This illustration shows headspace measurement for the popular .308 Winchester cartridge, which headspaces on the shoulder. Image copyright 2015 Ultimate Reloader.
In this Brownells Tech Tip Video, Brownells gun tech Steve Ostrem explains what headspace is and why it’s one of the most critical measurements for nearly all firearms. Even if you’re an experienced rifle shooter, it’s worth watching this video to refresh your understanding of headspace measurements, and the correct use of “GO” and “NO-GO” gauges.
Headspace Definition
In firearms, headspace is the distance measured from the part of the chamber that stops forward motion of the cartridge (the datum reference) to the face of the bolt. Different cartridges have their datum lines in different positions in relation to the cartridge. For example, 5.56x45mm NATO ammunition headspaces off the shoulder of the cartridge, whereas .303 British headspaces off the forward rim of the cartridge. If the headspace is too short, ammunition that is in specification may not chamber correctly. If headspace is too large, the ammunition may not fit as intended or designed and the cartridge case may rupture, possibly damaging the firearm and injuring the shooter. (Source: Wikipedia)
Problems Caused by Too Much Headspace
Excessive headspace issues can include: light primer strikes, failure to fire, bulged/blown cases, case separations, split shoulders, or unseated primers after firing. Case ruptures caused by excessive headspace can lead to catastrophic failures causing serious injury. That is why headspace is such an important measurement.
Problems Cause by Too Little Headspace
Insufficent (or excessively tight) headspace can prevent the firearm from going into battery, resulting in failure to fire or deformation of the cartridge case. Various feeding and functioning problems can be caused by cases with too little headspace, even if a round can be chambered (with effort).
Headspace Gauges
Headspace is measured with a set of two headspace gauges: a “Go” gauge, and a “No-Go” gauge. Headspace gauges resemble the cartridges for the chambers they are designed to headspace, and are typically made of heat-treated tool steel. Both a “Go” and a “No-Go” gauge are required for a gunsmith to headspace a firearm properly. A third gauge, the “Field” gauge, is used (as the name implies) in the field to indicate the absolute maximum safe headspace. This gauge is used because, over time, the bolt and receiver will wear, the bolt and lugs compress, and the receiver may stretch, all causing the headspace to gradually increase from the “factory specs” measured by the “Go” and “No-Go” gauges. A bolt that closes on “No-Go” but not on “Field” is close to being unsafe to fire, and may malfunction on cartridges that are slightly out of spec. (Source: Wikipedia)
You need to understand Headspace Gauges and how to use them. There are “Go”, “No-Go”, and “Field” gauges. The “Field” is actually the longest. Brownells explains: “The GO gauge corresponds to the SAAMI minimum chamber length, while the FIELD gauge usually matches the maximum chamber depth, or slightly less. NO-GO gauges are an intermediate length between minimum and maximum, that, technically, is a voluntary dimension. A firearm that closes on a NO-GO gauge and does not close on a FIELD gauge may not give good accuracy and may have very short cartridge case life [.]”
Second Amendment advocacy groups have been vital to the protection of our gun rights. Successful litigation has protected Americans’ rights to purchase and carry guns for sport, hunting, and self-defense. We’re very pleased to see that Brownells is supporting by gun rights efforts by donating 5% of Brownells’ website sales to Gun Owners of America (GOA) this week. From Monday, July 21, through Sunday, July 27, 2025, every purchase made at Brownells.com will help support GOA’s mission. And there’s a bonus for Brownells customers — you can save 10% on orders over $350.00 with Brownells Code SAVE4GOA. So if you buy $400 worth of products you’ll save $40.00.
Gun Owners of America (GOA) Defends Second Amendment Rights
The Gun Owners of America (GOA) is an organization dedicated to protecting and defending the constitutional right to keep and bear arms. GOA’s lawyers have pursued legal efforts throughout the nation, in local, state, and Federal Courts, challenging unconstitutional gun control laws, executive actions, and federal overreach.
Gun Owners of America is actively engaged in some of the most critical Second Amendment legal battles today, including a forthcoming federal lawsuit to dismantle the remaining provisions of the National Firearms Act. GOA, along with the Gun Owners Foundation (GOF), has also filed a lawsuit against the United States Postal Service (USPS), seeking to overturn the Prohibition-era federal ban on the mailing of handguns. Additionally, Gun Owners of America has defended the right to build and own homemade firearms while fighting back against ATF overreach on pistol braces and other regulatory abuses. Brownells is proud to stand with GOA in defending the rights of law-abiding gun owners.
New Legal Actions by GOA to Eliminate National Firearms Act Restrictions
The GOA has recently commenced new legal actions in Federal Court to curtail remaining restrictions in the NFA. This could help make suppressors easier to obtain at much lower prices. That would benefit both hunters and target shooters.
About Gun Owners of America
Founded in 1975, Gun Owners of America (GOA) is known as “The only no-compromise gun lobby in Washington.” GOA works to protect the Second Amendment rights of Americans through grassroots activism, legal action, and by holding lawmakers accountable. GOA fights against federal and state-level infringements, challenges unconstitutional regulations in the courts, and leads efforts to advance pro-2A policies across the nation. For more information about GOA or to make a direct donation, visit GunOwners.org.
If you’ve been thinking about a big purchase at Brownells, here are some money-saving codes. Brownells is currently offering $50 Off a $500+ purchase, $25 Off a $250+ purchase, and 10% Off most purchases (through the end of July). It’s simple to get these discounts — there are no buyers’ clubs to join, no forms to fill out. Just use the appropriate Discount Code during online check-out.
Listed below are the Codes to use. Simply use the appropriate Code for your purchase at Brownells.com. As these Codes may be deactivated without notice, if one Code doesn’t work, try a different Code and you can still save some buck$. Also if the highest value code no longer works, try a lesser value CODE.
Coupon Code: OUTLAW10 — 10% Off sitewide
Expiration date: 7/30/2025
Coupon Code: PRIMER10 — 10% Off sitewide
Expiration date: 7/29/2025
Coupon Code: JULY50 — $50 off $500 or more
Expiration date: 7/31/2025
Coupon Code: JULY25 — $25 Off $250 or more
Expiration date: 7/31/2025
NOTE: If a specific code does not work, try another code. Some of these codes have no listed expiration date, so Brownells could terminate them at any time. Accordingly, we recommend you do your shopping soon.
Readers often ask “What’s the difference between a Weaver scope rail and a Picatinny Rail?” The answer is not as simple as it seems. The dimensions of a Picatinny Rail should be consistent (from one rail-maker to another), since there IS a government spec. Conversely, there is some variance in “Weaver-style” rails. The width of the groove is the most important difference between Picatinny Rails and Weaver-type rails. “Mil-spec” Picatinny rails will have a grove width of 0.206″ while Weaver rails typically have a narrower, 0.180″ groove width.
Does your rifle have a Weaver Rail or Picatinny Rail? Check the dimensions to be sure.
A while back, Brownells had a helpful GunTech™ Article that discussed the Picatinny Rail vs. Weaver Rail. That article explained:
What are the differences between the ‘Picatinny’ and the ‘Weaver’ systems? The profile of the two systems is virtually identical. Depending on the quality of the machining done by the manufacturer, the two systems should be indistinguishable from the profile. The key difference lies in the placement of the recoil grooves and with width of the grooves. MIL-STD-1913 (Picatinny) grooves are .206″ wide and have a center-to-center width of .394”. The placement of these grooves has to be consistent in order for it to be a true Picatinny MIL-STD system. Weaver systems have a .180” width of recoil groove and are not necessarily consistent in a center-to-center measurement from one groove to the next.
In many instances, a Weaver system has a specific application that it is machined for, so interchangeability is not necessarily an issue. A MIL-STD-1913 system must adhere to the specifications listed above in order for it to be considered MIL-STD, since the military desires uniformity in the recoil grooves to allow for different systems to be mounted on the weapon with no concern for compatibility.
Now, what does this mean? Boiled down, it means that accessories designed for a Weaver system will, in most cases, fit on a Picatinny system. The reverse, however, is probably not the case. Due to the larger recoil groove, Picatinny accessories will not fit a Weaver system. There are, of course, exceptions to every rule, but for a good rule-of-thumb, [full-width] Picatinny won’t fit Weaver, but Weaver accessories WILL fit Picatinny.
Brownells is a well-known retailer of guns, gun parts, tools, accessories, ammo, and pretty much everything gun-related. What you may not know is that Brownells has a very active video production department that releases new “how-to” and product information videos every week. These videos offer helpful advice on gun cleaning/maintenance, reloading, as well as selecting/assembling components for various kinds of rifles. And every week Brownells serves up a new products video. There now over 3000 videos on the Brownells YouTube Channel, which is truly a remarkable resource.
Here are seven of our favorite videos from Brownells. There’s a helpful guide to scope installation, a guide to using the OAL tool properly, and a good video on building a rifle with a Howa barreled action. There’s a helpful video on air travel with rifles, and all gun owners should watch the video on ammunition storage.
Scope-Mounting — Common Mistakes to Avoid
Always be careful when mounting a rifle scope. This isn’t a super-complex or highly technical task, but there are ways you can mess it up. This video explains common pitfalls to avoid when mounting a scope.
1. Make sure the rings don’t touch ANY part of the turret housing, objective bell, or eyepiece.
2. Be certain the scope rings are tightly clamped to the scope base. Grasp the scope with one hand and the rifle with the other, then ensure there is no play.
3. Make sure there’s clearance between the objective bell and the rifle. No part of the scope should touch the rifle itself.
4. NEVER over-tighten the scope rings. You can actually crush the scope tube and damage the optic beyond repair. Stick to the torque specs!
Affordable Precision Rifle Build with Howa 1500 Barreled Action
In this video, Caleb from Brownells walks through a step-by-step build of an affordable precision rifle using a Howa 1500 barreled action, MDT stock, and Vortex optic — putting together a highly capable long-range setup for under $1,200. The video covers key components and shows the assembly tools needed (4:38). The video explains how to build a reliable, accurate bolt gun on a budget, with honest insight into gear selection and assembly techniques. From the stock and trigger to rings, base, and scope setup, this video is a very helpful guide for anyone looking to build an affordable precision rifle. Installation of the Howa 1500 barreled action into the MDT stock is shown in detail at 6:00 minute mark.
How to Use Hornady OAL Tool and Hornady Bullet Comparator
Gun Tech Steve Ostrem explains how to properly use Hornady’s Overall Length Gauge to determine length-to-land precisely. The OAL Gauge uses a “Modified Case” that threads onto the tool and holds a bullet. Push on the back of the gauge until you feel the bullet just touch the rifling. (We do this gently at first, tapping the rod a couple time to ensure the bullet is aligned correctly). Once you’ve got the length, then use the tool with a comparator on your calipers to get the length-to-lands. NOTE: We recommend taking the measurement 3-4 times in a row to get a reliable number. With a little practice your should be able to get repeatable measurements within .0015″.
How to Store Ammunition Safely and Securely
This is one of the most popular Brownells videos — with over 2.5 million views. Here’s the deal — ammunition WILL keep for a long time if you store it properly. DO store ammunition in a cool, dry place that doesn’t have wide temperature swings. Temperature cycling will also degrade primers and powder. Put it in airtight ammo cans to keep out the moisture. Tupperware containers will work too. Brownells also recommends putting moisture-absorbing silica packs in your ammo containers. DON’T just keep ammo in factory cardboard factory boxes stacked in the basement, attic, or garage (especially on the floor). Factory ammo boxes can absorb moisture which can degrade primers and corrode the brass cases. Yes, sealed military ammo will usually handle this kind of storage for quite a while, but it’s still not wise.
Air Travel with Firearms — Key Regulations You Must Follow
You can travel on commercial airlines with firearms. But you must follow the TSA regulations, and your particular airline’s rules. First, make sure your guns are UNLOADED before your leave home. Guns need to be carried in proper hard-sided cases that cannot be pried open. Be prepared to unlock the case if the TSA wants to inspect what’s inside. TSA agents can cut the locks if they need to open the case but can’t locate you. If you use special TSA-approved locks, TSA agents have master keys that let them open the case without destroying your locks. You CAN transport up to 11 pounds of ammunition — with restrictions explained in the video.
Cleaning Advice for .22 LR Rimfire Rifles
Gun Techs Steve Ostrem and Caleb Savant debunk some myths about cleaning .22 LR barrels. One myth is that cleaning will harm the accuracy of a .22 LR barrel. Caleb thinks this myth is the result of people cleaning a barrel from the muzzle and damaging the muzzle crown, which CAN diminish accuracy. If it’s done right, cleaning won’t damage the bore. However, you certainly do NOT have to clean your 22 LR’s bore every time you go to the range. But DO clean the action every time you shoot the rifle, especially on a semi-auto. What about shooting a lot of lead bullets? Won’t that lead up the bore? The guys give us the straight skinny on lead fouling, too. When you see your .22 LR rifle’s groups opening up, you may want to consider cleaning.
Must-Have Spare Parts for AR-Platform Rifles
In this video, two knowledgeable gun techs answer the question: “What spare parts should I keep on hand for my AR-15?” On the list are: Gas Rings, Buffer Spring, Extractor Spring and Pin. NOTE: You may want to try the one-piece spiral gas ring rather than the standard rings which require alignment. The cotter pin and cam pin can also easily get lost when the Bolt Carrier Group is disassembled for cleaning. On the lower receiver you’ll want spare springs and detents for the pivot/takedown pins. If you’re using lighter-power springs, keep standard-power spares on hand. If your rifle stops working, swap in the factory-spec springs to find out if the problem is the gun or your ammo. Also, if you have upgraded your trigger, always keep the original trigger as a backup.
This article is Copyright 2023 AccurateShooter.com. Reproduction on any other website gives rise to monetary damages.
Brownells hosts the 4th Annual 2A Day (Second Amendment Day) on February 22, 2025, a nationwide event dedicated to celebrating Second Amendment rights, advocating for their preservation, and strengthening the firearms community. On 2A Day, you can visit a participating range and take advantage of free firearm rental or limited free ammo. There are participating ranges in Scottsdale, Arizona; Johnston, Iowa; Ballwin, Missouri; Omaha, Nebraska; and Auburn, Virginia. And some other local ranges may offer free firearm rentals or limited free ammo. Or head to the range of your choice and shoot for fun.
With support from sponsors including CCI, Federal, Fiocchi, Henry, Hornady, Leupold, Magpul, Remington, Smith & Wesson, and Volquartsen, 2A Day provides multiple ways for firearm enthusiasts to participate:
CELEBRATE — Brownells is partnering with shooting ranges across the country to offer free range time and limited complimentary ammunition for participants.
ADVOCATE — Brownells encourages gun owners to actively support the Second Amendment by engaging with lawmakers at both the state and federal levels. The Brownells 2A Day webpage provides links to help individuals contact their elected representatives.
JOIN — Gun owners are encouraged to join national and state organizations committed to protecting gun rights, such as the 2nd Amendment Foundation (SAF) and the Gun Owners of America (GOA). Brownells will donate 4% of all sales from February 18-23 to 2A advocacy groups.
Second Amendment Day Official Target (Download for FREE)
“February 22nd is a day we, as a nation, can recognize, celebrate and do our part to secure one of the most important rights guaranteed by our Constitution – the right to keep and bear arms,” said Pete Brownell, Chairman of the Board at Brownells. “I hope Americans from all walks of life visit the range on this one day – 2/22 … and safely exercise their Second Amendment right, which is the underpinning of safety and security in America.”
Many Remington 700 rifle owners swap out the factory trigger. This is not a difficult task, but you need to follow the proper procedure so you don’t damage any important parts during installation, and so that you don’t interfere with the operation of the bolt and safety. This Do-It-Yourself video from Brownells leads you through step by step how to safely and correctly replace your Remington 700 trigger. This installation video covers the common methods used to install most of the popular after-market Rem 700 triggers. Importantly, the video also shows how to function test after installation, and how to make sure your safety is working properly.
Many Rem 700 owners fit Timney triggers to their rifles.
Video find by ELR Researcher. We welcome reader submissions.
Scary stuff — AK-74 after firing corrosive ammo and not being cleaned for a week.
Image courtesy ADCOFirearms.com.
No doubt you’ve heard the term “corrosive” used with respect to ammunition. But what exactly is “corrosive ammunition” (and how does it different from non-corrosive ammo)? What is the chemistry that leads to corrosion, and what cleaning procedures should you follow if you shoot corrosive ammunition? Brownells has come up with answers to these and other questions in a helpful TECH TIP video about corrosive ammo.
In this informative video, Brownells gun tech Steve Ostrem explains the primer-related chemistry that makes some ammo corrosive. The video then reviews suggested cleaning procedures you should follow after you have fired corrosive ammo through any firearms.
What Is “Corrosive” Ammunition?
What makes ammo “corrosive”? Generally speaking, primers are the problem. When corrosive ammunition is fired, the ignited primers leave a residue of corrosive salts. Typically these primers contain potassium chlorate, or sodium petrochlorate which, when burned, change into potassium chloride or sodium chloride. Sodium chloride is also known as common table salt.
Potassium chloride and sodium chloride are both very hygroscopic (i.e. they attract water). Because of that, these alkalis are rust generators. When exposed to the hydrogen and oxygen in the air (and moisture) potassium chloride and sodium chloride can form an acid that quickly causes metal rifle parts to rust and pit.
Given a choice, you may wish to avoid corrosive ammo altogether. However, for some types of fire-arms, particularly older military-style rifles, the most affordable ammunition may be corrosive. If you choose to use corrosive ammo, it is important to clean the gun thoroughly after use. After firing, you want to use an element that will neutralize the primer salts. Brownells suggests a water soak (see video above). Alternatively, Windex with ammonia can help neutralize the salts, but that doesn’t finish the job. After the salts have been neutralized and flushed away, basic anti-corrosion protectant (such as Eezox or other gun oil) should be applied to all metal parts.
This video ahows the effects of Corrosive Ammo after one month without cleaning:
Paul Markel, host of the popular Student of the Gun TV series, offered smart advice on the proper procedures for cleaning rifles exposed to corrosive ammo: “Windex (with ammonia) is the Corrosive Ammo shooter’s best friend. After you are done shooting your corrosive ammunition for the day, squirt the window cleaner liberally from the chamber down the barrel. Pull the bolt / bolt carrier / op rod if there is one and douse them as well. A couple of old cotton t-shirts will come in handy. A cotton barrel swab is a nice accessory but you can make do with patches. Some folks will rinse all of the ammonia and loosened corrosive salts off with hot water. Others prefer to wipe it all down and let the ammonia evaporate. Either way, once the corrosive salts have been tackled with the window cleaner, it is time for an all-purpose brush (old toothbrush) and some gun oil.”
Video Tip from EdLongrange. We welcome reader submissions.
If you’ve been thinking about a big purchase at Brownells, here are some money-saving codes. Brownells is currently offering $125 Off a $1000 purchase, $55 Off a $500 purchase, $20 Off a $200 purchase, $15 Off a $150 purchase, and $10 Off a $100 purchase. In addition, you can get 10% off all purchases of $150 or more. It’s simple to get these discounts — there are no buyers’ clubs to join, no forms to fill out. Just use the appropriate Discount Code during online check-out.
Listed below are the Codes to use. Simply use the appropriate Code for your purchase at Brownells.com. These codes have no listed expiration date, so Brownells could terminate them at any time. Accordingly, we recommend you do your shopping soon. Also if the highest value code no longer works, try a lesser value CODE.
Coupon Code: SEPT125 — $125 Off $1000+
Expiration date: 9/30/2024
Coupon Code: SEPT55 — $55 Off $500+
Expiration date: 9/30/2024
Coupon Code: SEPT20 — $20 Off $200+
Expiration date: 9/30/2024
NOTE: None of the above codes include FREE or Discounted Shipping. You may want to check other vendors such as Scheels.com which offer free shipping with certain minimum purchases ($75 mininum at Scheels). This might result in a lower overall price than purchasing from Brownells.
This illustration shows headspace measurement for the popular .308 Winchester cartridge, which headspaces on the shoulder. Image copyright 2015 Ultimate Reloader.
In this Brownells Tech Tip Video, Brownells gun tech Steve Ostrem explains what headspace is and why it’s one of the most critical measurements for nearly all firearms. Even if you’re an experienced rifle shooter, it’s worth watching this video to refresh your understanding of headspace measurements, and the correct use of “GO” and “NO-GO” gauges.
Headspace Definition
In firearms, headspace is the distance measured from the part of the chamber that stops forward motion of the cartridge (the datum reference) to the face of the bolt. Different cartridges have their datum lines in different positions in relation to the cartridge. For example, 5.56x45mm NATO ammunition headspaces off the shoulder of the cartridge, whereas .303 British headspaces off the forward rim of the cartridge. If the headspace is too short, ammunition that is in specification may not chamber correctly. If headspace is too large, the ammunition may not fit as intended or designed and the cartridge case may rupture, possibly damaging the firearm and injuring the shooter. (Source: Wikipedia)
Problems Caused by Too Much Headspace
Excessive headspace issues can include: light primer strikes, failure to fire, bulged/blown cases, case separations, split shoulders, or unseated primers after firing. Case ruptures caused by excessive headspace can lead to catastrophic failures causing serious injury. That is why headspace is such an important measurement.
Problems Cause by Too Little Headspace
Insufficent (or excessively tight) headspace can prevent the firearm from going into battery, resulting in failure to fire or deformation of the cartridge case. Various feeding and functioning problems can be caused by cases with too little headspace, even if a round can be chambered (with effort).
Headspace Gauges
Headspace is measured with a set of two headspace gauges: a “Go” gauge, and a “No-Go” gauge. Headspace gauges resemble the cartridges for the chambers they are designed to headspace, and are typically made of heat-treated tool steel. Both a “Go” and a “No-Go” gauge are required for a gunsmith to headspace a firearm properly. A third gauge, the “Field” gauge, is used (as the name implies) in the field to indicate the absolute maximum safe headspace. This gauge is used because, over time, the bolt and receiver will wear, the bolt and lugs compress, and the receiver may stretch, all causing the headspace to gradually increase from the “factory specs” measured by the “Go” and “No-Go” gauges. A bolt that closes on “No-Go” but not on “Field” is close to being unsafe to fire, and may malfunction on cartridges that are slightly out of spec. (Source: Wikipedia)
You need to understand Headspace Gauges and how to use them. There are “Go”, “No-Go”, and “Field” gauges. The “Field” is actually the longest. Brownells explains: “The GO gauge corresponds to the SAAMI minimum chamber length, while the FIELD gauge usually matches the maximum chamber depth, or slightly less. NO-GO gauges are an intermediate length between minimum and maximum, that, technically, is a voluntary dimension. A firearm that closes on a NO-GO gauge and does not close on a FIELD gauge may not give good accuracy and may have very short cartridge case life [.]”
Headspace Gauges
No doubt you’ve heard the term “corrosive” used with respect to ammunition. But what exactly is “corrosive ammunition” (and how does it different from non-corrosive ammo)? What is the chemistry that leads to corrosion, and what cleaning procedures should you follow if you shoot corrosive ammunition? Brownells has come up with answers to these and other questions in a helpful TECH TIP video about corrosive ammo.
