|
|
Post by Encore64 on Mar 30, 2022 19:32:43 GMT -5
This possibly should be in the Gunsmithing Section of the Forum. But, really doesn't involve actual gunsmithing.
Also, I'm not sure there is a way to validate any thoughts. But, here goes...
Some revolvers, both single and double actions, tend to have thin forcing cones. It's simply a reality of bore diameter and barrel size.
So, do bullets with a rounded or tapered profile hit the forcing cone with a more gentle impact than a 90° shoulder such as a SWC?
Is a thin forcing cone, such as a GP100 44 Special, prone to live longer if not loaded with SWCs?
Does bullet hardness have an impact?
We know pressure and velocity does, but what about other factors...
|
|
|
|
Post by blackmamba on Mar 30, 2022 20:01:10 GMT -5
Valid questions, and I would guess that that the answer to all your questions is "yes." Easy to see how softer, tapered ogives would have less impact on forcing cones. I can also see how line-bored cylinders could have less impact on forcing cones, at least spreading the impact evenly around the entire bore instead of slamming into one section of the cone.
|
|
|
|
Post by bradshaw on Mar 30, 2022 20:34:13 GMT -5
This possibly should be in the Gunsmithing Section of the Forum. But, really doesn't involve actual gunsmithing. Also, I'm not sure there is a way to validate any thoughts. But, here goes... Some revolvers, both single and double actions, tend to have thin forcing cones. It's simply a reality of bore diameter and barrel size. So, do bullets with a rounded or tapered profile hit the forcing cone with a more gentle impact than a 90° shoulder such as a SWC? Is a thin forcing cone, such as a GP100 44 Special, prone to live longer if not loaded with SWCs? Does bullet hardness have an impact? We know pressure and velocity does, but what about other factors... ***** Huey.... can break discussion into two parts, single and double action. From there, the family tree grows wide. A swing-out double action frame needs room for the crane (yoke) between cylinder axle and barrel tenon. The BOLT PATTERN or chamber spacing factors. Basically, everything radiates from the cylinder axis. While it would be nice to have a thicker barrel tenon on a Model 19 or Python, the barrel socket in the frame must have at least a little meat at 6 o’clock. There is no free lunch in trying to chamber a belly gun for a meatball. Protrusion of barrel into window means less support for the forcing cone/barrel face. Stress imposed on a thin forcing cone by high pressure loads is aggravated by:* Runout----chamber-to-bore misalignment. * Runout + heavy bullet. * Tenon protrusion. * RTP----Rise to Pressure (steepness of curve). For a given pressure, a spike is more stressful than a curve. * Point of Peak Pressure----is pressure dome in chamber, in barrel/cylinder gap, in forcing cone, or in the barrel? * Volume of fire. Wear factor of heat & pressure. Reckon the softer the bullet, the greater its cushion. Lead softer than copper, copper softer than brass. To test sharp shoulder vs ogive vs gradual cone would require same weight bullets, powder & charge, with same pressure.... and beaucoup ammo, with an identical revolver for each style bullet. I approached loading 180 to 200 grain bullets in Colt Pythons very slowly, and didn’t care for the trajectory with 200’s. Also, the thin forcing cone quickly ended experiments with Hornady .358 200 grain rifle bullets in the Python. IHMSA All-Americans Skip & Cheryl Hird shared a Dan Wesson Arms M-15-2 .357 Mag. With somewhere between 8,000 and 9,000 rounds of Speer .358 Flat Point rifles bullets through the M-15----a championship in Pennsylvania----the barrel sails downrange. Barrel socket in frame split @ 6 o’clock. I was spotting the shooter to the right of Skip and, during the ceasefire, walked down as he picked up his barrel. Don’t remember whether the forcing cone split. I think the cylinder was fine. The frame was scrap. David Bradshaw |
|
|
|
Post by Encore64 on Mar 30, 2022 20:52:15 GMT -5
I agree and exactly why I asked these questions as opinions. I'm not convinced any of this could be proven regardless of ammo spent.
In my mind, frightening as that is, better alignment, bullet tapering gently, softer allow or jacket, etc would all extend the forcing cone life. But, none of these can be proven correct and my thoughts certainly don't make them correct.
Good point on powder burn temp and heat build up from more rounds fired. Lil Gun would definitely heat things up faster than Unique. Heat/cooling cycles definitely alter steel integrity.
|
|
|
|
Post by potatojudge on Mar 30, 2022 21:19:40 GMT -5
Does anybody know if short or no barrel tenon protrusion is completely protective against forcing cone splits?
|
|
|
|
Post by lar4570 on Mar 30, 2022 21:37:13 GMT -5
Sounds like a Dynamics Engineering question. Unfortunately that class was awhile ago and all of my books went up in the fire...
Assume same weight bullets of same composition only differing in the profile of the nose...
The angled surface, of the nose of a LFN style bullet, meeting another angled surface, of the forcing cone, would tend to spread the impact over a larger area. This would decrease the stress on any one particular spot. However... this impact would more or less happen all at once.
The sharp corner, of a swc bullet, impacting the angled surface of the forcing cone would concentrate all of the impact at one contact point. If the bullet was made of a very hard material, the forcing cone would probably Crack and fail at this contact point. However... given a lead or lead alloy bullet, the sharp corner of the swc front driving band would not have much material to support it's shape. I would think that it would start to deform on impact and take on the angle of the forcing cone. This deformation would spread the impact over a longer period of time. This should start the stress on the forcing cone out relatively low and then ramp up until the driving band conforms to it's new shape.
So which is more destructive
A sudden glancing impact that happens at the same time, but where the stress is applied over a larger area?
Or
A glancing impact that starts out low, but quickly ramps up and probably applies it's energy over a smaller space?
|
|
|
|
Post by 2 Dogs on Mar 30, 2022 21:43:19 GMT -5
This possibly should be in the Gunsmithing Section of the Forum. But, really doesn't involve actual gunsmithing. Also, I'm not sure there is a way to validate any thoughts. But, here goes... Some revolvers, both single and double actions, tend to have thin forcing cones. It's simply a reality of bore diameter and barrel size. So, do bullets with a rounded or tapered profile hit the forcing cone with a more gentle impact than a 90° shoulder such as a SWC? Is a thin forcing cone, such as a GP100 44 Special, prone to live longer if not loaded with SWCs? Does bullet hardness have an impact? We know pressure and velocity does, but what about other factors... I’m a bit concerned for my Jeff Quinn GP100 44 Spl for sure. My experience is based on having broken 2 Smith Scadium frames at the barrel threads. That had to be from the pounding that the forcing cone took. A 3rd Smith 625 PC just absolutely would not shoot for me and after some fire lapping it sure looked like it was wearing more on one side of the forcing cone. Still, Alan Harton built my .257 JR so precisely that it had like zero forcing cone. So in my opinion, as long as your alignment is good then your forcing cone should be as well. |
|
|
|
Post by 2 Dogs on Mar 30, 2022 21:44:34 GMT -5
Does anybody know if short or no barrel tenon protrusion is completely protective against forcing cone splits? I would think so except possibly with the exception of the ultra light frame guns. That said, I’m pretty good at breaking stuff… |
|
|
|
Post by 2 Dogs on Mar 30, 2022 21:51:29 GMT -5
Huey, I think that if your bullets are smacking the forcing cone it would show up on the target as not so good accuracy. It might even be reflected by “skidding” in the barrel. I always try to stay with the fundamentals. Are my throats right and am I shooting the right size/alloy bullet? Do I have a lube star on the muzzle? What condition is my bore after 3 or 4 cylinders? Have I addressed any thread restriction? If all these things are right and I still have poor results on target it’s time to take a look at my alignment…Before I break my sixgun…
|
|
|
|
Post by leadhound on Mar 30, 2022 21:53:19 GMT -5
Is this like the "Which came first the chicken or the egg?" Is it the bullet causing the fracture, the barrel material giving up due to stress, or is it a defect induced by manufacturing or assembly?
|
|
|
|
Post by Encore64 on Mar 30, 2022 21:55:30 GMT -5
This possibly should be in the Gunsmithing Section of the Forum. But, really doesn't involve actual gunsmithing. Also, I'm not sure there is a way to validate any thoughts. But, here goes... Some revolvers, both single and double actions, tend to have thin forcing cones. It's simply a reality of bore diameter and barrel size. So, do bullets with a rounded or tapered profile hit the forcing cone with a more gentle impact than a 90° shoulder such as a SWC? Is a thin forcing cone, such as a GP100 44 Special, prone to live longer if not loaded with SWCs? Does bullet hardness have an impact? We know pressure and velocity does, but what about other factors... I’m a bit concerned for my Jeff Quinn GP100 44 Spl for sure. My experience is based on having broken 2 Smith Scadium frames at the barrel threads. That had to be from the pounding that the forcing cone took. A 3rd Smith 625 PC just absolutely would not shoot for me and after some fire lapping it sure looked like it was wearing more on one side of the forcing cone. Still, Alan Harton built my .257 JR so precisely that it had like zero forcing cone. So in my opinion, as long as your alignment is good then your forcing cone should be as well. I know the rifling should be throated to start inside the threaded portion. This provides support when the bullet impacts the rifling. |
|
|
|
Post by bula on Mar 31, 2022 8:38:22 GMT -5
My only revolver with a thin enough forcing cone to cause me concern is my Bulldog 44spec.. With no data, only logic, which you can question, I'll skip using SWC's in it. I had this concern quite a few years ago, and it was refreshed in my mind when the GP100 44spec's came out, and questions followed.
|
|
rkrcpa
.30 Stingray
Posts: 259
|
Post by rkrcpa on Apr 1, 2022 4:19:46 GMT -5
I've thought about this with regard to my 696. I wonder what bullet size has to do with any of this. My 696 has small throats (<.429) so I use small, soft bullets in this particular revolver instead of the normal 429421 sized to .431 that my other 44 specials use. My reasoning is there must be less stress on the forcing cone from a (slightly) smaller, softer bullet impacting at 850fps rather than Skeeter's load.
Or, at least I sleep better thinking it helps.
|
|
|
|
Post by bradshaw on Apr 1, 2022 8:01:45 GMT -5
My only revolver with a thin enough forcing cone to cause me concern is my Bulldog 44spec.. With no data, only logic, which you can question, I'll skip using SWC's in it. I had this concern quite a few years ago, and it was refreshed in my mind when the GP100 44spec's came out, and questions followed. ***** Were your Bulldog mine, it might feed on SWC more than anything else. Chamber-to-bore alignment and pressure are the major concern. Don’t see any point in feeding it anything heavier than 240 grain, and the first I’d load is Dick Thompson’s 5.5/Win 231 or Hodgdon HP-38 (Same Olin powder). Dick’s 5.5 in .44 Spl case and my 5.5 under deep seated 240 SWC in .44 Mag case are twins. A load which performs above its paper numbers. Accuracy + work = performance. As fore lighter bullets, I killed a couple of deer in Texas with the Federal .44 Special soft Lead Hollow Point. Lungshot, one barely reacted, then slowly collapsed; reckon when its brain ran out of oxygen. The other bounded a short distance and folded, slowly. Neither apparently adrenalized. Those two shots were from an early 5-1/2” Redhawk, which posted more dramatic endings with Federal .44 Mag 180 JHP and 240 JHP. My experience with the Charter Arms Bulldog .44 Special dates decades, with the impression it was conceived around traditional .44 Special pressure, before the +P jazz rocked SAAMI. Were I to specify a .44 Special load for SAAMI, I’d start with a POWDER COAT 230 SWC over Dick’s 5.5/231, and test from there. David Bradshaw |
|
|
|
Post by magnumwheelman on Apr 2, 2022 8:21:04 GMT -5
General thoughts sound like a softer bullet is part of the answer… but I’m wondering if too soft a lead alloys may aid in leading of the throat, and actually increase a “sticking” surface to the throat, as well as reduce its diameter, increasing the chance of cracking, with another bullet, that may not have normally been a problem, before the throat leaded???
|
|
