GMR-15 with WSF

[drysideshooter]

I finally had a chance to work up a load for my new GMR-15.  I have a lot of MG 124CMJ's and WSF on hand, so thought I would start there.  I ended up at 4.9 grains of WSF, loaded to 1.120" OAL.  I'm getting a consistent 1,100fps.  I'm happy enough with it to use that load to get some rounds through the gun.  One of the things I enjoy about having a range at home is the ease of working up loads.  I left a target and chrono set up and slowly worked up to the 4.9.  It was a little more WSF than I was anticipating based on WSF loads I've used in handguns.  

 

I think I may switch to MG JHP's once I run through my remaining CMJ's. It sounds like quite a few of you have had good success with JHP's?

 

I really like the GMR-15 so far. I currently have the standard short stroke SCS with 5 steel.  I think I will order a couple of the tungsten weights to experiment with.  Shooting a USPSA target at 20 yards yesterday it was easy to get 2 A zone hits as quick as I could pull the trigger, but I think I may be able to tame the muzzle rise a bit further. Will be fun to try anyway.  

[egd5]

In my gmr 15 with 14.5 barrel + comp I use 4.2 wsf with the RMR 124 rn fmj bullet at 1.115 to 1.120 oal. I have the scs short stroke with 5 steel also.

I would think you could back off of 4.9 a good amount unless you just like them a little hotter, which is fine.

 

ETA, My friend shoots the same gun with a similar power factor load and he has the 2 tungston,3 steel setup. He likes it but it doesn't feel good to me. It's like I can feel the weights moving back and forth in his gun. But it's just personal preference imo.

Edited June 29, 2020 by egd5

[drysideshooter]

1 hour ago, egd5 said:

In my gmr 15 with 14.5 barrel + comp I use 4.2 wsf with the RMR 124 rn fmj bullet at 1.115 to 1.120 oal. I have the scs short stroke with 5 steel also.

I would think you could back off of 4.9 a good amount unless you just like them a little hotter, which is fine.

 

ETA, My friend shoots the same gun with a similar power factor load and he has the 2 tungston,3 steel setup. He likes it but it doesn't feel good to me. It's like I can feel the weights moving back and forth in his gun. But it's just personal preference imo.

The 4.9 was a surprise to me as well.  I started at 4.2 and was only a bit over 900fps. 1x fired federal brass, CCI SPP #500. Also with the 14.5" with pinned/welded comp.   Have you chronoed your load?

-

Edited June 29, 2020 by drysideshooter

[egd5]

It has occurred to me that bullet length may be a factor here also. A RN bullet is usually about the longest style. If those MG 124 cmj's are a lot shorter ( I have no knowledge of them) then at the same oal as me you would have less bullet inside the case and would need more powder to get the same PF.

 

Yes, it's been a while but about 1050 to 1100.

Edited June 30, 2020 by egd5

[fyr4efect]

18 hours ago, drysideshooter said:

I finally had a chance to work up a load for my new GMR-15.  I have a lot of MG 124CMJ's and WSF on hand, so thought I would start there.  I ended up at 4.9 grains of WSF, loaded to 1.120" OAL.  I'm getting a consistent 1,100fps.  I'm happy enough with it to use that load to get some rounds through the gun.  One of the things I enjoy about having a range at home is the ease of working up loads.  I left a target and chrono set up and slowly worked up to the 4.9.  It was a little more WSF than I was anticipating based on WSF loads I've used in handguns.  

 

I think I may switch to MG JHP's once I run through my remaining CMJ's. It sounds like quite a few of you have had good success with JHP's?

 

I really like the GMR-15 so far. I currently have the standard short stroke SCS with 5 steel.  I think I will order a couple of the tungsten weights to experiment with.  Shooting a USPSA target at 20 yards yesterday it was easy to get 2 A zone hits as quick as I could pull the trigger, but I think I may be able to tame the muzzle rise a bit further. Will be fun to try anyway.  

 

Currently thru my FX-9 8" with  PD JHP 124 gr, WSF 4.9, OAL 1.110, 1100 fps. Switched to 147gr JHP Everglades 4.1gr ,1.130,  950 fps. Noticeably less recoil and subsonic. Got a can comming and a GMR- 15. Also use coated SnS 147 FN with same specs but cheaper.

[drysideshooter]

I did a couple more rounds of testing with the chrono today as it was more cloudy and ideal.  4.9 is still right at 1,100fps consistently.

 

Here is a question for those of you with a GMR and the pinned-welded comp.  What have you found to be the best way to remove carbon from the crown?  The crown has a fair distance of threaded comp in front of it, so it's a bit tough to get right to.  I'm thinking something like hanging the upper with the end of the barrel/ comp soaking in a container of solvent, and then plastic dental type picks to remove any more stubborn deposits? 

 

Has anyone tried D-Zolve 339?  It's designed to remove carbon deposits in engines, but the manufacturer also lists firearms.  From what I can tell it's only available in 5 gallon pails or 55 gallon drums. A magazine article said it really dissolved and softened firearm carbon.  

 

[egd5]

Use a 50/50 solution of vinegar and hydrogen peroxide and stick the comp end of the barrel down in it and let it work. It may take a while if you have a big buildup but it will do the job. When done dip in baking soda and water then rinse with hot water.