Advice wanted for a 458 wm build...

[charlie b]

And it is good advice. Especially the deeper seating being equal to a new cartridge.

Deep seating depends on the case. Some cases taper in thickness more toward the mouth than others. If you seat a bullet in the thicker region then you may have trouble chambering the cartridge or you may 'swage' down the bullet to a smaller size.

I'd rather use a filler for some loads. There is a sticky on using fillers that will help if you decide to go that way.

https://castboolits.gunloads.com/sho...use-of-fillers

PS forgot the other issue with deep seating. The bullet has to 'jump' further to get to the rifle bore. Many bullets do not like a long jump. Better to seat to the factory OAL and use filler if you need to.

PPS many powders do not need a filler with reduced charges. Most of my .308 cast loads are near 50% capacity and they shoot very well, around MOA out to beyond 300yd.

[mbarasing]

Article from M.L. McPherson: (I just ordered a book of his and hopefully can get more info)
"Deep Seating

First, seat bullets deeper and roll a gentle crimp over the ogive or driving band instead of into the crimping groove. You will need to reduce powder charge accordingly. Several years ago, I did a piece on this for Handloader's Digest, wherein I developed a table including corrections for every bore size and charge level. Quite boring. For most readers here I can simply suggest the basis of that table and let them do their own figuring.

Measure the percentage change in usable case capacity between load with deep-seated bullet and load with regularly seated bullet, then reduce charge precisely 3/4 of that percentage – e.g., if deep seating the bullet reduces usable capacity (volume under seated bullet) from 10 grains of water to 8 grains of water, percentage reduction is 20%. If, in standard load, correct charge is 5 grains of powder, correct charge in deep-seated load will be about 4.2 grains (20% x ¾ = 15%, 15% of 5 is 0.75, 5 – 0.75 = 4.25). This correction will be very close to ideal.
For those with a chronograph, to match pressure in both loads, look for a percentage velocity difference equal to 1/5 the percentage difference in usable capacity (with both cast and swaged bullets, peak pressure is basis of accuracy). Again, consider our example, if the full-length load launches bullet at 1000 fps, shorter version will generate same peak pressure when it launches bullet at about 960 fps (1/5 x 20% = 4%, 4% of 1000 = 40, 1000 – 40 = 960). Unless volume difference becomes unusually large, perhaps >33%, these corrections will hold with sufficient accuracy for the purpose.

Advantages of deep seating are legion. First, this approach provides for significantly greater bullet pull, which retards initial bullet movement and improves shot-to-shot ignition consistency. Second, more of charge will burn before bullet base clears case mouth and subsequently barrel-cylinder gap, which makes for a cleaner load. Third, with less unused boiler room, primer will do a better job of igniting charge, which improves consistency. Fourth, charge will more nearly fill boiler room, which can significantly reduce powder position effect – see below. Finally, bullet will move further before clearing cylinder, so that more energy will have been imparted into bullet before venting begins – for various reasons, this improves ballistic uniformity."

William C. Davis, Jr. says –

“It is obviously possible also to increase the free run simply by seating the bullet more deeply in the case. That has two effects on chamber pressure, which are in opposite directions. The increased free run tends to decrease pressure, but the decrease in powder space increases the loading density, which tends to increase pressure. Which effect will predominate depends on the characteristics of the particular load and gun. In most full-charge loads, it is found that the pressure decreases at first as the bullet is seated farther away from the lands, but beyond some particular seating depth, the pressure begins to rise again as the powder space is further reduced. In revolvers, the free run through the cylinder is always relatively great, and increased seating depth always increases the chamber pressures.”

And here is a study from University of Michigan:
https://deepblue.lib.umich.edu/bitst...354?sequence=4

"IX. PRELIMINARY OBSERVATIONS ON THE EFFECT OF SEATING DEPTH ON MAXIMUM
CHAMBER PRESSURE IN THE.30-06 CARTRIDGE
(R. Sinderman, K. Jacob and L. E. Brownell)
A. Reasons for Tests
There was no intent to investigate the effect of seating depth in these preliminary studies. However, the investigation of reported
crusher gage values versus pressures determined by strain gage measurements for various loads for the.30-06 cartridge inadvertently introduced the problem of seating depth. One experimental loading involved a charge of 53 grains of 1MR 4o64 powder used with the 150 gr. Remington SPCL *Receiver No. 614677, U.S. Springfield Armory was used in high-pressure
tests.


The 220 gr. Remington SPCL bullets used as a standard of reference were round-nosed and for this reason the first firings of the 150 gr. Remington SPCL bullets also used a round-nosed (30-30 type) bullet. The seating depth required to give an overall cartridge length of 3.27 inches gave only about 1/8 of an inch of bullet seat within the case. Firing these rounds produced
unexpectedly high pressures in excess of 70,000 psi absolute pressure.
An attempt was made to investigate the unusually high pressures obtained. Remington produces three different 150 gr. SPCL bullets designed for three different seating depths and we first thought that the wrong bullet was being used. The pointed version of the SPCL bullet gives a more reasonable depth of bullet seat in the case for an overall length of 3.27 inches listed by NRA.* Therefore firings loaded with IMR 4064 powder with various seating depths were made with the 150 gr. SPCL (RN) Remington bullet. However, high pressures were still observed over a range of seating depths as shown in Table II and Figure 19. Substituting the pointed SPCL bullet for the round-nosed bullet failed to give a crusher value less than 54,000 psi at any seating depth.
The Du Pont handloading tables for center-fire rifle(l) report that 52.0 gr. of 4064 powder give a crusher value of 49,700 psi. An
additional charge of 1.0 grains would be expected to raise the pressure possibly 3,000 to 5,000 psi. Other loading sources such as The Speer Handbook(l2) and P. 0. Ackley(l3) indicate that 53 grains of 4064 powder and a 150 gr. bullet is approximately maximum for the 30-06 cartridge. The pressure reported by NRA for this load appears to be low. To compare the observations on seating depth with data obtained on IMR 3031 powder and the 220 gr. Remington SPCL bullet a second series of preliminary tests were made as described in Table III and shown in Figure 20.
B. Discussion
Two opposing factors influencing the chamber pressure are believed to be involved if bullets are seated at various depths with a
given charge of powder. One effect is that of change in the volume of the case to the bullet base. Boyle's Law for gases states that if the temperature is not varied the pressure of a confined gas times its volume remains a constant. Or, stated as an equation.
PxV = C
where
P = gas pressure, psi,
V = volume of confined gas, cu. in. and
C - is a constant which depends on the mass of the gas, (grains), the temperature of the gas, and the average molecular weight of the gases produced by burning of the powder.

For a given type of powder, the temperature of the powder gas versus fraction of powder charge burned and the average molecular weight of the gases may be considered to be fairly constant. Therefore, the mass of the gas will be determined mainly by the weight of powder burned. If a given per cent of the charge is burned the larger charge will produce a greater pressure; i.e., if a charge of 40 grs. of a certain powder is used, one would expect to get a larger number for the constant than if 30 grs. of the same powder were used. Also, if one were to increase the temperature of the confined gas, the product of the pressure
and volume would increase (according to Charles' Law) thereby increasing the constant, C.
The second effect is termed gas leakage. In most rifles the bullet is allowed to travel some distance before engaging the rifling
of the barrel. This distance is termed "free-travel distance". Some gas will leak past the bullet after the rise in chamber pressure expands the neck of the cartridge case but before the bullet starts to move. In other words, some of the gases produced by the burning powder actually enter the barrel before the bullet during the period of the "free-travel" of the bullet and before it is forced tightly into the rifling. High-speed photography has been used to record this phenomenon and show that a small portion of the powder gases actually come out of the muzzle before the bullet. The egress of initial volume of gas is followed by the bullet
and then by the major volume of powder gas.

Because of the larger volume of this larger charge
it was impossible to seat the bullet more than 3/16 inch into the case
from the cannelure. Also, because of the shorter length of the bullet
it was impossible to seat the bullet out far enough to engage the rifling. However, the two opposing effects were still observed as shown in Figure 19. The chamber pressure reached a minimum value when the bullet was seated out 1/16 inch from the cannelure; but if the bullet was seated 5/16 inch out or 3/16 inch in from the cannelure a higher maximum pressure was produced. This indicates that the minimum value for maximum chamber pressure can be expected to be different for different powder charges and bullet weights. A difference of about 6,250 psi was observed between the minimum and maximum values of absolute maximum chamber pressure.
In the second series of tests a 220 gr. Remington SPCL bullet was used with a charge of 38 grs. of IMR 3031 powder. The charge of 38 grs. of IMR 3031 produces a moderate pressure when the bullet is seated at the cannelure. The effects on pressure of the extremes of seating the bullet: (1) out to the rifling, and (2) in tOethe point of powder compression were not known, therefore, a reduced load seemed advisable. The reduced charge of 38 graihs also permitted seating the bullet completely into the case without causing the powder grains to be excessively compressed or to be partially broken. Bullets were seated over a range from 1/4 inch out from the cannelure to 13/16 inch from the cannelure. Seating the bullets out 1/4 inch actually engaged the 220 gr. Remington SPCL bullets with the rifling when the bolt was closed. This seals the barrel so as to produce a minimum of gas leakage past the bullet. Consequently, essentially all of the gases produced by the burning of the powder contributed to increase of the pressure in the chamber. This tends to produce a higher maximum chamber pressure in spite of the slightly larger case volume
produced by seating 1/4 inch out from the cannelure.
At the other extreme of seating the bullets were pushed into the case 13/16 inch past the cannelure. The bullet at this seating must travel about 1-1/16 inches of "free-travel" before engaging the rifling. An increase in pressure again was noted. This is a result of Boyle's Law effect. When the bullet is seated into such an extreme the case volume is reduced to such an extent that the pressure increases in spite of the greater leakage of gas.

Intermediate seating depths produced intermediate pressures as shown in Figures 19 and 20. Figure 20 for IMR 3031 powder and 220 Remington SPCL bullets indicate that the pressure reaches a maximum at the smallest seating depth of 1/4 inch with the bullet in contact with the rifling. As the seating depth of the bullet is increased pressure decreases due to the gas leakage past the bullet into the rifle barrel.
Boyle's Law would predict that the pressure would rise because of the decrease in volume, but apparently this is overshadowed by the gas leakage past the bullet. The chamber pressure appears to reach a minimum value at a seating depth of about 1/4 inch in from the cannelure. This corresponds to a total bullet seating depth of 13/16 inch. At greater seating depths the pressure rises again. This rise in maximum chamber pressure, as stated previously, is believed to be due to the predominence of Boyle's Law effect. Though considerable gas is leaking past the bullet, gas leakage is now overshadowed by the large decrease in the case
volume to the base of the bullet. This decrease in case volume increases the maximum pressure rapidly as shown by Figure 20. The maximum pressure is over 5,000 psi greater than the minimum value produced with the bullet seated 1/4 inch in from the cannelure. On the other hand the maximum pressure increases about 10,000 psi above this minimum when the bullet is seated out so that it engages the rifling. Thus, some danger of excessive pressure is involved if seating depths are used which differ
appreciably from those used in loadings known to be safe."

[mbarasing]

And it is good advice. Especially the deeper seating being equal to a new cartridge.

Deep seating depends on the case. Some cases taper in thickness more toward the mouth than others. If you seat a bullet in the thicker region then you may have trouble chambering the cartridge or you may 'swage' down the bullet to a smaller size.

I'd rather use a filler for some loads. There is a sticky on using fillers that will help if you decide to go that way.

https://castboolits.gunloads.com/sho...use-of-fillers

PS forgot the other issue with deep seating. The bullet has to 'jump' further to get to the rifle bore. Many bullets do not like a long jump. Better to seat to the factory OAL and use filler if you need to.

PPS many powders do not need a filler with reduced charges. Most of my .308 cast loads are near 50% capacity and they shoot very well, around MOA out to beyond 300yd.

I will experiment with fillers...And thanks for the link...I found a thread on this forum mentioning using corn starch packing peanuts as filler too. cool idea. My only concern with fillers, and it may be for not, is creating problems with the suppressor. The ideal solution would be to maintain factory spec COAL--although I am finding that factory 458 WM rounds vary by a quarter inch or more in length and the chamber is designed with 1.1" jump before bullet engages rifling, from the factory! Apparently weatherby's also use a large free bore design although I have yet to tackle that subject.

[44MAG#1]

You are reaching into brain over.oad for someone that isn't into reloading. That can have a negative effect just as lack of knowledge can have. Get educated at a rate you as an individual can handle and absorb. Most of us started out being carried, then crawling, then walking and then running.
Knowledge is the same.
As you found out 458 Mags have a long throat. That us the reason zi wouldn't shoot 2 in cases. At least a deep seated bullet in a 458 Mag case will have some support to the bullet as it traverses to the throat in that extra half in longer case instead of no case support for that half inch.
If you have a Freebore that is a very close fit to the bullet the wobble won't be as bad as a hog wallow Freeborn. There again YOUR experimenting will deliver the answer to your particular case.
Let me give an example with the 45/70. Garrett Custom ammo, which is an excellent ammo deep seats a 540 grain bullet and the Hornady 500 grain Solid so both will fit the Marlin Lever action. Both bullets have a crimp groove but both are placed for the 458 Mag rifles not the 45/70. The ammo is taper crimped on the bullet sides.
Ask me how I know.

[mbarasing]

You are reaching into brain over.oad for someone that isn't into reloading. That can have a negative effect just as lack of knowledge can have. Get educated at a rate you as an individual can handle and absorb. Most of us started out being carried, then crawling, then walking and then running.
Knowledge is the same.
As you found out 458 Mags have a long throat. That us the reason zi wouldn't shoot 2 in cases. At least a deep seated bullet in a 458 Mag case will have some support to the bullet as it traverses to the throat in that extra half in longer case instead of no case support for that half inch.
If you have a Freebore that is a very close fit to the bullet the wobble won't be as bad as a hog wallow Freeborn. There again YOUR experimenting will deliver the answer to your particular case.
Let me give an example with the 45/70. Garrett Custom ammo, which is an excellent ammo deep seats a 540 grain bullet and the Hornady 500 grain Solid so both will fit the Marlin Lever action. Both bullets have a crimp groove but both are placed for the 458 Mag rifles not the 45/70. The ammo is taper crimped on the bullet sides.
Ask me how I know.

It's just how I research things... Also this gun has been on my mind for quite a while. I have no problems starting slow, but before even getting involved I want to know if the end goal and the possibilities align.

And... I am using this thread to collect the information I find so I will have single place to go to.

Also... How do you know?

[kenton]

On the SMS website you linked on the first page the description for the 77/44 says they have 8" of rifling for a 20" barrel. I'm not sure you will get much of anything out of that for a 458 win mag other than a bunch of un burnt powder in your suppressor. If you go with 14" of rifling I don't think you will get much sound moderation with a 6in suppressor.

I recommend deciding exactly what you want your gun to do. Then get in touch with the company and explaining what you want to accomplish. They will probably have a better idea how to do what you want to do using their product.

I suspect they will recommend a smaller case that can use faster burning powder, if I understand your goals correctly.

[44MAG#1]

I have shot Garrett ammo and disassembled one of each. Plus I have shot Hornady 500 gr Solids in my rifle and handgun.

[mbarasing]

On the SMS website you linked on the first page the description for the 77/44 says they have 8" of rifling for a 20" barrel. I'm not sure you will get much of anything out of that for a 458 win mag other than a bunch of un burnt powder in your suppressor. If you go with 14" of rifling I don't think you will get much sound moderation with a 6in suppressor.

I recommend deciding exactly what you want your gun to do. Then get in touch with the company and explaining what you want to accomplish. They will probably have a better idea how to do what you want to do using their product.

I suspect they will recommend a smaller case that can use faster burning powder, if I understand your goals correctly.

Good suggestion, I have done so and await feedback. As far as deciding what I want my gun to do: I want a 45-70 bolt action, or the closest thing to it, that I can shoot without ear protection. (The only reason I even want it bolt action is for the integral suppressor, otherwise I'd be fine staying with a lever.)

[mbarasing]

Ed Harris's "The Load" using Red Dot shotgun powder for reduced load rifles

https://www.hensleygibbs.com/edharri...The%20Load.htm

[richhodg66]

The .458 Win Mag loads down easy. Shot mine quite a bit with Trap Door level loads of Unique out of the old Lyman manual. REcoil is nothing, but my rifle weighs about 13 pounds.

Data is here; http://marvinstuart.com/firearm/Manu...-%20Reduce.pdf

[mbarasing]

I have shot Garrett ammo and disassembled one of each. Plus I have shot Hornady 500 gr Solids in my rifle and handgun.

Your Encore... does it have a 14" barrel? How short of a barrel is too short? I've been emailing Suppressed Weapon Systems, they won't guarantee hearing safety on the 458 win mag under 28" (that's barrel and suppressor), they are also figuring off of factory loads. They also can suppress a lever BLR (no mag tube) so I'm trying to see if they can do 45-70 in a BLR, which oddly isn't currently offered by Browning.

[44MAG#1]

Your Encore... does it have a 14" barrel? How short of a barrel is too short? I've been emailing Suppressed Weapon Systems, they won't guarantee hearing safety on the 458 win mag under 28" (that's barrel and suppressor), they are also figuring off of factory loads. They also can suppress a lever BLR (no mag tube) so I'm trying to see if they can do 45-70 in a BLR, which oddly isn't currently offered by Browning.

My Encore 458 Win Mag has a 14 inch barrel. It will safely do slightly over 1900 fps with a 500 grain Hornady bullet. My 45/70 Encore has a 15 inch barrel and will do close to 1500 with a 550 grain cast. I have had it slightly over 1500 fps.

[mbarasing]

My Encore 458 Win Mag has a 14 inch barrel. It will safely do slightly over 1900 fps with a 500 grain Hornady bullet. My 45/70 Encore has a 15 inch barrel and will do close to 1500 with a 550 grain cast. I have had it slightly over 1500 fps.

Any idea how a 10 or 12" barrel would perform? The builder recommends 8" of baffle stack. I'd be satisfied with 1700 fps at 350-400 grain bullet. Maybe closer to 2000 on some 250-300 grains

[44MAG#1]

Any idea how a 10 or 12" barrel would perform? The builder recommends 8" of baffle stack. I'd be satisfied with 1700 fps at 350-400 grain bullet. Maybe closer to 2000 on some 250-300 grains

A 458 Mag will easily get that. So Will a 45/70 that is in the Encore class. An SSK Contender 14 inch barrel will get 1550 to 1600 with a 400 grain Speer bullet and 1350 or so with a 500 grain Hornady. But, that barrel has a long throat so the 500 gain Hornady can be seated out. My 45/70 Encore barrel is what I call a 'No throat" barrel. But the Encore is stronger than the Contender.
I almost never piddled with light bullets. I did shoot some 300 grains Barnes bullets in the 458 and got substantially over 2000 fps

[44MAG#1]

MBARASING,

Sent you a PM

[mbarasing]

The .458 Win Mag loads down easy. Shot mine quite a bit with Trap Door level loads of Unique out of the old Lyman manual. REcoil is nothing, but my rifle weighs about 13 pounds.

Data is here; http://marvinstuart.com/firearm/Manu...-%20Reduce.pdf

Thanks for the rresource! Somehow I missed it last night.

[Jim22]

Before I put away what has beeen working for me and spending a bunch of moolah on new guns, reloading equipment, and suppressors I would find someone who has a few suppressors I can try. My experience is limited but what I do know is that suppressors are not vrey effective on supersonic rounds like the .243, .30-30, or the Creedmoor. Even with the best suppressors these cartridges still produce more than 100 dB of noise. That will still give you hearing damage. There are good reasons why subsonic rounds like a 200 gr. .300 BLK were developed. They don't create the sonic boom "Crack".

[mbarasing]

Before I put away what has beeen working for me and spending a bunch of moolah on new guns, reloading equipment, and suppressors I would find someone who has a few suppressors I can try. My experience is limited but what I do know is that suppressors are not vrey effective on supersonic rounds like the .243, .30-30, or the Creedmoor. Even with the best suppressors these cartridges still produce more than 100 dB of noise. That will still give you hearing damage. There are good reasons why subsonic rounds like a 200 gr. .300 BLK were developed. They don't create the sonic boom "Crack".

Good advise. I have an integrally suppressed 300 blk on an AR. I have used a twist on for a 6.5 CM for predator hunting and it has been great... but it throws the balance off and the length is awkward getting in and out of truck, or even climbing on top of truck with it. Your right in that none of them whisper. And even with subsonic 300 blk all the pigs run once you shoot one anyway. But I've never used ear protection with a suppressor even with supers and I've never had my ears ring. Probably not the best test...but the ear ring test is enough for me.

It's so nice when everyone one your team for a predator competition has a silencer... you can all talk and BS and then listen for critters answering calls and still shoot at anytime.

And over the years I believe I have tried every passive and powered ear protection available...with and without amplifiers and so on. Nothing has been better than a suppressed weapon for me so far

So now I want to take the suppressors out of the shooting range and fixed position predator calling or target practice world and put it on what I shoot most often with...the truck gun, the gun I throw in the boat when I head down river, the gun that is grabbed anytime for anything. The gun I can open up with when the pigs run by even if my kids are in the truck helping me haul hay. Get it?

My cousin doesn't get it and that's OK... he uses a twist on for long range competitive shooting. He likes being able to change barrels out or upgrade them without getting a new stamp. All his guns are already half a mile long and heavy as !!!! anyway. They have nice hardcases to relax in until the next use, my truck gun has no case. That's his world...mine is different.

[pacomdiver]

been browsing this thread, i havent seen a suggestion of building a 458 socom yet, its a big 45 cal bullet with knockdown power and can be easily suppressed without any fillers and there have been multiple builds off rem 700 actions
and even integral suppressor with the McCree chassis, it should be abt 26 to 28 inches folded, that plenty short for a truck gun

a 250g bullet at 2150fps is carrying 2565 ft lbs of torque and
a 600g bullet at 1000 fps is still carrying 1336 ft lbs of torque, pretty much a flying cinder block

[ulav8r]

Torque definitions: n. The measure of a force's tendency to produce torsion or rotation about an axis, equal to the product of the force vector and the radius vector from the axis of
rotation to the point of application of the force; the moment of a force.
n. A turning or twisting force.

The torque of a bullet has no practical effect. The energy measured in foot pounds does have effects on impact with a target.