Velocity differences

[Bkingnsmth]

Happened to be out at my gunclub with my hunting rifle. A friend hauled out his chronograph and did what checks he needed done. Before he put it away I asked him to check my hunting loads. I use a Win M92 chambered in 38/40. Loading 18.3 gr of 2400 in both the jacketed 180gr hp and the Lee 180gr cast tc. Now the jhp went 1662fps and I was pleased that it should make a decent hunting load. Next we tried the 180gr Lee cast and powder coated, it chronoed at 1880fps. I was really impressed, not only does it shoot well, it really is close to what I want for a hunting load. Now has anyone else experienced this? A pc'd bullet going faster than a jacketed? I used same lot of powder, same lot of cases, same bullet weights. Thanks.

[Rcmaveric]

Yes. Copper is harder and has a higher friction coefficient.

PC may be faster or slower than lubed.

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[Bkingnsmth]

Actually they were brass jackets from Montana gold.


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[Jim22]

That impresses me as well. That slightly exceeds the performance of my .357 Magnum in a 16" barrel. Is that a bit hot for the M92?

[PositiveCaster]

....That slightly exceeds the performance of my .357 Magnum in a 16" barrel. Is that a bit hot for the M92?

Good question. I’m not aware of pressure-tested loads above SAAMI levels, although Ken Waters’ Pet Loads shows he developed .38-40 M92 loads with up to 22.0 grains of 2400 under a jacketed 180 - his max load at 1866 fps. He didn’t really recommend that load, and because it was developed over 45 years ago I personally wouldn’t use it with current lots of 2400.



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[missionary5155]

From all I have read the nickel steel 92's were rated for the upper power Winchester jacket rounds they produced until WW2.
Than figure in all the 92s that were made into 45 Colt and 44 Mag and no blowups I have read about.
And if Ken Waters printed it I would trust it in a rifle that is in good shape.

[missionary5155]

Velocities I have seen the same over our Crony. Cast always slips along faster. PC may also but I have not tested it toe to toe with Jackets.

[Bkingnsmth]

That impresses me as well. That slightly exceeds the performance of my .357 Magnum in a 16" barrel. Is that a bit hot for the M92?

Jim22
No that's no where near max for a M92 it's near max for me. It's quite light.


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[Rcmaveric]

After shooting many riffles for many years. I find I never enjoyed shooting full power loads.


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[Larry Gibson]

Bkingnsmith

How many of each load were chronographed?

[Bkingnsmth]

Bkingnsmith

How many of each load were chronographed?

Larry,in all truthfulness only fired 1 ea as I did not have that many along with me.


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[Texas by God]

If the accuracy is there, that dog will hunt with either load. Your average velocity will probably be fairly close to your one sample. I’d like to see a five shot average of the two you have and add conventional lubed bullets to the trial. It would be interesting.

[Bkingnsmth]

Texas
The accuracy is there and they do both print close to same point. I used the jacketed only one at a time because they haven't got a cannelure and the mag spring pushes into the case. I can crimp the pc boolits and load only those in the tube. Had I known what they ran vel wise, I would not have bothered to use the jhp. The old Lyman books don't have the velocity near what I'm getting with pc'd .


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[Larry Gibson]

Larry,in all truthfulness only fired 1 ea as I did not have that many along with me.


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A one shot chronograph test gives no indication of anything other than the velocity of that one shot. Also the 1st shot of a test with a cast bullet, especially if the barrel is fouled by another load (in this case a jacketed bullet) almost invariably gives the higher velocity or one of the highest in a test string. Conversely, limited testing has indicated shooting a jacketed bullet in a barrel fouled with cast many times give the lowest velocity. Given the unknown ES of either load I would not take away too much from a 1 shot test of any load in comparison to any other load.

While there is an apparent interesting difference the two loads may not be as different as this limited one shot test suggests.

[bowfishn]

Happened to be out at my gunclub with my hunting rifle. A friend hauled out his chronograph and did what checks he needed done. Before he put it away I asked him to check my hunting loads. I use a Win M92 chambered in 38/40. Loading 18.3 gr of 2400 in both the jacketed 180gr hp and the Lee 180gr cast tc. Now the jhp went 1662fps and I was pleased that it should make a decent hunting load. Next we tried the 180gr Lee cast and powder coated, it chronoed at 1880fps. I was really impressed, not only does it shoot well, it really is close to what I want for a hunting load. Now has anyone else experienced this? A pc'd bullet going faster than a jacketed? I used same lot of powder, same lot of cases, same bullet weights. Thanks.

What was the COAL on each, as well as Bullet length? The less case fill will change pressures drastically, changing velocity.

[quilbilly]

I have found on my chronograph that Alox lubed CB's in rifles of several calibers with some exceptions seem to be about 10% faster than jacketed of the same size with the same powder charge. That Alox definitely makes a boolit more slippery. I haven't started PCing yet since I have a surplus of Lee Alox so I can't say much about the effect of PCing the same CB's.

[Win94ae]

"Fit is King!" Isn't that a saying around here? It is true, and that is why.

[dtknowles]

You mentioned the jacketed bullet does not have a cannelure. You don't say what you are hunting but on a big deer that might not be a good choice as it is probably a bullet designed for 40 S&W and will not penetrate well. It will probably over expand and maybe even breakup at your velocities. I would stick with the cast bullet.

Tim

[Bkingnsmth]

The ranges I usually encounter are 50 to 100 yds so blowup is not a real concern, but yes I will be using the cast bullets exclusively from now on, as they will be loaded in the tube. The others have to be single loaded.


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[Bkingnsmth]

What was the COAL on each, as well as Bullet length? The less case fill will change pressures drastically, changing velocity.

Bowfishn:
The oal of the jhp .620 the cast TC .595. Coal of the jhp 1.589 the coal of the TC 1.585


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[bowfishn]

Bowfishn:
The oal of the jhp .620 the cast TC .595. Coal of the jhp 1.589 the coal of the TC 1.585


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It would appear that is not enough to make the velocity difference according to QL . Both should be close to 1800 fps with a 20" barrel.
As the others have said you need to run a string with each to tell the actual velocity.

Also the less friction on a bullet or in the barrel equals less pressure which equals less velocity. (exception would be long barrel and low powder volume where barrel length begins to slow down bullet. In that case less friction can equal more velocity. Example 22LR with long 24" barrel, some friction proofing products have seen increase in velocity)
I run HBN on all my jacketed rifle bullets and when I switched from non coated to HBN coated I lost velocity with 2 different 30-06 rifles, 2 different 6.5 CM rifles, a 308 win and a 243 win. The lower friction allows adding a bit more powder and in the end gaining velocity. (with the 6.5 CM using RL26 it was .5 grains to equal velocity loss)

[Bkingnsmth]

Had I gone to do chrono work I would have taken more ammo, as it was I only went with enough to check my sights.


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[Jim22]

I find it sad that some want to make light of Bkingnsmth's report. We all know that a string of one shot across a chronograph is not very representative but he reported it any way. I thank him for the information.

[Larry Gibson]

Whom is "making light of it"?

Seems a good discussion to me.

[Goofy]

Well, I’ll jump into the deep end just for grins. I’ve not attempted to investigate the issue but have some observations that support the OP in general terms. 170 gr jacketed bullets from my Mod 94 Trapper use more powder and are slower than 180 gr gas checked cast. It’s not a big difference in velocity, around 50-75 FPS, but I think the surprise comes in seeing this with 3-5 grains less powder. Why? Haven’t a clue, but it’s chronograph data, not my imagination. I normally shoot 5 shot groups. I have seen similar results with a Marlin 94 shooting the .25-20 Win, but in this case the J-bullet is 75 gr and the cast is 85.

It is what it is and I couldn’t care less. YMMV

[44MAG#1]

I have posted data and it was quite rapidly started to be picked apart.
I hesitate now to post any data on anything that I have obtained.

[dtknowles]

When I post data. Data is data. People can try and pick it apart but that does not change the data. Ask questions that is fine but don't insinuate that I am not posting the facts. Exceptions are made for groups sizes. I don't believe any group sizes that don't have corroborating witnesses with multiple repetitions. One group is meaningless. Averages or aggregates are what matters.

Tim

[Larry Gibson]

I have posted data and it was quite rapidly started to be picked apart.
I hesitate now to post any data on anything that I have obtained.

Yup, happens all the time to most all of us.....look at what happened to the data I posted in the recent thread about using SR primers in the 9mm. As with dtknowles, I certainly don't mind anyone asking questions or analyzing the data. I'm more than happy to answer questions where I can. I also don't think anyone should object to a analysis that might differ from theirs but should discuss it intelligently because we all may just learn something in the end. In the case here, the OP has posted velocity from only a one shot test using one bullet and comparing it to the velocity of another using a different bullet, both with the same load. Based on my own extensive experience chronographing thousands of different loads since '73 it is my opinion attempting to draw any meaningful comparison as why the discrepancy between the two velocities is not really meaningful.

No criticism of anyone who is trying. because as I stated earlier it is unknown what the ES of each of those loads actually is. Additionally, I have done considerable velocity/pressure testing of different cartridges attempting to answer the question as to whether, with a given load and similar weight bullets, using jacketed bullets results in more pressure and less velocity than cast bullet or visa versa or any combination of pressure and/or velocity. So far my testing has shown there is no rule of thumb to answer that question. Sometimes there is more pressure and more velocity with either bullet, sometimes more pressure and less velocity and sometimes there is less pressure and more velocity. Just too many variables to get a concrete answer.....

The data I post is factual based on velocity and/or pressure testing I've done myself. I have a MagnetoSpeed, 2 different Oehler chronographs and the Oehler M43 PBL which measures velocity pressure and a myrid of other internal and external ballistics. Problem is, while the data speaks for itself, many misinterpret the data or take offense because it goes against their preconceived ideas based on the writings in gun magazines/books. Sometimes the discussion can seem heated but if personal attacks are left out I don't mind. As my daughter used to say; "no sense getting a wedgie over it".....

[44MAG#1]

And so it goes in the world of firearms, ammunition and reloading/handloading.
And the world of Confimation Bias among us.

[Goofy]

Kinda like flying a chopper inverted. First time doesn’t tell you much other than it’s fun and you want to do it again. Question that puzzled me, is that flying or controlled falling. Anyone know?