The Feed Ramp Again

With some exceptions, the majority of common automatic pistols have a feed ramp. They have to have one because the ammo is fed from below and behind the barrel and its chamber. In the feeding and chambering cycle, the fresh cartridge moves forward and up to its place in the chamber. This is a simple invention that has been used since the very first pistols. More often than not, a small portion of the chamber mouth has a radius to form this feed ramp. This creates a small crescent of surface of the cartridge that is not supported by steel chamber walls. In firing, this area takes the full pressure for just an instant. But it takes the pressure at the head of the cartridge where the brass—a wonderfully elastic material—is thickest and strongest. Literally, billions of rounds of ammunition have been loaded, fired, extracted and ejected from typical pistols since the first one was fired.

The barrel in the 1911 pistol bearing serial No.1 has a feed ramp. If you replaced that barrel with a new one that had a fully supported chamber, I guarantee it would not work. It would appear that condemning a manufacturer for using an unsupported chamber as an unsafe practice is unsound. Manufacturers fired thousands of rounds through samples of before releasing it for sale. The testers also used a variety of ammunition even fired a few shots of proof loads, which are deliberately loaded to be over maximum pressure. But they did not use somebody’s handload, which was concocted to produce SAAMI-maximum pressures. And the reason they did not do that is because they have no control over what went into that load. And that is why they will never warrantee guns with handloads. I love the fact that Americans have the right and the means to concoct their own ammunition. However, doing so involves a major dose of common sense and discretion.


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5 Responses to The Feed Ramp Again

John wrote:
July 02, 2012

Never, heared about problems with Glocks and unsupported chambers. Even my $309 Ruger P95 has a supported chamber.

Gary wrote:
June 13, 2012

FROM Lone Wolf Distributors: Reloading Issues: Ammunition that is fired from an original Glock factory barrel produces (very) expanded case heads. This expansion occurs because of the large chamber used in Glock factory barrels. FROM .40 S&W IPSC Loads List Compiled By: Jeff Maass, USPSA L-1192 SPECIAL .40 S&W LOADING SAFETY NOTES: Shooting reloaded ammunition in your Glock handgun will void the warranty. In addition, there are many, many stories of burst cases in Glock handguns chambered for .40S&W. I cannot recommend that you use any reloaded rounds in your Glock handgun unless the barrel has been replaced with one of the aftermarket barrels which fully supports the case head.///That's enough. Since I wanted to maintain credibility, I only cut and pasted quotes from reliable sources. If I had added all the blogs, forum postings, and videos, I would have brought down the server. I did run into other information pertaining to Glocks that owners should be aware of. They can fire out of battery which exposes even more case to a kaBoom. Replace your recoil spring to prevent that from happening. Loading a round from the magazine, unloading that round from the chamber, replacing that round in the magazine and reloading that same round in the chamber over and over again will gradually decrease the OAL and can GREATELY increase pressure. Hirtenberg Ammunition Company of Austria (at the request of GLOCK, Inc.) determined that, with a .40 caliber cartridge, pushing the bullet back into the case 1/10 of an inch doubled the chamber pressure. This is higher than a proof load. This can occur with but one chambering since it is dependent on how well the case was crimped or sealed to the bullet. Okay, Mr. Clapp, have I proved my case?

Gary wrote:
June 13, 2012

FROM Lee Bulge Buster Kit: Glock Cases: We do not recommend "fixing" cases fired in pistols with unsupported chambers, because there is no way to make them safe once they have bulged. The case wall is thinned where it bulges, and resizing the outside of the case back down to the correct diameter does not restore the case back to its original thickness. If this case is fired in a pistol with an unsupported chamber again, and this thinned section of brass happens to line up with the unsupported part of the chamber, there is a high probability that the case will rupture. FROM GUN WIKI: Controversy arose over Glock's safety standards when several instances of explosive malfunction occurred in Glock pistols sold to police departments in the United States. Upon pulling the trigger, the cartridge case would rupture and cause an explosion that would tear apart the gun and sometimes send fragments into the shooter's face. The cause of this malfunction was traced to issues with a purposely oversized (loose), and partially unsupported chamber in Glock's pistols chambered in .40 S&W, .45 GAP, and 10mm. The chamber lacks full support in the rear by the feed ramp in order to facilitate feed reliability. The lack of support in the chamber, usually combined with lead bullets, reloaded ammunition, or poor-quality factory ammunition, would cause the case to fail... However, there continues to be controversy over the presence of an unsupported chamber, critics arguing that it is not necessary and is a liability for the company. One can notice a bulge in the fired case ejected from the pistol (even with target loads) to see the result of the unsupported chamber. FROM MAGSAFE AMMO: For greater safety and less wear on customer's guns, we now use .38 Special +P nickel brass for the .38 MAX, & Triton's .45 Super brass for the .45 MAX and .45 Super SWAT Loads. Glock 45s have huge throats; be careful.

Gary wrote:
June 13, 2012

I am not trying to bad-mouth Glock, it is just that Glock is the Poster Boy for unsupported chamber problems. All of my quotes are meant to convince Mr. Clapp that unsupported chambers are a big deal for those of us that reload. If you shoot only factory ammunition I doubt that you will ever have a problem. My argument is that when a RELOADER is looking to buy a new pistol, he should be made aware of which pistols have supported chambers and which don't. Then he can make an informed decision on which one to buy.

Gary wrote:
June 11, 2012

Some pistol manufacturers have mastered the art of providing a fully-supported chamber along with a feed ramp. If you were to tell us which pistols have this feature in your gun reviews, we would be safer shooters. This is a well-known problem and has attracted the attention of our leading reloading and ammunition companies. Don't ignore the problem, read the following: FROM LEE: WARNING: DO NOT USE reloads in Glock or similar guns with chambers that do not fully support the cartridge due to the intrusion of the feed ramp. FROM SPEER: SAFETY NOTICE: Some pistols chambered for the .40S&W cartridge may not provide complete support of the case head. If this condition exists, normal pressure loads such as those shown here can cause the case wall to bulge or rupture at the unsupported point. FROM HODGDON: WARNING: This data(.40 S&W)is intended for use in firearms with barrels which fully support the cartridge in the chamber. Use of this data in firearms which do not fully support the cartridge may result in bulged cases, ruptured cases, case head separation, or other condition which may result in damage to the firearm and/or result in injury or death of the shooter and/or bystanders. ACCURATE ARMS: SPECIAL WARNING:...Although this practice (unsupported-chamber) is acceptable with some calibers such as the 45ACP which generate relatively low pressures,this kind of incomplete support can be a real problem with high performance calibers such as the 9mm, 38 Super, 40S&W and 10mm...BUFFALO BORE:(.40 S&W +P) Buffalo Bore loads their ammunition with the highest quality components available to maximize the performance of the ammunition. This ammunition is safe to use in all 40 S&W chambered firearms with a fully supported chamber. Most Glock 40 S&W do not have a fully supported chamber do not use this ammunition in Glock 40 S&W or other unsupported chamber pistols. This ammunition is new production, non-corrosive, in boxer primed, reloadable brass cases.