Monthly Archives: December 2022

Bullet Stability/Barrel Twist – Browning X-Bolt 7mm Remington Magnum – UPDATED

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I purchased a Browning X-Bolt for Christmas. Hurray! But bullets are a bit harder to find. I did find a 175grain Nosler ABLR bullet that I liked and purchased it but later calculated the bullets stability to be 1.37, just below the 1.5 military stability criteria in my 1 in 9.5 twist rate barrel. Bullet length included the polymer tip in overall length. Without the polymer tip as part of the bullet length, the formula now says the bullet is very stable. 

Experts argue about including polymer tips or not.  I will load some in a week or so.  

Lets take a look at this imperfect science…

It is known that barrel twist rate and a given bullets size, length, BC and velocity effects bullet stability. As a general rule bullets that are exiting the barrel have some yaw or as some say “yaw spiral” or gyroscopic effect.

It is the bullets “yaw” that can affect the grouping of a bullet, but yaw diminishes as it travels down range making groups tighter..

Calculators

You will need the length of the bullet below to enter this in the stability formula. Some folks subtract the polymer tip from bullet length. The JBM formula below takes the polymer tip into account. Measure the bullets overall length and measure the polymer tip length. 

https://www.jbmballistics.com/ballistics/lengths/lengths.shtml

https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

At typical 100 yard ranges your bullet may exhibit some yaw thus grouping may be somewhat larger than expected. I ran into this with the .243 Winchester and my former 338 Win Mag where yaw was pronounced with heavy, longer bullets. 

The good news is, this minor yaw will disappear at longer distances and stability and grouping improves, 

The only way to know how stable your bullet is, is to shoot some at temperatures and distances your going to hunt in.

Accordingly, I would fire them at 100 and 150 yards and then shoot out to my max hunting distance of say 500 to 600 yards for group. 

UPDATE

I had some Nosler 140g E-Tips and 7mm brass in my cupboard and eagerly loaded and shot them at 100 yards with 62g IMR 4831 powder clocking an estimated 2900 ± fps at the muzzle. Yes, that is a bit slow, but Nosler recommends working up loads with gilding copper E-Tips.

Below is the very first 100 yard 3 shot bench rest group. It measured 3/4 inch. Sub-MOA! Luckily there was no measurable wind and I used a COL of 3.24 inches where my bullets had at least 0.05 inches off the lands.

 

Can’t wait for my heavier bullets to arrive. 

Good Shooting!

 

Browning X-Bolt Speed Rifle under the Christmas Tree

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X-Bolt Speed

Browning X-Bolt Speed in 7mm Rem Mag

My readers are aware that I am hunting moose in Newfoundland again. My last moose fell to a single shot from my .375 Ruger, but because of recoil, I took precious seconds to chamber a second round. By the time I had a round in the chamber, the moose fell.

I did not practice this chambering of a second round. I suppose if I were hunting Cape Buffalo, my practice would have been quite different …as if my life depended on it. 

As many have said, “Moose often do not fall quickly to a single shot.” And they can move quickly into cover making a second shot more difficult.

The shooter must be prepared to quickly, eject the spent case, rechambering a new round and  follow-up with a second or even third shot. There is plenty of video evidence of this follow-up on the internet. 

With larger traditional heavy recoiling rifle calibers like.  a 300 Win Mag or heavier, the shooter takes more time due to recoil. He lifts the Mauser like bolt high at 90 degrees, pulls back hard to empty the chamber and closes the bolt with a second round. 

The Browning X-Bolt “Speed” in 7mm Remington Magnum above has one of the fastest bolt throws on the market today. The “speed” refers to the short bolt throw 60 degrees to eject and smoothly chamber a second round.

Bolt throw Speed was key to my purchase and I tested many bolts first hand as I shopped. 

I purchased this rifle with a 26 inch fluted barrel in 7mm Remington Magnum with a removable muzzle brake. I installed my Leupold VX-6 3-18 just like in the image above. Love that scope!!

Since I reload, I found some new reloading dies for it.

Trigger pull is adjustable down to 3 pound but came set to 4 pounds.  The caliber choice 7mm Remington Magnum works for both short or long range shots out to 500 yards with Nosler’s 175g ABLR.  On  paper, ballistic data says the ABLR leaves the muzzle at around 3000 fps with max load RL 22 powder. We will see what I get for accuracy as some rifle barrel twist rates have stability issues for the bullet.

 My ballistics chart says, at 500 yds at sea level and 40ºF the 175g ABLR will clock 2332 fps and have  2113 ft-lbs of delivered energy.

More soon!!

© Copyright 2022

 

 

Die-Hard Moose – Practice for an Immediate Follow-up Shot

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My last moose taken in 2019 was killed with a single shot from my .375 Ruger, but I held off as he stood bewildered and collapsed after a few seconds.

My rifle recoil was significant as I sent a 300 grain Nosler AccuBond at him.  At the greater recoil, it took me longer to eject the spent shell and put a new one in the chamber.

I was too slow to cycle the bolt because I did not practice it in advance.

I am moose hunting again in Newfoundland this coming year, and If I can’t cycle the .375 to my liking, I’m debating to shoot a rifle that allows a faster bolt cycle but still has plenty of down range energy. I’m thinking 7mm Rem Mag or 30 cal like the 30-06 Springfield. 

In researching moose kills, most require MORE than one shot to anchor them. Their nervous system appears slow to react to a kill shot.

Accordingly, practice should include cycling the bolt in earnest and get a second shot into your moose to anchor it. Yes, your first shot is still critical but cycle the bolt and be ready for a second shot.

Further, listening to other big game hunters, to try to use less scope magnification for a wider field of view and follow your bullet contrail hit.

 

Newfoundland offers enough open landscape for shots out to 500 yards or more. Shooting a rifle that has poor energy e.g., 1000 ft lbs at these distances limits the hunters ability to reach out. Spitzers with sectional densities above .250 to .300 for good penetration and G1 ballistic coefficients (BC) of at least .4 or more to hold its downrange energy is ideal.

My personal moose killing energy minimum is 1800 ft-lbs and around 2000 fps for a good bullet mushroom. Accuracy should be sufficient to hit a pie plate size kill zone from your rest. Make it a goal to learn to use a ballistic calculator. I use

https://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

Your bullet must arrive with enough killing energy and ability for your bullet to mushroom at those distances. It is sometimes the case that you have penetrating energy but the bullet does not adequately mushroom. Check that your bullet speed at the game should be near 2000 fps at the hit for mushrooming (lead core) and energy in the 1800 to 2000 ft-lbs. or greater.

Bullet manufacturers often publish the range of speeds that produce adequate mushrooming for your bullet choice.

Practicing for the first shot and follow-up shot to quickly cycle the bolt will give confidence to the hunter. I use a Bog Death Grip tripod for distant field shots.

Good Hunting!

© Copyright 2022. 

Age of Hornady’s Precision Rifle Cartridges 6.5, 7mm, 300 PRC Target and Hunting?

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The truth is that the 6.5 PRC is faster than the 6.5 Creedmoor, the 7mm PRC is faster than the 7mm Remington Magnum and the 300 PRC is faster than the 300 Win Mag.

Having said that: Should hunters run out and sell the Creedmoor, 7mm Rem Magnum or the 300 Win. Mag?

I think not, if you own them already. I love my 6.5 CM but am open to the 7mm PRC.

Well, The Creedmoor, 7mm Rem and 300 Win have great accuracy and punch for hunting already.

These PRC cartridges were designed for long range target accuracy and are somewhat faster, kick a bit more, than the aforesaid cartridges but not enough to replace them as a hunting cartridge. Others think similarly. 

As for target shooters, ceteris paribus, (all else being equal) it takes a faster bullet to win a match against the wind at long range, where fractions of an inch make the difference in point score. The PRC’s were designed “first” for target, having no belt, extremely concentric and in some cases can shoot a heavier bullet with a rifle with a faster twist.  

But, for example,  if you don’t own a PRC rifle or load for the cartridge, getting a new rifle in a PRC may be a good choice as a hunter hand-loader.

Note, the PRC cartridges and rifles are not in every gun store at this time.  

I love my 6.5 CM for deer and thin skin game hunting but do not as of this writing have a 7mm rifle, so I am keeping that in mind.

There are only a few rifles in manufacture at this time for the 7mm PRC but more are coming. Still cant go wrong with a custom 7mm Rem Mag or Weatherby Mag or even a 280 Rem.

In the final analysis, the rifle quality may make the difference in my choice, not just the cartridge. 

More on this coming.

Good Hunting!

® Copyright 2022

 

Calling all Coyotes –

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Below is a reprint of an article I wrote 5 years ago in pursuit of Coyotes.  I would carry a sidearm today for calling in coyotes. You may instead also be calling in bobcats (we are not allowed to hunt or trap bobcats in New Hampshire at this time, I am hopeful that the rule changes soon and we resume hunting and trapping them.)

This last fall my deer hunting friend, during muzzleloader season, blew on his grunt tube after he set up. In less than a minute a coyote came running at him looking for the deer. He fired hastily at it and missed it at 5 feet but parted some hair. 

New Hampshire Coyotes Soon Begin Looking For A Mate – Take Advantage

 

Calls for Coyotes

https://www.nhrifleman.com/calls-for-coyote-hunters

 

North Eastern coyotes are larger than western coyotes due to the great lakes grey wolf mating with coyotes in winter. See my article below. 

 

Wolf in Coyote Clothing?

Coyotes are attacking children today, beware!

Good Hunting

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