Anyone deal w/700 Rem w/long throat? New gun, not shot out. Rem do this on purpose?

[Lefty7mmstw]

Re: Anyone deal w/700 Rem w/long throat? New gun, not shot out. Rem do this on purpo

What if the bullet exits the case neck before it reaches the lands? This is what is happening in the WBY 340 I am working on. At least with boat-tails. Seems to me then, that the bullet has a very real chance of skewing in the freebore region, especially if that area is cut loose and not to tight specs.

I have perhaps been lucky to never have to deal with this much freebore before.

I've dealt with .5" freebore on my 7rum using 140 sierra pro hunter pills. The bullet was actually out of he case as it contacted the lands and it still did .3 moa at 100 yards for three shots and .9 moa for 5 as fast as you could aim and fire at 100 yards. The rifle was terribly finicky as to bullet, and I only found a couple of bullets it liked, the other being the 175 hornady interlock. When it liked what you were doing it was a very happy rifle though.

As to your 270 freebore, both my tikka and my marlin in 270 win are rather short throated, and basically identical in throat dimensions. I load the 130 mrx (for my tikka) and 130 hornady mono (for my marlin) at 3.297" and 3.295" respectively and the 130 interbond on the lands to 3.345" for the tikka.

 

[Thebear_78]

Re: Anyone deal w/700 Rem w/long throat? New gun, not shot out. Rem do this on purpo

I have a good friend who is a gunsmith and he built a 338 edge for another buddy of ours. This guy wanted it throated out so that he could use the added OAL of his extended wyatt magazine. He was all impatient to get it done so my buddy gave him the 338 throater and t handle, said to just take a little at a time until he got the depth he wanted. Next thing we know the guy had screwed this thing in until the 7 handle hit the back of the action. This left him with pretty much 7-8" of freebore.

Even with that much freebore he was able to get a couple of loads that would shoot around 1.25-1.5" at 100 yards. Never could get the accuracy he wanted out of it and ended up trashing that rather expensive barrel.

The only time I really worry too much about getting out to the lands is with VLD style bullets like the berger hunting bullet. Even then sometimes you can get them to shoot pretty decent with a jump.

 

[Trickymissfit]

Re: Anyone deal w/700 Rem w/long throat? New gun, not shot out. Rem do this on purpo

What if the bullet exits the case neck before it reaches the lands? This is what is happening in the WBY 340 I am working on. At least with boat-tails. Seems to me then, that the bullet has a very real chance of skewing in the freebore region, especially if that area is cut loose and not to tight specs.

I do appreciate the long post. Points #1 and 2 are out of my control in a gun I do not own, #3 does not apply to the 270, and #4 is exactly what I do with my guns. I have a nice 7mm SAUM that I have shooting about .5" groups. Only thing custom is the Shilen barrel I screwed in. And I guess the pillar bedding I did myself......

I have perhaps been lucky to never have to deal with this much freebore before.

if the diameter of the free bore is tight, then you'll see little loss in accuracy, but if the free bore is big you might as well have a shot gun. I think it was no other than Randy Robinette that proved this out before he did his "no free bore" chamber designs in 30BR. His experiments in throat designs pioneered the path for the rest of us. By the way just about every rifle built has some free bore built into it
gary

 

[Ridgerunner665]

Re: Anyone deal w/700 Rem w/long throat? New gun, not shot out. Rem do this on purpo

Its not a 270 thing...its a Remington thing...all Rem 700's have more freebore than they need...I've owned just about every caliber ever offered in a Rem 700 and all had very long throats...its not a recent development...most of them do tend to shoot OK even with the long throats.

The new Winchester M70's do not have this problem....FWIW...short throats, long magazines...even VLD's can be seated to kiss the lands and still feed through the mag.

 

[idaho elk hunter]

Re: Anyone deal w/700 Rem w/long throat? New gun, not shot out. Rem do this on purpo

We brought a lot of this on ourselves because we wanted "More Velocity" So in order to stay with the market trends Almost all of the newer cartridges have more free bore. So they boosted the pressure from 55,000 average to 65,000 PSI. In order to do this they had to add more free bore.

All of the WSMs, SAUMs, RUMs have At least .200 thousandths free bore or more.

When Winchester came out with there 270 Average pressures went from 46,000 - 52,000 to
over 55,000 so they increased the free bore to manage pressures and limited the mag length
to prevent loads that could reach the lands making pressures exceed max.

Roy figured this out and decided to make all of his rifles with lots of free bore in order to gain velocity
over everyone else. Because Velocity sells.

To address the accuracy issue there are a few different rules to get the desired accuracy from a
belted case with lots of free bore.

1= The chamber must be perfectly aligned with the bore centerline.
2= The action and bolt must also be square and on the same centerline as the chamber and bore.
3= Head space with a belted case should be the minimum (Just enough to close the bolt) If there is
more than .001 or .002 thousandths head space the need to fire form becomes very important.
4= Once the case has been fire formed, sizing correctly is the secret to accuracy (Only size enough to close the bolt "No More") . when you size to the minimum you are essentially shooting a shouldered case because it is head spacing on the shoulder and with Zero head space the case fits the chamber
perfectly and is aligned perfectly with the bore. The bullet will still be held centered by the case even
after it reaches the lands and starts to engrave.

Back in the day we had to seat the bullets where they touched the lands in order to make up for the
quality of chambers, Reamers, brass, bullets and in general, workman ship. Now with all of the improvements in all of the above, It is easy to achieve outstanding accuracy.

1/2 MOA groups are a starting point now days with these cartridges and Sub 1/10 th MOA groups are possible and not to uncommon.

The 270 Winchester is a fine old cartridge and very capable of 1/2 MOA @ 600 yards. especially now days.

Sorry for the long post.

J E CUSTOM

JE you really know your stuff==1 on all of your post on this. Especially on the longer bearing surface is helping with the accuracy. This is why I recommend Barnes and the Partition to all for starting loads. Another member on here criticizes me for these recommendations. I can only hope he and others understand what you just said.