The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Hypothetical Question: If you have a large diameter chamber...?Go | New | Find | Notify | Tools | Reply | |
| Hypothetical Question: If you have a large diameter chamber...? | Login/Join |
| one of us |
Here is my Question: If you have a large diameter chamber, which is resulting in SLOWER than normal velocities for a given bullet/powder charge (slower by 200-250fps).........is it safe to increase the powder charge (all the while looking for signs of pressure) to reach published BOOK velocities??? For example: for a 300H&H 180grain bullet & RL-22 powder The Nosler Reloading Book lists the following 300H&H load as a MAX Load: 180 gr. Nosler Partition & 71.0grs RL-22 for a book velocity of 3023fps I have two 300H&H rifles and the exact same load is giving me very different velocities (using new Remington brass & Federal #215 primers) Rifle 1 with a 26" barrel: 180gr Nosler Partition & 71.0grs RL-22 gives me a chronographed velocity of 2961fps [near BOOK veolcity] Rifle 2 with a 25" barrel: 180gr Nosler Partition & 71.0grs RL-22 gives me a chronographed velocity of 2780fps [~200fps SLOWER] Is it safe/acceptable to increase the charge weight for Rifle 2 to reach NORMAL ACCEPTED VELOCITIES??? | ||
|
one of us |
I wouldn't say acceptable, but what works in one rifle may not work in another. There is a reason one rifle is getting 200fps less. vel. There are no free lunches & increases in vel. often come w/ increases in pressures too. If you have no signs of pressure, then add powder & see what you get. WHile it's never wise to go beyond printed, tested data, there is a a lot of varying data out there. Think about it, it's how wildcat shooters make it work. LIFE IS NOT A SPECTATOR'S SPORT! | |||
|
One of Us |
IT IS safe to increase the powder charge, watching for excessive pressures, as you noted-IF you quit and drop back if you get signs that you have gone too far. Doing it carefully this way, usually permits you to stop before the gun is endangered. The brass will usually fail before the steel! Whether you can keep increasing until you reach the published velocities, however, is another, separate question. It all depends on what your rifle will permit! "Bitte, trinks du nicht das Wasser. Dahin haben die Kuhen gesheissen." | |||
|
One of Us |
Pressure is the only thing that means anything. You can increase the load as much as you want as long as the pressure remains in an acceptable range. Book velocity can pretty much be ignored though it's interesting. If the pressure is in an acceptable range the velocity you get may be less, equal to or more than book velocity. Again, pressure is the important factor. In addition, a large diameter chamber doesn't necessarily mean pressure will be lower. Barrel diameter, free bore and other factors all influence pressure. For instance, I have 2 44 Mag. handguns. Cartridges loaded for one have very safe pressure while they're of quite excessive pressure for the latter even though the latter one has a bigger chamber. | |||
|
one of us |
actually r22 is about the slowest powder for 180gr bullets, You may want to try a faster powder say imr 4831 or 4350. I had no problems getting 3000f/s out of a couple h&h's with a max load of these powdeers. Dav | |||
|
One of Us |
 If you follow the advice to increase your loads gardually Make sure you test these loads out in both rifles at the same time and study your stepping results; velocity, primer appearance, case swelling,bolt handle lift and accuracy while you're at it. Note the differences as you go.  You may find that one rifle is more tolerant than the other. For this reason you might not want to have loaded ammo around that is OK in one rifle but bolt jamming in the other.roger rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
|
One of Us |
I read these statements (assuming the lower velocity is due to large chambers) all too often and have never read of anyone ever measuring the chamber to show how much larger it is from standard......in fact i really don't believe one can possibly have a chamber so large as to cause a 250 FPS drop in velocity..... To the question: There's only one thing that justifies an increase in powder and that's the complete lack of any pressure signs.....and that assuming you have a modern strong action. Just why one is short of the published data remains a mystery to me but I'm not at all buying the "large chamber" or "slow barrel" or other common assumptions. I can readily subscribe to the differences between military and commercial brass as being quite large in internal combustion volume as to cause fairly large differences in pressure..... but to say that this pressure difference can cause 250 FPS difference in velocity doesn't compute. When one looks at the enormous difference in the volume of the .308 and .30-06 and realizes that there's still not 250 FPS difference in these two cartridges it just makes one wonder what can cause that much difference in a single round......and tolerances just don't add up to an appropriate answer. Mind you guys, I'm not saying I know what it is.....but I think we send ourselves in the wrong direction by assuming it's "this" or "that"....personally I suspect it's more related to variances in manufacturing of powder than anything but can't prove that either. Again.....if you are experiencing low pressure or no signs of excessive pressure then add 1% powder to the charge and see what you get.... it's why we reload....to maximize the things we want from our ammo. /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
|
| one of us |
I'm with Vapo on this one. My first reaction was exactly the same as his. You can prove or disprove your theory very easily. 1. Find two cases that have the same water capacity after FL sizing. 2. Load them with identical loads. 3. Fire one in each rifle. 4. Measure the water capacity of the fired cases. 5. Report back Ray Arizona Mountains | |||
|
| one of us |
+2 on V-dog I've seen over-diameter throats/leads/freebore cause lower velocities, but unless your chamber is 300 Woundabeast sized you won't get that kind of velocity drop from a "over size chamber" alone. Personaly I'd skip the above suggested "water test" and go straight to a chamber cast, paying paticular attention to the area between the case mouth and the rifling proper. | |||
|
one of us |
+3 I've shot the same loads in the same barrel in a std case before and after increasing the capacity by 11% and didn't see a 250fps drop in velocity. As usual just my $.02 Paul K | |||
|
One of Us |
Ummmmm.... just one small problem there. What about case springback? Wouldn't that skew the results? Regards 303Guy | |||
|
| One of Us |
Nope.....not at all as it would be the same for both the normal and the trial case.....resulting in cancellation. In fact it is a fine method of measuring the difference in the two chambers.....remember we're looking for a fairly large difference.... /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
|
| one of us |
You raise some good points in your post. The 300H&H loads were loaded from the same batch of: bullets, primer and Remington brass, even on the same day. I did not measure/sort the cases before loading and I have not measured the case volume post firing. I agree with your orginal thought/post.......there isn't going to be 200-250fps of case volume differance, so it is probably something else. Rifle 1 is a pre-64 M-70 (supergrade) with a factory 26" barrel. Rifle 2 is a custom job with a 25" Lija 1 in 10 twist with only 3 grooves. It "should" be the smoother of the two barrels. Both rifles will shoot less than sub-MOA groups one is just a little LAZY. I still have a lot of powders to try and I will switch to a faster burning powder. I just picked up a copy of the newest Nosler Reloading Book and they had a lot of loads using some of the newer powders. | |||
|
| one of us |
Also agree with Vapo and all the other posts as well. As usual, the answer is Maybe and Maybe Not. You would be far better off to forget the Velocity all together - leave the chronograph at home, sell it, or trash it - than to measure a Velocity and fret over how it relates to any other firearm or manual. Speculation on what actually causes the Velocity difference between firearms is a fine topic to discuss, but I doubt there will be a definitive answer. From my perspective Everything in the firing process contributes to the variability, except how hard you Yank the Trigger. Best of luck to you. | |||
|
one of us |
John Barsness once wrote that "velocity increases at 1/4 the rate of case capasity at equal pressure" as a rule of thumb. If this ratio is true it would take a very large case/chamber to show 200fps increase or drop in speed. ------------------------------------ The trouble with the Internet is that it's replacing masturbation as a leisure activity. ~Patrick Murray "Why shouldn`t truth be stranger then fiction? Fiction after all has to make sense." (Samual Clemens) "Saepe errans, numquam dubitans --Frequently in error, never in doubt". | |||
|
| One of Us |
You're right! The Lee Enfield’s had varying chambers, up to very large indeed! The case showed that 'largeness' very well. Often the shoulder would be moved forward quite considerably. Regards 303Guy | |||
|
| Powered by Social Strata |
 | Please Wait. Your request is being processed... |
|
The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Hypothetical Question: If you have a large diameter chamber...?
Visit our on-line store for AR Memorabilia