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Ammo Ballistics Rim Fire

How to Prevent Rimfire Misfires

by Allan Jones   |  October 17th, 2012 13
Rimfire_001

Today’s rimfire ammo is so good that a misfire is usually due to the gun rather than the ammo. For example, a DA revolver can develop a bit of extra headspace, which can result in bullet lubricant and unburned powder getting under the extractor. Forgetting to clean this area can cause a misfire.

Misfires are anathemas to shooters. Getting a “click” when you expect a “bang” is infuriating whether you are plinking into the riverbank or have a 7×7 elk in your crosshairs. This subject is complex enough to warrant two columns, and for the first I’ll focus on rimfire ammo. For the sake of this discussion, let’s omit cases when a user deliberately modified some component of the firearm’s ignition hardware.

In spite of its unheralded success, rimfire priming is a primitive system with inherent weaknesses. The big ones are weatherproofing, crush protection, and vibration resistance. The only protection against liquid incursion is the outside coating of bullet lube. The ring of primer compound is protected from crushing by a thin envelope of cartridge brass. The compound itself is essentially glued into the rim cavity with the binders that hold the compound together. Too much shock or vibration can cause a piece of the compound to fall out of the cavity. If that’s where the firing pin happens to land, you get a “click.” Fortunately, the industry has access to better binders than it did 50 to 75 years ago, reducing the “chipped pellet” as a misfire cause.

Still, manufacturers have overcome most of these weaknesses, and today’s rimfire ammo is so well made that you should look for a firearm problem first unless you know the ammo is decades old, took a bath, or is of questionable origin. In rimfire, the major gun-related factors are excessive headspace, worn chamber mouths, damaged or misaligned firing pins, and too much firing pin surface.

The Causes & The Cures
Excessive headspace leaves insufficient case support for the “rim pinch” to occur that’s required for rimfire reliability. The result is a “light hit.” Many inexpensive rimfire rifles control headspace with the root of the bolt handle engaging a recess in the receiver. After years of wear, this contact can grow loose, and headspace increases. A sure sign of this approaching problem is in the fired case. If the rim looks thicker after firing than before, misfires are not far away.

Rimfire_003

Improper firing pin strike can be the cause of a rimfire’s misfire. In this illustration, only one of the firing pin strikes can produce 100-percent reliable ignition.

The chamber mouth can become deformed from dry-firing or from careless application of a steel cleaning rod. This also reduces rim support.

The rimfire priming system requires fairly precise placement of the firing pin strike on the case head. If a rifle’s firing pin has lateral play due to wear or poor tolerances, it can “drift” enough to cause a misfire. Likewise, any wear/damage to the tip of the pin can change the contact area with the case from the original design criteria.

The tip’s shape can affect reliability. A friend picked up an older European rimfire rifle. The firing pin tip was big and round, some 0.080 inch in diameter. There was too much surface area for the available spring tension, and replacement springs were virtually impossible to find. He removed the firing pin and beveled the edge of the tip in two places, reducing the surface area about 10 percent, and the misfires went away.

Revolvers—especially double actions—can, and will, develop excessive headspace with normal use. The cylinder recoils before the rest of the firearm, bashing into the breechface and rebounding onto the yoke or crane tube that supports it and controls headspace. As this battering shortens the tube, the cylinder’s at-rest position becomes farther forward, requiring more firing pin reach.

It’s normal to have enough reserve firing pin length and spring power to fire the cartridge, but this slight extra space often gets filled by bullet lubricant and unburned propellant getting under the extractor. Forgetting to clean this area can cause misfires.

Semi-automatic rimfire rifles and pistols can also misfire from too much debris and too few cleanings. The area where the bolt seats must be reasonably free of debris. An accumulation here can stop the bolt before it is fully “home,” requiring the firing pin to reach farther. Check both the breech end of the barrel and the breechface on the bolt and clean if needed.

While I was in college, I bought a used Remington Nylon 66 rifle. It shot accurately enough, but was not 100 percent in function. It tended to misfire and jam occasionally. After getting it home, I pulled the action cover and extracted the barrel to find the action full of sand.

Rimfire_002

The “open-top” design of this vintage Colt Woodsman collects a lot of dirt in the field, but it’s easy to clean. Keeping the breech area clean reduces misfires in semi-automatics.

Being young and dumb, I attached a hose to the tap in my mom’s bathtub, let the water run until hot, and blasted the entire action area with a jet of water. The bottom of the tub was full of coarse sand, but at least it was no longer in the rifle. The big sand grains were preventing the bolt from closing fully and caused light firing pin hits. A thorough hosing with a water-displacing spray finished the job, and the rifle never hiccupped again. And someone was watching over me—it never rusted!

Most of the things I mentioned are easy to check. Even headspace problems are heralded by a thickened rim, but you can’t check everything. A dirty or damaged firing pin spring in a rifle may be hard for the end user to access, so get a pro to check it.

If I get a misfire in a rimfire gun, I check the gun first. It’s a tribute to our manufacturers that they pack so much reliability and accuracy into cartridges that still cost so little to shoot.

  • North Woods Chuck

    I disagree with the statement that today's rimfire ammunition is well made, and believe it doesn't have the same quality as years ago. I can qualify that statement because my follow shooters and I have all experienced failures to fire and when the bullet is pulled and the powder emptied, the culprit is almost always a lack of primer compound in the base and sometimes there is even no powder in the case. Other times we've noticed primer compound that only covers part of the base, and as luck would have it, the firing pin struck that particular area. It should be said that we are rather fussy about keeping our old and new .22's spotless, and regardless of the ammo manufacturer, these problems appear across the board. In my buddy's new Walther, the case of one well known manufacturer split wide open, and I would not have believed it if I hadn't been right there to see it. I've personally had many more than a few failures to fire in every .22 pistol and rifle of mine just this year alone. All of the ammunition is new and recently purchased, and we shoot a lot. We are in our 60's and have been shooting since teenagers and have years of experience with firearms of all shapes and sizes but shoot .22’s because it is inexpensive and provides plenty of practice.

  • East Texas Shooter

    I agree with North Woods Chuck. Shooting an assortment of Rugers, both rifle and pistol, Walther, Marlin, and Remington rimfires, I have consistently found about 2-10% misfires, varying from lot to lot of bulk rounds. The worst luck I've had is with the stuff in the green boxes. Federals are the best bulk bullets, with probably around 2% misfires, although I've had pretty good luck with Winchester. I haven't found any difference in reliability between lead or plated bullets. I don't shoot a lot of high-end match stuff, so can't speak to that. All you have to do is take a poll of the discarded misfires at the gun range, and you can figure out pretty quick which manufacturer(s) to avoid. And my guns always go to the range clean and oiled.

  • Big Jack

    I absolutely agree with NW Chuck & E Tex. Over the last couple of years the quality of the Wally World bulk ammo has tanked. Over the years I have found Federal American Eagle HPs to be the most accurate ammo in most of the guns I shoot, even beating out high buck target ammo. Go figure. When I discovered this 5-6 years ago I laid in a supply of ~ 20,000 rounds. As it ran low recently I bought some current Am Eagle and it is not quite as good, although WAAAAYYY better that that horrid Golden Bullet junk. I do a considerable amount of gunsmithing on rimfire guns and most of the misfiring guns I get have been shooting Golden Bullets. A good cleaning and switching brands almost always solves the problem.
    I should also mention that I am the the range tester on a monthly video magazine and I shoot many different rimfire guns every year.

  • John

    I do not doubt that you folks have had the problems you commented about. I do feel that given the billions of rounds of .22 ammo produced each year that the few problems we actually have are very small compared to the number of rounds produced. Yes I have had an ocasional .22 round that wouldn't fire. The quality control of todays .22 ammo is in my opinion is very good.

  • Mike

    Well, I guess I be a contrarian to y'all…I shoot smallbore and bullseye and use old rifles and pistols and some new ones as well. I have rarely had a problem with the ammo of today. most cases it was something on the firearms. Be it dirt and debris or mismatching the ammo to the firearm chamber….it was usually the firearm and not the ammo… except for right before and after Obama coming on the scene … seems quality went south for a bit as things got scarce. I shoot CCI SV, eley, aquila,and other standard velocity ammos and can make one ragged hole on the target. people forget to measure the rounds and check their chamber dimensions, headspace, etc and then blame the ammo – for something it had no control over. A man needs to know his firearm intimately. just my thoughts….

  • LarryK

    I am surprised that anything stopped the Remington Nylon 66, as it is the AK-47 of .22 semi-autos in terms of reliability. When it came out the advertisements showed a guy sitting on a small mountain of fired ammo that was put through the rifle without cleaning. Plus, I just saw my goofy chrome & black Nylon 66 at a gun show with a $600 price tag on it, although I think that price is crazy. I bought mine used also, for $75 ten years ago.

  • captom

    Don't know what NWS, ETS, or BJ are talking about. 2-10% misfire rate–get real!!!! Just several weeks ago my grandsons and I put 650 rounds of mini-mags through my Ruger 22/45 without a single misfire. I do not experience misfires on any appreciable scale with any of my 22s. I either shoot mini-mags or Rem target ammo. My experience them is that they are virtually perfect!!

    • Mack Missiletoe

      CCI is one of the best! I hear horror stories of Remington Golden Bullets all the time–they are cheap. They are supposedly very dirty which causes problems.

      I think that a few misfires in a bulk box is normal. The stuff is cheap. I just wish it cost $15 like in my 'good ol days'! Not the $19-22+ I am seeing now!

      If I got any misfires with the medium-end stuff I'd be upset.

      In my experience it is 1) A dirty gun or 2) A bad cartridge that causes misfires.

      Have a good one!

  • Mack Missiletoe

    Hey what revolver is that at the top of this article? It looks to have wood target grips and is blued. It sure looks nice! It seems to be some sort of Smith and Wesson. I would like to know the model, thanks.

    • Gary M.

      S&W 17 or 34 with Herrett custom grips

  • North Woods Chuck

    Since my original post, I have also had a Remington .22 split wide open in the chamber, failing to extract and jamming the gun. There have been an inordinate number of misfires with this same ammunition, however CCI, Winchester and Federal brands all perform well. Occasionally I will have a Fed round fail to fire, but this is infrequent. Bullet weights range from the 40 gr to what seems to be the more popular 36 gr hollow points and have been purchased at both gun stores and Wal-Mart, and other than the packaging and the price, I see no difference in overall performance of the individual brands.

  • Bruce

    I have experienced misfires, from my S&W 617, when I am not careful to fully chamber each round into the cylinder. That tiny bit of space softens the firing pin strike.

  • Steve

    Been there done that. 2165 rds of all brands from Mart and gun shops. Bulk big green is the worst. CCI Stinger and mini mag performed the best. All this in a Bretta model 21 stainless steel. Weigh 100 from each box and you will know what works. Marine/68

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