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Punctured & Cratered Primers
victorj19
Member Posts: 3,642 ✭✭✭
First thanks for the advice.
I forgot about reducing the load for military brass. Definately had some hot loads. I did some research, reduced the loads and had 2 sub MOA groups out of a bunch of different loads yesterday. These were with 748 and CCI primers. I'll need to pick up some CCI 400M primers and retry the H335 again. and different bullet weights, weigh my brass, etc. Does the quest for accuracy ever end?? Nah, because its fun!
Can you help narrow down the cause(s)?
I just sorted my brass from a trip to the range Wednesday, and finished inspecting the brass and found a number with punctured primers. This is a newer 223 Howa 1500 with perhaps 200 to 300 rounds through it. I've been trying various loads to find what works best. The brass is once fired Lake city 5.56 that I loaded (trimmed, FL sized, swaged). About 100 rounds fired. About 95% were 05 LC and the balance a mix of all different years. All used H335 and safely below the max loads in a couple of manuals. All used CCI400 primers. There is no chance that I used small pistol primers I understand they are thinner material. Bullet weights ranged from 52 to 55 grains and a mix of various makes and types.
The 6 rounds with puncured primers were all LC 05s. There was no noticeable blowback. Six out 95 seems too many to be a coincidence. I consciously kept the brass from my reloads separate from range pick ups so I could inspect them later.
The cratering is barely noticeable to obvious but is found in perhaps 90% of all cases. I inspected the bolt face with a 17x magnifying glass and there was nothing obvious to me that would cause the cratering unless the hole is oversize. I don't have the spec for the hole or a way of measuring it.
All of the primer indentations were solid. Also had 2 FTFs. One eventually did fire on the 3rd attempt. I need to tear the other down to see if has powder and, since there was no report, I doubt that primer fired. I mentioned the FTFs only since it may hold a clue to the other concerns.
Is there a problem with the bolt?
Does this bolt come apart similar to a Mauser 98 or Rem 700 bolt? If so, I'll take it apart to examine the firing pin.
What else could cause the cratering or puntured primers? Bad firing pin, Excessive firing pin hole size? A bad lot of primers? The LC brass (doubtful to me)?
My first range session with this rifle produced many sub MOA groups. All groups from the 2nd trip produced were over 1 MOA at 100yards and some were 2 to 3 MOA. It was gusty. Halfway through my range time I found that the scope ring screws were loose. I tightened them. There was some improvement but not that much. I completely free floated the barrel (syn stock). The action isn't bedded. Was this a mistake? If so, I'll use something to add a bit of pressure it the forward area of the barrel channel. I could experiment and try a bit of silicon caulk since it can easily be removed.
Whatever input you can offer would be appreciated.
Jim
I forgot about reducing the load for military brass. Definately had some hot loads. I did some research, reduced the loads and had 2 sub MOA groups out of a bunch of different loads yesterday. These were with 748 and CCI primers. I'll need to pick up some CCI 400M primers and retry the H335 again. and different bullet weights, weigh my brass, etc. Does the quest for accuracy ever end?? Nah, because its fun!
Can you help narrow down the cause(s)?
I just sorted my brass from a trip to the range Wednesday, and finished inspecting the brass and found a number with punctured primers. This is a newer 223 Howa 1500 with perhaps 200 to 300 rounds through it. I've been trying various loads to find what works best. The brass is once fired Lake city 5.56 that I loaded (trimmed, FL sized, swaged). About 100 rounds fired. About 95% were 05 LC and the balance a mix of all different years. All used H335 and safely below the max loads in a couple of manuals. All used CCI400 primers. There is no chance that I used small pistol primers I understand they are thinner material. Bullet weights ranged from 52 to 55 grains and a mix of various makes and types.
The 6 rounds with puncured primers were all LC 05s. There was no noticeable blowback. Six out 95 seems too many to be a coincidence. I consciously kept the brass from my reloads separate from range pick ups so I could inspect them later.
The cratering is barely noticeable to obvious but is found in perhaps 90% of all cases. I inspected the bolt face with a 17x magnifying glass and there was nothing obvious to me that would cause the cratering unless the hole is oversize. I don't have the spec for the hole or a way of measuring it.
All of the primer indentations were solid. Also had 2 FTFs. One eventually did fire on the 3rd attempt. I need to tear the other down to see if has powder and, since there was no report, I doubt that primer fired. I mentioned the FTFs only since it may hold a clue to the other concerns.
Is there a problem with the bolt?
Does this bolt come apart similar to a Mauser 98 or Rem 700 bolt? If so, I'll take it apart to examine the firing pin.
What else could cause the cratering or puntured primers? Bad firing pin, Excessive firing pin hole size? A bad lot of primers? The LC brass (doubtful to me)?
My first range session with this rifle produced many sub MOA groups. All groups from the 2nd trip produced were over 1 MOA at 100yards and some were 2 to 3 MOA. It was gusty. Halfway through my range time I found that the scope ring screws were loose. I tightened them. There was some improvement but not that much. I completely free floated the barrel (syn stock). The action isn't bedded. Was this a mistake? If so, I'll use something to add a bit of pressure it the forward area of the barrel channel. I could experiment and try a bit of silicon caulk since it can easily be removed.
Whatever input you can offer would be appreciated.
Jim
Comments
Military brass is thicker a tends to build higher pressure with loading data set using comerical cases.
Inspect the firing pin. It should have a ball point not a cone. Look at the fit of pin in bolt face, should not be sloppy.
I would try some factory .223 ammo to see what the result is before going any further.
I have 2 Howa rifles and have not noticed such a problem with either when using CCI 400 or #41.
I doubt that silicone caulk will give the desired result as it will still be flexible and give to the barrel vibrations in addition to getting softer with heat.
Both my Howa's prefer 50 grain bullets seated off the lands a fair amount.
1. Check the firing pin, it should have no gas cutting or deformities. 2. Firing pin protrusion should be checked. Internet search shows .055" to be about right for an AR15. Check with a gun smith as each firearm might be different. 3.The firing pin must stay in contact with the primer on firing. A weak hammer spring on an AR or a weak firing pin spring like on a Rem 700 bolt action will let the firing pin rebound on primer piercing when the hot gas pushes the pin backwards. 4.If the hole the pin sits in is to larger in diameter, the primer flowes back into this hole till the center of the primer separates and fall into the action or travels into the firing pin area. Bushing the firing pin hole will fix this. Or you may want to try a magnum primer with a thicker cup. Military ammo may have a crimp that needs to be removed before seating a new primer. The crimp is removed by shaving or swaging the primer pocket. Swaging may be needed here so the prime can be seated lower in the pocket. High primer = misfires & pierced primers. There is also a high pressure sign visible. The reloader was using a "starting" load and CCI 400 primers. The pressure sign may have formed on firing the factory ammo. I just shot some XM193F factory, the web area expanded .0015" on firing. This is a sigh of a "hot" load.
52 grain bullets: 23.5 to 24.5 gr of H335
53 grain bullets: 22.3 to 25.3 gr of H335
55 grain bullets: 22.3 to 25.3 gr of H335
I reinspected all the brass. No other signs of high pressure like those in 243xb's post.
Pulled the bolt apart. Firing pin looks fine.
Overall it appears that some of my loads were too hot. My worst would likely be the 25.3 gr of H335 with the 55 gr bullets.
What would you recommend as upper limits of H335 for 52, 53 & 55 gr bullets? I'll work up to them.
I have a pound of Win 748 that I'll try eventually.What would you recommend as upper limits of 748 for 52, 53 & 55 gr bullets?
Oh, I'll look for some 50 gr bullets too.
That you had to do three strikes on one leads me to ask if you have a lightened hammer, hammer spring or titanium firing pin?
You could also gage primer flash holes on cases that blew primers.
They could be oversize.
This is the maximum powder charge on Hodgdons website for a 55 GR. SPR SP bullet. The bearing surface can be different between brands of bullet. Longer = more pressure. Seating into the rifling = more pressure. Heavey jacket construction = more pressure.
The prev test load with 100 g bullet and H4350,36gr was all ok.
All was Winchester brass once fired.
I checked firing pin hole, firing pin protrusion at .050, (recommended was .025 to .060 with a rounded ball tip)
I shortened the firing pin by .005 and rounded the tip, while I had it apart. I checked headspace as right on. Still same issue when retested 9 1/2 primers with the firing pin shortened! I found some bolt guns had .040 firing pin protrusion and some at .065, but they were not using Win 9 1/2 primers! When doing a google search for reviewing pierced primers I seen in a article that a guy mentioned that Rem 9 1/2 steel colored prmers were the old style and had a harder sheel as compared to the newer brass shell primers!
I tested CCIBR2 and Federal 210M (match) with the same load and shot approx 75 rounds and all ok!
For lake city brass or military brass you need to champher the primer hole so as the priimers can be seated good to the bottom of the hole, reduce your loads by at least 10% or better yet go to name brand brass, like Win or Rem, start at min load and maybe try CCIBR4 primers. You can get a idea if you have a thick brass hull by comparing their weight, heavier brass has less space inside and may produce a unsafee higher pressure if expermienting with a max load.
I would also consider buying a box of factory Box of 223 Remington shells and test. (don't buy the cheap china made FMJ with the steel hulls)
Some of the guys in this thread are referring to pics and indicating that YOU are overloading by looking at YOUR brass. I do not see a pic of YOUR brass posted???
You can review your question about taking your bolt apart and checking firing pin protrusion by a google search.
Do wear safety glasses and stay safe when having the pierced primer issues, because you can get a eyeball damaged easily, and its hard to shoot a good group with schrapnel burning the face or worse yet blind in one eye or both! even with pressure relief hole in the chamber or bolt, primers pieces can get your eyes![B)]