Reloading assumptions

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TriggR

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I am reloading for a 10 mm Glock 29 with a three and three quarter inch barrel. all of my loads straight out of the book do not meet the listed muzzle velocities obviously a shorter than tested Barrel. my assumption would be that the pressures are not reaching what is printed in the book also, does this mean that I can use a few tenths more powder and inch up closer to listed muzzle velocities will the pressures follow.
 
I would strongly reccomended against exceeding max in the book. Presure is measured the the chamber and generally decreases as the bullet travels down the barrel.

What powder and bullet weight are you using?
What velocity are you ecpecting, what are you actually getting
What chronographed are you using, how far away is it from where you are shooting.
 
TriggR said:
I am reloading for a 10 mm Glock 29 with a three and three quarter inch barrel. all of my loads straight out of the book do not meet the listed muzzle velocities obviously a shorter than tested Barrel. my assumption would be that the pressures are not reaching what is printed in the book also, does this mean that I can use a few tenths more powder and inch up closer to listed muzzle velocities will the pressures follow.
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Your assumption is wrong. The burning rate powder used in a 10mm probably builds max pressure when the bullet is less than 2" down the barrel. Probably closer to 1".
 
I do understand the pressure is measured in the barrel but a shorter Barrel does not allow the pressure to build as it would in a longer Barrel before being released. I am not expecting the pressures or muzzle velocity to be by the book in the smaller Barrel that is a known
 
I'm just thinking out loud why would the muzzle velocity be less if the pressures were the same no matter what size Barrel
 
Pressure doesn't build in a longer barrel, it decreases as the bullet travels down the barrel. A simple Quickload simulation shows that the maximum pressure in the 10mm occurs at about 1/4 inch bullet travel. Whether the barrel is 2 inches, 4 inches or 6 inches has no effect on the maximum pressure. Increasing the powder charge will increase the maximum pressure above limits, likely to an unsafe level that could result in damage and/or injury.
 
my assumption would be that the pressures are not reaching what is printed in the book
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I would not assume that. As others have stated, pressure is measured in the chamber, and is not a function of barrel length. Peak pressure almost always occurs when the bullet has traveled down the barrel very little. It's also important to understand that there is no direct connection between peak pressure and velocity. Velocity is much more related to average pressure. (That's the extent of my knowledge. Somebody smarter than me can add on/clarify.)

I have and load ammo for a Glock 29 (and Glock 20). I just did a quick check of my chrono data and compared to the books (Speer & Hornady). My loads slightly exceed their posted velocities - even with my shorter bbls. This is a classic "your mileage may vary."

I don't have a lot of different loadings for the 10mm, as I consider it a utilitarian - rather than recreational - cartridge. But I'd be happy to share data if you believe it may be of assistance.
 
Yes I have tried long shot and it can produce some very fast bullets I was impressed. I also tried Red Dot no big results there, I also tried 2400 lower muzzle velocities very accurate. I have been using 700x in the 950 muzzle velocity range because I have so much of it. So can someone explain why a longer Barrel produces higher muzzle velocities when you would think that it would slow it down some.
 
does this mean that I can use a few tenths more powder and inch up closer to listed muzzle velocities will the pressures follow.
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NO!

Pressure and velocity are not linear with each other. They are related, certainly, but its not a straight "one for one" thing. In other words, an increase in pressure does not automatically result in an equal percentage of increase in velocity.


I'm just thinking out loud why would the muzzle velocity be less if the pressures were the same no matter what size Barrel
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mostly because longer barrels let the pressure push the bullet longer. While there are situations with measurable variances, essentially long barrel or short, the pressure doesn't push the bullet significantly harder, but it gets to accelerate the bullet LONGER in the longer barrel. SO the bullet goes faster, not because it is being pushed harder but because it is being pushed longer, so it gains more speed from the longer duration of the push.

Some other points to consider is that every gun and ammo combination has the potential to be different, due to the numerous tolerances and factors involved, and even the exact same make, model and barrel length gun used in the testing, shooting the same ammo used in the testing, may NOT deliver the same velocity as the test gun & ammo. It may be less, it may even be more. It may be (and usually is only a small difference) but the possibility of a large difference always exists.

I've seen 3 different 6" barrel pistols shooting the same ammo, vary by 100fps. That's uncommon, but not so rare as to be unknown.

Generally, you won't get "listed velocity" from a 3.5" barrel when the test gun is a 5" or 6" barrel. Increasing your powder charge to make up the difference MIGHT result in a slightly higher velocity, or it might result in just blowing more powder out the barrel with no significant gain. AND it MIGHT also result in raising chamber pressures beyond normal working limits. Don't try.
 
I'll make an imperfect analogy. Its not something I want to argue with the nitpickers in the wings. Its just to help "see"

Think drag racing. Equate availble horsepower with pressure. Try to make too much horsepower or pressure,the engine may fail. Adding more boost or nitrous or powder at some point will be catastrophic

Now,equate barrel length to 1/4 versus 1/8 mile drag strip. Acceleration time and distance. .The car will reach higher top speed on the longer track.

Like most handloaders with a chronograph, I too,am fascinated with higher velocity. Velocity has obvious advantages. If nothing else "MORE!" is better!!

So what advantage do you think you "should" get? 5% ? 10% ? 100 fps??

OK. I find some magic pixie dust powder and grant you your 100 fps!!.

Aside from more recoil slowing your effective rate of fire, What do you gain?
Remember reliability rates really high in priorities. Pushing the limits compromises reliability

In measurable terms? Trajectory? Run ballistic tables. See what you gain in max point blank range.
Penetration? Spend a couple of hours studying Lucky Gunner gel tests.

I suggest not getting too fixated on a number floating in your head. Penetration matters. Wound channel/bullet performance matters. Trajectory matters. Recoil and reliabilty matter. Measurable results matter.

A number in your head (1200 vs 1300 fps) probably does not matter to your target. Forget "My gun shoots Super Ammo" My gun shoots "Darn good ammo every time" is good.
Focus on smooth,fast,hits on target. Jerry Miculek is an inspiration.

"Just a little more powder than max load" AT BEST diminishes your margin of safety. A weak piece of brass. Lot to Lot variation. A little hickup ot the powder measure. A hot day. Line all those up. Blow a case head when someone is shooting at you. Now what?

.
 
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Still waiting on the bullet weight, powder, and charge weight. As well as what velocities you are expecting vs what you are actually getting.

Peak pressure is in the chamber. However a longer barrel allows the remaining pressure to continue pushing on the bullet longer and imparting more velocity.
 
I'm shooting 180 grain barys Target and round nose so I do not want to get into the 1200 feet per second range which I could easily do with long shot . I'm trying to get into the thousand something average I would like to use at this time 700x because I'm trying to get rid of some. 6.0 gns 700x 180 gn average in the 950 960 range I would like to average in the 1050 range I've used four different primers Magnum and standard three different brands did not notice an ounce of difference in primers.
 
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Im assuming hodgdon 700x. If so thats a fairly fast burning power in general, especially for 10mm. I would expect velocity to be lower than expect based on that alone based on past experience playing with fast powders. Where did you get your data? Neither my hornady or hodgdon listed that powder for 10mm. Im guessing its a powder selection problem. Your probably gonna have to switch powders to get the velocity up where your wanting it.
 
I actually have quite a few books that list 700x for 10 mm and it is IMR 700x. Including one of the paperback IMR load data books or magazines. I just lowered the bullets to 1.252 I was at 1.262 I will do some checking and see if that changed anything I meter each round with the RCBS 1500 for testing.
 
Takes me further out of subsonic velocities. Gets me a little closer to the Underwood 1500 ft per second loads that I would carry in the woods and I was looking for a little bit more felt recoil I know I can change powders that's obvious with the long shot test as those were some pretty stout muzzle velocities at just under 1200 ft per second using 11.9 grains I have booked data that allows me to go to 12.4 again trying to use up some 700x pounds of it
 
ok, another question, how old is the powder. Looking for the IMR 700x it appears to have been discontinued, but I can't find an exact date. If its older, or had been stored in a damp or hot place it could be deteriorating, and losing some of its punch. Not saying you stored it wrong, just don't know how long it sat till you got it, or got a chance to use it.

I did some testing a few years back. Comparing some velocities in a 38spl with a snubbie. tested a few powders, fast and slow to see what the effect was. The over all result was, I got more much consistent velocities with the fast powder, Hodgdon clays. I was getting a full burn in the shorter barrel. However I sacrificed close to 100fps over the slower powders, HP38 and Power pistol. It also significantly reduced muzzle flash. Same pressure, slower bullet. I suspect that as the faster powders generally have a smaller volume they produce less gas. meaning the pressure drops off faster and you dont get as many FPS for each inch of barrel as you do with the slower burning powders. At least that is how I understand it.

At this point if you at max, I would still not go above it. That's all that powder has to give unfortunately. I don't seen any possible way to coax another 100fps out of it. I have been there. I have lots of powders on my shelf that I am trying to find uses for to prove it. It sucks, but sometimes if you have a set goal, you have to swap powders to get there. That's my advice for whatever its worth.

As far as the longshot goes. according to Hodgdon, with a 180g bullet 10mm max is around 8.2-8.4g at around 1200fps with a 5in barrel. my Hornady manual maxes out at 8.2g, but shows 7.3g of longshot to give 1050fps. out of a 5in barrel.

CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

I ran a gordons reloading tool simulation for longshot at the 1.252 col you listed. it shows a max of 8.7g of longshot, at 37354 psi and 1156fps.

it also shows a load of 7.7g to give you a muzzle velocity of 1055fps

according to GRT the 11.9g load of longshot (in post #19) is at 79,514 psi, and I dont know how you gun is in one piece.
 
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