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> 7mm08 factory ammo
7mm08 factory ammo
@ 10:09 pm (GMT) |
Chris HuntJust being measuring factory ammo federal, Winchester and hornady superformance 139 sst case lengths and O.A.L's and found that they very quite alot is that why it is better to reload ? about 5 out of 20 bullets are the same in case length and O.A.L that's without checking powder loads ! I have found the knowledge base very helpful in the way that 7mm 08 to get the best out of the cartridge you have to reload ! what do you guys think ? |
Replies
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@ 11:02 am (GMT) |
Nathan FosterRe: 7mm08 factory ammoHi Chris, firstly, sorry for the late reply, I have been very busy of late.From an accuracy stand point, it all depends on the rifle. A while ago I was testing ammo for a manufacturer. I tried the supplied ammo in two fully accurized rifles, the first rifle grouped .6", the second rifle grouped 1.6". A while later I tried the ammo in a third accurized rifle which grouped .3". Therefore, regardless of ammo manufacturer tolerances, the barrels are the final deciding factor and have a major influence on results, more so than variations within the ammo- within reason. In the rifle that grouped 1.6", the options are obvious, either try a different factory load (hoping for different harmonics) or hand load (deliberately altering harmonics via experimenting). That particular rifle does very well with hand loads, under .5". From the perspective of killing performance, a lot can be gained from hand loading. Increased velocities with heavy bullets are a factor. With the light 140 grain bullets, Hornady have this covered, it is near impossible to duplicate or improve on the 139gr Superformance velocities without Superformance powder. However some hunters may prefer a 150 to 162 grain bullet driven as fast as possible. Just bare in mind, the Superformance ammo is very good and as long as it is accurate in your rifle, will work well on lighter bodied medium game out to moderately long ranges. The 139gr SST can be used on larger bodied deer (Red / Mule) but where penetration is a concern, is best used beyond 200 yards. The KB has more info. Unfortunately, I need to update the Federal 150 grain Speer factory data in the KB as I have listed the velocity at 2750fps but in recent test rifles, I have found the velocities to be averaging 2630fps in typical sporting rifles, about 20fps below advertised specs. This is now a rather slow killing load with rear lung shots, though still a good bush hunting load for deer. For long range work, hand loading allows the user to adopt a fully frangible bullet that will produce wide wounding at long ranges in the absence of high velocity, the 162 grain A-Max being a classic example. The low MV of the 7mm-08 (2650fps) works in its favour, allowing the A-Max to be used at close ranges without risk of shallow penetration. In this sense, one load can be developed for a range of tasks. In a recent client rifle, accuracy with hand loads using 140 grain bullets became poor at anything over 2800fps. Factory ammo went well but again, anything fast was no good. Best accuracy was at 2753fps (hand load 139gr SST) which is a bit of a slouch as deer rifles go. In this instance, it is more productive to actually drop the velocity to 2600fps and change to the A-Max. Reasoning- if its going to be a slow rifle, we might as well utilize a bullet that works well at low velocities, giving wide wounding right down to 1400fps. This takes away the need to push the rifle beyond its limits. |
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@ 07:33 pm (GMT) |
Chris HuntRe: 7mm08 factory ammoThanks Nathan for the reply. Since the 2nd of may I went out a brought some reloading gear. worked up some loads with Adi 2208 powder behind 120 ttsx and federal primers, OAL 2.830" no luck with groupings all went over a inch so far, more loading to do with that load.But loaded the 162 a-max just 3 bullets with the 2208 powder 40grns and with O.a.L OF 2.875" to see if they would stabilize in my tikka t3 and wow best group i have ever shot .7" no key holes there . Should i now shoot it out to 300 yards and recheck for stabilization ? twist rate is 1-9.5 standard 22" barrel. Have you loaded the a-max in 7mm 08 tikka's before ? I don't want to buy the h4350 powder if it doesn't stabilize. Also my est M.V is 2528fps I don't have a crony yet does that speed sound about right ? sorry so many questions but I cant find the info I want on the net. Thanks Chris from Hawkes Bay. |
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@ 12:34 pm (GMT) |
Nathan FosterRe: 7mm08 factory ammoHi Chris, sounds like a good start.I have heard this business of T3 rifles not stabilizing 162 grain bullets and I really don't buy into it. There are often other factors at play which shooters fail to take into account,such as trying to seat long rather than seating for concentricity, failure to hold the T3 steady under increased recoil. Actually that last factor is such a big one, people totally underestimate the effects of recoil in the T3 platform. Anyway, a 1:9.5 twist is fine, heck I have set rifles up with the 180gr VLD utilizing this twist rate. So keep at it. Please stay with ADI 2208, is is the optimum powder for you, the gains are 'worthwhile' if changing to 2209,your not going to see an extra 100fps etc. Your velocities sound about right. Keep working up loads till you find max (look for shiny extractor marks on the case head and flattened primers). You will then have the full picture. Work up in half grain increments, 3 shot groups. You'll probably start to hit max at about 42.5 grains,maybe a bit higher, depends on your bore tolerances. After this (if need be), observe your targets, take the most accurate target and work loads either side of it in .2 grain increments. Keep that recoil issue in mind. Tight sling,good forend control, trigger backed off to 1.5lb for precision work. Let the barrel cool between shots. Like I say, itsounds like you are going well already. Goal group size for your rifle should be 12mm/.5", technique will be a major factor. |
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@ 12:45 pm (GMT) |
Nathan FosterRe: 7mm08 factory ammoThere is no need to check it at 300 yards with that twist rate at those MV's. Either its stable at 100 or it isn't. ES will be a bigger factor (velcoity spread from shot to shot) keep to the basics for now.Regarding the COAL, you have two options in the T3. Either seat to feed smoothly with the magazine as it is- or modify the magazine by removing the plastic block and opening it right up to 85mm, then seating close to the lands. You have probably already the COAL info I have written on the site (knowledge base and forum) which should help. For someone who has just started reloading, I think you are doing extremely well. Try to remain patient, the learning process is ongoing so don't put too much pressure on yourself. When I say a goal of .5", it should not be read that your .7" group is poor because it is quite fine and straight off the bat with its current MV and group size using your hand loads, the rifle is already an adequate 600 yard shooter. |
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@ 07:48 pm (GMT) |
Chris HuntRe: 7mm08 factory ammoThanks again for the reply I have read most of the knowledge base and forums that interest me. research about reloading is the key !I am lucky to have a good set up at the in-laws farm so I practice shooting a lot ! Remington core-lock was the most accurate at .9 by the way. and holding that for-end really helps. Just about got stuck looking cool shooting cross armed u.s style. Until I read KB !. I shoot off a day bag shooting steel 10"x10" From 300 out to 650yrds for practice for in the field for sika and reds and oh and I was also lucky to start hunting and shooting at a ripe old age of 5yrs got my first rabbit. any way thanks alot for the info just ordered a stock stabilizer kit from you. Cheers Chris Hunt. |
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@ 12:52 pm (GMT) |
Adrian RegnaultRe: 7mm08 factory ammoGood discussion guys. I started shooting a 7-08 at the end of last year and quickly got into hand loading on a cost basis, not thinking I could replicate the accuracy of factory ammo. My rifle is based on a Howa 1500 action, with a Tikka barrel, bedded into a Boyds laminated stock, all put together by Alan Carr. It will shoot 140 gr Corelokts into 12 mm groups at 100 (2747 fps), and Federal 150s into 20mms (2599 fps). After several months of experimentation and practice I'm now shooting Nosler 140 BTs into a single ragged 15 mm hole at 100m (2779 fps) using 43.5 gr of AR2208, which is over the max recommended load but there are no pressure signs in my rifle. I'm also using this load in my mates Tikka T3 Lite and I do notice the increased level of felt recoil from the lighter rifle, and so far we haven't got below 20 mms, with the same load.I have also been experimenting with 139gr Hornady SSTs but can not get them under 25 mm at 100m (using the same load, which is on the rec max for 139 gr) at 2810 fps (42.5 gr of AR2208 as giving me 2730 fps and a 33mm 5 shot group). I haven't noticed any pressure signs with this load until the other weekend when I was shooting hares at 200 m and had difficulty lifting the bolt on a couple of rounds. Someone suggested that this may be due to the seating the bullet too far out and onto the lands. I tend to seat at the max OAL as I have found this usually gives me the best accuracy. Can I expect better from the 139 SST bullet, as it about half the cost of the Nosler and as such is much cheaper to shoot? Thanks for such a great site. Cheers Adrian |
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@ 09:44 pm (GMT) |
Chris HuntRe: 7mm08 factory ammoHi AdrianMy tikka t3 lite also doesn't like to shoot under an inch with the the 139 SST bullet or the 120 ttsx bullet i have tried a lot of loads and seating depth's but have given up and just kept the 120 ttsx at one inch at a hot load of 47gns for close range bust hunting, out to 300y max. I have a longer range load 0f 43gns of 2208 pushing a 162 amax grouping .5 0r better if i do my part ! I have read some where that the 139 SST is an finicky bullet and needs a small jump to the lands .2 or something ? as well as the 120 ttsx Barnes bullet. I am not onto single loading for a bush rifle at close range and medium ranges for follow up shots or 2 deer one after the other. So with the amount of travel i have with my bolt and modified mag length bullets are 2.875 coal standard, mag can house 2.830 bullets there will be riffles out there that will shoot those 139's under .5 just some rifles are harder to find those sweet spots with some bullets. And from what I have read Berger vld and Hornady amax are easier to get shooting good. Good luck with the 139's Chris |
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@ 02:39 pm (GMT) |
Nathan FosterRe: 7mm08 factory ammo... and hand loadsHi guys, I just want to go over COAL's. Please bare with me.Bullets need to be seated deep enough in the case that they are squared up to the bore. If you seat shallow, you will have projectiles that are off centre by minute amounts. Such projectiles will not shoot accurately. The 7mm-08 is designed with freebore like the .308Win and Weatherby's. If a hand loader tries to get close to the lands, the projectiles end up being seated shallow, accuracy is lost. With the 139gr SST optimum concentricity is at a COAL of 72mm or 2.835" The max COAL with the 139gr SST is around 76.14mm or 3.100" in SAAMI spec chambers touching the lands. But this figure is moot as it cannot be used. So bullet jump is long, about 4mm or .157". In rifles with standard short magazines which are 72mm (.2835" long), COAL needs to be 71mm or 2.795". This poses no problems. As suggested, Tikka magazines and a few others can accommodate longer COAL's. The A-max calls for an even longer max COAL (when the bullet is touching the lands), up around 77.44mm. But if seated to max, the projectile is barely in the case neck. Seated for optimum concentricity, bullet jump is very long. Accuracy is fine though. I have said very often, that the SST does like to be seated close to the lands, as close as .2mm. However, the effects are more pronounced at magnum velocities where small discrepancies cause big errors. In both the 7mm-08 and .308, the SST's can handle a very long bullet jump, so there is no need to try and get close to the lands, seat for concentricity, then utilize incremental powder charge weights to find sweet spots. 43.5 grains of 2208/Varget is a typical sweet spot / good accuracy. I test loads all the way up to 44.5 grains, sometimes further. My personal preference is for the 162 grain A-Max which I will test up to 43 grains or so. All of my typical test loads are well over manual maximums so be warned, they are not recommended loads. Watch for pressure signs with all load development. If any readers need more help with COAL's, please refer to the COAL article in the KB. |
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@ 11:06 am (GMT) |
Nathan FosterRe: 7mm08 factory ammoCleaned up some of my typos, hope the above makes sense.Nathan. |
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@ 03:52 am (GMT) |
Adrian RegnaultRe: 7mm08 factory ammoThanks for your help guys. I've had a go at measuring my COAL as per method 1 in the KB but are yet to put some loads together with the adjusted the seating. However, I tried 43 gr of AR2208 with the 139 SSTs and shot a reasonable 5 shot group, apart from 1 flyer. Also tried some 154 gr SSTs with 41 gr of AR2208, which are showing promise. Cheers Adrian |
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