Bolt face erosion??

[SPAK]

Hey guys, I started noticing a dark ring around my firing pin hole. Right where the primer contacts the bolt face. Most of it comes off with a nylon brush, but the ring is still there none the less.

I've had a few blown primers and primer piercings. These were from new win brass that were undersized and primers pierced and blew out during fireforming with full power loads. I've sinced backed down the fireforming load to get the case to fit the chamber better and that solved the primers blowing out and piercing.

But since then I've still got that dark ring.

Howa 1500 action, 22" Mcgowen barrel hand lapped 6 groove, sammi min spec chamber.

Load I'm running: .30-06 win brass 59.0gr RL 22 under 208gr Amax cci 200 and I've run some 208gr amax over 53.5gr RL 17. No primer cratering, primers still have some radius on the edges. Easy bolt lift and extractions. Velocity is right around 2720fps. There doesn't seem to be any noticeable carbon between the primer and pocket edges but maybe in a spot here or there. Pockets are not tight like new brass, but I still feel resistance in seating primers. I'm on the 10th loading so far with this batch of brass.

I'm away for a few weeks so I can't get pics up very easily. I know the pics would be worth more than me writing all this.

Thanks in advance!

 

[Fuzzball]

Re: Bolt face erosion??

"'ve had a few blown primers and primer piercings."

You have bigger problems than a dark ring on the bolt face.

 

[5R Milspec]

Re: Bolt face erosion??

hey I am not that familiar with R22 in a 30/06.but if you are blowing and pierceing primers you need to stay away from that load.it does not take a full case to fire form.just a standard load will form the case to the chamber.unless you are fire forming a 300H&H to a 300 Ackley imp.then you need to fill the case to the neck and seat the bullet into the lands.

it just sounds like it to me you are loading them to hot.so I wold back down some and see what happens.would even change the case's,and throw away the case you are useing now.just start over and stay away from the hotter loads.no need for speed unless you really want it.

 

[MitchAlsup]

Re: Bolt face erosion??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Frogman77</div><div class="ubbcode-body">Load I'm running: <blah> cci 200 </div></div>

If you are going to continue shooting this load, you need a mitary primer (or something with a thicker shell material; not this CCI 200 primer.

And of course, when you change anything in a load recipie, back down 3%-5% and work back up.

 

[Jerry m]

Re: Bolt face erosion??

The gas from the blown primers is etching the bolt. Stop using this load! Evaluate your cartridge/reloading data/components and come up with a safe load.

Good luck

Jerry

 

[Hummer]

Re: Bolt face erosion??

Back in the 80s there were numerous incidences of bad primers. As I remember the edge of the primers were drawn too thin. I knew several guys that had pierced primers including myself and we were not running hot loads. The result of pock marked circle in bolt face corresponding with edge of primer.

 

[SPAK]

Re: Bolt face erosion??

ok, let me clarify. Two blown primers and two pierced when I was doing load development with RL 22 due to excess headspace with the new brass. I solved the issue by using new primers (meaning primers that werent 7 years old) and two using a medium power load to fireform first, then running my load development with full power loads now that headspace is no longer excessive.

I have not blown any primers or piereced any primers with either the 59.0gr of RL 22 or 53.5gr RL17. Both of these loads are .25-.5moa loads consistently. I am on the 10th loading of the brass and primer pockets are not super tight as they were new, but still requires a little effort against the resistance to seat the primers.

In doing load development 61.5gr RL 22 blew one primer and bolt was sticky. Stopped and dropped back down to 59.0gr. With RL 17 55gr blew one primer with sticky bolt. Stopped and dropped down to 53gr and found an accuracy node at 53.5gr.

As I said, since then I haven't had any more blown or piereced primers. NOW I understand that overpressure loads can cause leaking from the primer pocket and this will cause that dark ring.

Will primer pockets still be tight if this is occuring?

Thank you all for your advice, I will drop back down and redo my development again. I'm not opposed to it. I'm not a velocity seeker, just accuracy. 59.0gr of RL 22 and the 53.5gr of RL17 just offered the best accuracy in my load work up.

fwiw (all seated .02" off the lands)

 

[AUJohn]

Re: Bolt face erosion??

"If you are going to continue shooting this load, you need a mitary primer (or something with a thicker shell material; not this CCI 200 primer."

Which is like changing out a 5amp fuse for a 15amp fuse. Not smart.


OP, if you are blowing primers in load "development" then you need to step back and stop being silly. Once you get to this stage you are well above where you need to be and have missed other signs. Running this hot means real issues going from a cold day to a hot one, throwing a heavy charge or many other problems. Happy to wind back your loads every summer? Best bet is to find an accurate window and load into the middle.

 

[Country]

Re: Bolt face erosion??

You would be better off using Remington primers as they are tougher. Also the primer pockets may be out off round and rough.
Truing the primer pocket may affect a better seal. You can buy a primer pocket reamer from Sinclair Int.
Also the primer pockets may be bulged and it would be better to get some new brass if thats the case.
Also your Reloader 17 load over the 208 Amax is over the Aliant recommended load for a 200 grain bullet .
I would also suggest you back off your loads a grain or two.

 

[SPAK]

Re: Bolt face erosion??

My load development was done in 60-70 deg temps. In alaska it doesn't get much warmer than that. IF it does it's a rare day. Most of my shooting is in 40 degree weather down into well below zero. I did my development during the summer for that purpose.

I'm not trying to be silly. Like I said, I'm not after speed. Just accuracy. This is where the load wanted to be. Both powders found there best accuracy when velocity hit right around 2700fps to 2730fps.

The point is, I'm not blowing primers using the current loads. I have had a 4 blown primers and two piereced primers out of 400 rounds. Two were in load development at the max and stopped, load was backed down 2 grains the other load 1.5 grains. Two other blown primers were from excessive headspace.

I just want to be clear that I'm not using a load that is blowing primers and piercing primers. In the OP I was trying to ask if those few incidences would have done enough damage to erode the bolt face already AND/OR am I having gas leakage even though my primer pockets are still relatively tight? I probably didn't write it out very clearly for sure.

If a dark ring around the firing pin hole is absolutely abnormal, is it always because of excess pressure?

 

[SPAK]

Re: Bolt face erosion??

will a primer pocket reamer make my pockets larger?? wouldn't that make the potential gas leaking worse?

When I get back I'll redo my load developement. It'll be a little difficult with the temps being so low but I'm not opposed to it. It's more trigger time regardless.

 

[Hummer]

Re: Bolt face erosion??

Primer pocket reamer? or Uniformer? A uniformer only cuts and squares the bottom. You don't want to take any material from the sides.
A reamer of sorts was made to remove primer crimps but the ones I had kept on cutting below the crimp and took material away and primers were loose thus I dumped that tool. I think it was a Lyman and from then on I only used primer pocket swagers.
You want your primer pockets snug or you will have leakage all the time. I saw a guy ruin a Model 70 bolt by continuing to load cases with loose primer pockets.

OP you are using a gun with excessive headspace? Have you had it checked? Will it take a NO Go Gage or field service gage or in other words how do you know it is excessive?

 

[SPAK]

Re: Bolt face erosion??

no, the chamber doesn't have excessive headspace. The new brass I measured was .015-.018" shorter than my once fired brass. Now Before doing any load development or shooting of my "heavier loads" I use a moderate load of Imr 4320 and a 180gr jacketed bullet. But to answer your question, no I haven't personally checked it with go no go guage, but was done by the custom gun builder before shipping it. My once fired brass measures 1.949-1.950" to the shoulder. I have found new win brass that measured as short as 1.932" to the shoulder.

So the uniformer will help seat the primer better? will it affect the "snugness" of the primer pocket? How loose is too loose? how snug is snug enough?
Which leads me to ask, if my primer pockets are "snug" is it possible to still have gas leakage? And is that from an overpressure situation?

 

[Hummer]

Re: Bolt face erosion??



So the uniformer will help seat the primer better? will it affect the "snugness" of the primer pocket? How loose is too loose? how snug is snug enough?
Which leads me to ask, if my primer pockets are "snug" is it possible to still have gas leakage? And is that from an overpressure situation?

The uniformer (Sinclair International) will deepen your primer pockets to a uniform length and square the bottoms. Factor pockets are iffy lot to lot and this will put all the primers the same depth BELOW CASE SURFACE.

As a quick and dirty rule you will learn that on new or once fired cases you should have resistance. As the cases are fired the seating resistance will get less and less. There is no rule as to when this will be. On Federal cases the pockets I have seen start to get loose on third firing. I load them three maybe four times and no more. On the other end of the spectrum you have LC Match cases and a hundred reloads they are still tight. I have a LC 30.06 Match case I have loaded 157 times and pocket is still snug.
Alot depends on your load. If you stay off the max loads you will get more brass life.
The finest brass I ever had the please of loading was DWM for a friend. As tight as those pockets were I bet they would take 200 loadings.
To get this long life you have to do minimal sizing.
See my post "Do you really need small base die?" for a longer explanation. Firing them in bolt gun will last longer. Gas guns eat brass for breakfast.
Since you are up there in the cold/wet I would take care to paint case heads with clear finger nail polish and then wipe excess off on news print. This will leave the area around the edge of the primers somewhat sealed up. Look at them with glass to insure the seal is good. I have seen primers exposed to light misting range killed in a matter of minutes due to water seapage around NEW FACTORY AMMO.
You guys need reliable guns and AMMO up there so I would take care not to get ammo wet and do the clear nail polish above. But then again some guys like to do RED and Pink to help identify their brass.
Oh yeah new cases are shorter than fired cases in the shoulder to base dimension. Also the shoulder angles are less. This should not cause problems.
If you have headspace on the long end like .006" over a GO gage and new cases less than a GO gage (normal condition) and the primers are not snug the primer can set back a bit, then fire and they will tend to look like they are flowing outwards on the edge a bit. This is common with commercial cases in M14 chambers and in some bolt guns.
When I encounter this I will load my ammo longer so the bullet touches the rifling, this should keep the case "on the bolt face" during the pressure curve rise and fall.
If I encounter a new rifle (had one two years ago) that will close on a GO Gage it goes back to factory. If it is a used rifle and I want to keep it I will screw off barrel, set it back one thread and rechamber to min headspace. This is rare as the rifles I get lately are only for the actions and I pull the barrels off and install target barrels on them with tight chambers.
Hope this helps.

 

[308isgreat]

Re: Bolt face erosion??

Frogman77:

To actually answer your original question: a few blown primers usually won't do enough damage to the bolt face to cause problems.

 

[Country]

Re: Bolt face erosion??

A primer pocket uniformer ( end reamer ) will not cut any off the internal diameter but it makes the bottom of the pocket square so the primer seats down better helping it seal better.
A pierced primer will cut the bolt face from the first blown primer , The damage that results is totally dependant on how much gass leakage occurs. Slight leakage over time will cause a black roughened ring. Extreem leakage will cut holes in the bolt face .
It is better to avoid scaring up your bolt face because its a big turnoff for selling the gun later . If I see a gass cut boltface I think " action subjected to overloads and bad handloader" even though it may be just one bad primer that caused it.
Soft CCI primers are notorious for rupturing at max loads.
I have 10000 of them and will not use them for any high pressure loads. However they are quite good for normal loads and also in guns with weak firing pin springs .
For max loads in 223 I use Rem 7 1/2 and in 308 I use Rem and Federal 210

 

[SPAK]

Re: Bolt face erosion??



the black ring I see comes off with cleaning. Usually some brake cleaner or clp break free and a nylon brush will take it off with a little scrubbing.

Thanks for the replies guys. I think I will look into a primer pocket uniformer. Is this done once or on each reloading?

 

[Country]

Re: Bolt face erosion??

In that case you have only minor leakage but as you reload the same cases it could lead to one big leakage that might do a bit more damage.
If the primers are still seating tight in the pocket it must be one off two things . Rough poorly shaped pockets or too much chamber pressure.
Try a primer pocket reamer it makes seating much better and might be all you need .
I ream every primer pocket for all my calibers and I never have trouble with leakage but have poped a few soft CCI primers in 223.
Try the Rem 7 1/2 primers in addition to reaming the pockets and I think it will help . I have not had any trouble since.
Maybe some better brass would also help Lapua is quite good I find.
Basicly you only ream once but as you reload a few times the case metal flows and changes shape a small amount . So you can reream after a few firings and get a bit more brass out. It does not hurt to reream a few times if you want.
You should use a primer pocket cleaner before you insert the reamer to get out as much carbon etc as possible as it tends to dull the cutting edges prematurely . Some people with plenty of money don't worry about that and use them as primer pocket cleaners anyway.
The reamer is set to a specific depth and can't ream below that depth. However the cutter will foul with brass shavings and need cleaning with an old toothbrush a few times as you go. That way the cutter will cut all the way to its max depth cleanly. Inspect each pocket with magnification after reaming . The object is a nice flat and burr free pocket base.
Most seating problems are caused by the radius that is left in the corner at the base of the pocket . It is stamped in when they form the pocket and can't be a neat sharpe shoulder by the very nature of punch press operations. The reamer cuts a better square shoulder and flat base . This allows the edge of the primer skirt to go right down evenly all around to the flat base.
You will feel the difference when seating primers.
Sometimes you think you have got all the way down but after you clean the cutter again it cutts a bit more .
Buy the kind of reamer that chucks into a power screwdriver and only use it on the slow speed as the cutter loads up with shavings real quick.

 

[SPAK]

Re: Bolt face erosion??

Thanks for the reply. I bought a primer pocket uniformer, and I'll redo my ladder again and see what happens.

do you ream as well as uniform the base of the pocket?? wouldn't there be a risk that reaming would make the pocket too big??

 

[Country]

Re: Bolt face erosion??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Frogman77</div><div class="ubbcode-body">Thanks for the reply. I bought a primer pocket uniformer, and I'll redo my ladder again and see what happens.

do you ream as well as uniform the base of the pocket?? wouldn't there be a risk that reaming would make the pocket too big?? </div></div>

Reaming and uniforming is the same thing . Its just my terminology . The uniformer just cuts the bottom of the pocket nothing else.

 

[Hummer]

Re: Bolt face erosion??

The ones Sinclair sells now are "pre set" and only cut so much. The first ones they sold (I got one) you could adjust it to cut so deep the striker wouldn't touch it. I was a pain to adjust.

 

[Country]

Re: Bolt face erosion??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hummer</div><div class="ubbcode-body">The ones Sinclair sells now are "pre set" and only cut so much. The first ones they sold (I got one) you could adjust it to cut so deep the striker wouldn't touch it. I was a pain to adjust.
</div></div>

I use the preset ones with no drama. The only thing I find is that you have to clean the cutters often.