7mm LRM

Thinking about rebarreling my M70 7mag with a 7LRM Barrel.
Is there any reason that this would not work. Does anyone know where a person can get reliable reloading data. thanks!

I lean more towards the 28 Nosler for this option. It's SAAMI approved and more available with comparable if not a little better performance, at least when comparing accuracy loads.

I use 71.5 grains of H=1000 over a CCI 250 under a 180 berger hybrid. The only downfall is that hornady brass is the only brass available and its through gunwerks. That being said I still like my 7LRM and have no immediate intention to get rid of it. The thing shoots lights out. My rifle was built by Jon Beanland using a gunwerks reamer. Even though gunwerks did not build my rifle they have not hesitated to assist through any stumbles I had through load development and some rather dumb questions I had. They certainly seem to be a pretty good bunch of folks.

I've been talking with them some and they are very helpful

Do it!

I just got a chance to shoot mine last week, it's fantastic. Mine was done by TS customs.

It's the lightest recoiling 7 magnum I've played shot; less than my father in laws custom 7 rem mag. That fat powder column must make a difference in the recoil impulse.

I'm working with the 180 vlds and h1000, and so far I've only taken it to 300 yards, but the accuracy has been fantastic. I only have one loading on the brass, so I can't comment on the quality, but I picked up enough to burn the barrel out before starting the project. I think Greg from Primal rights keeps a stock of brass on hand if you can't get it from gunwerks.

Do it, you wont regret it.

I had one built by Lane Precision Rifles that would shoot in the same hole. I took an elk a couple of years ago in New Mexico at 650 plus yards with Berger 180 Hybrids. I sold it since I already had another Lane rifle that would shoot nearly as well in 300 WM. In hindsight, I should have kept it.

Like mentioned before. Brass has to be obtained through Gunwerks, but these guys are great to work with.

I have had a 7LRM since they came out. If you look at case dimensions and what the cartridge "should do" then it looks great. From my experience the brass is junk and Gunwerks has had a difficult time controlling their brass quality coming out of hornady. From a lot of experience on this one I would steer clear of clambering something in a 7LRM.

I have a 7mm-375 Ruger which is similar to the 7 LRM just a little longer, Gunwerks pushed the shoulder back a little so they could have a longer neck. This rifle of mine has a long throat with a loaded round being 3.69 COAL. I have been shooting the 195 Berger's with Reloder 33 and getting 3005 avg fps with an ES of 5. The gun was built by Circle W custom guns He is on this forum. Scott form Circle W sent me 100 pieces of brass and I have 4 reloads on the first 50 and just loaded up the next 50 new ones. The Hornady brass isn't bad... For the price. If you prep it right and anneal once in awhile it gives just as good of accuracy. last string of shots I took with my magneto speed on had a high velocity of 3007 and a low of 3002.

I hated my LRM. I liked the potential of the ballistics well enough, but the Hornady brass and Hornady dies were nothing short of GARBAGE.

I had the rifle rebuilt to 28 Nosler and am much happier.

I remember firstcoues's issues. He was supplied with brass that had thicker necks which wasn't discovered by Hornady or Gunwerks until many users complained of blown primers and erratic groupings. Some comments I kept from my documents file:

TDean: "shooting 2" and 3" groups at 100 and blowing primers and leaving ejector marks from excessive pressure. there's definitely a problem here I Just don't know if gunwerks realizes it. I have talked to the guys at gunwerks numerous times but they are not too enthusiastic about my concerns."

"Gunwerks also told me that i should anneal the brass necks after every 2 firings for whatever that's worth. I'm sure they wish they could get better brass. Most of the primer pockets are loose after just 1 firing. "
"I got a call from Gunwerks, they have offered me a refund for some of the work and the dies and brass i bought. I would like to say that i appreciate their integrity and that they now believe me after others have had similar issued with the brass. "

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The explanation for excessive pressure and loading issues from a few years ago:

FirstCoues just had his gunsmith make him a 7 LRM. He was damaging the 175 LR Accubond when he seated them.

I asked him to get some measurements:

The brass and dies were supplied by Gunwerks. The Hornady die is a FL/bushing die and came with a .316" bushing (I suggested to him he get a .317" bushing as well)

His reamer has a .321" neck dimension

The first few pieces of brass he measured had a neck ODs of .3175" - .318" This translates into necks slightly less than or exactly .017" thick

IF all the brass is no more than .017" thick the bullet release per side in the chamber neck is .002"
That is approaching clearances that are used in BR shooting. Quite frankly it is cutting the clearance too close for brass that isn't neck turned. I would bet that some brass would come with neck wall thicknesses greater than .017".

Sure enough my friend measured one case that he ran through his .317" bushing that had an ID of .277"! That computes to neck wall thickness of .020" WOW! If he were to seat a bullet and try to put it into the chamber it wouldn't fit. OD would be .324"

He is going to use the supplied sizer ball and size a bunch of brass. He will then seat bullets for measurement. (he doesn't have a ball mike) He will then carefully measure all neck ODs. I think he will find quite a few that are thicker. I told him he really should turn all his necks to ensure he doesn't have any pressure issues. Heck even some variance would ruin LR groups.

He says he believes the gunsmith borrowed the reamer from Gunwerks. Will report on that when I know for sure.

Our mutual friend Dennis turned the necks for FirstCoues which solved this issue.
----------------------

Perhaps I have discovered the reason why some cannot duplicate Gunwerk's pet load without excessive pressure. TDean appears to be correct, the Hornady brass is varying in its dimensions.
--------------
After many customers complained Gunwerks dealt with the thicker neck wall dimension issue. IIRC they offered to buy back the out of spec brass.

If I were considering making a new 7mm I would go with the 28 Nosler using Norma brass.



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AZShooter said:

I remember firstcoues's issues. He was supplied with brass that had thicker necks which wasn't discovered by Hornady or Gunwerks until many users complained of blown primers and erratic groupings. Some comments I kept from my documents file:

TDean: "shooting 2" and 3" groups at 100 and blowing primers and leaving ejector marks from excessive pressure. there's definitely a problem here I Just don't know if gunwerks realizes it. I have talked to the guys at gunwerks numerous times but they are not too enthusiastic about my concerns."

"Gunwerks also told me that i should anneal the brass necks after every 2 firings for whatever that's worth. I'm sure they wish they could get better brass. Most of the primer pockets are loose after just 1 firing. "
"I got a call from Gunwerks, they have offered me a refund for some of the work and the dies and brass i bought. I would like to say that i appreciate their integrity and that they now believe me after others have had similar issued with the brass. "

------------------
The explanation for excessive pressure and loading issues from a few years ago:

FirstCoues just had his gunsmith make him a 7 LRM. He was damaging the 175 LR Accubond when he seated them.

I asked him to get some measurements:

The brass and dies were supplied by Gunwerks. The Hornady die is a FL/bushing die and came with a .316" bushing (I suggested to him he get a .317" bushing as well)

His reamer has a .321" neck dimension

The first few pieces of brass he measured had a neck ODs of .3175" - .318" This translates into necks slightly less than or exactly .017" thick

IF all the brass is no more than .017" thick the bullet release per side in the chamber neck is .002"
That is approaching clearances that are used in BR shooting. Quite frankly it is cutting the clearance too close for brass that isn't neck turned. I would bet that some brass would come with neck wall thicknesses greater than .017".

Sure enough my friend measured one case that he ran through his .317" bushing that had an ID of .277"! That computes to neck wall thickness of .020" WOW! If he were to seat a bullet and try to put it into the chamber it wouldn't fit. OD would be .324"

He is going to use the supplied sizer ball and size a bunch of brass. He will then seat bullets for measurement. (he doesn't have a ball mike) He will then carefully measure all neck ODs. I think he will find quite a few that are thicker. I told him he really should turn all his necks to ensure he doesn't have any pressure issues. Heck even some variance would ruin LR groups.

He says he believes the gunsmith borrowed the reamer from Gunwerks. Will report on that when I know for sure.

Our mutual friend Dennis turned the necks for FirstCoues which solved this issue.
----------------------

Perhaps I have discovered the reason why some cannot duplicate Gunwerk's pet load without excessive pressure. TDean appears to be correct, the Hornady brass is varying in its dimensions.
--------------
After many customers complained Gunwerks dealt with the thicker neck wall dimension issue. IIRC they offered to buy back the out of spec brass.

If I were considering making a new 7mm I would go with the 28 Nosler using Norma brass.



.

Click to expand...

I had the same exact issue. Same exact experience as firstcoues that AZShooter explained in the above post. I got some new brass and it's better but could never achieve their published speeds with the 180 berger. Shot their load yesterday and it's only going 2978. They originally stated 3100 fps.

My Mountainx only get 2950 FPS with 71.0 H1000. My friends LRM started blowing primers after shooting their recommended load for three seasons. Same load as mine. He called Gunwerks and they said 71.0 was hot and they reduced it to 70.5. How about letting people who bought lrm know? I also know another person who had a 7lrm built by Gunwerks. After several years of inconsistent groupings, he re-barreled it for 7RM.

For another option, maybe take a look at have it chambered in 7mm Blaser Mag. It has a tick more case capacity than the 7 Rem mag, Norma brass that is available and pretty easy to get, Redding dies and they are easily available too.

I had Defensive Edge Rifles build me one last fall. Used a LA Rem 700, Hart #4 finished at 26 inches and topped it off with a NF 5.5-22x50. Shawn gave it his +P throat design. Currently shooting RL26, 180 Bergers, and using 215M's. That load produces right at 3050fps out of a 26in. tube, shoots in the .3's relatively easy and using one of their brakes, recoil is VERY minimal.

IMO, the larger cases like the 28 Nosler and 7 RUM need a 28in tube to really start to shine. If you want to stay in the 26 inch range something like the 7mm Blaser mag will run right with them but with considerably less powder.

firstcoueswas80 said:

Hornady brass and Hornady dies were nothing short of GARBAGE.

Click to expand...

The hornady dies are awful. I was fortunate enough to be able to borrow my smiths dies to load a few rounds for the custom dies I had made.

Failing that, I would have had my smith ream out a Forster ultra seating 284 win die to 7lrm and then punched the necks with an expander, loaded, fired and then sent the brass off to whidden for a custom sizer.

Brass doesn't seem bad, at least for this lot, but I have one firing so I can't say for sure.