True 6mm-06 / 6mm-06AI velocities?

[Rugerjim]

Hi guys. New member!
Been cruising some of the threads and note that many of you own calibers chambered in 6mm-06. One person was shooting 55grn pills at 4500fps. Would love that load info!
I'm considering making my own first wildcat. I really am interested in high velocity 6mm (243) rounds. I would love to shoot a 55gr pill at 4500 or a 70gr pill at 4000fps (ballpark).
If you dont mind me asking, what velocities are your truly getting from these cartridges with 55-70gr pills?
What twist rate do you use for lighter pills? Was thinking 1:10/1:12.
Thanks for any info supplied. Much appreciate your time.
Jim!

 

[sandwarrior]

I shoot a 6-284, which has the same capacity as the 6mm-06. I can easily get 3800 from an 87 gr. projectile. Although, to save the barrel, I typically shoot them around 3600. I have played around with lighter bullets, but since my game is reaching out farther, I stick to the heaviest projectiles that will stabilize in my rifle. But, 70 gr. are capable of 4000 out of it. It takes a tougher bullet to do that, as a thin jacketed bullet will come apart due to the high rotation.

That said, if you goal is hyper velocity light bullets, you need a slow twist. For 55's only, you want a 1-14" twist. For, 55's and 70's you need a 1-13" twist. But, you might have to sacrifice speed on the 55's so as not to blow them apart.

 

[Rugerjim]

If a 6mm-06 can honestly shoot a 70gr pill at 4000fps than I am totally going for it! Is there any kind of load data/reference someone can show me?

 

[sandwarrior]

Rugerjim,

Here's a place to start.

http://www.hodgdonreloading.com/data/rifle

I happened to be looking at it when you posted back. I like Hodgdon's website as they cover a lot of wildcat cartridges like the 6mm-06 and 6.-284. But, they don't go high on the loads for liability reasons. You will have to find what your rifle likes and where you end up at max pressures. I found with my 6-284 that the top load wasn't even up to my starting load. My whole case was smoked back. Typical of a way underloaded case. I upped the powder until it quit smoking. I'm running 100 gr. BTSP's at about 3400. That's minimum pressure for that cartridge in my rifle. Again though, it's liability thing and you'll have to find max pressures in your own rifle.

As an aside, do you reload much? Sometimes with wildcats, things get sticky quickly. I'm not a fan of the 40 degree shoulder of the Ackley cases. At the top end pressure curves go way too high, way too fast. If you were interested in a 6mm-06 IMP, look up the RCBS version. it's got a 28 degree shoulder and is less dramatic when increasing loads at the top end.

 

[Rugerjim]

Hi Sandwarrior, yeah I reload a few different calibers. I was going to chamber my own barrel on my lathe. Basically I'm trying to justify not just using a plain old 243. If I can push a 55gr pill 4500 or a 70 gr pill at 4000 than I can justify spending the money. The reason I asked about the AI cases is I figured if i'm gonna go nuts I may as well go all out and try to push it as fast as I can. But if a 6mm-06 on its own gets those figures I'll simply go with that. Still looking for decent data, most reports of velocities has been from people who own them, there doesn't appear to be listed data. So the search continues at this stage. But are we thinking a 6mm-06, (not AI) will hit those numbers? If so I'm in.

 

[sandwarrior]

Yes, it will hit 4k. Using a slow powder (4831, RE-19 or 22) in a long barrel. As noted, you only need a 1-13" twist for those 70's.

 

[Dogsniper]

You could probably get those same velocities with the straight 25-06 and a 70 gr pill Sierra blitz

 

[Mike Casselton]

Yes, it will hit 4k. Using a slow powder (4831, RE-19 or 22) in a long barrel. As noted, you only need a 1-13" twist for those 70's.

I shoot a couple of 6BRs and both barrels are 1-14 twist. I don't hot rod them and both shoot 70gr bullets without issue.

If you are going for speed, I'd recommend the 1-14.

However, keep in mind if your goal is to blow up rodents, a faster twist increases rotational velocity and bullet expansion with light jacketed bullets.

Having a choice, I would build the 6-284 with a 8-9 twist just in case I wanted to deer hunt with it.

YMMV

 

[sandwarrior]

I shoot a couple of 6BRs and both barrels are 1-14 twist. I don't hot rod them and both shoot 70gr bullets without issue.

If you are going for speed, I'd recommend the 1-14.

However, keep in mind if your goal is to blow up rodents, a faster twist increases rotational velocity and bullet expansion with light jacketed bullets.

Having a choice, I would build the 6-284 with a 8-9 twist just in case I wanted to deer hunt with it.

YMMV

I agree, I bought this rifle with the 1-10" twist and have now set it back twice. It'll kill varmints to 1k, but gets pretty iffy past that. Next time is gonna be a tight twisted barrel. I may go through barrels, but I want good ballistics at one mile.

So, with that said, Rugerjim, as Mike said, he's stabilizing the 70's with a 1-14" twist, and all-out speed is what you're after that would be the way to go. I would say, that if you had to wait on a 14" vs. a 13" or one was higher than the other, I wouldn't go the harder route. Get a good barrel at the best price and go for it.

 

[Rugerjim]

Thanks for the info guys, on monday I'm calling the smith and asking what barrel blanks he has available in 6mm- 12/13/14 twist. I think its about $720AU for the barrel and then I'll base it off a weatherby/howa action. Plan was to neck down 6.5-06 brass.
Truth be told I want a rocket ship, since I have to set up and call for feral dogs some of the shots I'll need to take might be 400 yrds. I really hope I can get those kinds of figures. Right now I'm shooting my 223 with 40gr vmax at 4000fps with a 1/8 twist and a really hot 2207 charge. Bullets aren't separating yet. I'm curious as to the why the 6-284? Looking at reloading info it's not quite as fast as what I hear can be achieved with the 6mm-06. I have someone pressuring me to just got 243AI, but I don't think it seems worth it when the 6mm-06 seems so much faster. Thanks for your time gents!

 

[b6graham]

https://shermanwildcatcartridges.com/6-sst

shoots a 115 around 3450. if you want speed. let's you do a short action too

 

[sandwarrior]

Rugerjim,

The 6-284 came along as the "littlest" brother to the .284 Win. When new cartridges came out, everything got necked up and down. Those that did the 6.-284 found with the then relatively high BC's and fast speed it was a great 1k gun. As long as there wasn't a ton of wind. Along came uber high BC projectiles. About the same time everybody figured out that "more room, was just really only more boom". Meaning, smaller more efficient rounds could push bullets nearly as fast without eating barrels nearly as fast. In a given neck/case diameter ratio, increasing the powder, decreases efficiency proportionately. Meaning an efficient case like the 6mm BR can be doubled in size only to get a few hundred feet more per second. Vast amounts of powder only eat barrels as they make marginal gains in velocity. They don't contribute to awesome velocity as much as we wish. The smaller the cartridge diameter the more pronounced this phenomena is.

If it's worth anything, one of my mentors, Skip Talbot, set seven 1k NBRSA records in a day with one back in 2000. Thus why years after his passing, I gave in to the urge and honored him with getting a 6-284.

Which brings me to ask, Why 4000? That is a magic barrel eatin' sumbitch number! You can get a lot of varmint killing out of a 3k medium to moderate weight 6mm bullet. Use an efficient bullet and you can kill varmints as far as you can see them! None of the long range shooters go 4k on their loads. They use efficient bullets pushed in the upper 2k's to lower 3k's. It's one thing if you are competing, but in varminting it's worth saving barrels. Even for competition, the 6-284 eats barrels too fast.

IMO, you'd be better off getting a 6XC, .243 Win, 6mm Creed. or a 6mm Rem. Stick with a short action in doing so. AI's, as noted above, have some advantages, but IMO, the disadvantages outweigh them.

 

[308220]

If youre set on a 6mm, go with the 6-284. Get an 8 twist. Shoot 100gr + bullets. Get double the barrel with not shooting 4000 fps. If your intent is "long range" varminting, this is your ticket. I would never limit myself with a slow twist barrel.

Run the numbers on a 103/108 eld at 3200 fps vs 55gr Nosler at 4000 fps. Especially at longer ranges. 600-700 yards+......youll see.

 

[Rugerjim]

Good question: why 4K? Because when looking at ballistic charts the 243win as standard can shoot a 55 gen bullet at 4K with very little drop. I just like the low drop rates of fast projectiles last 200 yards. It hits hard at extended ranges. Make it a 70gr pills and the improvement is massive. I already have a 223, 308, 270 and 243. I just want a build a dedicated night vision/thermal long range flat shooting dog gun. Run a 55 to 70 grain flat out, if I burn barrels... well I burn barrels. Dogs are worth a bit of coin to me so it’s important I have a good rig. Maybe a plain 6mm-06 is the ticket, when it’s done, i can ream it to make 6mm-06 AI brass ? I can get cheap 24” 1:10 243 barrels. Then maybe ream it just out, or get a 26” made for 720... hmmm.

 

[Dewey7271]

I run an 8 twist 6-284 w a 26.
I run 105s at 3140-3150. There’s more but no need for it.
While I agree barrels are consumables, the speeds you’re talking will eat barrels. If you don’t mind that then carry on.
Don’t forget though that the lighter pills are going to let the wind dick with you since you mentioned extended range.

 

[stello1001]

Good question: why 4K? Because when looking at ballistic charts the 243win as standard can shoot a 55 gen bullet at 4K with very little drop. I just like the low drop rates of fast projectiles last 200 yards. It hits hard at extended ranges. Make it a 70gr pills and the improvement is massive. I already have a 223, 308, 270 and 243. I just want a build a dedicated night vision/thermal long range flat shooting dog gun. Run a 55 to 70 grain flat out, if I burn barrels... well I burn barrels. Dogs are worth a bit of coin to me so it’s important I have a good rig. Maybe a plain 6mm-06 is the ticket, when it’s done, i can ream it to make 6mm-06 AI brass ? I can get cheap 24” 1:10 243 barrels. Then maybe ream it just out, or get a 26” made for 720... hmmm.

When you say you want a dedicated night vision/thermal long range flat shooting dog gun, what exactly do you mean by long range? Like how far?

 

[Rugerjim]

Probably 400 yards. Problem is the doggies are really smart, often in packs, so follow up shots must be quick, bullet needs to get there quick, maybe even on the run. They typically turn and look back for a fleeting moment before hitting cover giving you just the smallest moment to get a second one. If I could get a 55 going 4500 or a 70grn going 4000-4100 I’d be in top shape. I’m not fussed about barrel life, happy to ream and chamber my own. Looks like the 6mm-06 might be the easiest to achieve, there are no 6-284s around. Even 257 WM isn’t available as standard. We are kinda limited that way here in aus.

 

[M338]

I ran a 30” barrel in my 6-284 and was comfortably launching 95gr nosler bt’s at 3600fps + with RL 22.

 

[sandwarrior]

Rugerjim,

What is available down in AUS? Reason being, the .270 Win you mentioned will push 100 gr. bullets VERY fast! If you can get 100 gr. .270 bullets down there. something to think about before you go all in on a new wildcat cartridge.

As to the 4k, I get you want the flattest shooting cartridge available. It would seem to me also, you have access to 6mm bullets where others aren't so plentiful? For me the problem is past 400-500 light bullets are iffy. The drops inside are pretty spectacular, but beyond, pretty unpredictable. If you don't see taking long shots, it's a moot point. Everyone needs a lazer, and mine is the 6-284. I laugh with chagrin when I've set the barrel back prematurely, but I smile when I can point and shoot as far out as I can.

If you ever do look at going longer with a more efficient cartridge, a little scope work can really help. Even just a duplex reticle gives you three elevations dead hold to use. And, you can vary off of those for longer or shorter shots. Zeroing at the point of the upper duplex, then graphing where you hit at the crosshair and the lower duplex point. Meaning you use a 100m zero for the upper duplex, and in your scope, say it's a 2moa drop so it hits dead on at 200m. Then say the lower duplex hits just low at 300m. Those are examples, not what your 6mm-06, or the scope you put on it, would be capable of.

You can get this flexibility out of any duplex scope, which is common, without having to dial. As you mentioned fast shots are going to be the norm, so that's kinda out. Quick, "known" holds is your best option. Might as well figure them all out now before you get all set to build the superduperloudnboomin'combustionchamber dogaroo nightmare.

 

[Rugerjim]

I’m running an ATN 4K atm. Great bit of kit. Will get a Thor when available in 640. The question is now, what action do I want. Options are Ruger, Remington, weatherby Vanguard/ Howa, or browning Abolt3. My plan now is to buy a 270 and Rebarrel it shortly after. The 06 cartridge is easy to get as is the long action. It’s also much easier to get a chassis/stock for rem, howa, ruger, but not for browning. I like the short bolt throw on some of them but am a fan of vanguards quality. Probably a 26 or 28 inch barrel. Might be a little while till it’s all done. Any thoughts on action?

 

[sandwarrior]

All good actions. I'm not a fan of the chassis stocks, but many do like them. Personally, I tend to like wood/laminate stocks that are contoured to be more ergonomical in their handling.

Long action cartridges can give a bit more speed and versatility for long range shooting. Short actions with the right set-up are all you need though. Recoil is a major issue in follow-ups. So, stock fit is crucial and since you want a fast cartridge, you might also think about threading the end for a muzzle brake. Noting quite like watching the entire firing process from squeeze to bullet impact, without ever moving off target.

I'm assuming since you are going to turn your own barrels, you might also have access to a mill where you can hog your own stock style out? make your own chassis?

 

[sandwarrior]

So I had some spare -06 rounds and thought I would make a dummy round for comparison. 6-284 on left, 6mm-06 on right. I found I had to "three-step" the neck as the brass wanted to crumple with that big of a size change.

 

[sandwarrior]

My first attempt. Straight down to 6mm

 

[Mike Casselton]

My first attempt. Straight down to 6mmView attachment 6971850

Have you tried running the case through an empty 6-06 seating die first?.
If you have a set of 270/280 dies around, they make for a great intermediate step.

Of course, starting with 270/25-06 brass is easiest.

 

[sandwarrior]

Have you tried running the case through an empty 6-06 seating die first?.
If you have a set of 270/280 dies around, they make for a great intermediate step.

Of course, starting with 270/25-06 brass is easiest.

That's the success story on the left. I ran it through a 7mm first, then the 6mm seater, then the 6mm sizing die.

 

[Mike Casselton]

The speed that the case goes into the die makes a big difference also.
I resized some 22-250 back up to 250 Sav and the first ten cases had crooked case mouths. When I went slower, the mouths came out visibly straight.

 

[502Chevelle]

I was wondering why you didn’t start with 25-06 brass as well.

 

[sandwarrior]

I was wondering why you didn’t start with 25-06 brass as well.

I didn't have any on hand. It's just a dummy round.

 

[Rugerjim]

I love the spirit of science and exploration! I have been doing my research and I’m goin with a 12 or 14 twist. I’m still deciding if I want to punt right out and go the 6-06Ai or just run a normal 6-06. So much conflicting info. I’m pretty much set on using a howa action now due to price and availability. Starting it’s life as a 270. Other option was ruger american. Alas no chassis for it

 

[Rugerjim]

So I bought a barrelled action in 270 yesterday and an MDT LSS-XL chassis, and a magazine to start the build. I did some ballistic calculations and a 270 with a 28" barrel is verrrry...verrry... close to a 6mm-06 in terms of drop with a 90 grain pill (270) vs a 70gr pill doing 4100/4200. 270 I could potentially push a 90gr pill at 3850... Might be a cheaper option I can run with... saving 90USD on a set of bushes and 150usd on a reamer... Hhhhmmmm talking to myself out loud...

 

[sandwarrior]

So I bought a barrelled action in 270 yesterday and an MDT LSS-XL chassis, and a magazine to start the build. I did some ballistic calculations and a 270 with a 28" barrel is verrrry...verrry... close to a 6mm-06 in terms of drop with a 90 grain pill (270) vs a 70gr pill doing 4100/4200. 270 I could potentially push a 90gr pill at 3850... Might be a cheaper option I can run with... saving 90USD on a set of bushes and 150usd on a reamer... Hhhhmmmm talking to myself out loud...

Keep that thought and see how it works out for you. Shoot it 'til it goes south on you then decide if you want to keep that route, or go a different route.

Like many on here I would advocate for a tighter twist and heavier bullet in whatever you choose. But, speed is it's own special thing. Anything based on the '06 case can give you that.

Keep an eye out for whats new in the shooting world and if you can get it. Can you get .25 cal? Reason I ask is there are now 131 gr. bullets that take a tighter twist and can be pushed from a 25-06 at 3200. You could shoot from one side of "Straya" to the other. shooting is a lot of fun to me, I just wish you guys had less limitations on you down there.

 

[M338]

It’s not so bad, we can get pretty much anything here For bolt rifles.The 25 cal is actually quite popular,there was a local guy over here making 25 cal 135gr vld type projectiles quite a few years back.It required a 8.5 twist.

 

[Rugerjim]

Should I consider using magnum primers in this rifle (6mm-06) or just regular? Thanks all.

 

[b6graham]

magnum in everything

 

[Rugerjim]

Haha holy moly.... I just did a mock up using 270 and 243 die... right is the 6-06... OMG lol... so excited for a laser beam!

 

[Rugerjim]

Do I AI this thing... or is that just getting stupid? I got a gunsmith with the reamers... how far does one go?!

 

[Rugerjim]

And here is the gun to be, gotta put the x-sight on yet, it’s on my 223 at the moment

 

[b6graham]

Do I AI this thing... or is that just getting stupid? I got a gunsmith with the reamers... how far does one go?!

Absolutely AI

The taper and shoulder just look silly

 

[Rugerjim]

Man really struggling to find dies for it. I was wondering, can I use a 270 die (without the neck pin) to resize the case, and run it through a 243 full size or neck sizer just to size the neck from 270 to 6mm, will this yield usable results in the interim?

 

[Rugerjim]

Hey guys just an update. I’ve got a 28” sourced ready to make a 6mm-06. Only twist rates are 10/12/14 so I’m thinking 12 or 14 most likely 14. I very nearly went to a 25-06 for ease but elected to stick with the lightning rod for better or worse. Using a 243 die to reload and neck size them. I have a 308 that I might be able to turn into a 6mm-284 later, unsure if it’s the same bolt, but I think the 6-06 has the velocity edge. If I destroy the barrel in silly time I’ll either go to a 25-06, 6-284, or 243AI.

I only shoot once a month at most out west so it should give me plenty of time. Knowing me though, I’ll probably shoot everything with it... from rats to deer. The lightest pill I can get for my 270 is a 90grain and there aren’t many options, but in a 28” barrel I recon it could hit damn near 3800, depending on how accurate quickload is with 2209 or 2215. It actually recons closer to 3900 but I think that’s a bit unrealistic. So that still is on the table however.
I’m rambling... but if only I had unlimited funds I’d have all of these, test them properly and report back.

 

[Bender]

Sounds fun! Send pics!

 

[Rugerjim]

Arghghg can’t decide between 1:12 or 1:14... stability calculators say they are all rather unstable...

 

[Rugerjim]

Finally got my 6-06!!! Still chasing some load data! However I am getting some 70gr pills and heading to the range on Monday. I can have noslers, hornady or Speer tnt. Not sure if I should run boat tails or flat bases. Out to 400 on dogs. ANy recommendations?

 

[sandwarrior]

Nice looking rifle Jim.

Hey guys just an update. I’ve got a 28” sourced ready to make a 6mm-06. Only twist rates are 10/12/14 so I’m thinking 12 or 14 most likely 14. I very nearly went to a 25-06 for ease but elected to stick with the lightning rod for better or worse. Using a 243 die to reload and neck size them. I have a 308 that I might be able to turn into a 6mm-284 later, unsure if it’s the same bolt, but I think the 6-06 has the velocity edge. If I destroy the barrel in silly time I’ll either go to a 25-06, 6-284, or 243AI.

I only shoot once a month at most out west so it should give me plenty of time. Knowing me though, I’ll probably shoot everything with it... from rats to deer. The lightest pill I can get for my 270 is a 90grain and there aren’t many options, but in a 28” barrel I recon it could hit damn near 3800, depending on how accurate quickload is with 2209 or 2215. It actually recons closer to 3900 but I think that’s a bit unrealistic. So that still is on the table however.
I’m rambling... but if only I had unlimited funds I’d have all of these, test them properly and report back.

Per This post, I suggest you ask your gunsmith to use the reamer he chambered your rifle for and make you a set of dies. Or at least get a set of factory dies. Reason being, the .243 sizing die is larger than your 6mm-06 body and can allow a LOT of runout during the sizing process. Get the dies right and your accuracy will be great. Do the short-cut method and you'll find accuracy will suffer.

As to swapping a .308 into any of the -.284 cases, it will only work if you want to use short bullets. The .284 case is about .160" longer than the .308 case. It limits your OAL in a short action. As your stated intention is light (short) bullets moving fast this will work. If you want to go long range, then you need to get a case with less length. One thing I've seen and I need to point it out here, is people who think you can push the ogive below the neck. BIG F'N NO-NO. If you find yourself in this dilema, STOP!, go back to short bullets and plan a different case to barrel that rifle into.

Also, you mentioned 'out west'. Are you in Australia? Or, here in the U.S.?

 

[Rugerjim]

Aus. I’ve got the Coal worked out to 3.1655 and am starting testing at 3.1500 with nosier ballistic tips.

 

[Rugerjim]

I didn't have a chrono on the day, but here's where I got to.
Non-magnum primers. (Mag primers another test is being done)

PROJECTILE: NOSLER 70GR BALLISTIC TIP (FLAT BASE)
COAL: 3.150"
CONDITIONS: Abysmal, blowing a gale, pissing down rain.

POWDER: 2209
MIN CHARGE: 54GR
MAX: 59.5GR

POWDER: 2213SC
MIN CHARGE: 57GR
MAX CHARGE: 62GR (NO PRESSURE SIGNS YET, THAT'S THE MOST I HAD LOADED TO IN A HURRY.)

I WILL BE HEADING OUT THIS WEEKEND AGAIN TO GO TO A FULL CASE OF 2213SC (ABOUT 64GR)
I HAVE SOME TEST CASES WITH MAG PRIMERS.

One thing I noticed was how incredibly dirty 2213SC is. (Maybe its due to using a non-mag primer) but after 3 shots it was absolutely black. Accuracy was great but the real test will be this weekend.

 

[sandwarrior]

I didn't have a chrono on the day, but here's where I got to.
Non-magnum primers. (Mag primers another test is being done)

PROJECTILE: NOSLER 70GR BALLISTIC TIP (FLAT BASE)
COAL: 3.150"
CONDITIONS: Abysmal, blowing a gale, pissing down rain.

POWDER: 2209
MIN CHARGE: 54GR
MAX: 59.5GR

POWDER: 2213SC
MIN CHARGE: 57GR
MAX CHARGE: 62GR (NO PRESSURE SIGNS YET, THAT'S THE MOST I HAD LOADED TO IN A HURRY.)

I WILL BE HEADING OUT THIS WEEKEND AGAIN TO GO TO A FULL CASE OF 2213SC (ABOUT 64GR)
I HAVE SOME TEST CASES WITH MAG PRIMERS.

One thing I noticed was how incredibly dirty 2213SC is. (Maybe its due to using a non-mag primer) but after 3 shots it was absolutely black. Accuracy was great but the real test will be this weekend.

Did you happen to record drop differences?

Added: Really dirty powder (that isn't otherwise too dirty in another case/cartridge) is indicative of a VERY underloaded cartridge. I wouldn't worry about secondary expolosion (backflash) unless your case was loaded less than halfway. By your numbers you are well above that.

 

[Rugerjim]

No mate just powder charges at the moment. Gimme 2 days and I'll do some tests and have some video etc.
I was suprised I could nearly fill the case with 2213 and it's not looking remotely high pressure yet.

 

[sandwarrior]

No mate just powder charges at the moment. Gimme 2 days and I'll do some tests and have some video etc.
I was suprised I could nearly fill the case with 2213 and it's not looking remotely high pressure yet.

I added some above.

 

[sandwarrior]

So, after doing some research online, I found there is a direct conversion for powders from ADI (who makes Hodgdon powders) to Hodgdon.

2213 is the equivalent of H4831sc. Same powder, different name for marketing purposes. I assume that is for proprietary purposes on Hodgdon's part? In any case, I can't bring up the 6mm-06. The largest case is the .240 Weatherby. Which BTW, IS NOT based on the 30-06 case. It has the same head, and the belt diameter is the same as the 30-06 body, but the body of the WBY case is 020" smaller than a 30-06. Which means a true 30-06 case body has more capacity. So, not limited to the 56 gr. that Hodgdon gives as a max load. Which, is also low to begin with. So, your latest load of 62 gr. isn't very high when in direct comparison. As long as you are not seeing pressure signs on your brass, you can continue to work up.

However, seeing that 2209 is the same powder as H4350, I would think that would be a better choice for that cartridge. Were you getting pressure signs at 59 gr.? One way to alleviate top pressure is to seat the bullet a little deeper so that it gets a run at the lands and won't stop momentarily at the lands causing a pressure spike. As long as the ogive is above the neck.

BTW, did you chamber the rifle with some freebore? It's the same principle as above except moving the lands back as opposed to the bullet in. Either way the bullet hits the lands at full speed and doesn't slow down which causes the pressure spike.