7 LRM and alternative powders

[firstcoueswas80]

I recently had a 7 LRM built by s local Smith here in Tucson, az. I have read everything I could get my mouse on, all signs obviously pointing to H1000. Luckily, I have about 5# on hand. I have only been able to fire 5 rounds though my gun. So far, it appears 70-71 grains will be my max, (175 LRAB).

Azshooter and I have been in constant communication about different powders to try.. he was even nice enough to sell me some.

So, other then H1000 what powder choices do I have? For this rifle, I have on hand h1000, US 869, Retumbo (scored 2# yesterday), RL 33, 25 & 22.

 

[JARHEAD1371]

One thing that could/will help dictate what powers to use is your barrel length. The shorter barrels usually do better with a faster burning powder (H4831SC for your LRM) and longer barrels with slower powders (Retumbo). If you fall somewhere in the middle, pick a couple and shoot and see which one/ones your rifle likes. Good luck and keep us posted to your progress.

 

[firstcoueswas80]

My rifle has a 26" 1/9 #4 fluted Brux.

 

[firstcoueswas80]

Anyone?

 

[moombaskier]

I just tried H1000 for mine and it worked great. I only tried Fed 215m's and the 180VLD's...got lucky there too. Gunwerks smithed my action and barrel when the 7LRM was just comming out. The reamer they used requires me to turn the necks and use a .020-.025 jump to the lands with the 180VLD. Neck tension is .002. During load development it never shot over 1.25" at 200 yrds and shoots less than 3/4" at 200yds now. To say I'm extremely pleased is an understatement.

 

[AZShooter]

Moombaskier,

First I have heard of neck turning with this cartridge. What neck wall thickness did you have and what thickness did you end up with?

I necked down the 375 Ruger and neck turning was part of the process before I ordered the reamer.
Neck wall thickness is .013" . Also using .002" neck tension.

Thanks!

 

[firstcoueswas80]

I was finally able to go shoot on paper today! My first group on paper ever with this gun was sub moa. 81 grains of US869 produced this group with the 175 LRAB @ 100.



I had a poor rest, and the wind was blowing pretty good so I'm sure I can get that third shot to touch the others with our to much issue.

 

[howco]

Try Retumbo. Everything pointed to H1000 for a buddies project with 175 long range nosler. Now that thing is responding well with Retumbo and brass from gunwerks. Both with 180 bergers and 175's.

 

[firstcoueswas80]

Try Retumbo. Everything pointed to H1000 for a buddies project with 175 long range nosler. Now that thing is responding well with Retumbo and brass from gunwerks. Both with 180 bergers and 175's.

I have several pounds on hand that I bought solely for this. Could you tell me where you started and ended with retumbo?

 

[firstcoueswas80]

Btt

 

[moombaskier]

Why not give the folks at Gunwerks a jingle? I'll bet they can help you with load data.

 

[firstcoueswas80]

Why not give the folks at Gunwerks a jingle? I'll bet they can help you with load data.

Last time I called and emailed all they said was H1000. No other options.


I have several other powders to try, I am trying to find out what and if others have had success with.

 

[moombaskier]

I believe their 7LRM load is 72.0 grs of H1000 with a .025" jump to the lands. I have loaded up to 73.6 grs of H1000 with some moderate pressure signs in mine. I would think you'd be OK starting at 71.0 and work up from there? Why not stick with H1000?

 

[firstcoueswas80]

I believe their 7LRM load is 72.0 grs of H1000 with a .025" jump to the lands. I have loaded up to 73.6 grs of H1000 with some moderate pressure signs in mine. I would think you'd be OK starting at 71.0 and work up from there? Why not stick with H1000?

Why have pb&j for lunch other day when there are other options?