|
|
|
Discussion Forums
Forum Index
> Rifles general discussion
> 85gr interbond
85gr interbond
@ 03:03 am (GMT) |
Tom GouldI am having problems with the Hornady 85gr Interbond in 243win have one load for it but am struggling to tighten it up do any of you guys shoot it and what are your loads. |
Replies
|
@ 02:38 pm (GMT) |
Nathan FosterRe: 85gr interbondHi Tom, unfortunately, I need more info to answer your question.Is the rifle typically very accurate with other bullet designs / hand loads? (removes the rifle as a variable) What is the current level of accuracy of this load (so I have an idea of how much more tweaking it needs) What is the max COAL and what bullet jump are you using. That should be about enough for me to give you are more definitive answer as to which direction to go in. |
|
@ 07:23 pm (GMT) |
Tom GouldRe: 85gr interbondHi NathanThank you for your intrest. Yes the rifle shoots one hole groups at 100m with 75gr vmax. I'm seating this round jammed in the lands seems to be working the best. the I'm getting a group out of five rounds three touching and two flyers the load I'm running is 44.5gr H380 at 3997fps av mv. My next shot is to try some 4831sc I have. I really like this bullet for its effects on game. |
|
@ 09:09 am (GMT) |
Nathan FosterRe: 85gr interbondHi Tom, there is a possibility that the rifle is a touch underloaded at 2997fps. Although rifles will often show two sweet spots, one at lowpressure and one at optimum pressures, it is sometimes more difficult to find the low pressure sweet spot, than it is to find accuracy at higher pressures.H4350 (ADI 2209) would be the optimum burn rate to experiment with regarding bulk density. This powder is responsive to incremental increases in charges, without sluggish plateaus or powder cramping which will most likely occur before you reach optimum pressures. Optimum accuracy will be found between the velocities of 3150 and 3250fps from a 22" barrel. Using H4350, this will most likely occur between 44 and 46gr. 44 grain fouler 44 x3 44.5 45 45.5 46 Total 16 shots Start with a seating depth of .2mm/ 10 thou of the lands. Initially, work up loads in half grain increments, watching the brass for pressure signs, monitoring extraction. Use 3 shot groups, not five shot groups as there will be plenty of testing to re-confirm. Shoot your groups, observe the targets looking for trends, observe velocities. If you did not reach 3200fps, the bore/chamber is loose and you will need to work up a couple more loads to explore pressures further. Now, if you have achieved desirable accuracy, a final 3 shot confirmation group is all that is required (giving you a final 6 shot group as opposed to five tested at once which can be wasteful during experimentation). If you have not achieved desirable accuracy, observe the most accurate groups you have, then work either side of the powder charge in .2 grain increments. Lets say the best group was with 45 grains 2209 but the small fliers remained. Test 44.8 grains and 45.2 grains. Observe results. Fouler 44.8 45.2 Total 7 shots If accuracy is still non existent, it is time to experiment with seating depths. We will now be seating the bullet lower into the case which will drop pressures a tad. Again, lets say the best accuracy was at 45 grains. Increase bullet jump to .5mm / 20 thou, then experiment with 44.8, 45, 45.2 and 45.5 grains. 1 fouler 44.8 45 45.2 45.5 13 shots If this still does not work, experiment with 1mm jump and the same charge rates as above. 13 shots. Ok, so lets have a look at the round count. The total is 49 shots. A final confirmation group will also be required. Yes, it is a lot of ammunition but this is what it takes if we are determined to work with one bullet due to its desirable killing performance combined with a goal of extreme accuracy. Changing the seating depth is about changing 'when' the bullet leaves the bore (timing). The goal is to try and find a repeatable point within the vibrational whip of the muzzle. Changing velocities also effects this. Another main consideration is that the V-Max bullet is very soft and swages easily to the bore. To achieve the same level of obturation with the Interbond, higher pressure may be required. Make sure you have all of your ducks in a row. The rifle will need to have a sound bedding job and a good bore- regardless of the fact that the rifle was accurate with the 75gr V-Max. A finnicky rifle platform may sometimes behave this way. Monitor the rate of fouling continuously during the test phase (see barrel break in article). Shooting technique must also be monitored. The increase in bullet weight and the suggested increase in pressures will yield higher recoil to both the rifle platform and shooter. Often, shooters will mistake groups opening up at optimum pressures as a sign that the rifle is overloaded when the reason for the decrease in accuracy is simply the increase in recoil uncovering poor technique. In many instances, such rifles may be 200fps below optimum operating pressures. Of course, this is much more common in such cartridges as the .270 Win and higher, but if your goal is extreme accuracy, it is something to be mindful of. Keep away from bipods during testing, read the hold that forend article and make sure the rifle platform is sound. |
|
@ 08:41 pm (GMT) |
Tom GouldRe: 85gr interbondNathanThanks for your help as you can see from my earlier post I am already running at an average MV of 3997 fps with H380. I am still getting half a dozen reloads to a case but am starting to get a proud ring on the primer around the firing pin so have stopped at 44.5gr of H380. the rifle is a T3 varmint so it has a 23.75" barrel. So from your reply I take it that you think that I am running the bullet too fast? I have only shot loaded this rifle with 55gr, 65gr and 75gr VMax in the past and they have all shot really well but not been reliable on neck and oblique chest shots on wild Fallow though I still use them for park and farm work. I will try your suggestion of H4350 next it is not a powder I have used before so I hope I can find it locally. Thank you again for your help. Tom |
|
@ 01:23 pm (GMT) |
Nathan FosterRe: 85gr interbondHi Tom, a .243 Win cannot generate 3977fps with an 85 grain bullet.Sounds like the chrony is mis-calibrated and needs to be returned for repairs. It does not sound like a loose spec bore as this would only account for 200fps and you are quoting a figure of 800fps above typical optimum velocities. So try to get this rectified asap. In the mean time, you can still test the loads suggested if you like, then do some final confirmations once the chrony is reapaired or replaced. H4350 is ADI 2209 powder. IMR 4350 is identical in burn rate, grain for grain. There are also other equivalents such as Norma 204, Vit N150 and N550. |
|
@ 10:07 pm (GMT) |
Tom GouldRe: 85gr interbondHi NathanBugger Thanks for pointing this out about the chrony I thought I found a fast load it is after all 6 grains over max so I will have to check this out I just ordered cds turrets for this load for another rifle. Tom |
|
@ 10:25 pm (GMT) |
Tom GouldRe: 85gr interbondNathanI just had a friend check this load out on quick load and it is very close to the chrony results. What do you think? Tom |
|
@ 07:47 am (GMT) |
Nathan FosterRe: 85gr interbondHi, unfortunately quick load does not take chamber dimensions, head space or bore tolerences into account so its usefulness is limited.It is quite common to have to go up to 7 grains over maximum in a loose dimension rifles of various calibers in order to achieve optimum working pressures. In some instances, the increase in powder charges will be required to simply bring velocities up to the 'normal' MV range. In this instance, 3200fps being the normal optimal range. But occasionally, the increase combined with loose chamber or dimnesions can allow us to go 100 to 150fps above typical velocities achieved within a cartridge design. So in this .243 / 85gr example, a rare rifle may allow a muzzle velocity of up to 3300fps or so, but again, this is rare. The .240 Weatherby Magnum, loaded to full potential is able to yield 3500fps with an 85 grain bullet and 26" barrel. No doubt rare examples will yield up to 3600fps or. But even in the Weatherby (6mm-06 imp), 4000fps is an impossible velocity. The same goes for the much larger cased .264 Win mag, even though it has a bore diameter .5mm wider for gas expansion. Yes, that is the problem with CDS turrets. These and the new Swaro turrets are a part of the new gimmick range of scopes designed for todays instant gratification world. Even if the rifle did achieve 4000fps, the turrets would be useless mid way through the barrel life if the loads have to be changed to suit gradual changes in the behavior of the bore. Same goes if you wish to change loads. Put simply, if you want to shoot long, get a long range scope and learn how to use it. I am glad you have brought this up, its hard for you I know, but it will help others. If you do wish to shoot long, the Interbond is not a good choice. So you will also need to re-think this. The Interbond does its best work at impact velocities above 2600fps. In the .243, you will see a large drop in performance at around 2400fps, some very slow kills if the bullet does not strike bone. This bullet is most effective inside 200 yards while 300 yards is starting to really push it if wind drift effects shot placement. The 105 grain A-Max is a superior killer if you wish to use a long range scope and take long range shots on lighter medium game. You have a lot to work through and as I suspected, this has uncovered a huge range of problems and variables that have been unaccounted for. This is a predicament for all hunters as they move towards more advanced goals. Its hard enough that we all have to learn from our own mistakes let alone the BS of sales pitches to wade through as well. Be patient, stick with it. |
|
@ 09:14 pm (GMT) |
im2lazyRe: 85gr interbondhey TomJust take a deep breath and work slowly through each issue as it comes up. Check, then check again. Don't get discouraged as it's very rewarding when you finally get each aspect sorted and you can make repeated hits at long ranges. |
|
@ 09:34 pm (GMT) |
Tom GouldRe: 85gr interbondsorry everyone I just let the dyslexic out again MV is only 3397 I just reread my posts.Quick load give 69626 psi for this load but I have had at least six reloads on the cases I'm using to work out this load so I consider it ok.Tom |
|
@ 09:36 pm (GMT) |
Tom GouldRe: 85gr interbond |
|
@ 09:53 pm (GMT) |
Tom GouldRe: 85gr interbondNathanCompaired to you I will not be hunting over long distance my land does not lend itself to any shots over 350m. I shot the load again over two different Chrony F1's and got the same results from ten shot strings. I asked for your help as you have done a huge amount of research into load development with the need for much more accuracy than the average hunter my initial problem was with the regular flyers that this bullet seems to chuck in I have made up some more loads on your advise and will put these to the test when it stops raining and report back. I do really value yours and others input |
|
@ 12:51 pm (GMT) |
Nathan FosterRe: 85gr interbondThat sounds better Tom, 3400fps.Ok, here are the next considerations. A loose bore will allow this extra 150fps. But things aren't relatively straight forwards at times. One might expect, that if the bore is loose, the bullet should be driven hard in order to achieve a good swage/obturation to the bore. But in some cases, the extra velocity only leads to greater instability. So this is where the full range of incremental testing is important. Generally with a loose bore, soft projectiles obturate more readily (like the V-Max/A-Max) while stout bullets (like the Interbond) have greater difficulty. In the middle, we have bullets like the SST. The Interlock is more towards the soft side which is why it can be easy to work with. Along with the above, a flat base bullet (like the 95gr SST) will sometimes obturate to a loose bore, better than a boat tail design. So although 3400fps may be achievable without pressure problems (if you are getting 6 reloads, pressure is likely mild), there is a chance that a degree of stability is lost at the higher velocities. But its not always the case so experimentation is the key. You may have to go much higher than my suggested loads but please continue to work through the full range as you are doing. Will be good to hear how you get on. |
Please wait
ABOUT USWe are a small, family run business, based out of Taranaki, New Zealand, who specialize in cartridge research and testing, and rifle accurizing.
|
KNOWLEDGEBASE |
KNOWLEDGEBASE |