BHSS Slide Velocity Synchronization – 1911 System 5″ barrel


What are the benefits of “Slide Velocity Synchronization”?

–         Reliability enhanced

–         Better Performance as Excessive Recoil is eliminated, means Better Control of firearm, faster follow-up shots

–         Superior Accuracy

–         Increased Shooter Confidence

–         Less wear of firearm parts


SLIDE VELOCITY SYNCHRONIZATION – BHSS DEFINITION: A combination of springs in a firearm, that, when used for shooting a specific type of ammunition, yields ejection distances of empty shell casings in the 4’-8’ range.


The rearward slide velocity of your semi-auto handgun, influences the distance of ejection of empty shell casings. (Other things influence ejection distance: condition of extractor and ejector and other parts, including cleaning and lubrication. For the purposes of this discussion, we’re assuming a well-maintained firearm where all parts and springs are in good condition.)


When a round is fired, there must be sufficient rearward slide velocity to reliably accomplish complete ejection of the empty bullet casing AND sufficient forward velocity of the slide, when returning to battery, to reliably pick up and chamber the next round in the magazine.

We use a range of 4-8 feet, as a general rule. Spring set-up combinations that

yield ejection distances of less than 4 feet, may be generally reliable – BUT – have you ever had a round of ammunition that just didn’t seem to be as strong as the rest in the box? Even the best factory ammunition can have one of these guys in the box! Your spring set-up should leave enough “margin” for that occasional underpowered round.


We generally use 8 feet as a “maximum”. There is no reason for your semi-auto pistol to be sending empty brass flying 15 feet. At 15 feet ejection distance, our testing has shown that slide velocity is excessive – the firearm is taking more punishment during recoil than is necessary – the shooter has less controllable excessive recoil – and the barrel is very likely unlocking from the slide before bullet leaves end of barrel – (which means the barrel is actually moving before the bullet leaves the barrel.)   Excessive ejection distance also has another downside…..the increased possibility of insufficient recoil spring strength to strip the next round from the magazine, chamber that round, and return the slide to it’s forward-most position.


So…..when thinking about ejection distance of spent shell casings…..we’re looking for “enough”, but not “too much”.


Why am I just hearing about this concept……Slide Velocity Synchronization?

The primary reason…..without the necessary springs to accomplish Slide Velocity Synchronization…..there’s nothing a shooter can do about it except to buy the brand and type of ammunition that ejects the desired distance in your firearm. A variety of springs are required to adapt your firearm to the wide variety of ammunition available today.


Considering only the 9x19mm caliber for a moment. Today, ammunition bullet weights range from ultra-light less than 90 gr bullet weights, and we’re now seeing the other extreme of bullet weights of 150 gr+.   Ammunitions of the standard pressure variety and +P pressure.


(As a point of reference, BHSpringSolutions LLC has done no testing with any ammunitions commonly rated as “+P+” and encourages all shooters to avoid ammunition carrying this kind of barrel pressure rating.)


BHSpringSolutions LLC offers spring kits for the Hi Power, Hi Power Clones and Compacts, 1911, Arcus 98DA and 98DAC, that make Slide Velocity Synchronization

MODEL 1911 – 5” Barrel – .45ACP



Model 1911

The Single Action (SA) Hi Power has a simpler recoil cycling design, compared to semi-auto pistols of a Double Action/Single Action (DA/SA) design. When cycling rearward, the slide encounters the resistance of the Main Spring as the slide re-cocks the hammer, and of course the slide also encounters the resistance of the Recoil Spring. Both springs do two jobs – both play a role in controlling rearward slide velocity (recoil). Although the two springs work together to control rearward slide velocity, after the slide moves fully rearward the Main Spring’s job is momentarily finished and the recoil spring finishes it’s job when it propels the slide into it’s forward most position (battery). The Main Spring finishes it’s job when the trigger is pulled, causing the Hammer to hit the Firing Pin with sufficient force that the Firing Pin overcomes the resistance of the Firing Pin Spring. We refer to this design as “simpler” because it can be easier to accomplish “Slide Velocity Synchronization” in the 1911, than in a DA/SA CZ 75 (as an example), where the trigger is “pulled” slightly rearward when the hammer is cocked by the slide, which also makes the resistance of the Trigger Return Spring part of the equation of controlling rearward slide velocity. The SA 1911 relies on only two springs to control rearward slide velocity which also means the Recoil Spring in a SA semi-auto will usually need to be stronger than the recoil spring in a DA/SA semi-auto. The heavier recoil spring translates into more authoritative forward slide velocity that strips and chambers the next round from the magazine.


Optimal 1911 Spring Set-Up Solves or Prevents Numerous Problems

  1. All 1911s are not created equal. Nobody seems to know how many firearms manufacturers have built a 1911 semi-auto pistol. And even though springs may be interchangeable between most of them, not all 1911s function best with the same recoil and main spring combinations.
  2. The design of the 1911 is so excellent, and so robust, that many 1911s continue to function, even after all the springs have become weak. This is both a blessing and a curse – because although the 1911 may seem to function fine with unhealthy springs – accuracy will suffer and rearward slide velocity will become excessive, causing premature wear of parts. In addition to causing your 1911 to wear out faster, weakened springs make great “riding partners” for a host of potential 1911 malfunctions, including: Encountering ammunition with “hard primers” (failures-to-fire) goes hand in hand with an unhealthy main spring that no longer causes the hammer to strike the firing pin with sufficient force. Experiences of failures-to-feed go hand in hand with a weakened recoil spring that no longer returns the slide to battery with sufficient authority.
  3. Variations in .45ACP ammunition, exist today, that did not exist in 1911. The varieties of bullet weights and pressures in ammunition today constitute a moving target.
  4. All coil springs in the 1911 are compressed, when installed. They are expending energy (wearing themselves out) just by being installed in a 1911.


                All BHSpringSolutions Optimizing Spring Kits, for the 5” barrel 1911 .45ACP, contain 3 Recoil Springs, 2 Main Springs, Optimal Firing Pin Spring, Plunger Spring, Magazine Latch Spring, and a Firing Pin Block Safety Spring in the Series 80 kits. All BHSS 1911 Spring Kits are “Slide Velocity Synchronizing” Spring Kits.


Why 3 Recoil Springs and 2 Main Springs?

Generally, the distance of ejection of empty shell casings, gives us feedback about function and slide velocity. And generally, we look for this distance to be in the 4’ – 8’ range. This is where “All 1911s are not created equal”, applies. During our testing with 230 gr standard pressure ammunition, we found distance of empty case ejection to be in the 4’ – 6’ range with our standard 16 lb recoil spring and our Heavy Main Spring. When we changed over to our Light Main Spring, distance of empty shell case ejection was an additional 1½’ – 2 ½’ further, depending on the ammunition being tested….giving us empty case ejection in the 6’ – 8’ range.   With the lighter main spring, we could then go to our heavier 18 lb recoil spring, and tame the recoil a bit, and reduced the empty shell case ejection distance and increased the authority of the slide’s return to battery. Our 18 lb Recoil Spring also nicely controlled +P .45ACP ammunition, particularly with the heavier main spring. These results were in our 1911 used for testing which is a recent production Remington R1. The owner of a Colt GI 1911, made in 1930, may find a slightly different combination to be optimal, and the owner of a Springfield 1911 may find yet a different combination to work best. And also, the right combination of Main Spring and Recoil Spring is not only about the basic science involved in measuring distance of empty shell casings – there is another factor – not all shooters are created equal. Our 3 Recoil Springs and 2 Main Springs, standard in all BHSpringSolutions 1911 Spring Kits, also take into account this other important fact: “It’s also a feel thing”……in other words, as long as function is reliable and the empty shell casing ejection distance is in the desired range, the right combination of recoil spring and main spring, in a particular 1911, for a particular shooter, also depends on which combination yields the best performance results for the shooter and his 1911. Many 1911s will function reliably with our 16 lb recoil spring and either of our Main Springs, and many 1911s will function well with standard pressure ammunition with our heavier 18 lb recoil spring and lighter Main Spring as a combination – and the final determination of “optimal” will be based on the combination that “feels” best, and enables the owner/shooter to perform best. Ultimately, this optimal combination is found by the 1911 owner and his handgun, together.


Many manufacturers go to great efforts to make quality 1911s, with consistency of build quality that, given today’s technology and modern machinery, is better than it’s ever been in history. Unfortunately, many 1911 owners (and manufacturers) are missing the best possible 1911 performance by not finding the best possible combination of Recoil and Main Spring. The importance of these two springs, working together like gears in a well-oiled machine, cannot be overstated with respect to the 1911.


What is the difference between a “Series 70” and a “Series 80” 1911?    

The Series 80 is a more modern design, containing a mechanical firing pin block safety, intended to prevent accidental discharge if the 1911 should be dropped on the muzzle with a live round in the chamber, by preventing the firing pin from moving forward except when the trigger is pulled. Series 70 1911s contain no such device and are fully dependent on the strength of the Firing Pin Spring, to retain Firing Pin in it’s rearward position, in the event the 1911 is dropped on the muzzle with a live round chambered.


Firing Pin Springs / Main Springs


Series 80 Spring Kits from BHSpringSolutions LLC contain a Firing Pin Block Safety Spring, a light Firing Pin Spring, and one each of our Heavy and Light Main Springs.

Series 70 Spring Kits from BHSpringSolutions LLC contain an enhanced (heavier) Firing Pin Spring because the Firing Pin Spring is your only protection against accidental discharge in the event of a muzzle drop, with a round chambered, in the Series 70 design.


More On Main Springs

Each Series 70 kit contains one Heavy Main Spring, and 2 Light Main Springs.

Because of the enhanced resistance created by the Series 70 Firing Pin Spring, shooters who prefer performance associated with the Light Main Spring should note that we suggest replacement of this Light Main Spring twice as often as other springs in the 1911 Series 70.   BHSpringSolutions recommends a “best practices” approach to 1911 spring replacement of “Every 5 Years or 5,000 rounds, whichever comes first”. The one exception is use of the Light Main Spring in combination with the Heavy Firing Pin Spring of the Series 70 – in which case we recommend replacement of the Light Main Spring at approximately 2 ½ years – this is the reason for two Light Main Springs in our Series 70 1911 Tune-Up and Optimization Spring Kits.


Plunger Spring:

Contained in all BHSpringSolutions LLC 1911 Optimizing Spring Kits. This multi-function spring is located inside the little tube you see on the left side of your 1911. One responsibility of this spring is keeping the manual safety in the “on safe” position. And, since “cocked and locked” also known as “Condition 1”, is the most common condition for carry of the 1911, keeping this spring healthy should be a priority for all 1911 owners. A healthy plunger spring reduces the chances of unintended movement of the manual safety from the “on safe” position to “fire” position. A correctly made plunger spring has an intentional “dog leg” in the center of the spring because this design works best. The Plunger Spring must push in opposite directions, simultaneously, all the time. The “kink”, or dog leg in the center of this spring creates a stationary position in the center of the spring because each half of the spring has it’s own job to do, in opposing directions. A side benefit is that the Plunger Spring doesn’t fly across the room during disassembly when it’s made with the “dog leg” design.


Magazine Latch Spring:

This spring is responsible for positive lock-up and retention of the magazine in the 1911 grip frame. If you read many handgun reviews, it probably won’t be long before you read a reviewer who comments that he or she unintentionally manipulated the magazine release during shooting or deholstering. Of course, no magazine latch spring can stop this from happening if a shooters thumb is going places it shouldn’t go at the wrong time…….but a healthy magazine latch spring does decrease the likelihood of untended manipulation of the magazine release, as much as possible. A healthy magazine latch spring provides maximum resistance on the magazine release, while still allowing smooth manipulation and function when release of the magazine is intended.




RECOIL SPRINGS – Your kit contains 3 Recoil Springs for a 5” Model 1911: 14 lb., 16 lb., and 18 lb. We have intentionally manufactured these springs in slightly different lengths. Standing these three springs side by side – the shortest of the three is the 14 lb Recoil Spring. The longest spring is the 18 lb Recoil Spring. The remaining 16 lb. Recoil Spring is generally regarded as the “Standard” Recoil Spring in the 5” 1911.


Main Springs – Contained in a separate bag, inside your kit bag, Series 70 Owners will find 3 Main Springs (2-Light and One Heavy (G.I.) Main Spring), Series 80 Owners will find 2 Main Springs – one each of the Light and Heavy Main Springs. The Light Main Spring is the shorter of the two Main Springs.