No one should any expectations that changing primer lots, or brands, will not change the pressure curve.

One other point, and this is actually very important, humans don't think in exponential terms, you think in linear terms. You think, 1,2,3,4. You don't think 1, 2, 4, 16. Therefore when encountering a pressure curve, which the slope is exponential, linear thinkers have no conception about the magnitude little changes will have on the pressure curve.

Al Bartlett: “The greatest shortcoming of the human race is our inability to understand the exponential function.

https://www.youtube.com/watch?v=LqcHG7QUK9k