Home Forums Hunting & Shooting Long Range Hunting The Big 7's......Which One?

My latest Mashburn Super, designed to be a walking gun, is a 1970's Rem 700 in 7 MM Rem punched out with 24" tube. I replaced the stock with a Brown pounder and X coil sporting clays pad. Glass is 6x33 Lupy with LR dots in Talleys. Weight is just at 7.4 lbs and calculated recoil 33 ft.lbs. I am currently doing load development and am at 73 gr. H1000 giving 2950 fps. with 175 Sierra's. Target is 3075 or so and will swap Sierras with Nosler PT when necessary. COL in this gun is 3.6" This gun is designed to be slightly weight forward.

My other Mashburn, a blind gun, started life as a Brown Precesion 7 MM Rem 24" punched out with 2.5x10 Swarvo Habitch at about 8.25 lbs. I shoot 162 gr Hornady BTSP Interlocks at 3269 fps. using 76 gr. RL-25 and get groups of .6" When sighted in 3" high at 100 it is on at 315 yds. or so. COL here is 3.56" Both COL's are bullet to the base of the neck.

All good !!!!!

7 allen mag

Doc loves this cartridge....don't blame him!...gets me in a lather to shoot something!

It's a fun one for sure...

Hornady says "No". Not sure what to think as Davidson says "Yes" and brass will be $1.80 a pop!!!


Further conversations confirmed this. I think the brass will have Gunwerks stamp on it. Too pricy for this conversion. A Mashburn would be the way to go.

Uh... where does one find someone with the tools to ream a 7RM to 7 Mashburn Super, taking into account all the subtle things that make the Mashburn do what it does in a 24 inch tube?

Rent Dubers reamer, rent my reamer, buy your own reamer and take it to a smith.

Call JGS and ask who has bought that reamer from them and then rent it. That is what I did before I bought my own.

Ah so, many thanks... is there a short list of recommend smiths on the fire for a Mashburn conversion?

thanks

I got the same response. I am guessing its going to be only sold through Gunwerks.

Dogger:

Almost any compatent smith who can PROPERLY ream a chamber should be able to punch out an existing 7 Rem to Mashburn. Some may want to turn off some part of a thread to get a good bottom on the belt, otherwise it will clean up the chamber nicely. The other thing is to make up a dummy round for proper throating. The original Mashburn spec. had a short COL. Mine is set up for 175's seated with the base of the boattail at the base of the neck. That gives a COL at 3.6" with a Sierra 175 GK. One of the nice things is that with a long neck you can load all your bullets down to 140's using the same COL and keep the same jump to the lands.

If you decide to throat for Bergers then use a smith that knows how to throat for Bergers or Matchkings and set the gun up to run those bullets with your max. box length, +/- 3.65"

Given the profile differences between Bergers and Sierra Matchkings, the throat should be pretty differant from normal ogive bullets such as Hornady Interlock, Nosler Pt & AB, Sierra GK, etc.

Most of those reamers are going to have a 1.5* throat. This works on those long range bullets pretty good. As long as you keep your jump the same, most bullets will shoot best at the same spot. If you spec a reamer to make the throat where you can shoot 180s seated out to 3.65 and then decide to shoot 110 TnTs you are going to have quite a jump to get there!!

Small 7 Big 7

docbill, that set-up makes sense to me... thanks for the additional info. my interest is in bullet weights from 140 to 175...

Doc/Dennis: Good posts and info!

My throating dummies used a 160 Partition, base of bullet to base of neck;the 175 Partition seats slightly deeper into the case.Both bullets shoot well,and BTW have essentially the same POI to 600 yards, despite the velocity differences (3075 vs 3175-3200).Can't recall precise OAL, but know both are a bit over 3.5;close to 3.6.My rifle has an Echols box.

This is handy but raises a conundrum of sorts, in that,I am having a hard time finding a reason to use anything other than the 175 in this cartridge...

There may be hunting chores that a 175 Partition at almost 3100 can't do,but I bet the count is not very high.....if the thoughts of keeping things rock-stupid simple appeals,this might be a way to go.

Bob, you may have found your huckleberry!

Good on ye....

Jeff I have never used a damned 175 on a friggin' thing yet!LOL!

So my imagination is running amock! I am getting good reports from folks on it.Have not had a chance to use it myself yet.

Like many I always viewed the 160's as being "best" all round in a mag 7mm and have used them a lot.

But I noticed that some clever guys who were wildcatting Big 7's off the 404 Jeffrey case in the pre RUM days,all said the 160 is good but the 175 gr is THE bullet driven fast from a big case...that stuck in my mind for years,so I figure....let's find out!

You'll always be able to buy ammo for the 7mm Remington Magnum.

Bob:

No lesser a saint than Warren K. Page his-on-self preferred the 175. And that was with the semi-pointed NP!

My attempt with this gun is to keep it SIMPLE and just swap Sierras and NP when necessary.

Doc: Basically, mine, too. With a Bitterroot here and there....

Turned out good....I can interchange the two without touching the scope.

Have you tried the 160 grain Accubond yet?

Yes, Bob we have shot them in two Mashburns...they are very accurate.But I don't hunt with them.