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) :veryconfu 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 ! :grin: 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

[jrayborn]

It seems to me that if you are having difficulty extracting fired cases that are well under book max, you may have an issue with the chambers. Have you inspected/measured the chambers for any rough machining or possible reverse taper?

[mozeppa]

maybe i missed it....what powder are you using and how much?

[onelight]

Have you tried any factory loads in it ?

[Tatume]

I've read this thread twice. The bullet isn't correct for the cartridge, the powder isn't named, the charge isn't specified, the velocity attained isn't given (except that it isn't enough), and the source of data isn't stated. I'm not willing to speculate on how to correct a problem when so little is known.

[memtb]

OK, thought the data was sufficient, but, I guess not!

Bullet: incorrect......please explain!
Powder: AA 1680, 38.0 grains some pressure signs (extraction) with only 1304 avg fps
WW 296, 31.0 grains, extremely difficult extraction with 1450 avg fps
Primer: Winchester LRM
Brass: Hornady
Cylinder/barrel clearance: 0.004”: as best I can determine onthe tight end of S&W specifications




Factory loads: Yes, Hornady 200 grain.....no extraction issues. Revolver clean or dirty
Chamber issues: uncertain! Do not have the means to do an exact, proper measurement or inspection. By visual.....they appear good! As stated previously.....factory loads showed no issues


I hope that this has better explained the many of the possible variables! memtb

[onelight]

The reason I ask about factory loads is a few full power factory loads will tell you if the gun is ok if you have no way to measure pressure and you starting with hot loads it's hard to tell if you have a problem with the load or the gun . I would hope to avoid buying those expensive factory loads but would sure be nice to test the gun before doing work ups .
44mag and hot 45 colt is the top of my experience in hand guns you are in a whole different category

[Tatume]

Factory 454 Casull ammo causes hard extraction sometime, and I wouldn't be surprised if factory 460 S&W does also. Remember they are running in the neighborhood of 60,000 PSI.

[Tatume]

OK, thought the data was sufficient, but, I guess not!

Bullet: incorrect......please explain!

You said the bullet is too long and you can't use the crimping groove, and you're considering shortening cases so you can use this bullet. That tells me the bullet is incorrect for the cartridge. That's not to say it can't be made to work. That's up to you.

[Tatume]

Bullet: incorrect......please explain!
Powder: AA 1680, 38.0 grains some pressure signs (extraction) with only 1304 avg fps
WW 296, 31.0 grains, extremely difficult extraction with 1450 avg fps
Primer: Winchester LRM
Brass: Hornady
Cylinder/barrel clearance: 0.004”: as best I can determine onthe tight end of S&W specifications

Factory loads: Yes, Hornady 200 grain.....no extraction issues. Revolver clean or dirty
Chamber issues: uncertain! Do not have the means to do an exact, proper measurement or inspection. By visual.....they appear good! As stated previously.....factory loads showed no issues

Your WW 296 load looks reasonable, I don't know AA 1680 very well. According to Hodgdon yor load is generating more than 45,000 PSI. If it were me I would be concerned about cracking the forcing cone unless the bullets are very, very hard. You should read about the 454 Casull and Freedom Arms suggestions on bullets.

[onelight]

Factory 454 Casull ammo causes hard extraction sometime, and I wouldn't be surprised if factory 460 S&W does also. Remember they are running in the neighborhood of 60,000 PSI.
Learned something new I do every time I show up .

[Tatume]

http://freedomarms.com/loading/index.html

454 Casull for comparison:

TIP #4: AFTER REFERRING TO YOUR FAVORITE RELOADING MANUAL.
An important fact to remember while loading above 1400 F.P.S.. The construction of the bullet is very important. The intent of the final loaded round is also important, and needs to be considered also. Most commercially made pistol bullets available today are designed for expansion at velocities below 1400 F.P.S. Using bullets above this velocity results in poor accuracy, because the bullets can not withstand the higher pressures generated at these higher velocities. The deformation of the bullets base when fired results in poor accuracy. The higher velocities also cause bullet jacket separation and bullet weight loss, during uncontrolled expansion. When the pressure is high enough the jacket could separate from the bullet in the cylinder, or in flight.

ALSO ANOTHER IMPORTANT FACT IS, THE FASTER THE VELOCITY AND THE SOFTER THE BULLET, THE QUICKER THE FORCING CONE AREA IN THE BARREL WILL WEAR OUT.

[memtb]

Load Data Source:
http://www.reloadammo.com/460sw.htm
https://www.hodgdonreloading.com/data/pistol
http://www.ballistics101.com/460_sw.php
http://www.accuratemolds.com/bullet_detail.php?bullet=45-400A-D.png

Bullet sized to 0.452”


Tatume, below are photos of the cartridge using the above bullet. The bullet on the left, is the factory, untrimmed 460 case. The cartridge on the right shows the shortened case (- 0.020”), with bullet seated as to crimp in the second groove.....putting the cartridge OAL very near the end of the cylinder, increasing internal loaded case capacity.
OAL with standard case, bullet seated to last crimp groove: 2.243”
OAL with trimmed case (-0.020”), bullet seated to second crimp groove: 2.350”

An OAL gain of 0.107” case internal capacity, which may not be of any help!

If time allows, I will test my theory today! memtb
https://i.imgur.com/KCdJUVFl.jpg

[memtb]

nawagner, I wasn’t aware that the “roll-crimp” could be used anywhere on a cast bullet. Thanks, I actually learned something all of this! The “roll crimp” may be the most beneficial and practical solution to a problem that really didn’t exist! Thanks, memtb

[memtb]

onelight, Thanks for the factory load suggestion. When purchasing the handgun, also acquired some factory rounds for brass. They exhibited no excessive case extraction issues. Some resistance yes.....but, not excessive!

According to all of the data that I’ve been able to accumulate, I shouldn’t be in an excessive pressure situation! memtb

[kenton]

It may not be an issue anymore but when my BIL first bought his 454 Casull he had a lot of issues with Hornady factory ammo having sticky extraction but no issues with other brands. Supposedly Hornady brass wasn't hard enough and would swell, causing problems. It might be worth while to try another brand of brass to rule that out.

[memtb]

Thanks kenton, just received some Starline brass, maybe can help! memtb

[memtb]

As per a question by Dusty Bannister through a pm, I may have discovered my problem. My bullets, though sized to 0.452”, will not easily pass through the cylinder throat. I have no means of measuring the throat diameter, unless I “slug” the throats. I couldn’t drive the bullets through the throat using a dowel and the palm of my hand....they’re pretty darn tight! memtb

[Tatume]

Cast bullets that are oversized to the throats are less likely to cause pressure excursions than bullets that are too soft and expand into the forcing cone. You should be using an alloy with a large antimony content and heat treatment (water quenching when dropped from the mold is the most usual).

I regularly shoot 320 grain bullets in two 454 Casull revolvers (FA 83 and Ruger SRH) well in excess of 1450 fps with no problems at all. They are cast of clip-on wheel weight metal and dropped from the mold into a bucket of water. They are hard as tempered masonry nails. The cases fall freely from the chambers, and they kill like lightning.

[memtb]

Cast bullets that are oversized to the throats are less likely to cause pressure excursions than bullets that are too soft and expand into the forcing cone. You should be using an alloy with a large antimony content and heat treatment (water quenching when dropped from the mold is the most usual).

I regularly shoot 320 grain bullets in two 454 Casull revolvers (FA 83 and Ruger SRH) well in excess of 1450 fps with no problems at all. They are cast of clip-on wheel weight metal and dropped from the mold into a bucket of water. They are hard as tempered masonry nails. The cases fall freely from the chambers, and they kill like lightning.

My goals are similar, kill like lightening, accurate, and in the 1400 fps range with no pressure issues! I do not recall if I stated......but, my bullets are cast from wheel weights as well!

I tried the bullet “drop test” through the cylinder using a jacketed bullet....it also stuck! I mic’d it to 0.452” as well.I think that perhaps the first order of business is to verify my micrometer accuracy, and go from there! The more questions I address....the more possibilities “rear their heads”! I may be several days before I validate the micrometer and get the barrel and cylinder “slugged”. Don’t give up on me....I will be back once a few things are verified!

Thanks for all of the help and suggestions, memtb

[Tatume]

There are lots of threads on this list that describe the ideal relationship between chamber throat diameter and barrel groove diameter. There are also many threads that explain how to measure both. Find them, or PM DougGuy for advice.

[memtb]

Thanks Tatume memtb