Thinking Outside the Box - Opinions Requested

[memtb]

Firearm: S&W 460 XVR, 8 3/8” barrel, 400 grain cast bullet


I started another thread concerning my high pressures with somewhat lowish velocities with below listed maximum loads!

I also measured cylinder to barrel gap @ 0.004”, plenty close. So, that shouldn’t be the cause for my lowish velocity.

Here is my thought! If I seat the bullet farther out.....will it lower chamber pressures appreciably? If so....to utilize my full cylinder length and have the ability to use the crimping grove, the bullet extends beyond the cylinder approximately 0.015”.

So, here’s the question. Should I shorten (trim) the case length by 0.020”,seat the bullet to have the crimping groove align with the case mouth.....thereby, keeping the OAL within the cylinder. Or.....is this an exercise in futility!

Thanks for your opinions on my little issue! memtb

[35remington]

Short answer is “no.”

Please explain low velocity at high pressure. What speed are you getting with what load? How do you know you have high pressure?

[Winger Ed.]

Shortening the case length,
and taking full advantage of the crimping grove would seem to be something that will increase pressure.

[USSR]

Would be helpful to know what cartridge and bullet we are talking about.

Don

[memtb]

First an apology.....I failed to indicate the firearm involved.....S&W 460 XVR!

Winger Ed, the OAL would be substantially increased, well in excess of the 0.025” the case was shortened. Technically, more case volume...with less bullet in the case and the bullet moved forward, toward the end of cylinder!

35remington, the pressure was high enough that the cases had to be driven from the cylinder with a wooden dowel. The load was above the starting load, but several grains below maximum. The velocity was approximately 75 tp 100 fps less than listed maximum using the maximum charge. I figured that the listed max should be within reasonable pressures, and with my load several grains below that....well within maximum pressures. I guess not!

I could live with the lower velocities, but not very difficult extraction. So, if I back the powder down to eliminate case sticking ....the velocities would likely get lower as well. So....there goes the velocity I could live with! memtb

[memtb]

Would be helpful to know what cartridge and bullet we are talking about.

Don

Sorry Don....I suffer from HURS(head up rectum syndrome) I failed to realize that you guys aren’t mind readers! memtb

[USSR]

No problem, memtb. Afraid I'm not gonna be much help here other than to say with a behemoth like that you probably get a little recoil and you sure do want to crimp into a crimp groove. Looks like if you want to use that bullet you're gonna have to shorten the case some what.

Don

[Winger Ed.]

Winger Ed, the OAL would be substantially increased, well in excess of the 0.025” the case was shortened. Technically, more case volume...with less bullet in the case and the bullet moved forward, toward the end of cylinder!

More space in the case decreases pressure. More crimp increases it.
You might be canceling them both out and end up where you started.

I'd try a different and slower powder.
Then get off into a taper or different amounts of a roll crimp.

I'd be concerned with pressure. Get pressure to a safe level, tinker with accuracy, and let speed fall where it does.

[memtb]

WingerEd, valid points.

However, a pretty good crimp is needed to stop bullet creep during recoil. While I’m crimping....I’m trying to minimally do so!

I only have two powders to work with...the other shows substantially(100+) lower velocities with mild pressure indications.

I hoping that with the increased case capacity, I might be able to stay with or slightly increase the charge weight.....yet stay out of pressure issues!

This may truly be an exercise in futility! Thanks for you advice!

[memtb]

Thanks Don, I’d really like to stay with this bullet....really don’t want to use that new mold for a trout line sinker! I’m just exploring possible options....thanks again! memtb

[Chad5005]

may i ask what bullet youre loading

[memtb]

may i ask what bullet youre loading

Yes sir.....400 grain cast WFP, from an Accurate Mold. memtb

[35remington]

Revolvers can be very individualistic in terms of velocity obtained with a given load.

I too would suggest another powder and trying again, but if you don’t already have it you won’t get it. Is the bullet used identical to that used in the reference data?

If it is not some differences or reasons for some difference in results may be found.

[nawagner]

memtb, have you actually measured bullet length of bullets that were in the gun after a firing to see if they are moving? I’ve found that the bullet creep is minimal if the right neck tension is there. You won’t know though until you check it. Also are you taper crimping or roll crimping? A roll crimp will work anywhere on a cast bullet and does not necessarily need to be in the crimp groove.

I shoot a Ruger 480 and don’t worry about being in the crimp groove and have no problems.

[memtb]

35remington, the bullet is not a replica, but very similar in design and 5 grains heavier! Again, your correct on all counts, however....I really thought I could get close to published velocities (100+/- fps) within safe pressure parameters! Perhaps the published data, is right on the edge of “too much”! memtb

[35remington]

Well, I suppose if seating depth varies between your bullet and the data bullet some variance might be expected.

In a practical sense, is there such a thing as an ineffective 460 load shooting a 400 grain bullet if it is accurate? Why not see how well you can get it to shoot, safely, and the speed you get is what it is. Highly doubt it will bounce off anything.

Sometimes accepting the (safe) results you get if accuracy is there is no great cross to bear.

[memtb]

Well, I suppose if seating depth varies between your bullet and the data bullet some variance might be expected.

In a practical sense, is there such a thing as an ineffective 460 load shooting a 400 grain bullet if it is accurate? Why not see how well you can get it to shoot, safely, and the speed you get is what it is. Highly doubt it will bounce off anything.

Sometimes accepting the (safe) results you get if accuracy is there is no great cross to bear.

35remington, again you have it covered pretty well. You’re quite correct, penetration will be a non-issue. I was hoping safely, accurately gain a little velocity, to help flatten trajectory as much as possible out to 150 yards or so! Thanks again for all of your comments! memtb

[500aquasteve]

Would it be safer to use published velocity as a pressure indicator and back off the charge until you find the culprit? When you are already almost 2x speed of sound, 100 ft/sec slower isn’t that much. Are your readings consistent? Accurate? What is the cylinder gap?

[memtb]

Would it be safer to use published velocity as a pressure indicator and back off the charge until you find the culprit? When you are already almost 2x speed of sound, 100 ft/sec slower isn’t that much. Are your readings consistent? Accurate? What is the cylinder gap?

Our speed of sound around here is about 1100 fps ! If I were only 100 fps short of 2200 fps....a non-issue. But, with substantially lower velocity potential....100 fps is a much higher percent reduction of velocity. Using published data.....I’m several grains below on powder charge, 150 fps below published velocities and must drive the cases out of the cylinder.

Velocities are fairly consistent, accuracy needs to be better (could be the shooter), and the cylinder gap is 0.004”. The cylinder gap was my first concern, but, I’m pleased with only 0.004”!

I’m shooting heavy bullets and hoping for somewhere north of 1400 fps (published data shows approx1525 fps) at safe, case extractable pressures! memtb

[500aquasteve]

0.004” is super high tolerance, you are Lucky. Mine had 0.010” and just got it back yesterday from S&W repair shop to measure 0.009” after they tightened the end play from 0.004” to 0.001”.

What primers are you using? I just watched a utube primer test video showing well over 100fps difference between federal magnum (215) and federal magnum match (GM215), the latter did not show a velocity response to published load pressures. I can find it if you want to view