I have factory barrelled Model 700 in 7mm RM that I would like to optimize for some of the modern hunting bullets like the Barnes TSX or the Nosler Accubond. Using the ole stoney point gage with the 140 TSX it touches the lands at a COAL of 3.275". Seating the bullet for a .050" jump to the lands puts the bullet deep, and the case mouth ends up aligned over the first of the relief grooves in the TSX. I don't like that very much and it is eating up case volume. If I seat the bullet long so that only the boat tail is seated beyond the neck base in the powder room, the case mouth lands on the bullet "land" aft of the second groove which is much better. But this does lengthen the round to 3.365" COAL. However it looks suitably rugged enough for a hunting round and it fits the mag and action without issues.
To accommodate the additional cartridge length I will need to ream .090" plus whatever freebore "jump" is required. I have a throat reamer coming.... What could possibly go wrong?

Questions for those that have done this before...
- Do these numbers sound like reasonable objectives if I'm committed to handloads?
- Do I explore what amount of freebore jump the rifle likes with that bullet now (before lengthening the throat) and then add that to the .090" and use that for the reaming target depth?
- How much will seating the bullet .140" farther out of the case effect the internal ballistics and propellant charge requirements/limits?

Reno: IME....nothing will go wrong if the job is done correctly.

I have never throated to the Barnes but friends and I have done quite a few 7RM barrels for the 160 gr NPT with base seated even with base of case neck. I cannot recall the precise OAL,but it is long,and yet will fit a Rem 700.Have also done the same with the 300 Win mag on H&H length M70's and Rem 700's.

It makes sense with the lighter mono you are using as many of these bullets are longer for their weight;it may be a minor thing really,but I sort of feel like you and hate bullets peeking out of cases when I have a magazine capable of handling the additional OAL.

This may be more fettish than substance but so is most of rifle looneyism...


I have hunted a good deal with rifles throated in this manner (both 7RM's and 300 Win)with no issues.There is enough neck tension to hold the bullets,at least with the bullets I used, there always was.

I can't comment on powder charges because there are too many other factors,and your load work up and chronograph will tell you where to stop.But I think it will work fine,giving you more flexibility.

1. I would not change a rifle to use TSX bullets unless I had to by law.

2. I would not spend on a 7mm RM what with that cartridges reputation for pressure spikes.

3. I would not spend on a 700 design but instead trade it for another rifle.

However stuff like throat reamers are just nickel and dime things as compared to the universe. If doing it motivates you to shoot and hunt more then do it.

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What exactly does the highlighted part mean?

There have been comments and articles for years like the one I reference here:

"Actually, there is a little truth to the "pressure spikes" in the 7mm Remington Magnum. I have gotten the story straight from some of the guys in ballistic labs.

For some unknown reason, the 7mm RM's pressures do vary more than in some other cartridges. You really can't call them pressure spikes, as in all of a sudden a case blows a primer or something like that. But the pressure do vary enough, especially with certain powders, that the SAAMI pressure standards were reduced somewhat from the original levels. And that's why the SAAMI average pressure is 61,000 rather than the 64-65,000 of most other belted magnums."
Mule Deer.

Link

I know all about that. Especially the part "you really can't call them pressure spikes" if you're going to accurately describe what's going on.

When it warms up a little more, it's 43F now, I am going to the range. The wind is supposed to be light all day.

I have a new 7mm WSM to shoot some more. I put the Minox 3-15 back on it.

Also the Kimber 243 will get shot some. Friday looks good for hunting coyotes and other pests.

Crank it up to 15x and check the parallax at 300 yards. Please let us know what you see.

- Like Savage 99 I would not touch a copper bullet unless forced to by law. The lead core bullets provide more controlled expansion over a wide velocity range and better ballistic coefficients.
- I would explore the freebore first. You most likely will find that your gun will shoot best just short of the lands or even a few thou into the lands. With a bullet seated the full length of the neck and with 0.002" or more neck tension there will be no risk of leaving the bullet in the barrel when you use a slight jam to the lands.
- Seating the bullet further out will reduce pressure slightly and if anything improve ballistics, but overall likely a negligible effect.
- You may want to give the Berger 168 VLD Hunting bullets a try if you have magazine capacity. They have a nice high BC. They will seat long in overall length, but will not touch the lands as soon due to the shorter bearing surface and longer nose.

Sure, ok.

As you know the Minox 3-15 lacks a parallax adjustment as does the 3-9 Conquest that was on the rifle. The 4.5-14 Conquest on the 243 has it.

I will try to check them all.

I'm wondering why they would make a 15x capable scope without it. Others have told me they didn't note any significant parallax at 300, but frankly I find that hard to believe for a 15x scope that's set to be parallax free at 100.

I guess the same goes for the Leupold 4.5-14. How dare the master craftsman make an error like that.

I have been shooting Rem 700's in 7 Mag since 1978. I would not have the throat lengthened, just seat the bullet out since 700's have very long magazines.

Pressure spikes in 7 mags are as common as trolls that live under bridges. Between dad, brothers, cousins, and friends, we have 20+ Remington 700's with a couple of Savages thrown in. We all shoot bullet weights of 150g and under with the exception of one guy that shoots 160g Sierra's and another that shoots the 162g SST. These pressure spikes must occur with heavy bullets or with certain powders because none of us have seen any issues.

I have a number of 700's in 7 Mag currently and not one of them shoots over an inch and most under 5/8" with 120g Tripple shocks and 140g Tripple shocks, 140 & 150g Nosler Ballistic tips and Accubonds, and the fantastic 154g Hornady SP.

Recently, I set up one rifle for a 162g SST at 3100 fps with Retumbo and another that is set up for a 154g SST with H4350 at 3150.

In every rifle I have, I seat the bullet touching the lands with the exception of the tripple shocks which I seat .040-.060 off the lands.

Sure does.

I tried to check the Minox 3-15 today for parallax. It was in the field and it was windy. The wind may have been shaking the rifle some.

However at 311 yds there may have been about an inch of parallax. I am not sure of this yet. I will try to check it again in the future.

A 4.5-14 Leupold that I have has an adjustable objective. This is the one with the external windage and elevation knobs.

Thanks for the replies (on the subject). Not sure that the rifle will like the TSX, but I'm thinking that I'd like the chamber lengthened anyway since I will likely only shoot high BC bullets of some kind from here on out since I've shot up all of the Federal premium with the Nosler 160 partitions, and like handloading. It's my only "long range" rifle so long bullets will be the only thing I shoot. The TSX has worked damned well for me and my buddy when I've hunted with him on hog hunts in condor country so I can't condemn them as bad as some. I do like the hole on both sides! They do seem to be more complicated to load though (regarding the guidance to load bullets back off the lands).