Cold weather .40 testing

[ewc]

Shot the .40 today with the new scope - VX-III 6.5x20x40 LR.

200SST and a F209A primer.

Range was 100 yards, but it was windy and cold (15 wind, 25 F).

Went more or less for testing speed, knew groups would not be great.

My load of 10/61 4759/Varget that shot 2,765 at 65 degrees, shot 2,657, 2,656, and 2,650 today. Very consistent, but minus 100 fps. About a 1+" group.

Loaded 14/61 of the same and hit some speed. Likely this load may be too hot in higher temperatures. It was 2,815, 2,847,2,903 for three shots. Shot them into and 1 1/2".

Loaded 15/62 of 4759 and RL-15 and it shot 2,807,2,820, and 2,865 and into a sub-1" group (with wind).

I'll digest some of this and post more, including a scan of the RL-15 load.

-Judd

[tar12]

That was all good!

[joe21a]

25 F That's not cold !!!!

[Deleted]

that last load sounds interesting!

[dougedwards]

Jan 17, 2009 15:16:47 GMT -5 ewc said:

My load of 10/61 4759/Varget that shot 2,765 at 65 degrees, shot 2,657, 2,656, and 2,650 today. Very consistent, but minus 100 fps. About a 1+" group.

-Judd

It appears that a slight increase of the faster burning powder is called for in colder weather but I am wondering if there was a significant shift in POI with this load that shoots over 100 fps less at 25 degrees than it does in 65 degree temps?

Doug

[sw]

I think I'd just give up on the 40 and go back to your Savage barrel. I don't think 40 sabotless will ever be viable. Still I appreciate your efforts. Maybe if there was enough bullet selection, it might be practical. I think you're just wasting time.

Concerning the velocity loss, 100'/sec doesn't seem particularly much, especially considering the velocity. You just can't have it all - low enough pressure to not go straight thru ventliners in a hurry, extreme accuracy, and little velocity loss. I'd happily settle for 100'/sec over a 60-70 degree temp change. The fast twist of our 40s will keep the groupings very close and the trajectory change will be minimal. I intentionally made my 11/46 load hot(2670 for only 57gs of powder) IOT have the same load thru Nov-Dec(and then the temp stayed relatively hot the whole time).
Your loads seem to be creeping up on the 2900'/sec mark . I'm working with similar loads except VV-110 as the primer and Varget, VV-133/135, H-4895, and H-4350(lots of this .

[rbinar]

I have to agree with Steve's obsevation (that's not the first time) about the change in speed.

There is no such thing as a perfect load that shoots exactly the same in near 50 degree weather changes. However the 40 caliber makes pressure easier than larger calibers and it is the caliber I'm least worried about temperature sensitive loads.

[dave d.]

:)ewc i personally like your first load better.those extreme spreads will equal better long distance accuracy.i agree 100fps loss in a 50,60 degree drop is not that bad.nice report

[dougedwards]

I have some questions concerning shooting sabotless in 40 cal. Firstly, since part of the benefit of shooting the smaller calibers is that it allows you to shoot lighter bullets such as 200SST and 195 Barnes thus lighter recoil, I am wondering about the pressures that are required to force these light bullets to obturate into the rifling. Knowing that a longer and heavier bullet will be more resistant to the push of ignition and thus more inclined to obturate inspires my question.

Secondly I am wondering about the long range capability of these lighter bullets at long range such as 250-350 yards. I know that you are shooting them very fast but I am wondering about wind deflection of the lighter bullet as opposed to the 250-300 grain variety. I wrote all of this extremely quickly without my glasses and hope it all makes sense.
Doug

[dave d.]

:)doug i've shot enough of these bullets down range at 300yrds that i think they are more then capable of everything that could be ask of them.i'm sure a 250gr or 300gr bullet in .40 would have a advantage but recoil will go way up and kind of defeats the whole concept of going down in caliber jmo.

[rbinar]

Jan 18, 2009 8:58:34 GMT -5 dougedwards said:

I have some questions concerning shooting sabotless in 40 cal. Firstly, since part of the benefit of shooting the smaller calibers is that it allows you to shoot lighter bullets such as 200SST and 195 Barnes thus lighter recoil, I am wondering about the pressures that are required to force these light bullets to obturate into the rifling. Knowing that a longer and heavier bullet will be more resistant to the push of ignition and thus more inclined to obturate inspires my question.

Doug

Doug it takes the same pressure to form the 200 grain bullet (assuming the same jacket material) as a 250 or 300 grain slug. The difference is how you get to that pressure.

As counter intuitive as it sounds it is actually much harder to create pressure in a bigger bore compared to a smaller caliber. That is why it is easier to find a number of loads to shoot a 200 grain bullet in 45 caliber as compared to a 250 grain bullet in 50 caliber.

In general the heavier the bullet the easier pressure is made. However this is only true when the same caliber is compared. The reason is simply the rule to compute area of a circle. Because the area changes with the square of the radius (versus simple multiplication) the expansion area is relatively large in bigger calibers even though the bullet is heavier.

Then it can be said a 45 makes pressure easier than a 50 and the 40 caliber makes pressure easier than the 45. Care must be taken not to conclude a 50 load will work in 45 or a 45 load will work in a 40.

That said the jacket of the bullet is usually made of copper and it takes the same force to form copper no matter the caliber.

[whyohe]

ok i know how and why temp can effect metals, but what is the key factor for temp effecting powders? is it the desity of the air?is it the fact that you dont have as much heat to ignight the powder? does the the powder directly in some way?

[sw]

Smokeless powder combustion is an exothermic chemical reaction. Exothermic chemical reactions go faster with increased temperatures and , of course, slower with cooler temps. It just combusts faster when it's warmer - more pressure, ie faster. The coatings on the powders are designed to lessen this tendency and to keep the combustion pressure(rate of burn actually) from having a wide variance. Hodgkin actually advertizes this with their "Extreme" series of powders.

[dougedwards]

Jan 18, 2009 14:55:53 GMT -5 rbinar said:

Doug it takes the same pressure to form the 200 grain bullet (assuming the same jacket material) as a 250 or 300 grain slug. The difference is how you get to that pressure.


In general the heavier the bullet the easier pressure is made. However this is only true when the same caliber is compared. The reason is simply the rule to compute area of a circle. Because the area changes with the square of the radius (versus simple multiplication) the expansion area is relatively large in bigger calibers even though the bullet is heavier.

Then it can be said a 45 makes pressure easier than a 50 and the 40 caliber makes pressure easier than the 45. Care must be taken not to conclude a 50 load will work in 45 or a 45 load will work in a 40.

That said the jacket of the bullet is usually made of copper and it takes the same force to form copper no matter the caliber.

That is an astounding statement. Does it really require the same pressure to obtain the flattening out (obturation) of a lighter bullet upon ignition as it does a longer and heavier one? It would seem that a lighter bullet would be more inclined to move forward towards the muzzle rather than resist that forward movement enough to squash out and engaging the rifleing and I am under the impression that this obturation is critical for proper ignition. I am of course speaking of bullets of the same caliber and make up but having different weights. Maybe I am missing something.

What type of pressures are required to do this in the 40 cal? Is it similar to the pressures created in the Savage 10ML shooting saboted bullets? I actually have never seen a 40 caliber bullet to be honest. I can only compare the lighter 50 caliber bullets which seem to be short and squatty like a pistol bullet in comparison to the longer more elliptical shaped projectiles that tend to have a higher BC.

I have no doubt that pressures are easier to create in a smaller caliber bore. That would only make sense. I am wondering if considerably more pressure is necessary for proper ignition in the 40 caliber using the 200 and 195 grain bullets than is created in the 50 cal using saboted bullets.

Doug

[dave d.]

:)doug i'm not going to answer for rb but from what i know about the .40 is it likes between 40 to 50,000psi.a .40 sst is .975 long so it's fairly long.how long are the .45 300sst's?

[sw]

:)The 40 will shoot to 3115'/sec with 200SST. It shoots 2898 +/- 4'/sec with 11 4759/75 H-4350. Pictures coming soon - maybe tonight. The recoil of the 3115'/sec load isn't as stiff as the 14/61 250SST load but it's close to a 42g 4759/250g bullet. The 2898'/sec load is still light. More soon.

[rbinar]

Jan 18, 2009 18:28:20 GMT -5 dougedwards said:

That is an astounding statement. Does it really require the same pressure to obtain the flattening out (obturation) of a lighter bullet upon ignition as it does a longer and heavier one? It would seem that a lighter bullet would be more inclined to move forward towards the muzzle rather than resist that forward movement enough to squash out and engaging the rifleing and I am under the impression that this obturation is critical for proper ignition. I am of course speaking of bullets of the same caliber and make up but having different weights. Maybe I am missing something.

What type of pressures are required to do this in the 40 cal? Is it similar to the pressures created in the Savage 10ML shooting saboted bullets? I actually have never seen a 40 caliber bullet to be honest. I can only compare the lighter 50 caliber bullets which seem to be short and squatty like a pistol bullet in comparison to the longer more elliptical shaped projectiles that tend to have a higher BC.

Doug

I haven't said anything astounding for some while. That generally requires I have my foot in my mouth or my toe in my ear.

To simplify let's consider two bullets in the same caliber. Suppose they are the 300 and 350 grain bullets I'm going to shoot sabot-less in my 50 caliber rifle.

The 350 grain bullet shot with say 66 grains of H-4198 will indeed make more pressure than the 300 grain bullet with the same amount. For the reasons you mention the 350 grain bullet will deform more and would probably work better with this load.

But is that the way you'd load these bullets and powder? I hope not. If the 350 grain bullet is shooting good with this load it's near certain the 300 grain bullet will require more powder to work as well. Why? Because this amount of powder would shoot a lower pressure than with a heavier bullet.

What you'd do is add more powder when shooting the 300 grain bullet. That would bring the pressure up to the same as the 350 grain bullet and it would work as well sabot-less as the heavy weight. Both loads will shoot about the same energy (bullet energy) but one will be moving faster than the other. The energy formed the bullet into the rifling and they were formed about the same because the load pressure was about the same.

A bullet requires about 40,000psi (or slightly less) to form fit the rifling for a sabot-less load. This is true despite the caliber or bullet weight. That is why it's possible to shoot slow sabot-less loads in 40 caliber. H-4198 and H322 will shoot a 200 grain bullet fine at only 2100 to 2300fps. This is because those powders are fast for this caliber and they reach the minimum pressure at low powder charge weights (between 43 and 50 grains).

This may be one reason no one has succeeded having very good accuracy with 50 sabot-less from a stock barrel. The load I mention for a 350 grain bullet may be too anemic to form the bullet. 50 Alaskan loads show 62 grains are needed to reach 35,000psi with a 435 grain bullet. This brings recoil into consideration. The Alaskan shoots to over 4200fpe even at these lower pressures.

[rbinar]

Jan 18, 2009 20:30:44 GMT -5 sw said:

:)The 40 will shoot to 3115'/sec with 200SST. It shoots 2898 +/- 4'/sec with 11 4759/75 H-4350. Pictures coming soon - maybe tonight. The recoil of the 3115'/sec load isn't as stiff as the 14/61 250SST load but it's close to a 42g 4759/250g bullet. The 2898'/sec load is still light. More soon.

Hmmmm! That's fast.

[dougedwards]

More powder doesn't necessarily mean more pressure if the resistance is reduced. Yes that makes sense now. I was thinking that very high pressures were probably needed for smaller caliber sabotless shooting with lighter bullets. This is good news for us recoil sensitive guys. Thanks for the explainations.

Doug

[ewc]

Jan 18, 2009 23:15:54 GMT -5 rbinar said:

Hmmmm! That's fast.

An understatement ;D. Good job Steve-