Mcguire Ballistics 195 + 300 NMI load dev!

[KH_Outdoors]

Recently replaced the barrel on my TS Customs 300 NMI and decided I wanted to put some work into the 195 Mcguire's. Figured why not document the process for others as well right? Not a ton of known info with this combination yet. Enjoy!

The barrel is broken in and ready to start getting baselines. So far it has shot exceptionally well with all my previous petloads for this chamber to include 245 EOL's, 230 Hybrids, & 225 ELDM's so I know its hammering to start.

For reference, I'm still using the brass from my previous barrel and starting load development after 50 or so rounds down the new barrel and a proper cleaning regiment.

Rifle Specs:

TS Built 300 NMI 35
Impact Precision NBK
26" Benchmark 8 tw, Med Palma spiral fluted
Triggertech Special
KS1 Adj TS exclusive stock
Hawkins bottom metal
SRS Pro 5 SS

Components:

Lapua 6x fired Brass
195 CRSF McGuire's
N570, N565, & Retumbo to start with
Fed215m

 

[KH_Outdoors]

Testing procedures

In the past I've had really good luck with the following method, not only testing McGuires but pretty much all bullets in general.

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Starting with a clean broken in barrel, with fired brass, and proper case prep.

Measure the OAL of the bullet/cartridge @ the lands, seat approximately .020-.030" off the lands. I favor .025-.030" to start. I usually remove the ejector from the bolt & build a dummy round.

Load powder combinations, starting below a safe starting point and increase in .5-1.0 gr increments. .5 gr in small magnums, 1.0 gr in larger. Load up to where you estimate pressure will be + 1-2 gr so you can stop at a comfortable point and pull the rest. Saves multiple trips to the range.

Shoot said ladder of charge weights at the same point of aim at 100 yards, noting the impact of each round, and recording velocity. Allow the barrel to remain cool through this process and looking for "pressure signs" like heavier bolt lift, click, ejector marks, flattened primers etc.. Discontinue when "pressure" is reached.

Select the powder with the best groupings & desired velocities to begin testing. Shoot 3 shot groups at multiple charge weights while recording velocities at 100 yards. Looking for consistent POI, group size, & ES/SD quality's.

Verify at distance & validate drops!

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I will do this with multiple powders on the same day usually. This will give me a baseline of a safe charge weight range to go start shooting groups. As well as give me an idea of what powder combination will yield the best accuracy & velocities I am after. This method has worked best for me especially with exploratory bullet & powder combinations without known data.

Stay tuned

 

[KH_Outdoors]

First round of ladders, looking for pressure!

N570
90-94 gr (ran out of case capacity)

N565
88-94 gr

Retumbo
87-94 gr

 

[Marky_mark]

Do you seat these similar to a lead bullet? No drive bands to worrry about?

 

[KH_Outdoors]

Do you seat these similar to a lead bullet? No drive bands to worrry about?

I seat them no differently.

 

[Northkill]

Glad for your contribution with this. Looking forward to the results.

 

[KH_Outdoors]

Glad for your contribution with this. Looking forward to the results.

Me too! Exited to give them a proper workup

 

[Huntnful]

Excellent write up and details! I do the exact same thing and it really is an awesome method. You get pressure info right away as well as know whether or not the barrel likes the bullet/powder combo by shooting at the same aim point.

Good info dude

 

[KH_Outdoors]

Excellent write up and details! I do the exact same thing and it really is an awesome method. You get pressure info right away as well as know whether or not the barrel likes the bullet/powder combo by shooting at the same aim point.

Good info dude

100% don't waste time and Components. Let the barrel speak

 

[KH_Outdoors]

Charge weight - Pressure ladders

N570

90 - 3149 (fouler)
90 - 3186
91 - 3222
92 - 3265
93 - 3300
94 - 3360

Notes: no initial pressure signs on this run and the total 6 shot group size was .593" accross 5 grains! Very promising, target below.

N565

88 - 3155
89 - 3208
90 - 3216
91 - 3284
92 - 3299
93 - 3343 - slightly heavier bolt
94 - discontinued

Notes: reached first signs of pressure with a slightly heavier bolt at 93 gr and discontinued. Overall 6 shot group size accross 6 grains, of .386" at 100 yards. This is looking phenomenal! Pic below,

Retumbo

87 - 3075
88 - 3163
89 - 3152
90 - 3204
91 - 3227
92 - 3294 - heavy bolt
93 - discontinued
94 - " "

Notes: this one is a clear example of why I try to contrast the differences between powders and doing so upfront to avoid chasing a load that was never meant to be. An overall group size of 2.067" for 6 shots accross 6 grains of charge weight comparative to the previous powders tested show me that this combination is just not meant to be. It also shows, my barrel loves that bullet but just not with Retumbo. Maybe it would group at one charge weight but I'm looking for forgiving here. I'm also not gaining any speed with Retumbo over N565, so discontinued from here. Pic below.

So... going forward with N570 & N565!

 

[KH_Outdoors]

First round of groups - N570

Decided to hone in on the 92-94 gr charge weight range. I normally do full 1 gr increments in larger cases, but decided to try .5 gr increments to see if there are any trends or wide tune windows. Velocities & groups below! For reference these were 3 shot groups and I've listed the group size, average velocities & ES/SD.

N570

92 - .202"

AV - 3239.8
ES - 15.8
SD - 6.8

92.5 - .532"

AV - 3278
ES - 27
SD - 13.5

93 - .596"

AV - 3320.9
ES - 41.3
SD - 18

93.5 - .803"

AV - 3319.9
ES - 38.1
SD - 15.9

94 - .229"

AV - 3338.4
ES - 44.4
SD - 18.6

Targets below

92-93.5

And 94

Notes: the groupings are fantastic for the first tests! Shows alot of potential at the top & low end of the charge weights I've tested. Couple things however, results seemed a little erratic.

- Firstly, the ES's are not as low as I'd like to see. Knowing full well that ES isn't everything and if it holds up at long range that's the final deciding factor.
- Second thing, 93-94 is full full! Going to switch to the drop tube for further N570 testing FYI.
- Lastly, I'm really excited about the speeds I'm getting but... I'm going to move over to N565 before and long range testing to see if it's yielding good results without the higher ES/SD's.

Lots of potential, and I will certainly circle back to N570 and see if i can make an tweaks like a primer change of neck tension etc... to get that dialed in.

 

[KH_Outdoors]

Next up - N565

Decided to test out the 89-92 gr charge weight range, and in 1 gr increments (my preference as you can see). Had a few pulled bullets from the pressure testing earlier, and wanted to "foul" the barrel with N565 from N570 testing just incase. Didn't want any funny business going on. So below 89 gr (fouler) group is using pulled bullets. Really I'd like to see 3200 fps + from this setup, so 90-92 is the focus... Results below

N565

89 (fouler) - .697"

AV - 3183.5
ES - 24.3
SD - 10.1

90 - .617"

AV - 3213
ES - 10.6
SD - 4.4

91 - .596"

AV - 3256.7
ES - 6.2
SD - 2.8

92 - .902"

AV - 3294
ES - 15.5
SD - 7.2

Target below

Notes: this is what I'm hoping to see in terms of group sizes & velocities! Very acceptable groupings for the first round with N565 and if I were to guess N565 will be the more stable & forgiving powder for long term use. Quick note though, I did get the slightest bolt click with rounds 2 & 3 on 92 gr's. So going to continue testing below that. Certainly there is alot of potential between 90-91 gr of N565 in that 3200-3250 fps range. We are off to a great start with a couple options to check at longer distances between N570 & N565. Several sub .5 moa groups, I'm sure it will keep trending in the right direction. Going to scrub the barrel and starting fresh after all the different powders ran through.

Stay tuned!

 

[Mike D Texas]

N570 looks the best to me so far. That 92.0 grain load looks like money.

 

[KH_Outdoors]

N570 looks the best to me so far. That 92.0 grain load looks like money.

I'm going to revisit all the sweet spots from both powders here shortly! Need to clean a barrel and process brass, then I'll be back on it. Those N570 groups were looking