@ 11:57 am (GMT)
Gavin ChauHi Gents,
I was wondering if anyone had an opinion on what was the optimum barrel length for a 7mm08 - I have a tikka varmint that I cut down to 20inches to save half a pound of weight and to improve the handling - I love the gun and the calibre but I've found the maximum velocity I can drive 162grain Amaxs is about 2600fps with 48gr of 2209 (which is also the upper accuracy node for this barrel) - but I was hoping for another 100fps or so to extend the range a little
I can only get the berger 168's out at 2550fps accurately with 47.5gr of 2209
I'm considering a rebarrel down the track and was wondering if there was much benefit in getting a slightly longer barrel?
@ 01:33 pm (GMT)
Re: optimum barrel length for a 7mm08?I just brought a 7mm08 too, it was suppressed. (20 inch barrel)
I sent it back the next day, the suppressor I felt didn't give enough benefit to warrant having it, and yes the heavy projectiles are slow.
it is what it is, if the barrel was longer I guess it would help velocity but not a great deal, maybe your lost 100fps
shoot 120's and get more speed, but oh the projectiles don't have a good b.c. , you cant have everything.
maybe next time try a 7mm rem mag, but you will get more recoil, noise.
@ 01:45 pm (GMT)
Re: optimum barrel length for a 7mm08?Gavin I have a 22" barrel 7mm08 and was able to push the 162 Amax to 2670 with 41.5 gr Varget, accuracy was poor (#1 contour fluted) and recoil was stout in the sub 7 lb. scoped rifle. Best accuracy was a 38.5 grs & 2580. Once hunting season is over I will explore other powders.
I am using a 150 Ballistic tip at 2630 this season that runs in the .3 MOA which I am good with as this is a point and shoot rifle to about 350 yards.
Hope this helps, happy hunting, Aj
@ 02:55 pm (GMT)
Re: optimum barrel length for a 7mm08?Hi Gavin, we put together a Tikka with True-Flite barrel a short while back. Sweet spot was 2670fps, though there was another at 2800fps. We opted for the 2670fps load as the upper load was near max.
On average, I find that the 7mm-08 shoots the A-Max to 2650fps whether fired in a 22-24" barrel. But I tend to opt for a 24" barrel because the most affective powder in the 7mm-08 is ADI 2208 (Varget) and over the years, I have found that this powder can prefer a 24" barrel to achieve full velocities in the 7mm-08 and .308. In short barreled .308 rifles, I use ADI 2206H (H4895) but in the 7mm-08, I use ADI 2208 whether the rifle has a 20" or 26" barrel. This is more a matter of case to bore ratio than powder efficiency. You get to know what works.
On the Tikka action, you can adopt a slightly stouter (than factory) barrel and at 24", the rig still feels very light, handles well in the field, shoots well, and does not heat up quite so fast. From the prone position, it is not so easily effected by discrepancies in shooting technique / conditions- a factor for precision shooting if thats your game.
Your T3 can also be fitted with a .30-06 length magazine, a .30-06 bolt stop.loaded longer than usual- and still feed smoothly.
That is the long answer. The short answer is- in barrels of 20-24", velocity will be 2600 to 2700fps. A difference in effective range of 50 yards.
Different strokes, different folks. A'J's rig is ultra light for climbing high, shooting to 300-400 yards and carrying out heavy loads of meat. Your take may be the same or different.
@ 09:41 pm (GMT)
Re: optimum barrel length for a 7mm08?Jason,
thanks for your reply I'm really only interested in shooting the 162's and 168's since I bought the rifle as a bit of an all-rounder but primarily to shoot pigs and goats at 600m - of course since then I've been seeing pigs at 750-800m :lol:
thanks for your reply - Can I assume you're in America? varget = 2208 in Australia (I believe 2209 = H4350) I always wondered why some people have a preference for Varget over H4350? in our powder manuals the highest velocities in the heaviest bullets for the 7mm08 are always achieved with H4350 or BM8208 (not sure what the US equivalent of that is) I've noticed the same thing with the Nosler BT 150gr behind 48gr of H4350 - its beautifully accurate for short range stuff averaging groups in the high 0.3's and some in the 0.2's - problem is the BC's are terrible! it limits the rifle to 450-500m shots
thanks for the detailed response - once again - I havent tested 2208 but I'm interested to see that you have tested it to higher velocities than 2209? I'll have to give it a go - I've read that the highest velocities in the longest barrels also tend to be the highest velocities in the shortest barrels regardless of powder type which is why I started with 2209 - I also happened to find it accurate with most of my loads. I've heard reloader17 is faster again with people achieving 2800fps in a 24inch barrel with the 162 amaxs (but its near impossible to find here in sydney at the moment)
My tikka has a manners stock on it and cdi bottom metal so its a touch heavier than the factory plastic version at 9.1lbs unscoped (and 10.8lbs scoped with a march tactical) - the good thing is I have a longer magazine than the factory version now and seat my bullets a little further out.
I only really just started messing around with with long range hunting and precision rifles last year (although I've been hunting for many years) so its been a pretty steep learning curve! Its also been a fascinating one.
the last mob of pigs I saw were at 800m - My 162 Amaxs would only be travellling roughly 1570fps by that stage and the berger 168's from my gun would be travelling around 1550fps (my initial thoughts were that this is not fast enoough to prevent these bullets from pinholing)
if an extra 100fps in launch speed only equates to an extra 50m in range - it sounds like I better start annealing projectiles or finding something that works with a lower impact velocity...!
@ 12:59 am (GMT)
Re: optimum barrel length for a 7mm08?Hey Gavin, nope I am a Canadian, live in the south east corner of B.C.
Why Varget, well I shoot a lot of it in the 308 and because of availability at the moment! H4350 is going to get a try as soon as the hunting season is over. The ADI number designations really threw me for a loop, I finally booked marked a comparison chart to reference.
It sounds like your at a bit of a cross roads similar to my self a few years back. The 7mm08 is a "new" rifle purpose built for sheep as 300 yards is an unusually long shot and also for a easy carry when I am not the intended shooter of the day. I also run a 7 SAUM, this is my go to rifle hands down but I am looking forward to re-barreling as the 22" is a handy cap, still I run a 162 Amax at 2830 with out standing accuracy. This has me over 1800 out to 900 yards. But 3 more inches of barrel should get me up over 2900 and in a rifle under 10 lbs with a NF 5.5x22. And then theres a 7mm Practical (thanks Nathan!) 162 load at 3200, and the 190 Matrix at 3030 with a BC.807, long hits get easier with more thump BUT the rifle weighs 13.5 lbs and is 50" long.
I see them as tools and depending on the day I try and pick the right tool based on terrain, game and the distance of a shot and how I am feeling (knees are getting a bit old LOL).
Gavin maybe a 7mm Remington mag would put a smile on your face next time the pigs are at 800m!?!
Well Happy hunting, Aj
@ 01:17 am (GMT)
Re: optimum barrel length for a 7mm08?oops sorry Aj!
I imagine there would be some awesome scenery hunting in Canada! NZ was beautiful as well (but I never got to hunt as I was there for the snow and to race dragonboats when I was younger)
for sure I think cross roads is the correct term - I probably should have stepped straight up to one of the big 7mm's in hindsight (or even a medium one like the 284) but at the time it seemed intimidating! Then again by the time this barrel is shot out in a couple years I'll probably have enough experience under my belt and I'll be ready
@ 05:34 am (GMT)
Re: optimum barrel length for a 7mm08?I have a Rem 700 SS Mountain Rifle, current model with Bell and Carlson Stock with 22" barrel.
I too use the 162 gr AMax, but I use ADI Bench Mark 8208
41.2 gr gave me the best groups but slight pressure signs and 2780 fps
I reduced to 41.0 gr for 2740 fps no pressure signs and 3 shots touching each other at 100 yd.
Hope this helps.
@ 05:38 am (GMT)
Re: optimum barrel length for a 7mm08?PS I live in Cairns, Tropical Queensland and tried Bench Mark 8208 for its temperature stability.
I don't think I can better these speeds.
@ 06:05 am (GMT)
Re: optimum barrel length for a 7mm08?
PS I live in Cairns, Tropical Queensland and tried Bench Mark 8208 for its temperature stability.
I don't think I can better these speeds.
I'm definitely going to give benchmark a go now - it also seems to require lower load densities than 2209 to achieve the same velocities - this is a bonus since full house loads of 2209 are actually heavily compressed and without adequate neck tension the bullet oal's actually begin to shift over time - hopefully they've sorted out these powder supply issues down here
(if it works I have to figure out what I'm going to do with the 5kgs of 2209 I have left!)
@ 10:39 am (GMT)
Re: optimum barrel length for a 7mm08?Haha, non taken Gavin! a we have some nice country to tromp around in here. I was in NZ a couple years ago and we found the south island quite similar to B.C. The one big difference was tho when you got up in the night and out of the hut/tent for a pee you don't have to shine a head lap around looking for bears first lol.
Mark it sounds like your onto something there! What kind of COL and jump is your load? 8208 is a interesting burn rate but if it works!! I'll be keeping my eye open for a pound or two to try.
@ 02:54 pm (GMT)
Re: optimum barrel length for a 7mm08?Aj,
Max COL for this chamber is 74.8mm or 2.9449in with the AMax.
Due to the Remington Magazine I am restricted to 71.8mm
I tried some loads at 74.7mm, manual feed but they showed no improvement over the shorter rounds so no need to change magazine setup for a hunting rifle.
Norma Brass, Federal 210 primers.
Rifle has a Jewell trigger and I use a NF 3.5-15x50 with NP2DD for testing. Action not bedded yet as I wanted to see if this barrel was any good (which it seems to be, more testing needed) or if I have to rebarrel.
My normal hunting scope for this rifle at the moment is a Minox ZA5 1.5-8x32 which I have only just got for it. I plan to use this setup for everything out to 400 yards. For longer ranges I am building up a Rem 700 SS SPS 300 Win Mag with Bell and Carlson Stock, Jewell Trigger and waiting on a NF 5.5-22x56 MOA turrets and Mil Dot Reticle. Do the same testing as the 7mm08 and if the barrel does not shoot, then rebarrel in 7mm Practicle and use the same brass
@ 11:18 am (GMT)
Re: optimum barrel length for a 7mm08?Mark thanks for the info! I too am restricted to mag length in the Remington "Model Seven" but your numbers are very encouraging!
300 win eh! What game are you going to be shooting? I have used a 208 Amax with H-1000 from Coyotes to Elk and Bear and its spectacular! H-4831sc also shot very well. Good luck with the build, and thanks!!