Bullet Design & Loading Considerations for the Browning .40-65 BPCR
By Wayne McLerran
10/2017
The .40-65 Winchester cartridge is arguably 2nd only in popularity to the .45-70 Government for silhouette competition. Approximately 1300 BPC rifles in caliber .40-65 were manufactured by Miroku for Browning. The rifles are popular and are common in matches around the country. The .40-65 is my preferred silhouette caliber. My experiences with the .40-65 Winchester cartridge in the Browning BPCR are the basis for this article. I will cover the results of testing four well-known bullets and give you some ideas why I decided to design a custom bullet for the rifle. Also discussed is the only bullet design software I’m aware of and design considerations I feel are important when designing a bullet.
Without a doubt a couple of the key factors in loading accurate ammo includes knowing the chamber and bore dimensions of your rifle along with a basic understanding of the pros and cons of various bullet designs. The chamber and bore of the Browning BPCRs are very consistent from rifle-to-rifle but there are slight differences which can only be determined by making a cast or impact impression of the chamber and throat of your rifle. Also helpful is an elementary knowledge of internal and external ballistics. I don’t profess to be an expert in any of these areas but have experimented with a few bullets and formed some opinions why some may be better suited than others for the Browning. Other factors that affect bullet design and selection include the type of bore conditioning techniques used. For example, will you be blow-tubing or wiping between shots?
Mould Suppliers
There are several custom mould manufacturers that will “cut” a mould to your specification. A partial list includes Hoch Custom Bullet Moulds, Accurate Molds, Brooks Tru-Bore Moulds, Buffalo Arms Co. (BACO), Sagebrush Products, Fred Leeth/Pioneer Products, Old West Bullet Molds, Boomers Bullet Moulds, KAL Tool & Die, NEI Handtools and Mountain Molds. Custom moulds range in price from $100 to $200, generally more than $150 for a high-quality single cavity mould without handles. BACO and several of the custom suppliers also sell “semi-custom” high-end moulds. Paul Jones (Paul Jones Precision Moulds), arguably the most well known of the custom suppliers, has retired.
A better option for a new shooter may be a “cataloged” (off-the-shelf) mould until you’re convinced that BPCR shooting is for you. Redding/SAECO, RCBS and Lyman make a line of good quality moulds in a price range of $70 to $90. Although the dimensions may vary slightly from mould to mould they will generally be sufficient to get started. Some experienced shooters continue to use moulds from these manufacturers with excellent results. If an off-the-shelf mould results in excellent accuracy, there’s little or no reason to change. As you will find in the following discussion, the off-the-shelf and semi-custom moulds I’ve tried so far, which were recommended for a Browning by others, did not work out as well as I would have liked. But there are many moulds/bullets available that can be used in a .40-65 cartridge. I’m just not willing to spend more time attempting to find one and decided a custom mould is the solution for me.
If you’ve made the decision to purchase a custom mould, the manufacturer will need as much information as possible. Most mould manufacturers list ordering requirements on their websites. The ideal information includes a drawing with precise dimensions, expected bullet weight and alloy used. But many new BPCR shooters only have a general idea what they want, hence the earlier recommendation of starting with an off-the-shelf mould.
In lieu of supplying a detailed drawing, the mould manufacturer can make an educated recommendation but will need some dimensions of the chamber and throat along with the groove and bore (land) diameters. Sending a chamber cast, impact impression or lead slug made by “slugging” the bore will also help but may not be necessary if precise measurements are provided from the cast or impression.
Prior to designing a custom mould, I tested four bullets that were suggested by shooters for the Browning .40-65. All are bore-riding designs, aiding in nose-to-bore alignment, and is discussed in further detail in the section titled, Nose Design. They were hand seated in the case with the case lip slightly flared (belled), making bullet insertion easier. The flair was not removed; helping to ensure the rear of the bullet is centered in the chamber. Following are the results.
Shooting Test Results
Figure 1
L to R: BACO JIM409400M4 “Money Bullet”, Lyman Snover 410663, Paul Jones 40001 Creedmoor, SAECO 740
As displayed in Figure 1, the following bullets were tested: BACO’s JIM409400M4 “Money Bullet”, Lyman Snover 410663, Paul Jones 40001 Creedmoor and SAECO 740. 16:1 alloy was used for the BACO Money Bullet and Lyman Snover, 25:1 with the Paul Jones Creedmoor and SAECO 740. The cartridge overall length (COAL) was determined with the bullets seated to contact the leade. Once the COAL was determined, each bullet was loaded with a range of powder amounts in one grain increments starting at approximately zero compression up to 0.250” of compression depending on the bullet design. Swiss 1.5Fg, 0.060” over-powder wad, White Lightning lube and Remington 2-1/2 (large pistol) and Winchester WLP (large pistol) primers were used.
Since a blow tube was used, with the exception of the SAECO 740, 10 cartridges plus 2 for fouling the bore were loaded for each powder increment and fired at 200 yd. at separate poster board targets using bench mounted cross sticks. The average velocity, extreme velocity spread and standard deviation was recorded for each shot. Subsequently, each bullet hole was closed and taped from the back of the targets in order to inspect for signs of bullet tipping. With vertical spread being the main selection criteria, the best load was selected for each bullet. See Figures 2 thru 5. Note that the vertical spread of all were approximately 1MOA (2”) or better at 200 yds.
Figure 2
Figure3
Figure 4
Figure 5
Next, after 2 shots to foul the bore, 10 cartridges of the selected loads were fired at 500 meter poster boards with ram size targets. See the results below. During all testing, the bore was cleaned after each 12-shot string. Needless to say, testing required many hours of loading and shooting. A total of 600 cartridges were fired during seven sessions at the range. Including target evaluations and documenting the results, approximately 70 hours was required to complete the exercise in addition to 35 lbs. of alloy, over 5 lbs. of powder, 600 primers and wads.
500 Meter Results
SAECO 740:
The results were poor with only 2 out of 10 bullets hitting the target. I attributed the poor showing to a combination of the short length and lighter weight coupled with the marginal aerodynamic nose design, believing the bullet became unstable as the velocity dropped due to the high drag nose. Also, the mould was slightly out of round. The driving band (body band and base band) diameters varied by 0.003” as the bullet was rotated. Or it may just be that the bullet is too short for the Browning 16:1 twist rate. Regardless, I’m not planning on spending additional time and effort to figure it out.
Lyman Snover 410663:
The Lyman Snover loads were a little better with 5 out of 10 bullets hitting the target. The relatively poor results were most likely due to inadequate lube capacity for the warm (95 degrees) shooting conditions. No muzzle lube star was evident afterwards. The bullet has a good reputation when used in the Browning, so I may retest the bullet when wiping between shoots. The Lyman tends to shoot well if bore fouling is controlled by favorable shooting conditions (mild temperatures and relatively high humidity) or wiping between shoots.
Paul Jones 40001 Creedmoor:
The results were good with all shoots hitting the target within a 12” vertical spread. Although the nose shape is very similar to the SAECO 740, it holds up better than the SAECO at longer distance due, in my estimation, to the longer length and additional weight. Also, it carries plenty of lube for blow tubing in the hot and dry central Texas summer conditions. By the way, since Paul Jones has retired, if you’re interested in trying his 40001 Creedmoor bullet design, Steve Brooks (Brooks TRU-BORE Bullet Moulds), the well-known custom mould manufacturer, offers a mould for the identical bullet.
BACO JIM409400M4 Money Bullet:
The BACO Money Bullet results were excellent with all shoots hitting within a 10” vertical spread. I really like the aerodynamic nose design resulting in increased velocity and flatter shooting characteristics. The BACO design has the 1st three body bands (includes the nose band) reduced with the remaining four bands at 0.409” (includes the base band). Therefore, in order for the bullet to contact the leade for alignment, the bullet seating depth is only 0.200”. And a minimum of 69grs of powder is required to fill the case with a 0.060” wad, resulting in a velocity of 1345 fps. Although it performed admirably, it’s my belief that with all driving bands the same (0.409” to 0.410”) diameter, and with deeper lube grooves, the bullet could be accurately loaded with less powder and fewer exposed lube grooves and “stand up” better in the central Texas summer heat. Although the muzzle lube star was thin, the bullet held sufficient lube during the tests, but the worse testing condition was a very humid 95 degrees. Based on the lube capacity I would not be surprised to find that it “runs out of lube” as the temperature approaches 100 degrees and the humidity drops to 30% or so.
Design Software
The aerodynamic benefits of various nose designs and the overall design of a cast bullet is a subject on which I’m certainly not an expert. What little I do know is likely just enough to get me into trouble. Therefore I must rely heavily on the knowledge and experience of others. I will suggest that if you are considering a custom mould made to your specifications, one of the quickest ways to come up to speed on the various aspects of bullet design and develop a basic understanding of the pros and cons of a variety of shapes and dimensions is to purchase a cast-bullet design software program.
There are numerous programs available that will provide exterior ballistic data on the flight of a bullet once the bullet characteristics are defined. Many are free or can be downloaded for a nominal fee. But finding an affordable good bullet design program is another story. Researching what is available results in either expensive computer intensive programs for military projectile design or very basic limited programs offered by bullet suppliers or bullet equipment manufacturers. The only affordable, comprehensive cast-bullet design software programs that I’m aware of are sold by TMT Enterprises (http://www.tmtpages.com/). Three programs are available: Basic, Advance and Professional, and an Ultimate Companion Module. Once the bullet design is completed the software provides a bullet specification file (see Figure 6) ready to send to a custom mould manufacturer. TMT Enterprises’ website will give you a good overview of the program capabilities. Considering the cost of moulds, reloading supplies and time spent finding an accurate bullet, the programs are relatively inexpensive.
Note – Keep in mind, to successfully design a bullet that closely fits a chamber and bore, a chamber cast or impact impression and bore slug will be required to determine the chamber, throat and bore dimensions of your firearm.
Figure 6
Typical .40 Caliber Money Bullet Specification
Figure 7 is the results of using the Ultimate Companion Module to overlay the images of the case and bullet over the chamber. Since Browning designed the throat of the .40-65 BPCR with a freebore diameter 0.002” larger than the groove diameter, TMT’s software identifies the transition from freebore diameter to grove diameter as the freebore leade. Also note the throat includes the freebore, freebore leade and leade, and the chamber transition step is included in the freebore length.
Figure 7
Browning .40-65 Chamber with Case & Money Bullet
Bullet Design Considerations
If you decide to have a custom mould made it’s definitely worth spending some time researching and becoming familiar with the features and dimensions of a bullet besides the diameter, weight and length. The following are discussed in more details below: bullet length, driving band diameters and contact lengths, lube quantity and contact length, location of the lube grooves, nose design and alloy mix. Other design considerations include: tangent and secant nose shapes, ogive radius, meplate diameter, center of pressure (C.P.) and center of gravity (C.G.).
Bullet Length
A well-known bullet designer and shooter determined that the preferred bullet length in the Browning is 1.375” to 1.400”. One longer would potentially become unstable in the 16-twist bore. The four bullets displayed in Figure 1 have a length of 1.400” or less as noted below. The SAECO #740 is the shortest of the four and resulted in the worse accuracy in the 500 meter tests detailed further on in this article. Since others have reported success with the bullet in 16-twist barrels the length may not be an issue. There could have been other reasons for the SAECO 740 poor showing. Refer to additional comments on the bullet under the section titled, Shooting Test Results.
Bullet Lengths:
BACO JIM409400M4: 1.400”
Lyman Snover: 1.380”
Paul Jones Creedmoor: 1.375”
SAECO 740: 1.320”
Driving Band Diameter
A common reloading technique to increase accuracy is selecting a bullet with driving band diameters that can be used in un-resized fire-formed cases which fit the chamber dimensions as close as possible. But this is not feasible in the Browning due to the generous chamber neck diameter averaging 0.436”. Under firing conditions the case neck outside diameter (OD) will expand to match the chamber neck inside diameter (ID) and then shrink, generally 0.001” or so, allowing for extraction. The result is an average fire-formed case OD of 0.435”. Assuming the case wall is 0.011” thick (0.022” inclusive) the diameter of the ideal bullet driving bands would be 0.413” for slip fitting to 0.414” with 0.001” of tension. But a bullet with either dimension is not a good idea because the Browning freebore and groove diameters average 0.411” and 0.409” respectively.
Besides the fact that the body bands will not fit into the freebore or throat, firing a bullet 0.004” to 0.005” over groove diameter is risking accuracy problems. The chamber-to-throat transition step and bore will squeeze the bullet to a smaller diameter, resulting in body band and base band fining (an irregular base) which can have a negative effect on accuracy. Additionally, if a bullet with driving band diameters larger than 0.411” is used, the bullet must be seated deeper in the case since it would be too large to slide into the freebore, resulting in less powder capacity (limited velocity) and, depending on the nose design, loss of nose alignment and support from the freebore, leade or bore. Therefore, a bullet with driving band diameters of 0.409” to 0.410” is the solution, which means resizing the fire-formed case neck to a smaller diameter.
Driving Bands Contact Length
To hold sufficient lube when blow tubing BPCR bullets typically have several, relatively long and deep, grease (lube) grooves separated by body bands. Therefore, while keeping in mind the required bullet length, weight, nose design and total lube contact length, the bullet designer has to make a trade off of lube groove lengths versus the lengths of the driving bands (body bands and base band). Another consideration is lead fouling tends to be directly proportional to the length of the driving bands. The longer the bands the more “bearing surface” contacts the bore, increasing the possibility of bore leading. Realistically, 0.025” is likely the lower limit of a body band length. Many common bullet designs feature body band lengths of 0.050” to 0.060” with a few approaching 0.100”.
The base band length is another consideration. Since gas-check bullets are not allowed in sanctioned NRA silhouette matches, BPCR bullets must have a base band designed to handle the high pressures of expanding powder gases and prevent or minimize gas blow-by while retaining its shape, which is critical to maximizing accuracy. Therefore, the base band is typically longer than the body bands, significantly more so in some designs. In lieu of having no analytical data to support a specific length or range of lengths, I use the base band design of several successful bullets, which have lengths ranging from 0.075” to 0.100”.
Lube Quantity & Contact Length
When wiping between shots, lube volume is less of a concern and the lube grooves can be relatively shallow. In fact some shooters that wipe between shots have reported success with bullets without lube grooves. The bullets were cast or swaged with a rough surface and dipped in lube. But when using a blow tube, not only must the bullet carry sufficient lubricant to coat the bore to the muzzle to eliminate leading, the lube is also essential in helping to keep the powder fouling soft from shot-to-shot; especially in hot and dry condition. Two factors are important when designing lube grooves: volume and contact length. Adding up the length of the lube grooves determines the lube contact length. A well-known bullet designer and shooter found through rigorous testing that 0.250” of lube contact length is the minimum necessary for blow tubing. The length and depth of the grooves determines the lube volume or carrying capacity. Although the lube contact length may be adequate, if the grooves are not deep enough to carry sufficient volume the bullet may run out of lube prior to reaching the muzzle. A good method to determine if the bullet holds enough lube is to check the muzzle for a lube star, lack of which indicates insufficient capacity or possibly poor quality lube. But the presence of a lube star does not indicate adequate contact length. For example, if the lube grooves were deep but very short the lube quantity may be sufficient but much of it would not be available to lubricate the bore and would be thrown out of the grooves as the bullet exits the muzzle, creating a lube star.
A good example of marginal, I consider it inadequate, contact length and insufficient lube quantity when using a blow tube is the Lyman Snover with a contact length of 0.200" and lube capacity of only 1 grain. It's a nice looking bullet with an aerodynamic nose design, and under the right conditions it can be very accurate, but when the ambient temperature increases and the humidity drops the shallow lube grooves can become a liability when blow tubing.
Listed below are the total lube contact lengths and lube capacities (weight in grains) and volume (in cubic centimeters) of the four bullets in Figure 1.
Paul Jones Creedmoor: 0.340”, 2.2gr, 0.15cc
BACO JIM409400M4: 0.250”, 1.5gr, 0.11cc
SAECO 740: 0.300”, 1.4gr, 0.10cc
Lyman Snover: 0.200”, 1.0gr, 0.07cc
Location of the Lube Grooves
Another design consideration concerning lube grooves is the location of the grooves. Note that one of the lube grooves in Figure 7 is located directly under the chamber transition step, which is a good practice when loading BPCR ammo. As the relatively soft bullet obturates (expands under pressure), unless prevented by lube, lead will fill the transition step and may be smeared back along the driving bands or remain in the chamber step as a lead ring. Both can have a negative effect on accuracy. The ideal configuration places a lube groove under the transition step when the bullet is seated at the preferred seating depth. Should you prefer that the bullet contact the leade to aid alignment, then the dimensions from the contact point to the transition step should be determined and used to define the location of a lube groove, which is easier said than done even with accurate chamber and throat dimensions.
Nose Design
As mentioned in the Design Software section, I don’t know enough about the aerodynamic benefits of various nose designs to discuss the subject intelligently other than noting that the Money Bullet nose design is very aerodynamic, resulting in a bullet with a high ballistic coefficient. And based on bullet tipping tests it holds up better (more stable) at longer distances than other nose designs I’ve tried in the Browning. My hats off to the late Dan Theodore for popularizing the “Money Bullet” design.
Concerning bullet alignment, it should not come as a surprise to anyone that it’s one of the most important factors affecting accuracy. One method to ensure nose alignment of a cast bullet with a nose larger than the bore is to force the nose into hard contact with the leade. Another technique is to use a bullet with a bore-riding nose design with a nose diameter that closely matches the bore diameter.
When starting BPCR shooting I choose to go with a bore-riding nose design simply because the Paul Jones #40001 bullet could be seated much further out of the case, resulting in additional powder capacity and higher velocity. At the time I did not appreciate the alignment benefits of using a bore-riding design, which allows the full length of the nose to slide into and ride (rest) on the bore. But to utilize the nose for alignment the diameter of a portion of the nose must matched the bore (land) diameter as close as possible and still slide into a fouled bore with minimum resistance. When using a blow tube, a nose diameter of 0.001” less than the bore (land) diameter is usually sufficient to allow for fouling. If the nose diameter is significantly smaller than the bore, alignment will be compromised even with adequate obturation (bullet expansion). In that case it helps if the 1st body band wider than the nose is forced into firm contact with the leade. When wiping between shots the nose diameter can approach the bore diameter since there is little or no fouling to interfere with the nose when chambering a round.
Alloy Mix
Having limited experience with various alloys I don’t intend to make a recommendation on the preferred mix for a specific bullet design other than to pass along what has worked for me. BPCR shooters have reported success with relatively soft 30:1 (lead:tin) alloys to the harder 16:1, with some reporting that wheel weight alloys, typically containing antimony, work well for them. Having accumulated around 1000 lbs. of wheel weight alloys, I plan on experimenting with it in the future.
Some shooters use a softer alloy to ensure a loose fitting bullet expands (obturates) quickly when fired to completely fill and align the bullet in the throat and bore. My definition of a loose fitting bullet is one that does not closely match the throat and bore dimensions. Others firmly believe that if a bullet with a diameter smaller than the groove diameter is seated out to almost touch the lands and is fired in a bore with an oversize freebore, it will obturate, filing the freebore and self-align prior to being forced into the leade. I disagree with these approaches, firmly believing that a bullet out of alignment with the bore will not be symmetrical after it obturates. So what has worked for me so far?
It’s pretty simple. For bullets such as BACO’s JIM409400M4 Money Bullet and Lyman Snover 410663 with aerodynamic streamline noses with relatively little nose-to-bore contact I use 16:1 alloy to eliminate the possibility of nose slump since a substantial portion of the nose is not supported by the rifle bore. If the alloy is too soft the nose may slump resulting in an unbalance and therefore unstable bullet, especially at longer distances. But keep in mind that when using a harder alloy it’s more important that the bullet dimensions closely match the throat and bore dimensions in case the harder alloy does not adequately obturate. 18:1 or 20:1 alloy may work just as well with these bullets but I have not sufficiently experimented with either.
For bullets with a significant amount of nose-to-bore contact I’ve settled on 25:1. Examples are the Paul Jones 40001 Creedmoor and SAECO 740. I tried 30:1, 25:1 and 20:1 alloys with the Paul Jones mould and found no real benefit of one over the other. I believe it’s because the mould produces bullets with very uniform dimensions that closely match the throat and bore of my rifle, and my loading technique ensures chamber and bore alignment.
My Baseline Bullet Features & Dimensions
For Blow Tubing
When using a blow tube in central Texas summer conditions, the bullet will have the following features and approximate dimensions: Length of 1.400”, diameters of all driving bands (body bands and base band) of 0.410”, a 0.800” long “Money Bullet” nose design with a diameter of 0.399” (to allow for fouling). The 5 lube grooves would be 0.060” long and 0.030” deep with a total lube contact length of 0.300” and hold a minimum of 1.75grs of lube capacity. The bullet would have a base band length of 0.100”, four 0.050” long body bands and weigh as close to 400grs as possible depending on alloy composition.
For Wiping Between Shots
When wiping between shots, since lube capacity is less critical and fouling should not be a factor, an appropriate bullet would have the following features and dimensions: length of 1.400”, diameter of all driving bands of 0.410”, a 0.800” long “Money Bullet” nose design with a diameter of 0.400”. The base band length would be 0.100”. To increase the weight the two rear body bands would have a length of 0.075” and the five lube grooves would be 0.050” long and 0.025” deep and hold a minimum of 1gr of lube capacity. The two forward body bands would have a length of 0.050”. The bullet will weigh as close to 410grs as possible depending on alloy composition.
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After evaluation the four bullets pictured in figure 1 I decided to switch from blow tubing to wiping between shots. Not being satisfied with the four bullets including BACO’s JIM409400M4 as discussed earlier, I requested BACO make a mould to my Money Bullet design for wiping between shots. BACO decided to add it to their .40 caliber bullet mould selection as JIM410410M3.
Figure 8 is the specification I sent BACO, which they later listed on their website as JIM410410M3. If you’re wondering why TMT’s software was not used to create the specification, it’s because I decided on two different body band lengths to allow positioning one of the lube grooves under the chamber transition step when loaded. I don’t know if the current version of TMT’s software will handle different body band lengths but the version I have will not.
Figure 8
Bullet Specification Submitted to BACO
Figure 9 is a photo of the actual JIM410410M3 bullet and cartridge loaded with the bullet. It may not be obvious but BACO made some minor changes. The bullet is close to the specification I sent with the following changes: the 1st lube groove is slightly longer than the rest and the body bands are slightly longer than I specified. I expect that BACO “played” with the design to obtain the requested weight. It weighs 408grs with 16:1 alloy and right at 411grs with 20:1 alloy, which is what BACO used for the sample bullet shipped with the mould. The lube capacity is a little over 1.3grs. After experimenting with the bullet I prefer it over all the others I’ve tried so far.
Figure 9
JIM410410M3 Bullet & Loaded Cartridge
Wishing you great shooting,
Wayne