7 LRM accuracy?

[SteveOak]

Looking for experience with 7 LRM accuracy. What sort of accuracy are you getting? Load specifics including/especially velocity and bullet weight/type/mfg would be greatly appreciated.

"LRM" is only three characters so the AS search engine rejects it. LOL I tried a Google search specific to AS but didn't get much either.

Seems when the cartridge was first introduced there was only Hornady brass and the results were sporatic. Gunwerks is supposedly getting brass now from ADG which is much better than Hornady.

I'm wondering if the reports of poor/spotty accuracy are left over from the Hornady brass or if perhaps the cartridge is beyond the tipping point of larger than amenable to accuracy which seems to be the case with the 28 Nosler but I would be happy to know that I am in error with that idea.

Thanks!

 

[troper]

Looking for experience with 7 LRM accuracy. What sort of accuracy are you getting? Load specifics including/especially velocity and bullet weight/type/mfg would be greatly appreciated.

"LRM" is only three characters so the AS search engine rejects it. LOL I tried a Google search specific to AS but didn't get much either.

Seems when the cartridge was first introduced there was only Hornady brass and the results were sporatic. Gunwerks is supposedly getting brass now from ADG which is much better than Hornady.

I'm wondering if the reports of poor/spotty accuracy are left over from the Hornady brass or if perhaps the cartridge is beyond the tipping point of larger than amenable to accuracy which seems to be the case with the 28 Nosler but I would be happy to know that I am in error with that idea.

Thanks!

If you contact GW with serial # they should furnish you the load data the gun was delivered with
My buddy's gun will hold .5 moa x3shots at 100 yards sometimes less 180 berger hybd

 

[SteveOak]

7 LRM is a cartridge which I am considering.

 

[Orr89rocz]

No help with the LRM but isnt it basically a 7-300 prc? With better brass available for that case id be inclined to lean that way. I have no doubt the LRM will be accurate tho, just not sure what you are looking for. Any of the 7 mags have been really accurate. I like my 28 nosler

 

[ShaunBrady]

"Gunwerks 7LRM" brings up plenty in my search engines.

It's similar to a 7-300PRC but ~0.150" shorter at the shoulder. Checked the ADG website and no sign of 7 LRM brass. They did have their 7-300PRC brass for sale. That was $220 I wasn't planning on spending, so thanks for that.

I'd been meaning to do a 7/300WM for ages. During the slump in gun and component prices during the first Trump administration, but before 'Rona came to town, I found 300PRC brass and a decent die set both on sale at Midway. I ordered them and a reamer. The sizer was a bushing die and I wanted to neck turn so I ordered a 7 SAUM one piece sizer to size the neck down to the shoulder.

Why not 28 Nosler? The 7-300PRC has about 94.5 grains of water capacity. It's case capacity to bore area ratio is close to a 300 Norma or 338 Lapua Improved. The barrel life should be similar to those cartridges. The 28 Nosler is closer to 100 grains of water. It's barrel life will be closer to 33XC or 375 Cheytac. The biggest deal was the PRC cartridges have a 0.532" case head. With their low body taper, they'll just clear the front guide ribs in AICS 338 Lapua mags. The Noslers use 0.550" case heads and the front of their cases drag.

The 7 LRM has a case capacity of around 89 grains of water. 7wsm, 7 RM, 7 PRC are in the 80-82 grain range. That 88-90 grain capacity lacks readily available 7mm brass. 7/300WM, 7 Weatherby, and 7 BooBoo, are all about that capacity but a little obscure or have belts.

I don't have a problem with Hornady brass. It won't take the pressure Lapua or boutique brands will, but if you go up in case capacity and do the velocity that way rather than pressure, the thing will be a lot easier to tune. The first 100 Hornady cases I bought had less than half the weight variation of the first 100 Lapua 300PRC cases. Lapua only included 99 in that 100 box.

78.0 grains of H1000 with 190 ATips gave 3040 fps from a 26" barrel. Extractor groove expansion measurements suggested the Hornady cases would go 6ish firings before the primer pockets started loosening up. 76.0 grains gave 3000 fps. 5 shot Extreme spreads were in the mid teens. ADG brass would likely be good for another 100 fps but it'd cost maybe 1/4-1/3 of the already short barrel life.

I shot a lot of 7/270WSM with 180 ELDm at 3030 fps from a 32" barrel as a 2200 yard practice gun. For a higher volume hobby 1k to 1mile gun, I'd go that way.

7RSAUM is around 73 grains of water capacity. For a mile with 180s, it's all that's really needed and the barrel life would be better. As long as you didn't have velocity remorse and run the pressure up.

 

[FURMAN]

The 7 LRM issues you are speaking of are due to the original use of basic brass by Gunwerks when the cartridge was first introduced. Turning necks fixed the original issue. They have long since switched to using ADG to make Gunwerks brass and those issue are gone. In my opinion, while the LRM is a great cartridge in 2025 the PRC makes more sense.

The PRCs and the Noslers both use a .532 case head. The body of the noslers are larger at .550 vs .532.

 

[SKWERLZ]

7RSAUM is around 73 grains of water capacity. For a mile with 180s, it's all that's really needed and the barrel life would be better. As long as you didn't have velocity remorse and run the pressure up.

That was my conclusion when I was looking into 7mm’s
7 saum, 7/300WSM or 7SS seemed like the most reasonable and 7SAUM was the easiest option with no real cons.

 

[ShaunBrady]

Good catch. The Noslers use a regular .532 magnum bolt face. They're larger after the extractor groove.

I have a 26 Nosler. It wasn't a huge deal to modify a magazine on the mill, but it has to stay with that gun.

The 2025 comment is also good. I was necking down 300 PRC cases. I take neck turning to be a given for neck down wildcats and set up the reamer accordingly. With factory brass available, a no turn chamber is possible.

I do think that a 7/300PRC is overkill on recoil and barrel life for a hobby level 1 mile gun. Especially if you want to shoot longer than 5 shot strings between cool downs.

 

[Jr solocam]

I ordered a 7 LRM before the 28 Nosler came out.

180 Berger Hybrid, 70g H1000, CCI 250, 26" - 2965 with my notes showing 3/8 to 5/8".
175 LRAB, 71g H1000, CC 250 - 3030 with my notes showing 1 1/4 being the best.

No doubt Retumbo or 560-570 would pick up some velocity. Hornady brass has been in my experience not the best...I just had it rebarreled to 7PRC. Factory 175 eldx chronos at 2766 with a 22" Bartlein. I hope to do better with R26 or N560. Or MRP.

I will be putting the LRM barrel up in the classifieds. 26" + brake, 8T, #3 Bartlein, diamond fluting black and burnt bronze. Less than 50 rd CT, and including dies and brass. Will be cheap not looking to profit....

 

[Orr89rocz]

The biggest deal was the PRC cartridges have a 0.532" case head. With their low body taper, they'll just clear the front guide ribs in AICS 338 Lapua mags. The Noslers use 0.550" case heads and the front of their cases drag.

Im trying to picture this…a lapua is a .587 case head, why would two smaller cases use a lapua mag and then why would they have issues?
For what its worth, accurate mag makes 300 RUM mags and i used them for my 28 nosler, no mods and feeds great! Feeds 300 prc too when i ran a case thru it

 

[diggler1833]

I went the easy route and did the 7-300 PRC. The Manson M2 reamer requires no neck turning, and brass is easy to acquire and not that expensive. I just neck down and mandrel to .002 under. I expect about 800-900 rounds of barrel life. I knew that coming in though.

I've only tried two bullets, and one powder. The 195 Berger and N568 has provided almost identical results downrange across three full grains of charge weight and .050 seating depth. I don't think I've had a barrel that showed any less of a preference before.

79gr of N568 got me 3,001 FPS on average out of my 27" Bartlein. I'm probably handicapping myself for the speed guys out there by not using a different powder (N570). 80gr got me ~3,040, but I also had some good ejector marks on my new Peterson brass by that point. Maybe I'll get away with a bit more on subsequent loadings. Right now, I'm sticking with 79gr. There are guys claiming 150FPS more than me, but I think they are definitely using a different powder and pushing as hard as they can.

Accuracy has been 2/3 - 3/4 MOA for five shot groups (300 to 650 yards). Nothing earth shattering, but I can't really gripe about that kind of performance either.

I'll come back and add a few photos.

 

[Fire Dog]

7 LRM is a cartridge which I am considering.

Post in thread 'Anybody shooing 7mm LRM?'

May 13, 2018

The 7 LRM is basically a 7mm-375 Ruger with the shoulder set back to give it a longer neck. It's a pretty good design actually.

Problem is Hornady brass is the pain in the ass on 375 Ruger parent widlcats. I have a 338-375 Ruger. It shoots great with excellent speed, but I will never know it's true potential without being able to get quality brass for it. So choose your chambering wisely. I have seen custom 7mm Remington Magnums shoot as good as any other rifles I've ever seen at long range. It will run 180gr bullets up at 3100 fps too. Anyone who says the old belted magnums won't shoot...

• Ledd Slinger

• 

 

[ShaunBrady]

Im trying to picture this…a lapua is a .587 case head, why would two smaller cases use a lapua mag and then why would they have issues?
For what its worth, accurate mag makes 300 RUM mags and i used them for my 28 nosler, no mods and feeds great! Feeds 300 prc too when i ran a case thru it

I've confused 2 projects. I did a 7/338LI that had problems with the front ribs on a standard 338 Lapua CIP mag. I twisted the larger taper of the lapua case to cover the base body diameter and give a larger shoulder. After measuring the 2 cases and pulling the gun out of the back of the safe, my error became clear.

I did the 26 Nosler project with a mid length 300WM mag and had to machine the one of the rear ribs to get it to feed.


The attraction of that mag was PTG makes cheap bottom metal that is a relatively simple fit into a long action R700BDL inlet. I had a bunch of them from earlier R700/300WM projects.

The Lapua case in back is a straight 300 Lapua. It was handy and close enough to the 338.