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5R Milspec Barrel Freebore
Hiram512
Member Posts: 5 ✭✭
I recently bought a Remington 700 with the 5R Milspec barrel. When I checked the freebore I found that I would have to seat a 168 gr. Match King at 2.965 OAL to get near the lands. This is not possible as the bullet would be too far out of the neck. Has any one else run into this. The rifle shoots tiny little groups with bullets seated at 2.800. I have read that if the freebore is very close to bullet diameter it will keep the bullet straight and you don't need to seat near the lands.
Comments
NRA Life Endowment Member
The "Seat to the lands" thing is a old wives tail that once held a grain of truth, of course back than high tech rifles were using pure lead bullets and black powder cartridges fired through over size throats.
As you have noticed, the real accuracy improvment comes from seating to match the harmonics of the barrel.
Some guys like a mag full of lead, I still prefer one round to the head.
This went over my head, what is an "5R milspec barrel"?[:I]
NRA Life Endowment Member
A lot of people told me to do that on my 308 and my gun would NOT shoot for nothing when I seated the 175SMK out to the lands. I just loaded 2.8 and the thing shoots 1/2MOA all the way out to 600yards. After that, my lack of skills open the groups up.
5R is a type of rifling. JustC was just explaning that to me the other night. It is the way the lands are cut.
It is possible to have your 168 gr. MK seated to 2.965" since it leaves 0.114" of bullet shank still in the case neck plus the boat tail. But, I don't think that it's advisable, just possible. It has been done under other circumstance, when firing single shot as opposed to magazine fed.
We've all run into chambers that have additional freebore or longer throats, especially those barrels that come from the larger primary manufacturers, such as but not limited to, Remington, Winchester, Ruger, et al. With your admission of 'tiny groups' when the OAL is limited to the 2.800" standard, I see no reason to attempt any other OAL adjustments or load development. You seem to have solved the problem. Congratulations!
Bullets that are concentric with the case, chamber and bore are straight period. The freebore has nothing to do with it. The bullet has to be seated straight from the beginning and there is very little that can be done to change this after loading the cartridge into the chamber. A straight neck and straight dies for seating will do the best job. A straight bolt and receiver are mandatory.
Seating bullets to the lands is definitely not an old wive's tale, at least not with the rifles that I and fellow competitors shoot. It is common in several of the benchrest venues as well as in the long range shoots and I've even found it to be true for some of my hunting rifles. Some not all. 'Nuf said.
5R is a style of rifling that we Americans borrowed from the Russians. '5' is the number of lands and 'R' is for Russian. Boots Obermeyer developed this rifling style and has been making it for several decades. Other barrel makers have permission from Boots to use this rifling form without compensation to Boots. Mike Rock at Rock Creek Barrels is one. Others have designed their own variations such as Shilen's Ratchet lands, and Broughton Barrels has the 5C for 'canted' lands. This design is basically a chamfer on the driving side of the lands or simply, a slope. This causes less deformation to the bullet as it travels down the barrel and achieves a better gas seal between the bullet and the barrel.
The 'Mil-Spec' is a reference to the multiple runs of barrels that Boots, Rock and Remington have made for the military under contract. It is short talk for military specifications. All outsourced products for the military have a set of specifications. Remington put a few of these on general run rifles and some of the PSS's and it was a legend in the making.
Best.
OK, now that makes sence to me.
NRA Life Endowment Member
If you want to long seat them, try to have the heel of the bullet at the shoulder/neck junction or don't advance it much past 1/3way up the neck. You will most likely now need to adjust powder charge a few .1's of a grain to make up for internal capacity changes.
now, you can have a gunsmith set the barrel back .050" and run the reamer with a shorter throat into that barrel to solve the problem. You'll not see any velocity loss either.
why chase the game when the bullet can get em from here?....
Got Balistics?
why chase the game when the bullet can get em from here?....
Got Balistics?